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authorLasse Collin <lasse.collin@tukaani.org>2012-06-14 10:52:33 +0300
committerLasse Collin <lasse.collin@tukaani.org>2012-06-22 09:31:42 +0300
commitef8b8e5f111469b5bc005975f7abb9abbd372b25 (patch)
treeaee6d9b35b2414719e696b225d8f43b82d522a17
parentDocs: Move xz_pipe_comp.c and xz_pipe_decomp.c to doc/examples_old. (diff)
downloadxz-ef8b8e5f111469b5bc005975f7abb9abbd372b25.tar.xz
Docs: Add new example programs.
These have more comments than the old examples and human-readable error messages. More tutorial-like examples are needed but these are a start.
-rw-r--r--doc/examples/00_README.txt27
-rw-r--r--doc/examples/01_compress_easy.c297
-rw-r--r--doc/examples/02_decompress.c287
-rw-r--r--doc/examples/03_compress_custom.c193
-rw-r--r--doc/examples/Makefile23
5 files changed, 827 insertions, 0 deletions
diff --git a/doc/examples/00_README.txt b/doc/examples/00_README.txt
new file mode 100644
index 00000000..a3b9eaa1
--- /dev/null
+++ b/doc/examples/00_README.txt
@@ -0,0 +1,27 @@
+
+liblzma example programs
+========================
+
+Introduction
+
+ The examples are written so that the same comments aren't
+ repeated (much) in later files.
+
+ On POSIX systems, the examples should build by just typing "make".
+
+ The examples that use stdin or stdout don't set stdin and stdout
+ to binary mode. On systems where it matters (e.g. Windows) it is
+ possible that the examples won't work without modification.
+
+
+List of examples
+
+ 01_compress_easy.c Multi-call compression using
+ a compression preset
+
+ 02_decompress.c Multi-call decompression
+
+ 03_compress_custom.c Like 01_compress_easy.c but using
+ a custom filter chain
+ (x86 BCJ + LZMA2)
+
diff --git a/doc/examples/01_compress_easy.c b/doc/examples/01_compress_easy.c
new file mode 100644
index 00000000..f79cade1
--- /dev/null
+++ b/doc/examples/01_compress_easy.c
@@ -0,0 +1,297 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file 01_compress_easy.c
+/// \brief Compress from stdin to stdout in multi-call mode
+///
+/// Usage: ./01_compress_easy PRESET < INFILE > OUTFILE
+///
+/// Example: ./01_compress_easy 6 < foo > foo.xz
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <lzma.h>
+
+
+static void
+show_usage_and_exit(const char *argv0)
+{
+ fprintf(stderr, "Usage: %s PRESET < INFILE > OUTFILE\n"
+ "PRESET is a number 0-9 and can optionally be "
+ "by `e' to indicate extreme preset\n",
+ argv0);
+ exit(EXIT_FAILURE);
+}
+
+
+static uint32_t
+get_preset(int argc, char **argv)
+{
+ // One argument whose first char must be 0-9.
+ if (argc != 2 || argv[1][0] < '0' || argv[1][0] > '9')
+ show_usage_and_exit(argv[0]);
+
+ // Calculate the preste level 0-9.
+ uint32_t preset = argv[1][0] - '0';
+
+ // If there is a second char, it must be 'e'. It will set
+ // the LZMA_PRESET_EXTREME flag.
+ if (argv[1][1] != '\0') {
+ if (argv[1][1] != 'e' || argv[1][2] != '\0')
+ show_usage_and_exit(argv[0]);
+
+ preset |= LZMA_PRESET_EXTREME;
+ }
+
+ return preset;
+}
+
+
+static bool
+init_encoder(lzma_stream *strm, uint32_t preset)
+{
+ // Initialize the encoder using a preset. Set the integrity to check
+ // to CRC64, which is the default in the xz command line tool. If
+ // the .xz file needs to be decompressed with XZ Embedded, use
+ // LZMA_CHECK_CRC32 instead.
+ lzma_ret ret = lzma_easy_encoder(strm, preset, LZMA_CHECK_CRC64);
+
+ // Return successfully if the initialization went fine.
+ if (ret == LZMA_OK)
+ return true;
+
+ // Something went wrong. The possible errors are documented in
+ // lzma/container.h (src/liblzma/api/lzma/container.h in the source
+ // package or e.g. /usr/include/lzma/container.h depending on the
+ // install prefix).
