122 lines
3.3 KiB
C++
122 lines
3.3 KiB
C++
#include "references.hh"
|
||
#include "hash.hh"
|
||
#include "util.hh"
|
||
#include "archive.hh"
|
||
|
||
#include <map>
|
||
#include <cstdlib>
|
||
|
||
|
||
namespace nix {
|
||
|
||
|
||
static unsigned int refLength = 32; /* characters */
|
||
|
||
|
||
static void search(const unsigned char * s, unsigned int len,
|
||
StringSet & hashes, StringSet & seen)
|
||
{
|
||
static bool initialised = false;
|
||
static bool isBase32[256];
|
||
if (!initialised) {
|
||
for (unsigned int i = 0; i < 256; ++i) isBase32[i] = false;
|
||
for (unsigned int i = 0; i < base32Chars.size(); ++i)
|
||
isBase32[(unsigned char) base32Chars[i]] = true;
|
||
initialised = true;
|
||
}
|
||
|
||
for (unsigned int i = 0; i + refLength <= len; ) {
|
||
int j;
|
||
bool match = true;
|
||
for (j = refLength - 1; j >= 0; --j)
|
||
if (!isBase32[(unsigned char) s[i + j]]) {
|
||
i += j + 1;
|
||
match = false;
|
||
break;
|
||
}
|
||
if (!match) continue;
|
||
string ref((const char *) s + i, refLength);
|
||
if (hashes.find(ref) != hashes.end()) {
|
||
debug(format("found reference to ‘%1%’ at offset ‘%2%’")
|
||
% ref % i);
|
||
seen.insert(ref);
|
||
hashes.erase(ref);
|
||
}
|
||
++i;
|
||
}
|
||
}
|
||
|
||
|
||
struct RefScanSink : Sink
|
||
{
|
||
HashSink hashSink;
|
||
StringSet hashes;
|
||
StringSet seen;
|
||
|
||
string tail;
|
||
|
||
RefScanSink() : hashSink(htSHA256) { }
|
||
|
||
void operator () (const unsigned char * data, size_t len);
|
||
};
|
||
|
||
|
||
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. */
|
||
string s = tail + string((const char *) data, len > refLength ? refLength : len);
|
||
search((const unsigned char *) s.data(), s.size(), hashes, seen);
|
||
|
||
search(data, len, hashes, seen);
|
||
|
||
unsigned int tailLen = len <= refLength ? len : refLength;
|
||
tail =
|
||
string(tail, tail.size() < refLength - tailLen ? 0 : tail.size() - (refLength - tailLen)) +
|
||
string((const char *) data + len - tailLen, tailLen);
|
||
}
|
||
|
||
|
||
PathSet scanForReferences(const string & path,
|
||
const PathSet & refs, HashResult & hash)
|
||
{
|
||
RefScanSink sink;
|
||
std::map<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) {
|
||
string baseName = baseNameOf(i);
|
||
string::size_type pos = baseName.find('-');
|
||
if (pos == string::npos)
|
||
throw Error(format("bad reference ‘%1%’") % i);
|
||
string s = 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<string, Path>::iterator j;
|
||
if ((j = backMap.find(i)) == backMap.end()) abort();
|
||
found.insert(j->second);
|
||
}
|
||
|
||
hash = sink.hashSink.finish();
|
||
|
||
return found;
|
||
}
|
||
|
||
|
||
}
|