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