forked from lix-project/lix
388 lines
10 KiB
C++
388 lines
10 KiB
C++
#include <cerrno>
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#include <algorithm>
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#include <vector>
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#include <map>
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#include <strings.h> // for strcasecmp
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <dirent.h>
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#include <fcntl.h>
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#include "archive.hh"
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#include "util.hh"
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#include "config.hh"
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namespace nix {
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struct ArchiveSettings : Config
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{
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Setting<bool> useCaseHack{this,
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#if __APPLE__
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true,
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#else
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false,
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#endif
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"use-case-hack",
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"Whether to enable a Darwin-specific hack for dealing with file name collisions."};
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Setting<bool> preallocateContents{this, false, "preallocate-contents",
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"Whether to preallocate files when writing objects with known size."};
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};
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static ArchiveSettings archiveSettings;
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static GlobalConfig::Register rArchiveSettings(&archiveSettings);
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const std::string narVersionMagic1 = "nix-archive-1";
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static string caseHackSuffix = "~nix~case~hack~";
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PathFilter defaultPathFilter = [](const Path &) { return true; };
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static void dumpContents(const Path & path, off_t size,
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Sink & sink)
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{
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sink << "contents" << size;
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AutoCloseFD fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
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if (!fd) throw SysError("opening file '%1%'", path);
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std::vector<char> buf(65536);
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size_t left = size;
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while (left > 0) {
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auto n = std::min(left, buf.size());
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readFull(fd.get(), buf.data(), n);
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left -= n;
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sink({buf.data(), n});
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}
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writePadding(size, sink);
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}
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static void dump(const Path & path, Sink & sink, PathFilter & filter)
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{
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checkInterrupt();
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auto st = lstat(path);
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sink << "(";
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if (S_ISREG(st.st_mode)) {
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sink << "type" << "regular";
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if (st.st_mode & S_IXUSR)
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sink << "executable" << "";
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dumpContents(path, st.st_size, sink);
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}
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else if (S_ISDIR(st.st_mode)) {
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sink << "type" << "directory";
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/* If we're on a case-insensitive system like macOS, undo
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the case hack applied by restorePath(). */
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std::map<string, string> unhacked;
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for (auto & i : readDirectory(path))
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if (archiveSettings.useCaseHack) {
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string name(i.name);
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size_t pos = i.name.find(caseHackSuffix);
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if (pos != string::npos) {
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debug(format("removing case hack suffix from '%1%'") % (path + "/" + i.name));
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name.erase(pos);
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}
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if (unhacked.find(name) != unhacked.end())
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throw Error("file name collision in between '%1%' and '%2%'",
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(path + "/" + unhacked[name]),
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(path + "/" + i.name));
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unhacked[name] = i.name;
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} else
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unhacked[i.name] = i.name;
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for (auto & i : unhacked)
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if (filter(path + "/" + i.first)) {
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sink << "entry" << "(" << "name" << i.first << "node";
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dump(path + "/" + i.second, sink, filter);
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sink << ")";
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}
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}
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else if (S_ISLNK(st.st_mode))
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sink << "type" << "symlink" << "target" << readLink(path);
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else throw Error("file '%1%' has an unsupported type", path);
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sink << ")";
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}
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void dumpPath(const Path & path, Sink & sink, PathFilter & filter)
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{
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sink << narVersionMagic1;
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dump(path, sink, filter);
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}
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void dumpString(const std::string & s, Sink & sink)
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{
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sink << narVersionMagic1 << "(" << "type" << "regular" << "contents" << s << ")";
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}
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static SerialisationError badArchive(string s)
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{
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return SerialisationError("bad archive: " + s);
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}
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#if 0
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static void skipGeneric(Source & source)
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{
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if (readString(source) == "(") {
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while (readString(source) != ")")
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skipGeneric(source);
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}
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}
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#endif
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static void parseContents(ParseSink & sink, Source & source, const Path & path)
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{
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uint64_t size = readLongLong(source);
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sink.preallocateContents(size);
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uint64_t left = size;
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std::vector<char> buf(65536);
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while (left) {
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checkInterrupt();
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auto n = buf.size();
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if ((uint64_t)n > left) n = left;
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source(buf.data(), n);
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sink.receiveContents({buf.data(), n});
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left -= n;
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}
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readPadding(size, source);
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}
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struct CaseInsensitiveCompare
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{
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bool operator() (const string & a, const string & b) const
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{
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return strcasecmp(a.c_str(), b.c_str()) < 0;
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}
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};
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static void parse(ParseSink & sink, Source & source, const Path & path)
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{
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string s;
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s = readString(source);
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if (s != "(") throw badArchive("expected open tag");
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enum { tpUnknown, tpRegular, tpDirectory, tpSymlink } type = tpUnknown;
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std::map<Path, int, CaseInsensitiveCompare> names;
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while (1) {
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checkInterrupt();
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s = readString(source);
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if (s == ")") {
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break;
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}
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else if (s == "type") {
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if (type != tpUnknown)