+ const char *msg;
+ switch (ret) {
+ case LZMA_MEM_ERROR:
+ msg = "Memory allocation failed";
+ break;
+
+ case LZMA_OPTIONS_ERROR:
+ msg = "Specified preset is not supported";
+ break;
+
+ case LZMA_UNSUPPORTED_CHECK:
+ msg = "Specified integrity check is not supported";
+ break;
+
+ default:
+ // This is most likely LZMA_PROG_ERROR indicating a bug in
+ // this program or in liblzma. It is inconvenient to have a
+ // separate error message for errors that should be impossible
+ // to occur, but knowing the error code is important for
+ // debugging. That's why it is good to print the error code
+ // at least when there is no good error message to show.
+ msg = "Unknown error, possibly a bug";
+ break;
+ }
+
+ fprintf(stderr, "Error initializing the encoder: %s (error code %u)\n",
+ msg, ret);
+ return false;
+}
+
+
+static bool
+compress(lzma_stream *strm, FILE *infile, FILE *outfile)
+{
+ // This will be LZMA_RUN until the end of the input file is reached.
+ // This tells lzma_code() when there will be no more input.
+ lzma_action action = LZMA_RUN;
+
+ // Buffers to temporarily hold uncompressed input
+ // and compressed output.
+ uint8_t inbuf[BUFSIZ];
+ uint8_t outbuf[BUFSIZ];
+
+ // Initialize the input and output pointers. Initializing next_in
+ // and avail_in isn't really necessary when we are going to encode
+ // just one file since LZMA_STREAM_INIT takes care of initializing
+ // those already. But it doesn't hurt much and it will be needed
+ // if encoding more than one file like we will in 02_decompress.c.
+ //
+ // While we don't care about strm->total_in or strm->total_out in this
+ // example, it is worth noting that initializing the encoder will
+ // always reset total_in and total_out to zero. But the encoder
+ // initialization doesn't touch next_in, avail_in, next_out, or
+ // avail_out.
+ strm->next_in = NULL;
+ strm->avail_in = 0;
+ strm->next_out = outbuf;
+ strm->avail_out = sizeof(outbuf);
+
+ // Loop until the file has been successfully compressed or until
+ // an error occurs.
+ while (true) {
+ // Fill the input buffer if it is empty.
+ if (strm->avail_in == 0 && !feof(infile)) {
+ strm->next_in = inbuf;
+ strm->avail_in = fread(inbuf, 1, sizeof(inbuf),
+ infile);
+
+ if (ferror(infile)) {
+ fprintf(stderr, "Read error: %s\n",
+ strerror(errno));
+ return false;
+ }
+
+ // Once the end of the input file has been reached,
+ // we need to tell lzma_code() that no more input
+ // will be coming and that it should finish the
+ // encoding.
+ if (feof(infile))
+ action = LZMA_FINISH;
+ }
+
+ // Tell liblzma do the actual encoding.
+ //
+ // This reads up to strm->avail_in bytes of input starting
+ // from strm->next_in. avail_in will be decremented and
+ // next_in incremented by an equal amount to match the
+ // number of input bytes consumed.
+ //
+ // Up to strm->avail_out bytes of compressed output will be
+ // written starting from strm->next_out. avail_out and next_out
+ // will be incremented by an equal amount to match the number
+ // of output bytes written.
+ //
+ // The encoder has to do internal buffering, which means that
+ // it may take quite a bit of input before the same data is
+ // available in compressed form in the output buffer.
+ lzma_ret ret = lzma_code(strm, action);
+
+ // If the output buffer is full or if the compression finished
+ // successfully, write the data from the output bufffer to
+ // the output file.
+ if (strm->avail_out == 0 || ret == LZMA_STREAM_END) {
+ // When lzma_code() has returned LZMA_STREAM_END,
+ // the output buffer is likely to be only partially
+ // full. Calculate how much new data there is to
+ // be written to the output file.
+ size_t write_size = sizeof(outbuf) - strm->avail_out;
+
+ if (fwrite(outbuf, 1, write_size, outfile)
+ != write_size) {
+ fprintf(stderr, "Write error: %s\n",
+ strerror(errno));
+ return false;
+ }
+
+ // Reset next_out and avail_out.
