code:
#pragma once

#include "hash.hh"
#include "serialise.hh"

#include <string>
#include <map>
#include <memory>

namespace nix {

typedef std::map<Path, Path> Roots;

struct GCOptions
{
    /* Garbage collector operation:

       - `gcReturnLive': return the set of paths reachable from
         (i.e. in the closure of) the roots.

       - `gcReturnDead': return the set of paths not reachable from
         the roots.

       - `gcDeleteDead': actually delete the latter set.

       - `gcDeleteSpecific': delete the paths listed in
          `pathsToDelete', insofar as they are not reachable.
    */
    typedef enum {
        gcReturnLive,
        gcReturnDead,
        gcDeleteDead,
        gcDeleteSpecific,
    } GCAction;

    GCAction action;

    /* If `ignoreLiveness' is set, then reachability from the roots is
       ignored (dangerous!).  However, the paths must still be
       unreferenced *within* the store (i.e., there can be no other
       store paths that depend on them). */
    bool ignoreLiveness;

    /* For `gcDeleteSpecific', the paths to delete. */
    PathSet pathsToDelete;

    /* Stop after at least `maxFreed' bytes have been freed. */
    unsigned long long maxFreed;

    GCOptions();
};

struct GCResults
{
    /* Depending on the action, the GC roots, or the paths that would
       be or have been deleted. */
    PathSet paths;

    /* For `gcReturnDead', `gcDeleteDead' and `gcDeleteSpecific', the
       number of bytes that would be or was freed. */
    unsigned long long bytesFreed;

    GCResults()
    {
        bytesFreed = 0;
    }
};

struct SubstitutablePathInfo
{
    Path deriver;
    PathSet references;
    unsigned long long downloadSize; /* 0 = unknown or inapplicable */
    unsigned long long narSize; /* 0 = unknown */
};

typedef std::map<Path, SubstitutablePathInfo> SubstitutablePathInfos;

struct ValidPathInfo
{
    Path path;
    Path deriver;
    Hash hash;
    PathSet references;
    time_t registrationTime = 0;
    uint64_t narSize = 0; // 0 = unknown
    uint64_t id; // internal use only

    bool operator == (const ValidPathInfo & i) const
    {
        return
            path == i.path
            && hash == i.hash
            && references == i.references;
    }
};

typedef list<ValidPathInfo> ValidPathInfos;

enum BuildMode { bmNormal, bmRepair, bmCheck };

struct BuildResult
{
    enum Status {
        Built = 0,
        Substituted,
        AlreadyValid,
        PermanentFailure,
        InputRejected,
        OutputRejected,
        TransientFailure, // possibly transient
        CachedFailure,
        TimedOut,
        MiscFailure,
        DependencyFailed,
        LogLimitExceeded,
        NotDeterministic,
    } status = MiscFailure;
    std::string errorMsg;
    //time_t startTime = 0, stopTime = 0;
    bool success() {
        return status == Built || status == Substituted || status == AlreadyValid;
    }
};

class StoreAPI
{
public:

    virtual ~StoreAPI() { }

    /* Check whether a path is valid. */
    virtual bool isValidPath(const Path & path) = 0;

    /* Query which of the given paths is valid. */
    virtual PathSet queryValidPaths(const PathSet & paths) = 0;

    /* Query the set of all valid paths. */
    virtual PathSet queryAllValidPaths() = 0;

    /* Query information about a valid path. */
    virtual ValidPathInfo queryPathInfo(const Path & path) = 0;

    /* Query the hash of a valid path. */
    virtual Hash queryPathHash(const Path & path) = 0;

    /* Query the set of outgoing FS references for a store path.  The
       result is not cleared. */
    virtual void queryReferences(const Path & path,
        PathSet & references) = 0;

    /* Queries the set of incoming FS references for a store path.
       The result is not cleared. */
    virtual void queryReferrers(const Path & path,
        PathSet & referrers) = 0;

    /* Query the deriver of a store path.  Return the empty string if
       no deriver has been set. */
    virtual Path queryDeriver(const Path & path) = 0;

    /* Return all currently valid derivations that have `path' as an
       output.  (Note that the result of `queryDeriver()' is the
       derivation that was actually used to produce `path', which may
       not exist anymore.) */
    virtual PathSet queryValidDerivers(const Path & path) = 0;

    /* Query the outputs of the derivation denoted by `path'. */
    virtual PathSet queryDerivationOutputs(const Path & path) = 0;

    /* Query the output names of the derivation denoted by `path'. */
    virtual StringSet queryDerivationOutputNames(const Path & path) = 0;

    /* Query the full store path given the hash part of a valid store
       path, or "" if the path doesn't exist. */
    virtual Path queryPathFromHashPart(const string & hashPart) = 0;

    /* Query which of the given paths have substitutes. */
    virtual PathSet querySubstitutablePaths(const PathSet & paths) = 0;

    /* Query substitute info (i.e. references, derivers and download
       sizes) of a set of paths.  If a path does not have substitute
       info, it's omitted from the resulting ‘infos’ map. */
    virtual void querySubstitutablePathInfos(const PathSet & paths,
        SubstitutablePathInfos & infos) = 0;

    /* Copy the contents of a path to the store and register the
       validity the resulting path.  The resulting path is returned.
       The function object `filter' can be used to exclude files (see
       libutil/archive.hh). */
    virtual Path addToStore(const string & name, const Path & srcPath,
        bool recursive = true, HashType hashAlgo = htSHA256,
        PathFilter & filter = defaultPathFilter, bool repair = false) = 0;

    /* Like addToStore, but the contents written to the output path is
       a regular file containing the given string. */
    virtual Path addTextToStore(const string & name, const string & s,
        const PathSet & references, bool repair = false) = 0;

    /* Export a store path, that is, create a NAR dump of the store
       path and append its references and its deriver.  Optionally, a
       cryptographic signature (created by OpenSSL) of the preceding
       data is attached. */
    virtual void exportPath(const Path & path, bool sign,
        Sink & sink) = 0;

    /* Import a sequence of NAR dumps created by exportPaths() into
       the Nix store. */
    virtual Paths importPaths(bool requireSignature, Source & source) = 0;

    /* For each path, if it's a derivation, build it.  Building a
       derivation means ensuring that the output paths are valid.  If
       they are already valid, this is a no-op.  Otherwise, validity
       can be reached in two ways.  First, if the output paths is
       substitutable, then build the path that way.  Second, the
       output paths can be created by running the builder, after
       recursively building any sub-derivations. For inputs that are
       not derivations, substitute them. */
    virtual void buildPaths(const PathSet & paths, BuildMode buildMode = bmNormal) = 0;

    /* Ensure that a path is valid.  If it is not currently valid, it
       may be made valid by running a substitute (if defined for the
       path). */
    virtual void ensurePath(const Path & path) = 0;

    /* Add a store path as a temporary root of the garbage collector.
       The root disappears as soon as we exit. */
    virtual void addTempRoot(const Path & path) = 0;

    /* Add an indirect root, which is merely a symlink to `path' from
       /nix/var/nix/gcroots/auto/<hash of `path'>.  `path' is supposed
       to be a symlink to a store path.  The garbage collector will
       automatically remove the indirect root when it finds that
       `path' has disappeared. */
    virtual void addIndirectRoot(const Path & path) = 0;

    /* Acquire the global GC lock, then immediately release it.  This
       function must be called after registering a new permanent root,
       but before exiting.  Otherwise, it is possible that a running
       garbage collector doesn't see the new root and deletes the
       stuff we've just built.  By acquiring the lock briefly, we
       ensure that either:

       - The collector is already running, and so we block until the
         collector is finished.  The collector will know about our
         *temporary* locks, which should include whatever it is we
         want to register as a permanent lock.

       - The collector isn't running, or it's just started but hasn't
         acquired the GC lock yet.  In that case we get and release
         the lock right away, then exit.  The collector scans the
         permanent root and sees our's.

       In either case the permanent root is seen by the collector. */
    virtual void syncWithGC() = 0;

    /* Find the roots of the garbage collector.  Each root is a pair
       (link, storepath) where `link' is the path of the symlink
       outside of the Nix store that point to `storePath'.  */
    virtual Roots findRoots() = 0;

    /* Perform a garbage collection. */
    virtual void collectGarbage(const GCOptions & options, GCResults & results) = 0;

    /* Return the set of paths that have failed to build.*/
    virtual PathSet queryFailedPaths() = 0;

    /* Clear the "failed" status of the given paths.  The special
       value `*' causes all failed paths to be cleared. */
    virtual void clearFailedPaths(const PathSet & paths) = 0;

    /* Return a string representing information about the path that
       can be loaded into the database using `nix-store --load-db' or
       `nix-store --register-validity'. */
    string makeValidityRegistration(const PathSet & paths,
        bool showDerivers, bool showHash);

    /* Optimise the disk space usage of the Nix store by hard-linking files
       with the same contents. */
    virtual void optimiseStore() = 0;

    /* Check the integrity of the Nix store.  Returns true if errors
       remain. */
    virtual bool verifyStore(bool checkContents, bool repair) = 0;
};

/* !!! These should be part of the store API, I guess. */

/* Throw an exception if `path' is not directly in the Nix store. */
void assertStorePath(const Path & path);

bool isInStore(const Path & path);
bool isStorePath(const Path & path);

/* Extract the name part of the given store path. */
string storePathToName(const Path & path);

void checkStoreName(const string & name);

/* Chop off the parts after the top-level store name, e.g.,
   /nix/store/abcd-foo/bar => /nix/store/abcd-foo. */
Path toStorePath(const Path & path);

/* Constructs a unique store path name. */
Path makeStorePath(const string & type,
    const Hash & hash, const string & name);

Path makeOutputPath(const string & id,
    const Hash & hash, const string & name);

Path makeFixedOutputPath(bool recursive,
    HashType hashAlgo, Hash hash, string name);

/* Preparatory part of addTextToStore().

   !!! Computation of the path should take the references given to
   addTextToStore() into account, otherwise we have a (relatively
   minor) security hole: a caller can register a source file with
   bogus references.  If there are too many references, the path may
   not be garbage collected when it has to be (not really a problem,
   the caller could create a root anyway), or it may be garbage
   collected when it shouldn't be (more serious).

   Hashing the references would solve this (bogus references would
   simply yield a different store path, so other users wouldn't be
   affected), but it has some backwards compatibility issues (the
   hashing scheme changes), so I'm not doing that for now. */
Path computeStorePathForText(const string & name, const string & s,
    const PathSet & references);

/* Remove the temporary roots file for this process.  Any temporary
   root becomes garbage after this point unless it has been registered
   as a (permanent) root. */
void removeTempRoots();

/* Register a permanent GC root. */
Path addPermRoot(StoreAPI & store, const Path & storePath,
    const Path & gcRoot, bool indirect, bool allowOutsideRootsDir = false);

/* Sort a set of paths topologically under the references relation.
   If p refers to q, then p preceeds q in this list. */
Paths topoSortPaths(StoreAPI & store, const PathSet & paths);

/* For now, there is a single global store API object, but we'll
   purify that in the future. */
extern std::shared_ptr<StoreAPI> store;

/* Factory method: open the Nix database, either through the local or
   remote implementation. */
std::shared_ptr<StoreAPI> openStore(bool reserveSpace = true);

/* Display a set of paths in human-readable form (i.e., between quotes
   and separated by commas). */
string showPaths(const PathSet & paths);

/* Export multiple paths in the format expected by ‘nix-store
   --import’. */
void exportPaths(StoreAPI & store, const Paths & paths,
    bool sign, Sink & sink);

MakeError(SubstError, Error)
MakeError(BuildError, Error) /* denotes a permanent build failure */

