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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 {
constexpr unsigned int kRefLength = 32; /* characters */
static void search(const unsigned char* s, size_t len, StringSet& hashes,
StringSet& seen) {
static bool initialised = false;
static bool isBase32[256];
if (!initialised) {
for (bool& i : isBase32) {
i = false;
}
for (char base32Char : base32Chars) {
isBase32[static_cast<unsigned char>(base32Char)] = true;
}
initialised = true;
}
for (size_t i = 0; i + kRefLength <= len;) {
int j = 0;
bool match = true;
for (j = kRefLength - 1; j >= 0; --j) {
if (!isBase32[s[i + j]]) {
i += j + 1;
match = false;
break;
}
}
if (!match) {
continue;
}
std::string ref(reinterpret_cast<const char*>(s) + i, kRefLength);
if (hashes.find(ref) != hashes.end()) {
DLOG(INFO) << "found reference to '" << ref << "' at offset " << i;
seen.insert(ref);
hashes.erase(ref);
}
++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);
/* 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(reinterpret_cast<const char*>(data),
len > kRefLength ? kRefLength : len);
search(reinterpret_cast<const unsigned char*>(s.data()), s.size(), hashes,
seen);
search(data, len, hashes, seen);
size_t tailLen = len <= kRefLength ? len : kRefLength;
tail =
std::string(tail, tail.size() < kRefLength - tailLen
? 0
: tail.size() - (kRefLength - tailLen)) +
std::string(reinterpret_cast<const char*>(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() == kRefLength);
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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