+ strm->next_out = outbuf;
+ strm->avail_out = sizeof(outbuf);
+ }
+
+ // Normally the return value of lzma_code() will be LZMA_OK
+ // until everything has been encoded.
+ if (ret != LZMA_OK) {
+ // Once everything has been encoded successfully, the
+ // return value of lzma_code() will be LZMA_STREAM_END.
+ //
+ // It is important to check for LZMA_STREAM_END. Do not
+ // assume that getting ret != LZMA_OK would mean that
+ // everything has gone well.
+ if (ret == LZMA_STREAM_END)
+ return true;
+
+ // It's not LZMA_OK nor LZMA_STREAM_END,
+ // so it must be an error code. See lzma/base.h
+ // (src/liblzma/api/lzma/base.h in the source package
+ // or e.g. /usr/include/lzma/base.h depending on the
+ // install prefix) for the list and documentation of
+ // possible values. Most values listen in lzma_ret
+ // enumeration aren't possible in this example.
+ const char *msg;
+ switch (ret) {
+ case LZMA_MEM_ERROR:
+ msg = "Memory allocation failed";
+ break;
+
+ case LZMA_DATA_ERROR:
+ // This error is returned if the compressed
+ // or uncompressed size get near 8 EiB
+ // (2^63 bytes) because that's where the .xz
+ // file format size limits currently are.
+ // That is, the possibility of this error
+ // is mostly theoretical unless you are doing
+ // something very unusual.
+ //
+ // Note that strm->total_in and strm->total_out
+ // have nothing to do with this error. Changing
+ // those variables won't increase or decrease
+ // the chance of getting this error.
+ msg = "File size limits exceeded";
+ break;
+
+ default:
+ // This is most likely LZMA_PROG_ERROR, but
+ // if this program is buggy (or liblzma has
+ // a bug), it may be e.g. LZMA_BUF_ERROR or
+ // LZMA_OPTIONS_ERROR too.
+ //
+ // It is inconvenient to have a separate
+ // error message for errors that should be
+ // impossible to occur, but knowing the error
+ // code is important for debugging. That's why
+ // it is good to print the error code at least
+ // when there is no good error message to show.
+ msg = "Unknown error, possibly a bug";
+ break;
+ }
+
+ fprintf(stderr, "Encoder error: %s (error code %u)\n",
+ msg, ret);
+ return false;
+ }
+ }
+}
+
+
+extern int
+main(int argc, char **argv)
+{
+ // Get the preset number from the command line.
+ uint32_t preset = get_preset(argc, argv);
+
+ // Initialize a lzma_stream structure. When it is allocated on stack,
+ // it is simplest to use LZMA_STREAM_INIT macro like below. When it
+ // is allocated on heap, using memset(strmptr, 0, sizeof(*strmptr))
+ // works (as long as NULL pointers are represented with zero bits
+ // as they are on practically all computers today).
+ lzma_stream strm = LZMA_STREAM_INIT;
+
+ // Initialize the encoder. If it succeeds, compress from
+ // stdin to stdout.
+ bool success = init_encoder(&strm, preset);
+ if (success)
+ success = compress(&strm, stdin, stdout);
+
+ // Free the memory allocated for the encoder. If we were encoding
+ // multiple files, this would only need to be done after the last
+ // file. See 02_decompress.c for handling of multiple files.
+ //
+ // It is OK to call lzma_end() multiple times or when it hasn't been
+ // actually used except initialized with LZMA_STREAM_INIT.
+ lzma_end(&strm);
+
+ // Close stdout to catch possible write errors that can occur
+ // when pending data is flushed from the stdio buffers.
+ if (fclose(stdout)) {
+ fprintf(stderr, "Write error: %s\n", strerror(errno));
+ success = false;
+ }
+
+ return success ? EXIT_SUCCESS : EXIT_FAILURE;
+}
diff --git a/doc/examples/02_decompress.c b/doc/examples/02_decompress.c
new file mode 100644
index 00000000..4c0f37cb
--- /dev/null
+++ b/doc/examples/02_decompress.c
@@ -0,0 +1,287 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file 02_decompress.c
+/// \brief Decompress .xz files to stdout
+///
+/// Usage: ./02_decompress INPUT_FILES... > OUTFILE
+///
+/// Example: ./02_decompress foo.xz bar.xz > foobar
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <lzma.h>
+
+
+static bool
+init_decoder(lzma_stream *strm)
+{
+ // Initialize a .xz decoder. The decoder supports a memory usage limit
+ // and a set of flags.