}


code:
#pragma once

namespace nix {

#define WORKER_MAGIC_1 0x6e697863
#define WORKER_MAGIC_2 0x6478696f

#define PROTOCOL_VERSION 0x162
#define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
#define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)

typedef enum {
    wopIsValidPath = 1,
    wopHasSubstitutes = 3,
    wopQueryPathHash = 4,
    wopQueryReferences = 5,
    wopQueryReferrers = 6,
    wopAddToStore = 7,
    wopAddTextToStore = 8,
    wopBuildPaths = 9,
    wopEnsurePath = 10,
    wopAddTempRoot = 11,
    wopAddIndirectRoot = 12,
    wopSyncWithGC = 13,
    wopFindRoots = 14,
    wopExportPath = 16,
    wopQueryDeriver = 18,
    wopSetOptions = 19,
    wopCollectGarbage = 20,
    wopQuerySubstitutablePathInfo = 21,
    wopQueryDerivationOutputs = 22,
    wopQueryAllValidPaths = 23,
    wopQueryFailedPaths = 24,
    wopClearFailedPaths = 25,
    wopQueryPathInfo = 26,
    wopImportPaths = 27,
    wopQueryDerivationOutputNames = 28,
    wopQueryPathFromHashPart = 29,
    wopQuerySubstitutablePathInfos = 30,
    wopQueryValidPaths = 31,
    wopQuerySubstitutablePaths = 32,
    wopQueryValidDerivers = 33,
    wopOptimiseStore = 34,
    wopVerifyStore = 35,
    wopBuiltinBuilders = 80
} WorkerOp;

#define STDERR_NEXT  0x6f6c6d67
#define STDERR_READ  0x64617461 // data needed from source
#define STDERR_WRITE 0x64617416 // data for sink
#define STDERR_LAST  0x616c7473
#define STDERR_ERROR 0x63787470

Path readStorePath(Source & from);
template<class T> T readStorePaths(Source & from);

}

license: mit


code:
#include "types.hh"
#include "util.hh"
#include "affinity.hh"

#if HAVE_SCHED_H
#include <sched.h>
#endif

namespace nix {

#if HAVE_SCHED_SETAFFINITY
static bool didSaveAffinity = false;
static cpu_set_t savedAffinity;
#endif

void setAffinityTo(int cpu)
{
#if HAVE_SCHED_SETAFFINITY
    if (sched_getaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1) return;
    didSaveAffinity = true;
    printMsg(lvlDebug, format("locking this thread to CPU %1%") % cpu);
    cpu_set_t newAffinity;
    CPU_ZERO(&newAffinity);
    CPU_SET(cpu, &newAffinity);
    if (sched_setaffinity(0, sizeof(cpu_set_t), &newAffinity) == -1)
        printMsg(lvlError, format("failed to lock thread to CPU %1%") % cpu);
#endif
}

int lockToCurrentCPU()
{
#if HAVE_SCHED_SETAFFINITY
    int cpu = sched_getcpu();
    if (cpu != -1) setAffinityTo(cpu);
    return cpu;
#else
    return -1;
#endif
}

void restoreAffinity()
{
#if HAVE_SCHED_SETAFFINITY
    if (!didSaveAffinity) return;
    if (sched_setaffinity(0, sizeof(cpu_set_t), &savedAffinity) == -1)
        printMsg(lvlError, "failed to restore affinity %1%");
#endif
}

}


code:
#pragma once

namespace nix {

void setAffinityTo(int cpu);
int lockToCurrentCPU();
void restoreAffinity();

}


code:
#define _XOPEN_SOURCE 600

#include "config.h"

#include <cerrno>
#include <algorithm>
#include <vector>
#include <map>

#include <strings.h> // for strcasecmp

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>

#include "archive.hh"
#include "util.hh"

namespace nix {

static string archiveVersion1 = "nix-archive-1";

static string caseHackSuffix = "~nix~case~hack~";

PathFilter defaultPathFilter;

static void dumpContents(const Path & path, size_t size,
    Sink & sink)
{
    writeString("contents", sink);
    writeLongLong(size, sink);

    AutoCloseFD fd = open(path.c_str(), O_RDONLY);
    if (fd == -1) throw SysError(format("opening file `%1%'") % path);

    unsigned char buf[65536];
    size_t left = size;

    while (left > 0) {
        size_t n = left > sizeof(buf) ? sizeof(buf) : left;
        readFull(fd, buf, n);
        left -= n;
        sink(buf, n);
    }

    writePadding(size, sink);
}

static void dump(const Path & path, Sink & sink, PathFilter & filter)
{
    struct stat st;
    if (lstat(path.c_str(), &st))
        throw SysError(format("getting attributes of path `%1%'") % path);

    writeString("(", sink);

    if (S_ISREG(st.st_mode)) {
        writeString("type", sink);
        writeString("regular", sink);
        if (st.st_mode & S_IXUSR) {
            writeString("executable", sink);
            writeString("", sink);
        }
        dumpContents(path, (size_t) st.st_size, sink);
    }

    else if (S_ISDIR(st.st_mode)) {
        writeString("type", sink);
        writeString("directory", sink);

        /* If we're on a case-insensitive system like Mac OS X, undo
           the case hack applied by restorePath(). */
        std::map<string, string> unhacked;
        for (auto & i : readDirectory(path))
	    unhacked[i.name] = i.name;

        for (auto & i : unhacked)
            if (filter(path + "/" + i.first)) {
                writeString("entry", sink);
                writeString("(", sink);
                writeString("name", sink);
                writeString(i.first, sink);
                writeString("node", sink);
                dump(path + "/" + i.second, sink, filter);
                writeString(")", sink);
            }
    }

    else if (S_ISLNK(st.st_mode)) {
        writeString("type", sink);
        writeString("symlink", sink);
        writeString("target", sink);
        writeString(readLink(path), sink);
    }

    else throw Error(format("file `%1%' has an unsupported type") % path);

    writeString(")", sink);
}

void dumpPath(const Path & path, Sink & sink, PathFilter & filter)
{
    writeString(archiveVersion1, sink);
    dump(path, sink, filter);
}

static SerialisationError badArchive(string s)
{
    return SerialisationError("bad archive: " + s);
}

#if 0
static void skipGeneric(Source & source)
{
    if (readString(source) == "(") {
        while (readString(source) != ")")
            skipGeneric(source);
    }
}
#endif

static void parseContents(ParseSink & sink, Source & source, const Path & path)
{
    unsigned long long size = readLongLong(source);

    sink.preallocateContents(size);

    unsigned long long left = size;
    unsigned char buf[65536];

    while (left) {
        checkInterrupt();
        unsigned int n = sizeof(buf);
        if ((unsigned long long) n > left) n = left;
        source(buf, n);
        sink.receiveContents(buf, n);
        left -= n;
    }

    readPadding(size, source);
}

struct CaseInsensitiveCompare
{
    bool operator() (const string & a, const string & b) const
    {
        return strcasecmp(a.c_str(), b.c_str()) < 0;
    }
};

static void parse(ParseSink & sink, Source & source, const Path & path)
{
    string s;

    s = readString(source);
    if (s != "(") throw badArchive("expected open tag");

    enum { tpUnknown, tpRegular, tpDirectory, tpSymlink } type = tpUnknown;

    std::map<Path, int, CaseInsensitiveCompare> names;

    while (1) {
        checkInterrupt();

        s = readString(source);

        if (s == ")") {
            break;
        }

        else if (s == "type") {
            if (type != tpUnknown)
                throw badArchive("multiple type fields");
            string t = readString(source);

            if (t == "regular") {
                type = tpRegular;
                sink.createRegularFile(path);
            }

            else if (t == "directory") {
                sink.createDirectory(path);
                type = tpDirectory;
            }

            else if (t == "symlink") {
                type = tpSymlink;
            }

            else throw badArchive("unknown file type " + t);

        }

        else if (s == "contents" && type == tpRegular) {
            parseContents(sink, source, path);
        }

        else if (s == "executable" && type == tpRegular) {
            readString(source);
            sink.isExecutable();
        }

        else if (s == "entry" && type == tpDirectory) {
            string name, prevName;

            s = readString(source);
            if (s != "(") throw badArchive("expected open tag");

            while (1) {
                checkInterrupt();

                s = readString(source);

                if (s == ")") {
                    break;
                } else if (s == "name") {
                    name = readString(source);
                    if (name.empty() || name == "." || name == ".." || name.find('/') != string::npos || name.find((char) 0) != string::npos)
                        throw Error(format("NAR contains invalid file name `%1%'") % name);
                    if (name <= prevName)
                        throw Error("NAR directory is not sorted");
                    prevName = name;
                } else if (s == "node") {
                    if (s.empty()) throw badArchive("entry name missing");
                    parse(sink, source, path + "/" + name);
                } else
                    throw badArchive("unknown field " + s);
            }
        }

        else if (s == "target" && type == tpSymlink) {
            string target = readString(source);
            sink.createSymlink(path, target);
        }

        else
            throw badArchive("unknown field " + s);
    }
}

void parseDump(ParseSink & sink, Source & source)
{
    string version;
    try {
        version = readString(source);
    } catch (SerialisationError & e) {
        /* This generally means the integer at the start couldn't be
           decoded.  Ignore and throw the exception below. */
    }
    if (version != archiveVersion1)
        throw badArchive("input doesn't look like a Nix archive");
    parse(sink, source, "");
}

struct RestoreSink : ParseSink
{
    Path dstPath;
    AutoCloseFD fd;

    void createDirectory(const Path & path)
    {
        Path p = dstPath + path;
        if (mkdir(p.c_str(), 0777) == -1)
            throw SysError(format("creating directory `%1%'") % p);
    };

    void createRegularFile(const Path & path)
    {
        Path p = dstPath + path;
        fd.close();
        fd = open(p.c_str(), O_CREAT | O_EXCL | O_WRONLY, 0666);
        if (fd == -1) throw SysError(format("creating file `%1%'") % p);
    }

    void isExecutable()
    {
        struct stat st;
        if (fstat(fd, &st) == -1)
            throw SysError("fstat");
        if (fchmod(fd, st.st_mode | (S_IXUSR | S_IXGRP | S_IXOTH)) == -1)
            throw SysError("fchmod");
    }

    void preallocateContents(unsigned long long len)
    {
#if HAVE_POSIX_FALLOCATE
        if (len) {
            errno = posix_fallocate(fd, 0, len);
            /* Note that EINVAL may indicate that the underlying
               filesystem doesn't support preallocation (e.g. on
               OpenSolaris).  Since preallocation is just an
               optimisation, ignore it. */
            if (errno && errno != EINVAL)
                throw SysError(format("preallocating file of %1% bytes") % len);
        }
#endif
    }

    void receiveContents(unsigned char * data, unsigned int len)
    {
        writeFull(fd, data, len);
    }

    void createSymlink(const Path & path, const string & target)
    {
        Path p = dstPath + path;
        nix::createSymlink(target, p);
    }
};

void restorePath(const Path & path, Source & source)
{
    RestoreSink sink;
    sink.dstPath = path;
    parseDump(sink, source);
}

}


code:
#pragma once

#include "types.hh"
#include "serialise.hh"

namespace nix {

/* dumpPath creates a Nix archive of the specified path.  The format
   is as follows:

   IF path points to a REGULAR FILE:
     dump(path) = attrs(
       [ ("type", "regular")
       , ("contents", contents(path))
       ])

   IF path points to a DIRECTORY:
     dump(path) = attrs(
       [ ("type", "directory")
       , ("entries", concat(map(f, sort(entries(path)))))
       ])
       where f(fn) = attrs(
         [ ("name", fn)
         , ("file", dump(path + "/" + fn))
         ])

   where:

     attrs(as) = concat(map(attr, as)) + encN(0)
     attrs((a, b)) = encS(a) + encS(b)

     encS(s) = encN(len(s)) + s + (padding until next 64-bit boundary)

     encN(n) = 64-bit little-endian encoding of n.

     contents(path) = the contents of a regular file.

     sort(strings) = lexicographic sort by 8-bit value (strcmp).

     entries(path) = the entries of a directory, without `.' and
     `..'.

