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archive.cc
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archive.cc
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#include <cerrno>
#include <algorithm>
#include <vector>
#include <map>
#include <strings.h> // for strcasecmp
#include "archive.hh"
#include "config-global.hh"
#include "posix-source-accessor.hh"
#include "source-path.hh"
#include "file-system.hh"
#include "signals.hh"
namespace nix {
struct ArchiveSettings : Config
{
Setting<bool> useCaseHack{this,
#if __APPLE__
true,
#else
false,
#endif
"use-case-hack",
"Whether to enable a macOS-specific hack for dealing with file name case collisions."};
};
static ArchiveSettings archiveSettings;
static GlobalConfig::Register rArchiveSettings(&archiveSettings);
PathFilter defaultPathFilter = [](const Path &) { return true; };
void SourceAccessor::dumpPath(
const CanonPath & path,
Sink & sink,
PathFilter & filter)
{
auto dumpContents = [&](const CanonPath & path)
{
sink << "contents";
std::optional<uint64_t> size;
readFile(path, sink, [&](uint64_t _size)
{
size = _size;
sink << _size;
});
assert(size);
writePadding(*size, sink);
};
std::function<void(const CanonPath & path)> dump;
dump = [&](const CanonPath & path) {
checkInterrupt();
auto st = lstat(path);
sink << "(";
if (st.type == tRegular) {
sink << "type" << "regular";
if (st.isExecutable)
sink << "executable" << "";
dumpContents(path);
}
else if (st.type == tDirectory) {
sink << "type" << "directory";
/* If we're on a case-insensitive system like macOS, undo
the case hack applied by restorePath(). */
std::map<std::string, std::string> unhacked;
for (auto & i : readDirectory(path))
if (archiveSettings.useCaseHack) {
std::string name(i.first);
size_t pos = i.first.find(caseHackSuffix);
if (pos != std::string::npos) {
debug("removing case hack suffix from '%s'", path / i.first);
name.erase(pos);
}
if (!unhacked.emplace(name, i.first).second)
throw Error("file name collision between '%s' and '%s'",
(path / unhacked[name]),
(path / i.first));
} else
unhacked.emplace(i.first, i.first);
for (auto & i : unhacked)
if (filter((path / i.first).abs())) {
sink << "entry" << "(" << "name" << i.first << "node";
dump(path / i.second);
sink << ")";
}
}
else if (st.type == tSymlink)
sink << "type" << "symlink" << "target" << readLink(path);
else throw Error("file '%s' has an unsupported type", path);
sink << ")";
};
sink << narVersionMagic1;
dump(path);
}
time_t dumpPathAndGetMtime(const Path & path, Sink & sink, PathFilter & filter)
{
auto path2 = PosixSourceAccessor::createAtRoot(path);
path2.dumpPath(sink, filter);
return path2.accessor.dynamic_pointer_cast<PosixSourceAccessor>()->mtime;
}
void dumpPath(const Path & path, Sink & sink, PathFilter & filter)
{
dumpPathAndGetMtime(path, sink, filter);
}
void dumpString(std::string_view s, Sink & sink)
{
sink << narVersionMagic1 << "(" << "type" << "regular" << "contents" << s << ")";
}
template<typename... Args>
static SerialisationError badArchive(std::string_view s, const Args & ... args)
{
return SerialisationError("bad archive: " + s, args...);
}
static void parseContents(CreateRegularFileSink & sink, Source & source)
{
uint64_t size = readLongLong(source);
sink.preallocateContents(size);
uint64_t left = size;
std::array<char, 65536> buf;
while (left) {
checkInterrupt();
auto n = buf.size();
if ((uint64_t)n > left) n = left;
source(buf.data(), n);
sink({buf.data(), n});
left -= n;
}
readPadding(size, source);
}
struct CaseInsensitiveCompare
{
bool operator() (const std::string & a, const std::string & b) const
{
return strcasecmp(a.c_str(), b.c_str()) < 0;
}
};
static void parse(FileSystemObjectSink & sink, Source & source, const CanonPath & path)
{
auto getString = [&]() {
checkInterrupt();
return readString(source);
};
auto expectTag = [&](std::string_view expected) {
auto tag = getString();
if (tag != expected)
throw badArchive("expected tag '%s', got '%s'", expected, tag);
};
expectTag("(");
expectTag("type");
auto type = getString();
if (type == "regular") {
sink.createRegularFile(path, [&](auto & crf) {
auto tag = getString();
if (tag == "executable") {
auto s2 = getString();
if (s2 != "") throw badArchive("executable marker has non-empty value");
crf.isExecutable();
tag = getString();
}
if (tag == "contents")
parseContents(crf, source);
expectTag(")");
});
}
else if (type == "directory") {
sink.createDirectory(path);
std::map<Path, int, CaseInsensitiveCompare> names;
std::string prevName;
while (1) {
auto tag = getString();
if (tag == ")") break;
if (tag != "entry")
throw badArchive("expected tag 'entry' or ')', got '%s'", tag);
expectTag("(");
expectTag("name");
auto name = getString();
if (name.empty() || name == "." || name == ".." || name.find('/') != std::string::npos || name.find((char) 0) != std::string::npos)
throw badArchive("NAR contains invalid file name '%1%'", name);
if (name <= prevName)
throw badArchive("NAR directory is not sorted");
prevName = name;
if (archiveSettings.useCaseHack) {
auto i = names.find(name);
if (i != names.end()) {
debug("case collision between '%1%' and '%2%'", i->first, name);
name += caseHackSuffix;
name += std::to_string(++i->second);
auto j = names.find(name);
if (j != names.end())
throw badArchive("NAR contains file name '%s' that collides with case-hacked file name '%s'", prevName, j->first);
} else
names[name] = 0;
}
expectTag("node");
parse(sink, source, path / name);
expectTag(")");
}
}
else if (type == "symlink") {
expectTag("target");
auto target = getString();
sink.createSymlink(path, target);
expectTag(")");
}
else throw badArchive("unknown file type '%s'", type);
}
void parseDump(FileSystemObjectSink & sink, Source & source)
{
std::string version;
try {
version = readString(source, narVersionMagic1.size());
} catch (SerialisationError & e) {
/* This generally means the integer at the start couldn't be
decoded. Ignore and throw the exception below. */
}
if (version != narVersionMagic1)
throw badArchive("input doesn't look like a Nix archive");
parse(sink, source, CanonPath::root);
}
void restorePath(const std::filesystem::path & path, Source & source, bool startFsync)
{
RestoreSink sink{startFsync};
sink.dstPath = path;
parseDump(sink, source);
}
void copyNAR(Source & source, Sink & sink)
{
// FIXME: if 'source' is the output of dumpPath() followed by EOF,
// we should just forward all data directly without parsing.
NullFileSystemObjectSink parseSink; /* just parse the NAR */
TeeSource wrapper { source, sink };
parseDump(parseSink, wrapper);
}
}