+ //
+ // The memory usage of the decompressor depends on the settings used
+ // to compress a .xz file. It can vary from less than a megabyte to
+ // a few gigabytes, but in practice (at least for now) it rarely
+ // exceeds 65 MiB because that's how much memory is required to
+ // decompress files created with "xz -9". Settings requiring more
+ // memory take extra effort to use and don't (at least for now)
+ // provide significantly better compression in most cases.
+ //
+ // Memory usage limit is useful if it is important that the
+ // decompressor won't consume gigabytes of memory. The need
+ // for limiting depends on the application. In this example,
+ // no memory usage limiting is used. This is done by setting
+ // the limit to UINT64_MAX.
+ //
+ // The .xz format allows concatenating compressed files as is:
+ //
+ // echo foo | xz > foobar.xz
+ // echo bar | xz >> foobar.xz
+ //
+ // When decompressing normal standalone .xz files, LZMA_CONCATENATED
+ // should always be used to support decompression of concatenated
+ // .xz files. If LZMA_CONCATENATED isn't used, the decoder will stop
+ // after the first .xz stream. This can be useful when .xz data has
+ // been embedded inside another file format.
+ //
+ // Flags other than LZMA_CONCATENATED are supported too, and can
+ // be combined with bitwise-or. See lzma/container.h
+ // (src/liblzma/api/lzma/container.h in the source package or e.g.
+ // /usr/include/lzma/container.h depending on the install prefix)
+ // for details.
+ lzma_ret ret = lzma_stream_decoder(
+ strm, UINT64_MAX, LZMA_CONCATENATED);
+
+ // Return successfully if the initialization went fine.
+ if (ret == LZMA_OK)
+ return true;
+
+ // Something went wrong. The possible errors are documented in
+ // lzma/container.h (src/liblzma/api/lzma/container.h in the source
+ // package or e.g. /usr/include/lzma/container.h depending on the
+ // install prefix).
+ //
+ // Note that LZMA_MEMLIMIT_ERROR is never possible here. If you
+ // specify a very tiny limit, the error will be delayed until
+ // the first headers have been parsed by a call to lzma_code().
+ const char *msg;
+ switch (ret) {
+ case LZMA_MEM_ERROR:
+ msg = "Memory allocation failed";
+ break;
+
+ case LZMA_OPTIONS_ERROR:
+ msg = "Unsupported decompressor flags";
+ break;
+
+ default:
+ // This is most likely LZMA_PROG_ERROR indicating a bug in
+ // this program or in liblzma. It is inconvenient to have a
+ // separate error message for errors that should be impossible
+ // to occur, but knowing the error code is important for
+ // debugging. That's why it is good to print the error code
+ // at least when there is no good error message to show.
+ msg = "Unknown error, possibly a bug";
+ break;
+ }
+
+ fprintf(stderr, "Error initializing the decoder: %s (error code %u)\n",
+ msg, ret);
+ return false;
+}
+
+
+static bool
+decompress(lzma_stream *strm, const char *inname, FILE *infile, FILE *outfile)
+{
+ // When LZMA_CONCATENATED flag was used when initializing the decoder,
+ // we need to tell lzma_code() when there will be no more input.
+ // This is done by setting action to LZMA_FINISH instead of LZMA_RUN
+ // in the same way as it is done when encoding.
+ //
+ // When LZMA_CONCATENATED isn't used, there is no need to use
+ // LZMA_FINISH to tell when all the input has been read, but it
+ // is still OK to use it if you want. When LZMA_CONCATENATED isn't
+ // used, the decoder will stop after the first .xz stream. In that
+ // case some unused data may be left in strm->next_in.
