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/*
* xz_pipe_comp.c
* A simple example of pipe-only xz compressor implementation.
* version: 2010-07-12 - by Daniel Mealha Cabrita
* Not copyrighted -- provided to the public domain.
*
* Compiling:
* Link with liblzma. GCC example:
* $ gcc -llzma xz_pipe_comp.c -o xz_pipe_comp
*
* Usage example:
* $ cat some_file | ./xz_pipe_comp > some_file.xz
*/
#include <stdio.h>
#include <stdint.h>
#include <inttypes.h>
#include <stdbool.h>
#include <lzma.h>
/* COMPRESSION SETTINGS */
/* analogous to xz CLI options: -0 to -9 */
#define COMPRESSION_LEVEL 6
/* boolean setting, analogous to xz CLI option: -e */
#define COMPRESSION_EXTREME true
/* see: /usr/include/lzma/check.h LZMA_CHECK_* */
#define INTEGRITY_CHECK LZMA_CHECK_CRC64
/* read/write buffer sizes */
#define IN_BUF_MAX 4096
#define OUT_BUF_MAX 4096
/* error codes */
#define RET_OK 0
#define RET_ERROR_INIT 1
#define RET_ERROR_INPUT 2
#define RET_ERROR_OUTPUT 3
#define RET_ERROR_COMPRESSION 4
/* note: in_file and out_file must be open already */
int xz_compress (FILE *in_file, FILE *out_file)
{
uint32_t preset = COMPRESSION_LEVEL | (COMPRESSION_EXTREME ? LZMA_PRESET_EXTREME : 0);
lzma_check check = INTEGRITY_CHECK;
lzma_stream strm = LZMA_STREAM_INIT; /* alloc and init lzma_stream struct */
uint8_t in_buf [IN_BUF_MAX];
uint8_t out_buf [OUT_BUF_MAX];
size_t in_len; /* length of useful data in in_buf */
size_t out_len; /* length of useful data in out_buf */
bool in_finished = false;
bool out_finished = false;
lzma_action action;
lzma_ret ret_xz;
int ret;
ret = RET_OK;
/* initialize xz encoder */
ret_xz = lzma_easy_encoder (&strm, preset, check);
if (ret_xz != LZMA_OK) {
fprintf (stderr, "lzma_easy_encoder error: %d\n", (int) ret_xz);
return RET_ERROR_INIT;
}
while ((! in_finished) && (! out_finished)) {
/* read incoming data */
in_len = fread (in_buf, 1, IN_BUF_MAX, in_file);
if (feof (in_file)) {
in_finished = true;
}
if (ferror (in_file)) {
in_finished = true;
ret = RET_ERROR_INPUT;
}
strm.next_in = in_buf;
strm.avail_in = in_len;
/* if no more data from in_buf, flushes the
internal xz buffers and closes the xz data
with LZMA_FINISH */
action = in_finished ? LZMA_FINISH : LZMA_RUN;
/* loop until there's no pending compressed output */
do {
/* out_buf is clean at this point */
strm.next_out = out_buf;
strm.avail_out = OUT_BUF_MAX;
/* compress data */
ret_xz = lzma_code (&strm, action);
if ((ret_xz != LZMA_OK) && (ret_xz != LZMA_STREAM_END)) {
fprintf (stderr, "lzma_code error: %d\n", (int) ret_xz);
out_finished = true;
ret = RET_ERROR_COMPRESSION;
} else {
/* write compressed data */
out_len = OUT_BUF_MAX - strm.avail_out;
fwrite (out_buf, 1, out_len, out_file);
if (ferror (out_file)) {
out_finished = true;
ret = RET_ERROR_OUTPUT;
}
}
} while (strm.avail_out == 0);
}
lzma_end (&strm);
return ret;
}
int main ()
{
int ret;
ret = xz_compress (stdin, stdout);
return ret;
}
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