     `+' denotes string concatenation. */

struct PathFilter
{
    virtual ~PathFilter() { }
    virtual bool operator () (const Path & path) { return true; }
};

extern PathFilter defaultPathFilter;

void dumpPath(const Path & path, Sink & sink,
    PathFilter & filter = defaultPathFilter);

struct ParseSink
{
    virtual void createDirectory(const Path & path) { };

    virtual void createRegularFile(const Path & path) { };
    virtual void isExecutable() { };
    virtual void preallocateContents(unsigned long long size) { };
    virtual void receiveContents(unsigned char * data, unsigned int len) { };

    virtual void createSymlink(const Path & path, const string & target) { };
};

void parseDump(ParseSink & sink, Source & source);

void restorePath(const Path & path, Source & source);

}


code:
/* GNU Guix --- Functional package management for GNU
   Copyright (C) 2012, 2013  Ludovic Courtès <ludo@gnu.org>

   This file is part of GNU Guix.

   GNU Guix is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or (at
   your option) any later version.

   GNU Guix is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

#include <gcrypt-hash.hh>
#include <assert.h>

extern "C" {

void
guix_hash_init (struct guix_hash_context *ctx, int algo)
{
  gcry_error_t err;

  err = gcry_md_open (&ctx->md_handle, algo, 0);
  assert (err == GPG_ERR_NO_ERROR);
}

void
guix_hash_update (struct guix_hash_context *ctx, const void *buffer, size_t len)
{
  gcry_md_write (ctx->md_handle, buffer, len);
}

void
guix_hash_final (void *resbuf, struct guix_hash_context *ctx,
		 int algo)
{
  memcpy (resbuf, gcry_md_read (ctx->md_handle, algo),
	  gcry_md_get_algo_dlen (algo));
  gcry_md_close (ctx->md_handle);
  ctx->md_handle = NULL;
}

}


code:
/* GNU Guix --- Functional package management for GNU
   Copyright (C) 2012, 2013  Ludovic Courtès <ludo@gnu.org>

   This file is part of GNU Guix.

   GNU Guix is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or (at
   your option) any later version.

   GNU Guix is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.  */

/* An OpenSSL-like interface to GNU libgcrypt cryptographic hash
   functions.  */

#pragma once
#include <gcrypt.h>
#include <unistd.h>

struct guix_hash_context
{
  /* This copy constructor is needed in 'HashSink::currentHash()' where we
     expect the copy of a 'Ctx' object to yield a truly different context.  */
  guix_hash_context (guix_hash_context &ref)
  {
    if (ref.md_handle == NULL)
      md_handle = NULL;
    else
      gcry_md_copy (&md_handle, ref.md_handle);
  }

  /* Make sure 'md_handle' is always initialized.  */
  guix_hash_context (): md_handle (NULL) { };

  gcry_md_hd_t md_handle;
};

extern "C" {
extern void guix_hash_init (struct guix_hash_context *ctx, int algo);
extern void guix_hash_update (struct guix_hash_context *ctx, const void *buffer,
			      size_t len);
extern void guix_hash_final (void *resbuf, struct guix_hash_context *ctx,
			     int algo);
}


code:
#include "config.h"

#include <iostream>
#include <cstring>

#ifdef HAVE_OPENSSL
#include <openssl/md5.h>
#include <openssl/sha.h>
#else
extern "C" {
#include "md5.h"
#include "sha1.h"
#include "sha256.h"
#include "sha512.h"
}
#endif

#include "hash.hh"
#include "archive.hh"
#include "util.hh"

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

namespace nix {

Hash::Hash()
{
    type = htUnknown;
    hashSize = 0;
    memset(hash, 0, maxHashSize);
}

Hash::Hash(HashType type)
{
    this->type = type;
    if (type == htMD5) hashSize = md5HashSize;
    else if (type == htSHA1) hashSize = sha1HashSize;
    else if (type == htSHA256) hashSize = sha256HashSize;
    else if (type == htSHA512) hashSize = sha512HashSize;
    else throw Error("unknown hash type");
    assert(hashSize <= maxHashSize);
    memset(hash, 0, maxHashSize);
}

bool Hash::operator == (const Hash & h2) const
{
    if (hashSize != h2.hashSize) return false;
    for (unsigned int i = 0; i < hashSize; i++)
        if (hash[i] != h2.hash[i]) return false;
    return true;
}

bool Hash::operator != (const Hash & h2) const
{
    return !(*this == h2);
}

bool Hash::operator < (const Hash & h) const
{
    for (unsigned int i = 0; i < hashSize; i++) {
        if (hash[i] < h.hash[i]) return true;
        if (hash[i] > h.hash[i]) return false;
    }
    return false;
}

const string base16Chars = "0123456789abcdef";

string printHash(const Hash & hash)
{
    char buf[hash.hashSize * 2];
    for (unsigned int i = 0; i < hash.hashSize; i++) {
        buf[i * 2] = base16Chars[hash.hash[i] >> 4];
        buf[i * 2 + 1] = base16Chars[hash.hash[i] & 0x0f];
    }
    return string(buf, hash.hashSize * 2);
}

Hash parseHash(HashType ht, const string & s)
{
    Hash hash(ht);
    if (s.length() != hash.hashSize * 2)
        throw Error(format("invalid hash `%1%'") % s);
    for (unsigned int i = 0; i < hash.hashSize; i++) {
        string s2(s, i * 2, 2);
        if (!isxdigit(s2[0]) || !isxdigit(s2[1]))
            throw Error(format("invalid hash `%1%'") % s);
        std::istringstream str(s2);
        int n;
        str >> std::hex >> n;
        hash.hash[i] = n;
    }
    return hash;
}

unsigned int hashLength32(const Hash & hash)
{
    return (hash.hashSize * 8 - 1) / 5 + 1;
}

// omitted: E O U T
const string base32Chars = "0123456789abcdfghijklmnpqrsvwxyz";

string printHash32(const Hash & hash)
{
    Hash hash2(hash);
    unsigned int len = hashLength32(hash);

    string s;
    s.reserve(len);

    for (int n = len - 1; n >= 0; n--) {
        unsigned int b = n * 5;
        unsigned int i = b / 8;
        unsigned int j = b % 8;
        unsigned char c =
            (hash.hash[i] >> j)
            | (i >= hash.hashSize - 1 ? 0 : hash.hash[i + 1] << (8 - j));
        s.push_back(base32Chars[c & 0x1f]);
    }

    return s;
}

string printHash16or32(const Hash & hash)
{
    return hash.type == htMD5 ? printHash(hash) : printHash32(hash);
}

Hash parseHash32(HashType ht, const string & s)
{
    Hash hash(ht);
    unsigned int len = hashLength32(ht);
    assert(s.size() == len);

    for (unsigned int n = 0; n < len; ++n) {
        char c = s[len - n - 1];
        unsigned char digit;
        for (digit = 0; digit < base32Chars.size(); ++digit) /* !!! slow */
            if (base32Chars[digit] == c) break;
        if (digit >= 32)
            throw Error(format("invalid base-32 hash '%1%'") % s);
        unsigned int b = n * 5;
        unsigned int i = b / 8;
        unsigned int j = b % 8;
        hash.hash[i] |= digit << j;
        if (i < hash.hashSize - 1) hash.hash[i + 1] |= digit >> (8 - j);
    }

    return hash;
}

Hash parseHash16or32(HashType ht, const string & s)
{
    Hash hash(ht);
    if (s.size() == hash.hashSize * 2)
        /* hexadecimal representation */
        hash = parseHash(ht, s);
    else if (s.size() == hashLength32(hash))
        /* base-32 representation */
        hash = parseHash32(ht, s);
    else
        throw Error(format("hash `%1%' has wrong length for hash type `%2%'")
            % s % printHashType(ht));
    return hash;
}

bool isHash(const string & s)
{
    if (s.length() != 32) return false;
    for (int i = 0; i < 32; i++) {
        char c = s[i];
        if (!((c >= '0' && c <= '9') ||
              (c >= 'a' && c <= 'f')))
            return false;
    }
    return true;
}

struct Ctx
{
    MD5_CTX md5;
    SHA_CTX sha1;
    SHA256_CTX sha256;
    SHA512_CTX sha512;
};

static void start(HashType ht, Ctx & ctx)
{
    if (ht == htMD5) MD5_Init(&ctx.md5);
    else if (ht == htSHA1) SHA1_Init(&ctx.sha1);
    else if (ht == htSHA256) SHA256_Init(&ctx.sha256);
    else if (ht == htSHA512) SHA512_Init(&ctx.sha512);
}

static void update(HashType ht, Ctx & ctx,
    const unsigned char * bytes, unsigned int len)
{
    if (ht == htMD5) MD5_Update(&ctx.md5, bytes, len);
    else if (ht == htSHA1) SHA1_Update(&ctx.sha1, bytes, len);
    else if (ht == htSHA256) SHA256_Update(&ctx.sha256, bytes, len);
    else if (ht == htSHA512) SHA512_Update(&ctx.sha512, bytes, len);
}

static void finish(HashType ht, Ctx & ctx, unsigned char * hash)
{
    if (ht == htMD5) MD5_Final(hash, &ctx.md5);
    else if (ht == htSHA1) SHA1_Final(hash, &ctx.sha1);
    else if (ht == htSHA256) SHA256_Final(hash, &ctx.sha256);
    else if (ht == htSHA512) SHA512_Final(hash, &ctx.sha512);
}

Hash hashString(HashType ht, const string & s)
{
    Ctx ctx;
    Hash hash(ht);
    start(ht, ctx);
    update(ht, ctx, (const unsigned char *) s.data(), s.length());
    finish(ht, ctx, hash.hash);
    return hash;
}

Hash hashFile(HashType ht, const Path & path)
{
    Ctx ctx;
    Hash hash(ht);
    start(ht, ctx);

    AutoCloseFD fd = open(path.c_str(), O_RDONLY);
    if (fd == -1) throw SysError(format("opening file `%1%'") % path);

    unsigned char buf[8192];
    ssize_t n;
    while ((n = read(fd, buf, sizeof(buf)))) {
        checkInterrupt();
        if (n == -1) throw SysError(format("reading file `%1%'") % path);
        update(ht, ctx, buf, n);
    }

    finish(ht, ctx, hash.hash);
    return hash;
}

HashSink::HashSink(HashType ht) : ht(ht)
{
    ctx = new Ctx;
    bytes = 0;
    start(ht, *ctx);
}

HashSink::~HashSink()
{
    bufPos = 0;
    delete ctx;
}

void HashSink::write(const unsigned char * data, size_t len)
{
    bytes += len;
    update(ht, *ctx, data, len);
}

HashResult HashSink::finish()
{
    flush();
    Hash hash(ht);
    nix::finish(ht, *ctx, hash.hash);
    return HashResult(hash, bytes);
}

HashResult HashSink::currentHash()
{
    flush();
    Ctx ctx2 = *ctx;
    Hash hash(ht);
    nix::finish(ht, ctx2, hash.hash);
    return HashResult(hash, bytes);
}

HashResult hashPath(
    HashType ht, const Path & path, PathFilter & filter)
{
    HashSink sink(ht);
    dumpPath(path, sink, filter);
    return sink.finish();
}

Hash compressHash(const Hash & hash, unsigned int newSize)
{
    Hash h;
    h.hashSize = newSize;
    for (unsigned int i = 0; i < hash.hashSize; ++i)
        h.hash[i % newSize] ^= hash.hash[i];
    return h;
}

HashType parseHashType(const string & s)
{
    if (s == "md5") return htMD5;
    else if (s == "sha1") return htSHA1;
    else if (s == "sha256") return htSHA256;
    else if (s == "sha512") return htSHA512;
    else return htUnknown;
}

string printHashType(HashType ht)
{
    if (ht == htMD5) return "md5";
    else if (ht == htSHA1) return "sha1";
    else if (ht == htSHA256) return "sha256";
    else if (ht == htSHA512) return "sha512";
    else throw Error("cannot print unknown hash type");
}

}


code:
#pragma once

#include "types.hh"
#include "serialise.hh"

namespace nix {

typedef enum { htUnknown, htMD5, htSHA1, htSHA256, htSHA512 } HashType;

const int md5HashSize = 16;
const int sha1HashSize = 20;
const int sha256HashSize = 32;
const int sha512HashSize = 64;

extern const string base32Chars;

struct Hash
{
    static const unsigned int maxHashSize = 64;
    unsigned int hashSize;
    unsigned char hash[maxHashSize];

