diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/examples/xz_pipe_comp.c | 127 | ||||
| -rw-r--r-- | doc/examples/xz_pipe_decomp.c | 115 |
2 files changed, 242 insertions, 0 deletions
diff --git a/doc/examples/xz_pipe_comp.c b/doc/examples/xz_pipe_comp.c new file mode 100644 index 00000000..9f9224bc --- /dev/null +++ b/doc/examples/xz_pipe_comp.c @@ -0,0 +1,127 @@ +/* + * 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; +} + diff --git a/doc/examples/xz_pipe_decomp.c b/doc/examples/xz_pipe_decomp.c new file mode 100644 index 00000000..d4b204d7 --- /dev/null +++ b/doc/examples/xz_pipe_decomp.c @@ -0,0 +1,115 @@ +/* + * xz_pipe_decomp.c + * A simple example of pipe-only xz decompressor 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_decomp.c -o xz_pipe_decomp + * + * Usage example: + * $ cat some_file.xz | ./xz_pipe_decomp > some_file + */ + +#include <stdio.h> +#include <stdint.h> +#include <inttypes.h> +#include <stdbool.h> +#include <lzma.h> + + +/* 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_DECOMPRESSION 4 + + +/* note: in_file and out_file must be open already */ +int xz_decompress (FILE *in_file, FILE *out_file) +{ + lzma_stream strm = LZMA_STREAM_INIT; /* alloc and init lzma_stream struct */ + const uint32_t flags = LZMA_TELL_UNSUPPORTED_CHECK | LZMA_CONCATENATED; + const uint64_t memory_limit = UINT64_MAX; /* no memory limit */ + 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 decoder */ + ret_xz = lzma_stream_decoder (&strm, memory_limit, flags); + if (ret_xz != LZMA_OK) { + fprintf (stderr, "lzma_stream_decoder 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 decompressed data + with LZMA_FINISH */ + action = in_finished ? LZMA_FINISH : LZMA_RUN; + + /* loop until there's no pending decompressed output */ + do { + /* out_buf is clean at this point */ + strm.next_out = out_buf; + strm.avail_out = OUT_BUF_MAX; + + /* decompress 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_DECOMPRESSION; + } else { + /* write decompressed 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_decompress (stdin, stdout); + return ret; +} + |