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SourceAccessor::readFile(): Support reading into a sink

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This commit is contained in:
Eelco Dolstra 2023-10-20 16:36:41 +02:00
parent 7a086a32bc
commit 57db3be9e4
5 changed files with 94 additions and 13 deletions
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58
src/libutil/source-accessor.cc
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@ -10,6 +10,28 @@ SourceAccessor::SourceAccessor()
{
}
std::string SourceAccessor::readFile(const CanonPath & path)
{
StringSink sink;
std::optional<uint64_t> size;
readFile(path, sink, [&](uint64_t _size)
{
size = _size;
});
assert(size && *size == sink.s.size());
return std::move(sink.s);
}
void SourceAccessor::readFile(
const CanonPath & path,
Sink & sink,
std::function<void(uint64_t)> sizeCallback)
{
auto s = readFile(path);
sizeCallback(s.size());
sink(s);
}
Hash SourceAccessor::hashPath(
const CanonPath & path,
PathFilter & filter,
@ -33,9 +55,41 @@ std::string SourceAccessor::showPath(const CanonPath & path)
return path.abs();
}
std::string PosixSourceAccessor::readFile(const CanonPath & path)
void PosixSourceAccessor::readFile(
const CanonPath & path,
Sink & sink,
std::function<void(uint64_t)> sizeCallback)
{
return nix::readFile(path.abs());
// FIXME: add O_NOFOLLOW since symlinks should be resolved by the
// caller?
AutoCloseFD fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
if (!fd)
throw SysError("opening file '%1%'", path);
struct stat st;
if (fstat(fd.get(), &st) == -1)
throw SysError("statting file");
sizeCallback(st.st_size);
off_t left = st.st_size;
std::vector<unsigned char> buf(64 * 1024);
while (left) {
checkInterrupt();
ssize_t rd = read(fd.get(), buf.data(), (size_t) std::min(left, (off_t) buf.size()));
if (rd == -1) {
if (errno != EINTR)
throw SysError("reading from file '%s'", showPath(path));
}
else if (rd == 0)
throw SysError("unexpected end-of-file reading '%s'", showPath(path));
else {
assert(rd <= left);
sink({(char *) buf.data(), (size_t) rd});
left -= rd;
}
}
}
bool PosixSourceAccessor::pathExists(const CanonPath & path)