    HashType type;

    /* Create an unusable hash object. */
    Hash();

    /* Create a zero-filled hash object. */
    Hash(HashType type);

    /* Check whether two hash are equal. */
    bool operator == (const Hash & h2) const;

    /* Check whether two hash are not equal. */
    bool operator != (const Hash & h2) const;

    /* For sorting. */
    bool operator < (const Hash & h) const;
};

/* Convert a hash to a hexadecimal representation. */
string printHash(const Hash & hash);

/* Parse a hexadecimal representation of a hash code. */
Hash parseHash(HashType ht, const string & s);

/* Returns the length of a base-32 hash representation. */
unsigned int hashLength32(const Hash & hash);

/* Convert a hash to a base-32 representation. */
string printHash32(const Hash & hash);

/* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
string printHash16or32(const Hash & hash);

/* Parse a base-32 representation of a hash code. */
Hash parseHash32(HashType ht, const string & s);

/* Parse a base-16 or base-32 representation of a hash code. */
Hash parseHash16or32(HashType ht, const string & s);

/* Verify that the given string is a valid hash code. */
bool isHash(const string & s);

/* Compute the hash of the given string. */
Hash hashString(HashType ht, const string & s);

/* Compute the hash of the given file. */
Hash hashFile(HashType ht, const Path & path);

/* Compute the hash of the given path.  The hash is defined as
   (essentially) hashString(ht, dumpPath(path)). */
struct PathFilter;
extern PathFilter defaultPathFilter;
typedef std::pair<Hash, unsigned long long> HashResult;
HashResult hashPath(HashType ht, const Path & path,
    PathFilter & filter = defaultPathFilter);

/* Compress a hash to the specified number of bytes by cyclically
   XORing bytes together. */
Hash compressHash(const Hash & hash, unsigned int newSize);

/* Parse a string representing a hash type. */
HashType parseHashType(const string & s);

/* And the reverse. */
string printHashType(HashType ht);

struct Ctx;

class HashSink : public BufferedSink
{
private:
    HashType ht;
    Ctx * ctx;
    unsigned long long bytes;

public:
    HashSink(HashType ht);
    HashSink(const HashSink & h);
    ~HashSink();
    void write(const unsigned char * data, size_t len);
    HashResult finish();
    HashResult currentHash();
};

}


code:
/* GNU Guix --- Functional package management for GNU
   Copyright (C) 2012  Ludovic Courtès <ludo@gnu.org>

   This file is part of GNU Guix.

   GNU Guix is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or (at
   your option) any later version.

   GNU Guix is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.  */

#include <gcrypt-hash.hh>

#define MD5_CTX guix_hash_context

static inline void
MD5_Init (struct MD5_CTX *ctx)
{
  guix_hash_init (ctx, GCRY_MD_MD5);
}

#define MD5_Update guix_hash_update

static inline void
MD5_Final (void *resbuf, struct MD5_CTX *ctx)
{
  guix_hash_final (resbuf, ctx, GCRY_MD_MD5);
}


code:
#include "serialise.hh"
#include "util.hh"

#include <cstring>
#include <cerrno>

namespace nix {

BufferedSink::~BufferedSink()
{
    /* We can't call flush() here, because C++ for some insane reason
       doesn't allow you to call virtual methods from a destructor. */
    assert(!bufPos);
    delete[] buffer;
}

void BufferedSink::operator () (const unsigned char * data, size_t len)
{
    if (!buffer) buffer = new unsigned char[bufSize];

    while (len) {
        /* Optimisation: bypass the buffer if the data exceeds the
           buffer size. */
        if (bufPos + len >= bufSize) {
            flush();
            write(data, len);
            break;
        }
        /* Otherwise, copy the bytes to the buffer.  Flush the buffer
           when it's full. */
        size_t n = bufPos + len > bufSize ? bufSize - bufPos : len;
        memcpy(buffer + bufPos, data, n);
        data += n; bufPos += n; len -= n;
        if (bufPos == bufSize) flush();
    }
}

void BufferedSink::flush()
{
    if (bufPos == 0) return;
    size_t n = bufPos;
    bufPos = 0; // don't trigger the assert() in ~BufferedSink()
    write(buffer, n);
}

FdSink::~FdSink()
{
    try { flush(); } catch (...) { ignoreException(); }
}

size_t threshold = 256 * 1024 * 1024;

static void warnLargeDump()
{
    printMsg(lvlError, "warning: dumping very large path (> 256 MiB); this may run out of memory");
}

void FdSink::write(const unsigned char * data, size_t len)
{
    static bool warned = false;
    if (warn && !warned) {
        written += len;
        if (written > threshold) {
            warnLargeDump();
            warned = true;
        }
    }
    writeFull(fd, data, len);
}

void Source::operator () (unsigned char * data, size_t len)
{
    while (len) {
        size_t n = read(data, len);
        data += n; len -= n;
    }
}

BufferedSource::~BufferedSource()
{
    delete[] buffer;
}

size_t BufferedSource::read(unsigned char * data, size_t len)
{
    if (!buffer) buffer = new unsigned char[bufSize];

    if (!bufPosIn) bufPosIn = readUnbuffered(buffer, bufSize);

    /* Copy out the data in the buffer. */
    size_t n = len > bufPosIn - bufPosOut ? bufPosIn - bufPosOut : len;
    memcpy(data, buffer + bufPosOut, n);
    bufPosOut += n;
    if (bufPosIn == bufPosOut) bufPosIn = bufPosOut = 0;
    return n;
}

bool BufferedSource::hasData()
{
    return bufPosOut < bufPosIn;
}

size_t FdSource::readUnbuffered(unsigned char * data, size_t len)
{
    ssize_t n;
    do {
        checkInterrupt();
        n = ::read(fd, (char *) data, bufSize);
    } while (n == -1 && errno == EINTR);
    if (n == -1) throw SysError("reading from file");
    if (n == 0) throw EndOfFile("unexpected end-of-file");
    return n;
}

size_t StringSource::read(unsigned char * data, size_t len)
{
    if (pos == s.size()) throw EndOfFile("end of string reached");
    size_t n = s.copy((char *) data, len, pos);
    pos += n;
    return n;
}

void writePadding(size_t len, Sink & sink)
{
    if (len % 8) {
        unsigned char zero[8];
        memset(zero, 0, sizeof(zero));
        sink(zero, 8 - (len % 8));
    }
}

void writeInt(unsigned int n, Sink & sink)
{
    unsigned char buf[8];
    memset(buf, 0, sizeof(buf));
    buf[0] = n & 0xff;
    buf[1] = (n >> 8) & 0xff;
    buf[2] = (n >> 16) & 0xff;
    buf[3] = (n >> 24) & 0xff;
    sink(buf, sizeof(buf));
}

void writeLongLong(unsigned long long n, Sink & sink)
{
    unsigned char buf[8];
    buf[0] = n & 0xff;
    buf[1] = (n >> 8) & 0xff;
    buf[2] = (n >> 16) & 0xff;
    buf[3] = (n >> 24) & 0xff;
    buf[4] = (n >> 32) & 0xff;
    buf[5] = (n >> 40) & 0xff;
    buf[6] = (n >> 48) & 0xff;
    buf[7] = (n >> 56) & 0xff;
    sink(buf, sizeof(buf));
}

void writeString(const unsigned char * buf, size_t len, Sink & sink)
{
    writeInt(len, sink);
    sink(buf, len);
    writePadding(len, sink);
}

void writeString(const string & s, Sink & sink)
{
    writeString((const unsigned char *) s.data(), s.size(), sink);
}

template<class T> void writeStrings(const T & ss, Sink & sink)
{
    writeInt(ss.size(), sink);
    foreach (typename T::const_iterator, i, ss)
        writeString(*i, sink);
}

template void writeStrings(const Paths & ss, Sink & sink);
template void writeStrings(const PathSet & ss, Sink & sink);

void readPadding(size_t len, Source & source)
{
    if (len % 8) {
        unsigned char zero[8];
        size_t n = 8 - (len % 8);
        source(zero, n);
        for (unsigned int i = 0; i < n; i++)
            if (zero[i]) throw SerialisationError("non-zero padding");
    }
}

unsigned int readInt(Source & source)
{
    unsigned char buf[8];
    source(buf, sizeof(buf));
    if (buf[4] || buf[5] || buf[6] || buf[7])
        throw SerialisationError("implementation cannot deal with > 32-bit integers");
    return
        buf[0] |
        (buf[1] << 8) |
        (buf[2] << 16) |
        (buf[3] << 24);
}

unsigned long long readLongLong(Source & source)
{
    unsigned char buf[8];
    source(buf, sizeof(buf));
    return
        ((unsigned long long) buf[0]) |
        ((unsigned long long) buf[1] << 8) |
        ((unsigned long long) buf[2] << 16) |
        ((unsigned long long) buf[3] << 24) |
        ((unsigned long long) buf[4] << 32) |
        ((unsigned long long) buf[5] << 40) |
        ((unsigned long long) buf[6] << 48) |
        ((unsigned long long) buf[7] << 56);
}

size_t readString(unsigned char * buf, size_t max, Source & source)
{
    size_t len = readInt(source);
    if (len > max) throw Error("string is too long");
    source(buf, len);
    readPadding(len, source);
    return len;
}

string readString(Source & source)
{
    size_t len = readInt(source);
    unsigned char * buf = new unsigned char[len];
    AutoDeleteArray<unsigned char> d(buf);
    source(buf, len);
    readPadding(len, source);
    return string((char *) buf, len);
}

template<class T> T readStrings(Source & source)
{
    unsigned int count = readInt(source);
    T ss;
    while (count--)
        ss.insert(ss.end(), readString(source));
    return ss;
}

template Paths readStrings(Source & source);
template PathSet readStrings(Source & source);

void StringSink::operator () (const unsigned char * data, size_t len)
{
    static bool warned = false;
    if (!warned && s.size() > threshold) {
        warnLargeDump();
        warned = true;
    }
    s.append((const char *) data, len);
}

}


code:
#pragma once

#include "types.hh"

namespace nix {

/* Abstract destination of binary data. */
struct Sink
{
    virtual ~Sink() { }
    virtual void operator () (const unsigned char * data, size_t len) = 0;
};

/* A buffered abstract sink. */
struct BufferedSink : Sink
{
    size_t bufSize, bufPos;
    unsigned char * buffer;

    BufferedSink(size_t bufSize = 32 * 1024)
        : bufSize(bufSize), bufPos(0), buffer(0) { }
    ~BufferedSink();

    void operator () (const unsigned char * data, size_t len);

    void flush();

    virtual void write(const unsigned char * data, size_t len) = 0;
};

/* Abstract source of binary data. */
struct Source
{
    virtual ~Source() { }

    /* Store exactly ‘len’ bytes in the buffer pointed to by ‘data’.
       It blocks until all the requested data is available, or throws
       an error if it is not going to be available.   */
    void operator () (unsigned char * data, size_t len);

    /* Store up to ‘len’ in the buffer pointed to by ‘data’, and
       return the number of bytes stored.  If blocks until at least
       one byte is available. */
    virtual size_t read(unsigned char * data, size_t len) = 0;
};

/* A buffered abstract source. */
struct BufferedSource : Source
{
    size_t bufSize, bufPosIn, bufPosOut;
    unsigned char * buffer;

    BufferedSource(size_t bufSize = 32 * 1024)
        : bufSize(bufSize), bufPosIn(0), bufPosOut(0), buffer(0) { }
    ~BufferedSource();

    size_t read(unsigned char * data, size_t len);

    /* Underlying read call, to be overridden. */
    virtual size_t readUnbuffered(unsigned char * data, size_t len) = 0;

    bool hasData();
};

/* A sink that writes data to a file descriptor. */
struct FdSink : BufferedSink
{
    int fd;
    bool warn;
    size_t written;

    FdSink() : fd(-1), warn(false), written(0) { }
    FdSink(int fd) : fd(fd), warn(false), written(0) { }
    ~FdSink();

    void write(const unsigned char * data, size_t len);
};

/* A source that reads data from a file descriptor. */
struct FdSource : BufferedSource
{
    int fd;
    FdSource() : fd(-1) { }
    FdSource(int fd) : fd(fd) { }
    size_t readUnbuffered(unsigned char * data, size_t len);
};

/* A sink that writes data to a string. */
struct StringSink : Sink
{
    string s;
    void operator () (const unsigned char * data, size_t len);
};

/* A source that reads data from a string. */
struct StringSource : Source
{
    const string & s;
    size_t pos;
    StringSource(const string & _s) : s(_s), pos(0) { }
    size_t read(unsigned char * data, size_t len);
};

void writePadding(size_t len, Sink & sink);
void writeInt(unsigned int n, Sink & sink);
void writeLongLong(unsigned long long n, Sink & sink);
void writeString(const unsigned char * buf, size_t len, Sink & sink);
void writeString(const string & s, Sink & sink);
template<class T> void writeStrings(const T & ss, Sink & sink);

void readPadding(size_t len, Source & source);
unsigned int readInt(Source & source);
unsigned long long readLongLong(Source & source);
size_t readString(unsigned char * buf, size_t max, Source & source);
string readString(Source & source);
template<class T> T readStrings(Source & source);

MakeError(SerialisationError, Error)

}


code:
/* GNU Guix --- Functional package management for GNU
   Copyright (C) 2012  Ludovic Courtès <ludo@gnu.org>

   This file is part of GNU Guix.

