Add xz compression function

This is used by the Hydra queue runner, but since it may also be
useful for the C++ rewrite of nix-push, I'm putting it here.
This commit is contained in:
Eelco Dolstra 2016-02-15 21:45:56 +01:00
parent bfdacb712c
commit eff5021eaa
2 changed files with 42 additions and 0 deletions

View file

@ -15,6 +15,46 @@ struct LzmaStream
lzma_stream & operator()() { return strm; }
};
std::string compressXZ(const std::string & in)
{
LzmaStream strm;
// FIXME: apply the x86 BCJ filter?
lzma_ret ret = lzma_easy_encoder(
&strm(), 6, LZMA_CHECK_CRC64);
if (ret != LZMA_OK)
throw Error("unable to initialise lzma encoder");
lzma_action action = LZMA_RUN;
uint8_t outbuf[BUFSIZ];
string res;
strm().next_in = (uint8_t *) in.c_str();
strm().avail_in = in.size();
strm().next_out = outbuf;
strm().avail_out = sizeof(outbuf);
while (true) {
if (strm().avail_in == 0)
action = LZMA_FINISH;
lzma_ret ret = lzma_code(&strm(), action);
if (strm().avail_out == 0 || ret == LZMA_STREAM_END) {
res.append((char *) outbuf, sizeof(outbuf) - strm().avail_out);
strm().next_out = outbuf;
strm().avail_out = sizeof(outbuf);
}
if (ret == LZMA_STREAM_END)
return res;
if (ret != LZMA_OK)
throw Error("error while decompressing xz file");
}
}
std::string decompressXZ(const std::string & in)
{
LzmaStream strm;

View file

@ -4,6 +4,8 @@
namespace nix {
std::string compressXZ(const std::string & in);
std::string decompressXZ(const std::string & in);
}