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Improve the FileSystemObjectSink interface

Browse source 
More invariants are enforced in the type, and less state needs to be
stored in the main sink itself. The method here is roughly that known as
"session types".

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This commit is contained in:
John Ericson 2023-12-20 14:47:05 -05:00
parent 966d6fcd01
commit 6365bbfa81
9 changed files with 357 additions and 219 deletions
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144
src/libutil/archive.cc
View file

@ -133,7 +133,7 @@ static SerialisationError badArchive(const std::string & s)
}
static void parseContents(FileSystemObjectSink & sink, Source & source, const Path & path)
static void parseContents(CreateRegularFileSink & sink, Source & source)
{
uint64_t size = readLongLong(source);
@ -147,7 +147,7 @@ static void parseContents(FileSystemObjectSink & sink, Source & source, const Pa
auto n = buf.size();
if ((uint64_t)n > left) n = left;
source(buf.data(), n);
sink.receiveContents({buf.data(), n});
sink({buf.data(), n});
left -= n;
}
@ -171,95 +171,107 @@ static void parse(FileSystemObjectSink & sink, Source & source, const Path & pat
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) {
auto getString = [&]() {
checkInterrupt();
return readString(source);
};
s = readString(source);
// For first iteration
s = getString();
while (1) {
if (s == ")") {
break;
}
else if (s == "type") {
if (type != tpUnknown)
throw badArchive("multiple type fields");
std::string t = readString(source);
std::string t = getString();
if (t == "regular") {
type = tpRegular;
sink.createRegularFile(path);
sink.createRegularFile(path, [&](auto & crf) {
while (1) {
s = getString();
if (s == "contents") {
parseContents(crf, source);
}
else if (s == "executable") {
auto s2 = getString();
if (s2 != "") throw badArchive("executable marker has non-empty value");
crf.isExecutable();
}
else break;
}
});
}
else if (t == "directory") {
sink.createDirectory(path);
type = tpDirectory;
while (1) {
s = getString();
if (s == "entry") {
std::string name, prevName;
s = getString();
if (s != "(") throw badArchive("expected open tag");
while (1) {
s = getString();
if (s == ")") {
break;
} else if (s == "name") {
name = getString();
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 break;
}
}
else if (t == "symlink") {
type = tpSymlink;
s = getString();
if (s != "target")
throw badArchive("expected 'target' got " + s);
std::string target = getString();
sink.createSymlink(path, target);
// for the next iteration
s = getString();
}
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);
}