   GNU Guix is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or (at
   your option) any later version.

   GNU Guix is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.  */

#include <gcrypt-hash.hh>

#define SHA_CTX guix_hash_context

static inline void
SHA1_Init (struct SHA_CTX *ctx)
{
  guix_hash_init (ctx, GCRY_MD_SHA1);
}

#define SHA1_Update guix_hash_update

static inline void
SHA1_Final (void *resbuf, struct SHA_CTX *ctx)
{
  guix_hash_final (resbuf, ctx, GCRY_MD_SHA1);
}


code:
/* GNU Guix --- Functional package management for GNU
   Copyright (C) 2012  Ludovic Courtès <ludo@gnu.org>

   This file is part of GNU Guix.

   GNU Guix is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or (at
   your option) any later version.

   GNU Guix is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.  */

#include <gcrypt-hash.hh>

#define SHA256_CTX guix_hash_context

static inline void
SHA256_Init (struct SHA256_CTX *ctx)
{
  guix_hash_init (ctx, GCRY_MD_SHA256);
}

#define SHA256_Update guix_hash_update

static inline void
SHA256_Final (void *resbuf, struct SHA256_CTX *ctx)
{
  guix_hash_final (resbuf, ctx, GCRY_MD_SHA256);
}


code:
/* GNU Guix --- Functional package management for GNU
   Copyright (C) 2012, 2015 Ludovic Courtès <ludo@gnu.org>

   This file is part of GNU Guix.

   GNU Guix is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or (at
   your option) any later version.

   GNU Guix is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.  */

#include <gcrypt-hash.hh>

#define SHA512_CTX guix_hash_context

static inline void
SHA512_Init (struct SHA512_CTX *ctx)
{
  guix_hash_init (ctx, GCRY_MD_SHA512);
}

#define SHA512_Update guix_hash_update

static inline void
SHA512_Final (void *resbuf, struct SHA512_CTX *ctx)
{
  guix_hash_final (resbuf, ctx, GCRY_MD_SHA512);
}


code:
#pragma once

#include "config.h"

#include <string>
#include <list>
#include <set>

#include <boost/format.hpp>

/* Before 4.7, gcc's std::exception uses empty throw() specifiers for
 * its (virtual) destructor and what() in c++11 mode, in violation of spec
 */
#ifdef __GNUC__
#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
#define EXCEPTION_NEEDS_THROW_SPEC
#endif
#endif

namespace nix {

/* Inherit some names from other namespaces for convenience. */
using std::string;
using std::list;
using std::set;
using std::vector;
using boost::format;

struct FormatOrString
{
    string s;
    FormatOrString(const string & s) : s(s) { };
    FormatOrString(const format & f) : s(f.str()) { };
    FormatOrString(const char * s) : s(s) { };
};

/* BaseError should generally not be caught, as it has Interrupted as
   a subclass. Catch Error instead. */
class BaseError : public std::exception
{
protected:
    string prefix_; // used for location traces etc.
    string err;
public:
    unsigned int status; // exit status
    BaseError(const FormatOrString & fs, unsigned int status = 1);
#ifdef EXCEPTION_NEEDS_THROW_SPEC
    ~BaseError() throw () { };
    const char * what() const throw () { return err.c_str(); }
#else
    const char * what() const noexcept { return err.c_str(); }
#endif
    const string & msg() const { return err; }
    const string & prefix() const { return prefix_; }
    BaseError & addPrefix(const FormatOrString & fs);
};

#define MakeError(newClass, superClass) \
    class newClass : public superClass                  \
    {                                                   \
    public:                                             \
        newClass(const FormatOrString & fs, unsigned int status = 1) : superClass(fs, status) { }; \
    };

MakeError(Error, BaseError)

class SysError : public Error
{
public:
    int errNo;
    SysError(const FormatOrString & fs);
};

typedef list<string> Strings;
typedef set<string> StringSet;

/* Paths are just strings. */
typedef string Path;
typedef list<Path> Paths;
typedef set<Path> PathSet;

typedef enum {
    lvlError = 0,
    lvlInfo,
    lvlTalkative,
    lvlChatty,
    lvlDebug,
    lvlVomit
} Verbosity;

}


code:
#include "config.h"

#include "util.hh"
#include "affinity.hh"

#include <iostream>
#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <sstream>
#include <cstring>

#include <sys/wait.h>
#include <unistd.h>
#include <fcntl.h>
#include <limits.h>

#ifdef __APPLE__
#include <sys/syscall.h>
#endif

#ifdef __linux__
#include <sys/prctl.h>
#endif

extern char * * environ;

namespace nix {

BaseError::BaseError(const FormatOrString & fs, unsigned int status)
    : status(status)
{
    err = fs.s;
}

BaseError & BaseError::addPrefix(const FormatOrString & fs)
{
    prefix_ = fs.s + prefix_;
    return *this;
}

SysError::SysError(const FormatOrString & fs)
    : Error(format("%1%: %2%") % fs.s % strerror(errno))
    , errNo(errno)
{
}

string getEnv(const string & key, const string & def)
{
    char * value = getenv(key.c_str());
    return value ? string(value) : def;
}

Path absPath(Path path, Path dir)
{
    if (path[0] != '/') {
        if (dir == "") {
#ifdef __GNU__
            /* GNU (aka. GNU/Hurd) doesn't have any limitation on path
               lengths and doesn't define `PATH_MAX'.  */
            char *buf = getcwd(NULL, 0);
            if (buf == NULL)
#else
            char buf[PATH_MAX];
            if (!getcwd(buf, sizeof(buf)))
#endif
                throw SysError("cannot get cwd");
            dir = buf;
#ifdef __GNU__
            free(buf);
#endif
        }
        path = dir + "/" + path;
    }
    return canonPath(path);
}

Path canonPath(const Path & path, bool resolveSymlinks)
{
    string s;

    if (path[0] != '/')
        throw Error(format("not an absolute path: `%1%'") % path);

    string::const_iterator i = path.begin(), end = path.end();
    string temp;

    /* Count the number of times we follow a symlink and stop at some
       arbitrary (but high) limit to prevent infinite loops. */
    unsigned int followCount = 0, maxFollow = 1024;

    while (1) {

        /* Skip slashes. */
        while (i != end && *i == '/') i++;
        if (i == end) break;

        /* Ignore `.'. */
        if (*i == '.' && (i + 1 == end || i[1] == '/'))
            i++;

        /* If `..', delete the last component. */
        else if (*i == '.' && i + 1 < end && i[1] == '.' &&
            (i + 2 == end || i[2] == '/'))
        {
            if (!s.empty()) s.erase(s.rfind('/'));
            i += 2;
        }

        /* Normal component; copy it. */
        else {
            s += '/';
            while (i != end && *i != '/') s += *i++;

            /* If s points to a symlink, resolve it and restart (since
               the symlink target might contain new symlinks). */
            if (resolveSymlinks && isLink(s)) {
                if (++followCount >= maxFollow)
                    throw Error(format("infinite symlink recursion in path `%1%'") % path);
                temp = absPath(readLink(s), dirOf(s))
                    + string(i, end);
                i = temp.begin(); /* restart */
                end = temp.end();
                s = "";
            }
        }
    }

    return s.empty() ? "/" : s;
}

Path dirOf(const Path & path)
{
    Path::size_type pos = path.rfind('/');
    if (pos == string::npos)
        throw Error(format("invalid file name `%1%'") % path);
    return pos == 0 ? "/" : Path(path, 0, pos);
}

string baseNameOf(const Path & path)
{
    Path::size_type pos = path.rfind('/');
    if (pos == string::npos)
        throw Error(format("invalid file name `%1%'") % path);
    return string(path, pos + 1);
}

bool isInDir(const Path & path, const Path & dir)
{
    return path[0] == '/'
        && string(path, 0, dir.size()) == dir
        && path.size() >= dir.size() + 2
        && path[dir.size()] == '/';
}

struct stat lstat(const Path & path)
{
    struct stat st;
    if (lstat(path.c_str(), &st))
        throw SysError(format("getting status of `%1%'") % path);
    return st;
}

bool pathExists(const Path & path)
{
    int res;
    struct stat st;
    res = lstat(path.c_str(), &st);
    if (!res) return true;
    if (errno != ENOENT && errno != ENOTDIR)
        throw SysError(format("getting status of %1%") % path);
    return false;
}

Path readLink(const Path & path)
{
    checkInterrupt();
    struct stat st = lstat(path);
    if (!S_ISLNK(st.st_mode))
        throw Error(format("`%1%' is not a symlink") % path);
    char buf[st.st_size];
    ssize_t rlsize = readlink(path.c_str(), buf, st.st_size);
    if (rlsize == -1)
        throw SysError(format("reading symbolic link '%1%'") % path);
    else if (rlsize > st.st_size)
        throw Error(format("symbolic link ‘%1%’ size overflow %2% > %3%")
            % path % rlsize % st.st_size);
    return string(buf, st.st_size);
}

bool isLink(const Path & path)
{
    struct stat st = lstat(path);
    return S_ISLNK(st.st_mode);
}

DirEntries readDirectory(const Path & path)
{
    DirEntries entries;
    entries.reserve(64);

