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#include "libstore/references.hh"
#include <cstdlib>
#include <map>
#include <glog/logging.h>
#include "libutil/archive.hh"
#include "libutil/hash.hh"
#include "libutil/util.hh"
namespace nix {
static unsigned int refLength = 32; /* characters */
static void search(const char* s, size_t len, StringSet& hashes,
StringSet& seen) {
for (size_t i = 0; i + refLength <= len;) {
absl::string_view ref(s + i, refLength);
bool match = Hash::IsValidBase32(ref);
if (!match) {
continue;
}
// TODO(kanepyork): convert StringSet to flat_hash_set, delay owned string
// conversion into the 'if'
std::string sref(ref);
if (hashes.find(sref) != hashes.end()) {
DLOG(INFO) << "found reference to '" << ref << "' at offset " << i;
seen.insert(sref);
hashes.erase(sref);
}
++i;
}
}
struct RefScanSink : Sink {
HashSink hashSink;
StringSet hashes;
StringSet seen;
std::string tail;
RefScanSink() : hashSink(htSHA256) {}
void operator()(const unsigned char* data, size_t len) override;
};
void RefScanSink::operator()(const unsigned char* data, size_t len) {
hashSink(data, len);
const char* data_ = reinterpret_cast<const char*>(data);
/* It's possible that a reference spans the previous and current
fragment, so search in the concatenation of the tail of the
previous fragment and the start of the current fragment. */
std::string s = tail + std::string(data_, len > refLength ? refLength : len);
search(s.data(), s.size(), hashes, seen);
search(data_, len, hashes, seen);
size_t tailLen = len <= refLength ? len : refLength;
tail = std::string(tail, tail.size() < refLength - tailLen
? 0
: tail.size() - (refLength - tailLen)) +
std::string(data_ + len - tailLen, tailLen);
}
PathSet scanForReferences(const std::string& path, const PathSet& refs,
HashResult& hash) {
RefScanSink sink;
std::map<std::string, Path> backMap;
/* For efficiency (and a higher hit rate), just search for the
hash part of the file name. (This assumes that all references
have the form `HASH-bla'). */
for (auto& i : refs) {
std::string baseName = baseNameOf(i);
std::string::size_type pos = baseName.find('-');
if (pos == std::string::npos) {
throw Error(format("bad reference '%1%'") % i);
}
std::string s = std::string(baseName, 0, pos);
assert(s.size() == refLength);
assert(backMap.find(s) == backMap.end());
// parseHash(htSHA256, s);
sink.hashes.insert(s);
backMap[s] = i;
}
/* Look for the hashes in the NAR dump of the path. */
dumpPath(path, sink);
/* Map the hashes found back to their store paths. */
PathSet found;
for (auto& i : sink.seen) {
std::map<std::string, Path>::iterator j;
if ((j = backMap.find(i)) == backMap.end()) {
abort();
}
found.insert(j->second);
}
hash = sink.hashSink.finish();
return found;
}
} // namespace nix
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