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libutil: Add callback-based FileSystemObjectSink::createDirectory

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This commit is contained in:
Sergei Zimmerman 2025-11-20 01:27:18 +03:00
parent fa380e0991
commit 09755e696a
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3 changed files with 62 additions and 44 deletions
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78
src/libutil/archive.cc
View file

@ -200,54 +200,54 @@ static void parse(FileSystemObjectSink & sink, Source & source, const CanonPath
}
else if (type == "directory") {
sink.createDirectory(path);
sink.createDirectory(path, [&](FileSystemObjectSink & dirSink, const CanonPath & relDirPath) {
std::map<Path, int, CaseInsensitiveCompare> names;
std::map<Path, int, CaseInsensitiveCompare> names;
std::string prevName;
std::string prevName;
while (1) {
auto tag = getString();
while (1) {
auto tag = getString();
if (tag == ")")
break;
if (tag == ")")
break;
if (tag != "entry")
throw badArchive("expected tag 'entry' or ')', got '%s'", tag);
if (tag != "entry")
throw badArchive("expected tag 'entry' or ')', got '%s'", tag);
expectTag("(");
expectTag("(");
expectTag("name");
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;
}
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(dirSink, source, relDirPath / name);
expectTag(")");
}
expectTag("node");
parse(sink, source, path / name);
expectTag(")");
}
});
}
else if (type == "symlink") {

11
src/libutil/fs-sink.cc
View file

@ -34,11 +34,12 @@ void copyRecursive(SourceAccessor & accessor, const CanonPath & from, FileSystem
}
case SourceAccessor::tDirectory: {
sink.createDirectory(to);
for (auto & [name, _] : accessor.readDirectory(from)) {
copyRecursive(accessor, from / name, sink, to / name);
break;
}
sink.createDirectory(to, [&](FileSystemObjectSink & dirSink, const CanonPath & relDirPath) {
for (auto & [name, _] : accessor.readDirectory(from)) {
copyRecursive(accessor, from / name, dirSink, relDirPath / name);
break;
}
});
break;
}

17
src/libutil/include/nix/util/fs-sink.hh
View file

@ -36,6 +36,23 @@ struct FileSystemObjectSink
virtual void createDirectory(const CanonPath & path) = 0;
using DirectoryCreatedCallback = std::function<void(FileSystemObjectSink & dirSink, const CanonPath & dirRelPath)>;
/**
* Create a directory and invoke a callback with a pair of sink + CanonPath
* of the created subdirectory relative to dirSink.
*
* @note This allows for UNIX RestoreSink implementations to implement
* *at-style accessors that always keep an open file descriptor for the
* freshly created directory. Use this when it's important to disallow any
* intermediate path components from being symlinks.
*/
virtual void createDirectory(const CanonPath & path, DirectoryCreatedCallback callback)
{
createDirectory(path);
callback(*this, path);
}
/**
* This function in general is no re-entrant. Only one file can be
* written at a time.