    AutoCloseDir dir = opendir(path.c_str());
    if (!dir) throw SysError(format("opening directory `%1%'") % path);

    struct dirent * dirent;
    while (errno = 0, dirent = readdir(dir)) { /* sic */
        checkInterrupt();
        string name = dirent->d_name;
        if (name == "." || name == "..") continue;
        entries.emplace_back(name, dirent->d_ino, dirent->d_type);
    }
    if (errno) throw SysError(format("reading directory `%1%'") % path);

    return entries;
}

unsigned char getFileType(const Path & path)
{
    struct stat st = lstat(path);
    if (S_ISDIR(st.st_mode)) return DT_DIR;
    if (S_ISLNK(st.st_mode)) return DT_LNK;
    if (S_ISREG(st.st_mode)) return DT_REG;
    return DT_UNKNOWN;
}

string readFile(int fd)
{
    struct stat st;
    if (fstat(fd, &st) == -1)
        throw SysError("statting file");

    unsigned char * buf = new unsigned char[st.st_size];
    AutoDeleteArray<unsigned char> d(buf);
    readFull(fd, buf, st.st_size);

    return string((char *) buf, st.st_size);
}

string readFile(const Path & path, bool drain)
{
    AutoCloseFD fd = open(path.c_str(), O_RDONLY);
    if (fd == -1)
        throw SysError(format("opening file `%1%'") % path);
    return drain ? drainFD(fd) : readFile(fd);
}

void writeFile(const Path & path, const string & s)
{
    AutoCloseFD fd = open(path.c_str(), O_WRONLY | O_TRUNC | O_CREAT, 0666);
    if (fd == -1)
        throw SysError(format("opening file '%1%'") % path);
    writeFull(fd, s);
}

string readLine(int fd)
{
    string s;
    while (1) {
        checkInterrupt();
        char ch;
        ssize_t rd = read(fd, &ch, 1);
        if (rd == -1) {
            if (errno != EINTR)
                throw SysError("reading a line");
        } else if (rd == 0)
            throw EndOfFile("unexpected EOF reading a line");
        else {
            if (ch == '\n') return s;
            s += ch;
        }
    }
}

void writeLine(int fd, string s)
{
    s += '\n';
    writeFull(fd, s);
}

static void _deletePath(const Path & path, unsigned long long & bytesFreed)
{
    checkInterrupt();

    printMsg(lvlVomit, format("%1%") % path);

    struct stat st = lstat(path);

    if (!S_ISDIR(st.st_mode) && st.st_nlink == 1)
        bytesFreed += st.st_blocks * 512;

    if (S_ISDIR(st.st_mode)) {
        /* Make the directory writable. */
        if (!(st.st_mode & S_IWUSR)) {
            if (chmod(path.c_str(), st.st_mode | S_IWUSR) == -1)
                throw SysError(format("making `%1%' writable") % path);
        }

        for (auto & i : readDirectory(path))
            _deletePath(path + "/" + i.name, bytesFreed);
    }

    if (remove(path.c_str()) == -1)
        throw SysError(format("cannot unlink `%1%'") % path);
}

void deletePath(const Path & path)
{
    unsigned long long dummy;
    deletePath(path, dummy);
}

void deletePath(const Path & path, unsigned long long & bytesFreed)
{
    startNest(nest, lvlDebug,
        format("recursively deleting path `%1%'") % path);
    bytesFreed = 0;
    _deletePath(path, bytesFreed);
}

static Path tempName(Path tmpRoot, const Path & prefix, bool includePid,
    int & counter)
{
    tmpRoot = canonPath(tmpRoot.empty() ? getEnv("TMPDIR", "/tmp") : tmpRoot, true);
    if (includePid)
        return (format("%1%/%2%-%3%-%4%") % tmpRoot % prefix % getpid() % counter++).str();
    else
        return (format("%1%/%2%-%3%") % tmpRoot % prefix % counter++).str();
}

Path createTempDir(const Path & tmpRoot, const Path & prefix,
    bool includePid, bool useGlobalCounter, mode_t mode)
{
    static int globalCounter = 0;
    int localCounter = 0;
    int & counter(useGlobalCounter ? globalCounter : localCounter);

    while (1) {
        checkInterrupt();
        Path tmpDir = tempName(tmpRoot, prefix, includePid, counter);
        if (mkdir(tmpDir.c_str(), mode) == 0) {
            /* Explicitly set the group of the directory.  This is to
               work around around problems caused by BSD's group
               ownership semantics (directories inherit the group of
               the parent).  For instance, the group of /tmp on
               FreeBSD is "wheel", so all directories created in /tmp
               will be owned by "wheel"; but if the user is not in
               "wheel", then "tar" will fail to unpack archives that
               have the setgid bit set on directories. */
            if (chown(tmpDir.c_str(), (uid_t) -1, getegid()) != 0)
                throw SysError(format("setting group of directory `%1%'") % tmpDir);
            return tmpDir;
        }
        if (errno != EEXIST)
            throw SysError(format("creating directory `%1%'") % tmpDir);
    }
}

Paths createDirs(const Path & path)
{
    Paths created;
    if (path == "/") return created;

    struct stat st;
    if (lstat(path.c_str(), &st) == -1) {
        created = createDirs(dirOf(path));
        if (mkdir(path.c_str(), 0777) == -1 && errno != EEXIST)
            throw SysError(format("creating directory `%1%'") % path);
        st = lstat(path);
        created.push_back(path);
    }

    if (S_ISLNK(st.st_mode) && stat(path.c_str(), &st) == -1)
        throw SysError(format("statting symlink `%1%'") % path);

    if (!S_ISDIR(st.st_mode)) throw Error(format("`%1%' is not a directory") % path);

    return created;
}

void createSymlink(const Path & target, const Path & link)
{
    if (symlink(target.c_str(), link.c_str()))
        throw SysError(format("creating symlink from `%1%' to `%2%'") % link % target);
}

LogType logType = ltPretty;
Verbosity verbosity = lvlInfo;

static int nestingLevel = 0;

Nest::Nest()
{
    nest = false;
}

Nest::~Nest()
{
    close();
}

static string escVerbosity(Verbosity level)
{
    return std::to_string((int) level);
}

void Nest::open(Verbosity level, const FormatOrString & fs)
{
    if (level <= verbosity) {
        if (logType == ltEscapes)
            std::cerr << "\033[" << escVerbosity(level) << "p"
                      << fs.s << "\n";
        else
            printMsg_(level, fs);
        nest = true;
        nestingLevel++;
    }
}

void Nest::close()
{
    if (nest) {
        nestingLevel--;
        if (logType == ltEscapes)
            std::cerr << "\033[q";
        nest = false;
    }
}

void printMsg_(Verbosity level, const FormatOrString & fs)
{
    checkInterrupt();
    if (level > verbosity) return;
    string prefix;
    if (logType == ltPretty)
        for (int i = 0; i < nestingLevel; i++)
            prefix += "|   ";
    else if (logType == ltEscapes && level != lvlInfo)
        prefix = "\033[" + escVerbosity(level) + "s";
    string s = (format("%1%%2%\n") % prefix % fs.s).str();
    writeToStderr(s);
}

void warnOnce(bool & haveWarned, const FormatOrString & fs)
{
    if (!haveWarned) {
        printMsg(lvlError, format("warning: %1%") % fs.s);
        haveWarned = true;
    }
}

void writeToStderr(const string & s)
{
    try {
        if (_writeToStderr)
            _writeToStderr((const unsigned char *) s.data(), s.size());
        else
            writeFull(STDERR_FILENO, s);
    } catch (SysError & e) {
        /* Ignore failing writes to stderr if we're in an exception
           handler, otherwise throw an exception.  We need to ignore
           write errors in exception handlers to ensure that cleanup
           code runs to completion if the other side of stderr has
           been closed unexpectedly. */
        if (!std::uncaught_exception()) throw;
    }
}

void (*_writeToStderr) (const unsigned char * buf, size_t count) = 0;

void readFull(int fd, unsigned char * buf, size_t count)
{
    while (count) {
        checkInterrupt();
        ssize_t res = read(fd, (char *) buf, count);
        if (res == -1) {
            if (errno == EINTR) continue;
            throw SysError("reading from file");
        }
        if (res == 0) throw EndOfFile("unexpected end-of-file");
        count -= res;
        buf += res;
    }
}

void writeFull(int fd, const unsigned char * buf, size_t count)
{
    while (count) {
        checkInterrupt();
        ssize_t res = write(fd, (char *) buf, count);
        if (res == -1) {
            if (errno == EINTR) continue;
            throw SysError("writing to file");
        }
        count -= res;
        buf += res;
    }
}

void writeFull(int fd, const string & s)
{
    writeFull(fd, (const unsigned char *) s.data(), s.size());
}

string drainFD(int fd)
{
    string result;
    unsigned char buffer[4096];
    while (1) {
        checkInterrupt();
        ssize_t rd = read(fd, buffer, sizeof buffer);
        if (rd == -1) {
            if (errno != EINTR)
                throw SysError("reading from file");
        }
        else if (rd == 0) break;
        else result.append((char *) buffer, rd);
    }
    return result;
}

//////////////////////////////////////////////////////////////////////

AutoDelete::AutoDelete(const string & p, bool recursive) : path(p)
{
    del = true;
    this->recursive = recursive;
}

AutoDelete::~AutoDelete()
{
    try {
        if (del) {
            if (recursive)
                deletePath(path);
            else {
                if (remove(path.c_str()) == -1)
                    throw SysError(format("cannot unlink `%1%'") % path);
            }
        }
    } catch (...) {
        ignoreException();
    }
}

void AutoDelete::cancel()
{
    del = false;
}

//////////////////////////////////////////////////////////////////////

AutoCloseFD::AutoCloseFD()
{
    fd = -1;
}

AutoCloseFD::AutoCloseFD(int fd)
{
    this->fd = fd;
}

AutoCloseFD::AutoCloseFD(const AutoCloseFD & fd)
{
    /* Copying an AutoCloseFD isn't allowed (who should get to close
       it?).  But as an edge case, allow copying of closed
       AutoCloseFDs.  This is necessary due to tiresome reasons
       involving copy constructor use on default object values in STL
       containers (like when you do `map[value]' where value isn't in
       the map yet). */
    this->fd = fd.fd;
    if (this->fd != -1) abort();
}

AutoCloseFD::~AutoCloseFD()
{
    try {
        close();
    } catch (...) {
        ignoreException();
    }
}

void AutoCloseFD::operator =(int fd)
{
    if (this->fd != fd) close();
    this->fd = fd;
}

AutoCloseFD::operator int() const
{
    return fd;
}

void AutoCloseFD::close()
{
    if (fd != -1) {
        if (::close(fd) == -1)
            /* This should never happen. */
            throw SysError(format("closing file descriptor %1%") % fd);
        fd = -1;
    }
}

bool AutoCloseFD::isOpen()
{
    return fd != -1;
}

/* Pass responsibility for closing this fd to the caller. */
int AutoCloseFD::borrow()
{
    int oldFD = fd;
    fd = -1;
    return oldFD;
}

void Pipe::create()
{
    int fds[2];
    if (pipe(fds) != 0) throw SysError("creating pipe");
    readSide = fds[0];
    writeSide = fds[1];
    closeOnExec(readSide);
    closeOnExec(writeSide);
}

//////////////////////////////////////////////////////////////////////

AutoCloseDir::AutoCloseDir()
{
    dir = 0;
}

AutoCloseDir::AutoCloseDir(DIR * dir)
{
    this->dir = dir;
}

AutoCloseDir::~AutoCloseDir()
{
    close();
}

void AutoCloseDir::operator =(DIR * dir)
{
    this->dir = dir;
}

AutoCloseDir::operator DIR *()
{
    return dir;
}

void AutoCloseDir::close()
{
    if (dir) {
        closedir(dir);
        dir = 0;
    }
}

//////////////////////////////////////////////////////////////////////

Pid::Pid()
    : pid(-1), separatePG(false), killSignal(SIGKILL)
{
}

Pid::Pid(pid_t pid)
    : pid(pid), separatePG(false), killSignal(SIGKILL)
{
}

Pid::~Pid()
{
    kill();
}

void Pid::operator =(pid_t pid)
{
    if (this->pid != pid) kill();
    this->pid = pid;
    killSignal = SIGKILL; // reset signal to default
}

Pid::operator pid_t()
{
    return pid;
}

void Pid::kill(bool quiet)
{
    if (pid == -1 || pid == 0) return;

    if (!quiet)
        printMsg(lvlError, format("killing process %1%") % pid);

    /* Send the requested signal to the child.  If it has its own
       process group, send the signal to every process in the child
       process group (which hopefully includes *all* its children). */
    if (::kill(separatePG ? -pid : pid, killSignal) != 0)
        printMsg(lvlError, (SysError(format("killing process %1%") % pid).msg()));

    /* Wait until the child dies, disregarding the exit status. */
    int status;
    while (waitpid(pid, &status, 0) == -1) {
        checkInterrupt();
        if (errno != EINTR) {
            printMsg(lvlError,
                (SysError(format("waiting for process %1%") % pid).msg()));
            break;
        }
    }

    pid = -1;
}

int Pid::wait(bool block)
{
    assert(pid != -1);
    while (1) {
        int status;
        int res = waitpid(pid, &status, block ? 0 : WNOHANG);
        if (res == pid) {
            pid = -1;
            return status;
        }
        if (res == 0 && !block) return -1;
        if (errno != EINTR)
            throw SysError("cannot get child exit status");
        checkInterrupt();
    }
}

void Pid::setSeparatePG(bool separatePG)
{
    this->separatePG = separatePG;
}

void Pid::setKillSignal(int signal)
{
    this->killSignal = signal;
}

void killUser(uid_t uid)
{
    debug(format("killing all processes running under uid `%1%'") % uid);

    assert(uid != 0); /* just to be safe... */

    /* The system call kill(-1, sig) sends the signal `sig' to all
       users to which the current process can send signals.  So we
       fork a process, switch to uid, and send a mass kill. */

