nix-super/src/libutil/archive.cc
John Ericson ac89bb064a Split up util.{hh,cc}
All OS and IO operations should be moved out, leaving only some misc
portable pure functions.

This is useful to avoid copious CPP when doing things like Windows and
Emscripten ports.

Newly exposed functions to break cycles:

 - `restoreSignals`
 - `updateWindowSize`
2023-11-05 12:20:02 -05:00

314 lines
8.4 KiB
C++

#include <cerrno>
#include <algorithm>
#include <vector>
#include <map>
#include <strings.h> // for strcasecmp
#include "archive.hh"
#include "config.hh"
#include "posix-source-accessor.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 Darwin-specific hack for dealing with file name 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 in 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)
{
PosixSourceAccessor accessor;
accessor.dumpPath(CanonPath::fromCwd(path), sink, filter);
return accessor.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 << ")";
}
static SerialisationError badArchive(const std::string & s)
{
return SerialisationError("bad archive: " + s);
}
static void parseContents(ParseSink & sink, Source & source, const Path & path)
{
uint64_t size = readLongLong(source);
sink.preallocateContents(size);
uint64_t left = size;
std::vector<char> buf(65536);
while (left) {
checkInterrupt();
auto n = buf.size();
if ((uint64_t)n > left) n = left;
source(buf.data(), n);
sink.receiveContents({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(ParseSink & sink, Source & source, const Path & path)
{
std::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");
std::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);
sink.closeRegularFile();
}
else if (s == "executable" && type == tpRegular) {
auto s = readString(source);
if (s != "") throw badArchive("executable marker has non-empty value");
sink.isExecutable();
}
else if (s == "entry" && type == tpDirectory) {
std::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('/') != std::string::npos || name.find((char) 0) != std::string::npos)
throw Error("NAR contains invalid file name '%1%'", name);
if (name <= prevName)
throw Error("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);
} else
names[name] = 0;
}
} else if (s == "node") {
if (name.empty()) throw badArchive("entry name missing");
parse(sink, source, path + "/" + name);
} else
throw badArchive("unknown field " + s);
}
}
else if (s == "target" && type == tpSymlink) {
std::string target = readString(source);
sink.createSymlink(path, target);
}
else
throw badArchive("unknown field " + s);
}
}
void parseDump(ParseSink & 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, "");
}
void restorePath(const Path & path, Source & source)
{
RestoreSink sink;
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.
NullParseSink parseSink; /* just parse the NAR */
TeeSource wrapper { source, sink };
parseDump(parseSink, wrapper);
}
void copyPath(const Path & from, const Path & to)
{
auto source = sinkToSource([&](Sink & sink) {
dumpPath(from, sink);
});
restorePath(to, *source);
}
}