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throw badArchive("multiple type fields");
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string t = readString(source);
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if (t == "regular") {
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type = tpRegular;
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sink.createRegularFile(path);
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}
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else if (t == "directory") {
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sink.createDirectory(path);
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type = tpDirectory;
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}
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else if (t == "symlink") {
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type = tpSymlink;
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}
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else throw badArchive("unknown file type " + t);
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}
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else if (s == "contents" && type == tpRegular) {
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parseContents(sink, source, path);
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}
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else if (s == "executable" && type == tpRegular) {
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auto s = readString(source);
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if (s != "") throw badArchive("executable marker has non-empty value");
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sink.isExecutable();
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}
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else if (s == "entry" && type == tpDirectory) {
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string name, prevName;
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s = readString(source);
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if (s != "(") throw badArchive("expected open tag");
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while (1) {
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checkInterrupt();
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s = readString(source);
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if (s == ")") {
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break;
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} else if (s == "name") {
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name = readString(source);
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if (name.empty() || name == "." || name == ".." || name.find('/') != string::npos || name.find((char) 0) != string::npos)
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throw Error("NAR contains invalid file name '%1%'", name);
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if (name <= prevName)
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throw Error("NAR directory is not sorted");
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prevName = name;
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if (archiveSettings.useCaseHack) {
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auto i = names.find(name);
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if (i != names.end()) {
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debug(format("case collision between '%1%' and '%2%'") % i->first % name);
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name += caseHackSuffix;
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name += std::to_string(++i->second);
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} else
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names[name] = 0;
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}
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} else if (s == "node") {
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if (name.empty()) throw badArchive("entry name missing");
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parse(sink, source, path + "/" + name);
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} else
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throw badArchive("unknown field " + s);
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}
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}
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else if (s == "target" && type == tpSymlink) {
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string target = readString(source);
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sink.createSymlink(path, target);
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}
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else
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throw badArchive("unknown field " + s);
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}
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}
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void parseDump(ParseSink & sink, Source & source)
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{
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string version;
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try {
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version = readString(source, narVersionMagic1.size());
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} catch (SerialisationError & e) {
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/* This generally means the integer at the start couldn't be
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decoded. Ignore and throw the exception below. */
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}
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if (version != narVersionMagic1)
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throw badArchive("input doesn't look like a Nix archive");
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parse(sink, source, "");
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}
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struct RestoreSink : ParseSink
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{
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Path dstPath;
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AutoCloseFD fd;
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void createDirectory(const Path & path) override
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{
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Path p = dstPath + path;
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if (mkdir(p.c_str(), 0777) == -1)
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throw SysError("creating directory '%1%'", p);
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};
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void createRegularFile(const Path & path) override
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{
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Path p = dstPath + path;
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fd = open(p.c_str(), O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0666);
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if (!fd) throw SysError("creating file '%1%'", p);
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}
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void isExecutable() override
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{
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struct stat st;
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if (fstat(fd.get(), &st) == -1)
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throw SysError("fstat");
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if (fchmod(fd.get(), st.st_mode | (S_IXUSR | S_IXGRP | S_IXOTH)) == -1)
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throw SysError("fchmod");
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}
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void preallocateContents(uint64_t len) override
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{
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if (!archiveSettings.preallocateContents)
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return;
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#if HAVE_POSIX_FALLOCATE
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if (len) {
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errno = posix_fallocate(fd.get(), 0, len);
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/* Note that EINVAL may indicate that the underlying
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filesystem doesn't support preallocation (e.g. on
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OpenSolaris). Since preallocation is just an
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optimisation, ignore it. */
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if (errno && errno != EINVAL && errno != EOPNOTSUPP && errno != ENOSYS)
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throw SysError("preallocating file of %1% bytes", len);
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}
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#endif
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}
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void receiveContents(std::string_view data) override
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{
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writeFull(fd.get(), data);
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}
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void createSymlink(const Path & path, const string & target) override
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{
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Path p = dstPath + path;
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nix::createSymlink(target, p);
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}
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};
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void restorePath(const Path & path, Source & source)
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{
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RestoreSink sink;
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sink.dstPath = path;
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parseDump(sink, source);
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}
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void copyNAR(Source & source, Sink & sink)
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{
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// FIXME: if 'source' is the output of dumpPath() followed by EOF,
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// we should just forward all data directly without parsing.
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ParseSink parseSink; /* null sink; just parse the NAR */
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TeeSource wrapper { source, sink };
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parseDump(parseSink, wrapper);
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}
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void copyPath(const Path & from, const Path & to)
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{
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auto source = sinkToSource([&](Sink & sink) {
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dumpPath(from, sink);
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});
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restorePath(to, *source);
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}
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}
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