    Pid pid = startProcess([&]() {

        if (setuid(uid) == -1)
            throw SysError("setting uid");

        while (true) {
#ifdef __APPLE__
            /* OSX's kill syscall takes a third parameter that, among
               other things, determines if kill(-1, signo) affects the
               calling process. In the OSX libc, it's set to true,
               which means "follow POSIX", which we don't want here
                 */
            if (syscall(SYS_kill, -1, SIGKILL, false) == 0) break;
#else
            if (kill(-1, SIGKILL) == 0) break;
#endif
            if (errno == ESRCH) break; /* no more processes */
            if (errno != EINTR)
                throw SysError(format("cannot kill processes for uid `%1%'") % uid);
        }

        _exit(0);
    });

    int status = pid.wait(true);
    if (status != 0)
        throw Error(format("cannot kill processes for uid `%1%': %2%") % uid % statusToString(status));

    /* !!! We should really do some check to make sure that there are
       no processes left running under `uid', but there is no portable
       way to do so (I think).  The most reliable way may be `ps -eo
       uid | grep -q $uid'. */
}

//////////////////////////////////////////////////////////////////////

pid_t startProcess(std::function<void()> fun,
    bool dieWithParent, const string & errorPrefix, bool runExitHandlers)
{
    pid_t pid = fork();
    if (pid == -1) throw SysError("unable to fork");

    if (pid == 0) {
        _writeToStderr = 0;
        try {
#if __linux__
            if (dieWithParent && prctl(PR_SET_PDEATHSIG, SIGKILL) == -1)
                throw SysError("setting death signal");
#endif
            restoreAffinity();
            fun();
        } catch (std::exception & e) {
            try {
                std::cerr << errorPrefix << e.what() << "\n";
            } catch (...) { }
        } catch (...) { }
        if (runExitHandlers)
            exit(1);
        else
            _exit(1);
    }

    return pid;
}

std::vector<char *> stringsToCharPtrs(const Strings & ss)
{
    std::vector<char *> res;
    for (auto & s : ss) res.push_back((char *) s.c_str());
    res.push_back(0);
    return res;
}

string runProgram(Path program, bool searchPath, const Strings & args)
{
    checkInterrupt();

    /* Create a pipe. */
    Pipe pipe;
    pipe.create();

    /* Fork. */
    Pid pid = startProcess([&]() {
        if (dup2(pipe.writeSide, STDOUT_FILENO) == -1)
            throw SysError("dupping stdout");

        Strings args_(args);
        args_.push_front(program);

        if (searchPath)
            execvp(program.c_str(), stringsToCharPtrs(args_).data());
        else
            execv(program.c_str(), stringsToCharPtrs(args_).data());

        throw SysError(format("executing `%1%'") % program);
    });

    pipe.writeSide.close();

    string result = drainFD(pipe.readSide);

    /* Wait for the child to finish. */
    int status = pid.wait(true);
    if (!statusOk(status))
        throw ExecError(format("program `%1%' %2%")
            % program % statusToString(status));

    return result;
}

void closeMostFDs(const set<int> & exceptions)
{
    int maxFD = 0;
    maxFD = sysconf(_SC_OPEN_MAX);
    for (int fd = 0; fd < maxFD; ++fd)
        if (fd != STDIN_FILENO && fd != STDOUT_FILENO && fd != STDERR_FILENO
            && exceptions.find(fd) == exceptions.end())
            close(fd); /* ignore result */
}

void closeOnExec(int fd)
{
    int prev;
    if ((prev = fcntl(fd, F_GETFD, 0)) == -1 ||
        fcntl(fd, F_SETFD, prev | FD_CLOEXEC) == -1)
        throw SysError("setting close-on-exec flag");
}

//////////////////////////////////////////////////////////////////////

volatile sig_atomic_t _isInterrupted = 0;

void _interrupted()
{
    /* Block user interrupts while an exception is being handled.
       Throwing an exception while another exception is being handled
       kills the program! */
    if (!std::uncaught_exception()) {
        _isInterrupted = 0;
        throw Interrupted("interrupted by the user");
    }
}

//////////////////////////////////////////////////////////////////////

template<class C> C tokenizeString(const string & s, const string & separators)
{
    C result;
    string::size_type pos = s.find_first_not_of(separators, 0);
    while (pos != string::npos) {
        string::size_type end = s.find_first_of(separators, pos + 1);
        if (end == string::npos) end = s.size();
        string token(s, pos, end - pos);
        result.insert(result.end(), token);
        pos = s.find_first_not_of(separators, end);
    }
    return result;
}

template Strings tokenizeString(const string & s, const string & separators);
template StringSet tokenizeString(const string & s, const string & separators);
template vector<string> tokenizeString(const string & s, const string & separators);

string concatStringsSep(const string & sep, const Strings & ss)
{
    string s;
    foreach (Strings::const_iterator, i, ss) {
        if (s.size() != 0) s += sep;
        s += *i;
    }
    return s;
}

string concatStringsSep(const string & sep, const StringSet & ss)
{
    string s;
    foreach (StringSet::const_iterator, i, ss) {
        if (s.size() != 0) s += sep;
        s += *i;
    }
    return s;
}

string chomp(const string & s)
{
    size_t i = s.find_last_not_of(" \n\r\t");
    return i == string::npos ? "" : string(s, 0, i + 1);
}

string statusToString(int status)
{
    if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
        if (WIFEXITED(status))
            return (format("failed with exit code %1%") % WEXITSTATUS(status)).str();
        else if (WIFSIGNALED(status)) {
            int sig = WTERMSIG(status);
#if HAVE_STRSIGNAL
            const char * description = strsignal(sig);
            return (format("failed due to signal %1% (%2%)") % sig % description).str();
#else
            return (format("failed due to signal %1%") % sig).str();
#endif
        }
        else
            return "died abnormally";
    } else return "succeeded";
}

bool statusOk(int status)
{
    return WIFEXITED(status) && WEXITSTATUS(status) == 0;
}

bool hasSuffix(const string & s, const string & suffix)
{
    return s.size() >= suffix.size() && string(s, s.size() - suffix.size()) == suffix;
}

void expect(std::istream & str, const string & s)
{
    char s2[s.size()];
    str.read(s2, s.size());
    if (string(s2, s.size()) != s)
        throw FormatError(format("expected string `%1%'") % s);
}

string parseString(std::istream & str)
{
    string res;
    expect(str, "\"");
    int c;
    while ((c = str.get()) != '"')
        if (c == '\\') {
            c = str.get();
            if (c == 'n') res += '\n';
            else if (c == 'r') res += '\r';
            else if (c == 't') res += '\t';
            else res += c;
        }
        else res += c;
    return res;
}

bool endOfList(std::istream & str)
{
    if (str.peek() == ',') {
        str.get();
        return false;
    }
    if (str.peek() == ']') {
        str.get();
        return true;
    }
    return false;
}

void ignoreException()
{
    try {
        throw;
    } catch (std::exception & e) {
        printMsg(lvlError, format("error (ignored): %1%") % e.what());
    }
}

}


code:
#pragma once

#include "types.hh"

#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>
#include <signal.h>
#include <functional>

#include <cstdio>

namespace nix {

#define foreach(it_type, it, collection)                                \
    for (it_type it = (collection).begin(); it != (collection).end(); ++it)

#define foreach_reverse(it_type, it, collection)                                \
    for (it_type it = (collection).rbegin(); it != (collection).rend(); ++it)

/* Return an environment variable. */
string getEnv(const string & key, const string & def = "");

/* Return an absolutized path, resolving paths relative to the
   specified directory, or the current directory otherwise.  The path
   is also canonicalised. */
Path absPath(Path path, Path dir = "");

/* Canonicalise a path by removing all `.' or `..' components and
   double or trailing slashes.  Optionally resolves all symlink
   components such that each component of the resulting path is *not*
   a symbolic link. */
Path canonPath(const Path & path, bool resolveSymlinks = false);

/* Return the directory part of the given canonical path, i.e.,
   everything before the final `/'.  If the path is the root or an
   immediate child thereof (e.g., `/foo'), this means an empty string
   is returned. */
Path dirOf(const Path & path);

/* Return the base name of the given canonical path, i.e., everything
   following the final `/'. */
string baseNameOf(const Path & path);

/* Check whether a given path is a descendant of the given
   directory. */
bool isInDir(const Path & path, const Path & dir);

/* Get status of `path'. */
struct stat lstat(const Path & path);

/* Return true iff the given path exists. */
bool pathExists(const Path & path);

/* Read the contents (target) of a symbolic link.  The result is not
   in any way canonicalised. */
Path readLink(const Path & path);

bool isLink(const Path & path);

/* Read the contents of a directory.  The entries `.' and `..' are
   removed. */
struct DirEntry
{
    string name;
    ino_t ino;
    unsigned char type; // one of DT_*
    DirEntry(const string & name, ino_t ino, unsigned char type)
        : name(name), ino(ino), type(type) { }
};

typedef vector<DirEntry> DirEntries;

DirEntries readDirectory(const Path & path);

unsigned char getFileType(const Path & path);

/* Read the contents of a file into a string. */
string readFile(int fd);
string readFile(const Path & path, bool drain = false);

/* Write a string to a file. */
void writeFile(const Path & path, const string & s);

/* Read a line from a file descriptor. */
string readLine(int fd);

/* Write a line to a file descriptor. */
void writeLine(int fd, string s);

/* Delete a path; i.e., in the case of a directory, it is deleted
   recursively.  Don't use this at home, kids.  The second variant
   returns the number of bytes and blocks freed. */
void deletePath(const Path & path);

void deletePath(const Path & path, unsigned long long & bytesFreed);

/* Create a temporary directory. */
Path createTempDir(const Path & tmpRoot = "", const Path & prefix = "nix",
    bool includePid = true, bool useGlobalCounter = true, mode_t mode = 0755);

/* Create a directory and all its parents, if necessary.  Returns the
   list of created directories, in order of creation. */
Paths createDirs(const Path & path);

/* Create a symlink. */
void createSymlink(const Path & target, const Path & link);

template<class T, class A>
T singleton(const A & a)
{
    T t;
    t.insert(a);
    return t;
}

/* Messages. */

typedef enum {
    ltPretty,   /* nice, nested output */
    ltEscapes,  /* nesting indicated using escape codes (for log2xml) */
    ltFlat      /* no nesting */
} LogType;

extern LogType logType;
extern Verbosity verbosity; /* suppress msgs > this */

class Nest
{
private:
    bool nest;
public:
    Nest();
    ~Nest();
    void open(Verbosity level, const FormatOrString & fs);
    void close();
};

void printMsg_(Verbosity level, const FormatOrString & fs);

#define startNest(varName, level, f) \
    Nest varName; \
    if (level <= verbosity) { \
      varName.open(level, (f)); \
    }

#define printMsg(level, f) \
    do { \
        if (level <= nix::verbosity) { \
            nix::printMsg_(level, (f)); \
        } \
    } while (0)

#define debug(f) printMsg(lvlDebug, f)

void warnOnce(bool & haveWarned, const FormatOrString & fs);

void writeToStderr(const string & s);

extern void (*_writeToStderr) (const unsigned char * buf, size_t count);

/* Wrappers arount read()/write() that read/write exactly the
   requested number of bytes. */
void readFull(int fd, unsigned char * buf, size_t count);
void writeFull(int fd, const unsigned char * buf, size_t count);
void writeFull(int fd, const string & s);

MakeError(EndOfFile, Error)

/* Read a file descriptor until EOF occurs. */
string drainFD(int fd);

