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#include "compression.hh"
#include "util.hh"
#include <lzma.h>
#include <cstdio>
namespace nix {
/* RAII wrapper around lzma_stream. */
struct LzmaStream
{
lzma_stream strm;
LzmaStream() : strm(LZMA_STREAM_INIT) { };
~LzmaStream() { lzma_end(&strm); };
lzma_stream & operator()() { return strm; }
};
static ref<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];
ref<std::string> res = make_ref<std::string>();
strm().next_in = (uint8_t *) in.c_str();
strm().avail_in = in.size();
strm().next_out = outbuf;
strm().avail_out = sizeof(outbuf);
while (true) {
checkInterrupt();
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");
}
}
static ref<std::string> decompressXZ(const std::string & in)
{
LzmaStream strm;
lzma_ret ret = lzma_stream_decoder(
&strm(), UINT64_MAX, LZMA_CONCATENATED);
if (ret != LZMA_OK)
throw Error("unable to initialise lzma decoder");
lzma_action action = LZMA_RUN;
uint8_t outbuf[BUFSIZ];
ref<std::string> res = make_ref<std::string>();
strm().next_in = (uint8_t *) in.c_str();
strm().avail_in = in.size();
strm().next_out = outbuf;
strm().avail_out = sizeof(outbuf);
while (true) {
checkInterrupt();
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");
}
}
ref<std::string> compress(const std::string & method, ref<std::string> in)
{
if (method == "none")
return in;
else if (method == "xz")
return compressXZ(*in);
else
throw UnknownCompressionMethod(format("unknown compression method ‘%s’") % method);
}
ref<std::string> decompress(const std::string & method, ref<std::string> in)
{
if (method == "none")
return in;
else if (method == "xz")
return decompressXZ(*in);
else
throw UnknownCompressionMethod(format("unknown compression method ‘%s’") % method);
}
}
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