/* Automatic cleanup of resources. */

template <class T>
struct AutoDeleteArray
{
    T * p;
    AutoDeleteArray(T * p) : p(p) { }
    ~AutoDeleteArray()
    {
        delete [] p;
    }
};

class AutoDelete
{
    Path path;
    bool del;
    bool recursive;
public:
    AutoDelete(const Path & p, bool recursive = true);
    ~AutoDelete();
    void cancel();
};

class AutoCloseFD
{
    int fd;
public:
    AutoCloseFD();
    AutoCloseFD(int fd);
    AutoCloseFD(const AutoCloseFD & fd);
    ~AutoCloseFD();
    void operator =(int fd);
    operator int() const;
    void close();
    bool isOpen();
    int borrow();
};

class Pipe
{
public:
    AutoCloseFD readSide, writeSide;
    void create();
};

class AutoCloseDir
{
    DIR * dir;
public:
    AutoCloseDir();
    AutoCloseDir(DIR * dir);
    ~AutoCloseDir();
    void operator =(DIR * dir);
    operator DIR *();
    void close();
};

class Pid
{
    pid_t pid;
    bool separatePG;
    int killSignal;
public:
    Pid();
    Pid(pid_t pid);
    ~Pid();
    void operator =(pid_t pid);
    operator pid_t();
    void kill(bool quiet = false);
    int wait(bool block);
    void setSeparatePG(bool separatePG);
    void setKillSignal(int signal);
};

/* Kill all processes running under the specified uid by sending them
   a SIGKILL. */
void killUser(uid_t uid);

/* Fork a process that runs the given function, and return the child
   pid to the caller. */
pid_t startProcess(std::function<void()> fun, bool dieWithParent = true,
    const string & errorPrefix = "error: ", bool runExitHandlers = false);

/* Run a program and return its stdout in a string (i.e., like the
   shell backtick operator). */
string runProgram(Path program, bool searchPath = false,
    const Strings & args = Strings());

MakeError(ExecError, Error)

/* Convert a list of strings to a null-terminated vector of char
   *'s. The result must not be accessed beyond the lifetime of the
   list of strings. */
std::vector<char *> stringsToCharPtrs(const Strings & ss);

/* Close all file descriptors except stdin, stdout, stderr, and those
   listed in the given set.  Good practice in child processes. */
void closeMostFDs(const set<int> & exceptions);

/* Set the close-on-exec flag for the given file descriptor. */
void closeOnExec(int fd);

/* User interruption. */

extern volatile sig_atomic_t _isInterrupted;

void _interrupted();

void inline checkInterrupt()
{
    if (_isInterrupted) _interrupted();
}

MakeError(Interrupted, BaseError)

/* String tokenizer. */
template<class C> C tokenizeString(const string & s, const string & separators = " \t\n\r");

/* Concatenate the given strings with a separator between the
   elements. */
string concatStringsSep(const string & sep, const Strings & ss);
string concatStringsSep(const string & sep, const StringSet & ss);

/* Remove trailing whitespace from a string. */
string chomp(const string & s);

/* Convert the exit status of a child as returned by wait() into an
   error string. */
string statusToString(int status);

bool statusOk(int status);

/* Parse a string into an integer. */
template<class N> bool string2Int(const string & s, N & n)
{
    std::istringstream str(s);
    str >> n;
    return str && str.get() == EOF;
}

/* Return true iff `s' ends in `suffix'. */
bool hasSuffix(const string & s, const string & suffix);

/* Read string `s' from stream `str'. */
void expect(std::istream & str, const string & s);

MakeError(FormatError, Error)

/* Read a C-style string from stream `str'. */
string parseString(std::istream & str);

/* Utility function used to parse legacy ATerms. */
bool endOfList(std::istream & str);

/* Exception handling in destructors: print an error message, then
   ignore the exception. */
void ignoreException();

}


code:
# GNU Guix --- Functional package management for GNU
# Copyright © 2012, 2013, 2014, 2015, 2016, 2018 Ludovic Courtès <ludo@gnu.org>
# Copyright © 2016 Mathieu Lirzin <mthl@gnu.org>
#
# This file is part of GNU Guix.
#
# GNU Guix is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or (at
# your option) any later version.
#
# GNU Guix is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

#
# Integration of the `guix-daemon' code taken from upstream Nix.
#

BUILT_SOURCES += %D%/libstore/schema.sql.hh
CLEANFILES += %D%/libstore/schema.sql.hh

noinst_LIBRARIES = libformat.a libutil.a libstore.a

# Use '-std=c++11' for 'std::shared_ptr', 'auto', lambdas, and more.
AM_CXXFLAGS = -Wall -std=c++11

libformat_a_SOURCES =				\
  %D%/boost/format/free_funcs.cc		\
  %D%/boost/format/parsing.cc			\
  %D%/boost/format/format_implementation.cc

libformat_headers =				\
  %D%/boost/throw_exception.hpp			\
  %D%/boost/format.hpp				\
  %D%/boost/assert.hpp				\
  %D%/boost/format/macros_default.hpp		\
  %D%/boost/format/format_fwd.hpp		\
  %D%/boost/format/format_class.hpp		\
  %D%/boost/format/exceptions.hpp		\
  %D%/boost/format/group.hpp			\
  %D%/boost/format/feed_args.hpp		\
  %D%/boost/format/internals_fwd.hpp		\
  %D%/boost/format/internals.hpp

libformat_a_CPPFLAGS =				\
  -I$(top_srcdir)/nix

libutil_a_SOURCES =				\
  %D%/libutil/archive.cc			\
  %D%/libutil/affinity.cc			\
  %D%/libutil/serialise.cc			\
  %D%/libutil/util.cc				\
  %D%/libutil/hash.cc				\
  %D%/libutil/gcrypt-hash.cc

libutil_headers =				\
  %D%/libutil/affinity.hh			\
  %D%/libutil/hash.hh				\
  %D%/libutil/serialise.hh			\
  %D%/libutil/util.hh				\
  %D%/libutil/archive.hh			\
  %D%/libutil/types.hh				\
  %D%/libutil/gcrypt-hash.hh			\
  %D%/libutil/md5.h				\
  %D%/libutil/sha1.h				\
  %D%/libutil/sha256.h				\
  %D%/libutil/sha512.h

libutil_a_CPPFLAGS =				\
  -I$(top_builddir)/nix				\
  -I$(top_srcdir)/%D%/libutil			\
  $(libformat_a_CPPFLAGS)

libstore_a_SOURCES =				\
  %D%/libstore/gc.cc				\
  %D%/libstore/globals.cc			\
  %D%/libstore/misc.cc				\
  %D%/libstore/references.cc			\
  %D%/libstore/store-api.cc			\
  %D%/libstore/optimise-store.cc		\
  %D%/libstore/local-store.cc			\
  %D%/libstore/build.cc				\
  %D%/libstore/pathlocks.cc			\
  %D%/libstore/derivations.cc			\
  %D%/libstore/builtins.cc			\
  %D%/libstore/sqlite.cc

libstore_headers =				\
  %D%/libstore/references.hh			\
  %D%/libstore/pathlocks.hh			\
  %D%/libstore/globals.hh			\
  %D%/libstore/worker-protocol.hh		\
  %D%/libstore/derivations.hh			\
  %D%/libstore/misc.hh				\
  %D%/libstore/local-store.hh			\
  %D%/libstore/sqlite.hh			\
  %D%/libstore/builtins.hh			\
  %D%/libstore/store-api.hh

libstore_a_CPPFLAGS =				\
  $(libutil_a_CPPFLAGS)				\
  -I$(top_srcdir)/%D%/libstore			\
  -I$(top_builddir)/%D%/libstore		\
  -DNIX_STORE_DIR=\"$(storedir)\"		\
  -DNIX_DATA_DIR=\"$(datadir)\"			\
  -DNIX_STATE_DIR=\"$(localstatedir)/guix\"	\
  -DNIX_LOG_DIR=\"$(localstatedir)/log/guix\"	\
  -DGUIX_CONFIGURATION_DIRECTORY=\"$(sysconfdir)/guix\"		\
  -DNIX_LIBEXEC_DIR=\"$(libexecdir)\"		\
  -DNIX_BIN_DIR=\"$(bindir)\"			\
  -DOPENSSL_PATH="\"guix-authenticate\""	\
  -DDEFAULT_CHROOT_DIRS="\"\""

libstore_a_CXXFLAGS = $(AM_CXXFLAGS)		\
  $(SQLITE3_CFLAGS) $(LIBGCRYPT_CFLAGS)

bin_PROGRAMS = guix-daemon

guix_daemon_SOURCES =				\
  %D%/nix-daemon/nix-daemon.cc			\
  %D%/nix-daemon/guix-daemon.cc

guix_daemon_CPPFLAGS =				\
  -DLOCALEDIR=\"$(localedir)\"			\
  $(libutil_a_CPPFLAGS)				\
  -I$(top_srcdir)/%D%/libstore

guix_daemon_LDADD =				\
  libstore.a libutil.a libformat.a -lz		\
  $(SQLITE3_LIBS) $(LIBGCRYPT_LIBS)

guix_daemon_headers =				\
  %D%/nix-daemon/shared.hh

if HAVE_LIBBZ2

guix_daemon_LDADD += -lbz2

endif HAVE_LIBBZ2

noinst_HEADERS =						\
  $(libformat_headers) $(libutil_headers) $(libstore_headers)	\
  $(guix_daemon_headers)

%D%/libstore/schema.sql.hh: guix/store/schema.sql
	$(AM_V_GEN)$(GUILE) --no-auto-compile -c		\
	  "(use-modules (rnrs io ports))			\
	   (call-with-output-file \"$@\"			\
	     (lambda (out)					\
	       (call-with-input-file \"$^\"			\
	         (lambda (in)					\
	           (write (get-string-all in) out)))))"

nodist_pkglibexec_SCRIPTS =			\
  %D%/scripts/list-runtime-roots		\
  %D%/scripts/substitute			\
  %D%/scripts/download

if BUILD_DAEMON_OFFLOAD

nodist_pkglibexec_SCRIPTS +=			\
  %D%/scripts/offload

endif BUILD_DAEMON_OFFLOAD

# XXX: It'd be better to hide it in $(pkglibexecdir).
nodist_libexec_SCRIPTS =			\
  %D%/scripts/guix-authenticate

# The '.service' files for systemd.
systemdservicedir = $(libdir)/systemd/system
nodist_systemdservice_DATA = etc/guix-daemon.service etc/guix-publish.service

etc/guix-%.service: etc/guix-%.service.in	\
			 $(top_builddir)/config.status
	$(AM_V_GEN)$(MKDIR_P) "`dirname $@`";	\
	$(SED) -e 's|@''localstatedir''@|$(localstatedir)|' <	\
	       "$<" > "$@.tmp";		\
	mv "$@.tmp" "$@"

# The '.conf' jobs for Upstart.
upstartjobdir = $(libdir)/upstart/system
nodist_upstartjob_DATA = etc/guix-daemon.conf etc/guix-publish.conf

etc/guix-%.conf: etc/guix-%.conf.in	\
			 $(top_builddir)/config.status
	$(AM_V_GEN)$(MKDIR_P) "`dirname $@`";	\
	$(SED) -e 's|@''localstatedir''@|$(localstatedir)|' <	\
	       "$<" > "$@.tmp";		\
	mv "$@.tmp" "$@"

CLEANFILES +=					\
  $(nodist_systemdservice_DATA)			\
  $(nodist_upstartjob_DATA)

EXTRA_DIST +=					\
  %D%/AUTHORS					\
  %D%/COPYING					\
  etc/guix-daemon.service.in			\
  etc/guix-daemon.conf.in			\
  etc/guix-publish.service.in			\
  etc/guix-publish.conf.in

if CAN_RUN_TESTS

AM_TESTS_ENVIRONMENT +=				\
  top_builddir="$(abs_top_builddir)"

TESTS +=					\
  tests/guix-daemon.sh

endif CAN_RUN_TESTS

clean-local:
	-if test -d "$(GUIX_TEST_ROOT)"; then		\
	  find "$(GUIX_TEST_ROOT)" | xargs chmod +w;	\
	 fi
	-rm -rf "$(GUIX_TEST_ROOT)"