+ lzma_action action = LZMA_RUN;
+
+ uint8_t inbuf[BUFSIZ];
+ uint8_t outbuf[BUFSIZ];
+
+ strm->next_in = NULL;
+ strm->avail_in = 0;
+ strm->next_out = outbuf;
+ strm->avail_out = sizeof(outbuf);
+
+ while (true) {
+ if (strm->avail_in == 0 && !feof(infile)) {
+ strm->next_in = inbuf;
+ strm->avail_in = fread(inbuf, 1, sizeof(inbuf),
+ infile);
+
+ if (ferror(infile)) {
+ fprintf(stderr, "%s: Read error: %s\n",
+ inname, strerror(errno));
+ return false;
+ }
+
+ // Once the end of the input file has been reached,
+ // we need to tell lzma_code() that no more input
+ // will be coming. As said before, this isn't required
+ // if the LZMA_CONATENATED flag isn't used when
+ // initializing the decoder.
+ if (feof(infile))
+ action = LZMA_FINISH;
+ }
+
+ lzma_ret ret = lzma_code(strm, action);
+
+ if (strm->avail_out == 0 || ret == LZMA_STREAM_END) {
+ size_t write_size = sizeof(outbuf) - strm->avail_out;
+
+ if (fwrite(outbuf, 1, write_size, outfile)
+ != write_size) {
+ fprintf(stderr, "Write error: %s\n",
+ strerror(errno));
+ return false;
+ }
+
+ strm->next_out = outbuf;
+ strm->avail_out = sizeof(outbuf);
+ }
+
+ if (ret != LZMA_OK) {
+ // Once everything has been decoded successfully, the
+ // return value of lzma_code() will be LZMA_STREAM_END.
+ //
+ // It is important to check for LZMA_STREAM_END. Do not
+ // assume that getting ret != LZMA_OK would mean that
+ // everything has gone well or that when you aren't
+ // getting more output it must have successfully
+ // decoded everything.
+ if (ret == LZMA_STREAM_END)
+ return true;
+
+ // It's not LZMA_OK nor LZMA_STREAM_END,
+ // so it must be an error code. See lzma/base.h
+ // (src/liblzma/api/lzma/base.h in the source package
+ // or e.g. /usr/include/lzma/base.h depending on the
+ // install prefix) for the list and documentation of
+ // possible values. Many values listen in lzma_ret
+ // enumeration aren't possible in this example, but
+ // can be made possible by enabling memory usage limit
+ // or adding flags to the decoder initialization.
+ const char *msg;
+ switch (ret) {
+ case LZMA_MEM_ERROR:
+ msg = "Memory allocation failed";
+ break;
+
+ case LZMA_FORMAT_ERROR:
+ // .xz magic bytes weren't found.
+ msg = "The input is not in the .xz format";
+ break;
+
+ case LZMA_OPTIONS_ERROR:
+ // For example, the headers specify a filter
+ // that isn't supported by this liblzma
+ // version (or it hasn't been enabled when
+ // building liblzma, but no-one sane does
+ // that unless building liblzma for an
+ // embedded system). Upgrading to a newer
+ // liblzma might help.
+ //
+ // Note that it is unlikely that the file has
+ // accidentally became corrupt if you get this
+ // error. The integrity of the .xz headers is
+ // always verified with a CRC32, so
+ // unintentionally corrupt files can be
+ // distinguished from unsupported files.
+ msg = "Unsupported compression options";
+ break;
+
+ case LZMA_DATA_ERROR:
+ msg = "Compressed file is corrupt";
+ break;
+
+ case LZMA_BUF_ERROR:
+ // Typically this error means that a valid
+ // file has got truncated, but it might also
+ // be a damaged part in the file that makes
+ // the decoder think the file is truncated.
+ // If you prefer, you can use the same error
+ // message for this as for LZMA_DATA_ERROR.
+ msg = "Compressed file is truncated or "
+ "otherwise corrupt";
+ break;
+
+ default:
+ // This is most likely LZMA_PROG_ERROR.
+ msg = "Unknown error, possibly a bug";
+ break;
+ }
+
+ fprintf(stderr, "%s: Decoder error: "
+ "%s (error code %u)\n",
+ inname, msg, ret);
+ return false;
+ }
+ }
+}
+
+
+extern int
+main(int argc, char **argv)
+{
+ if (argc <= 1) {
+ fprintf(stderr, "Usage: %s FILES...\n", argv[0]);
+ return EXIT_FAILURE;
+ }
+
+ lzma_stream strm = LZMA_STREAM_INIT;
+
+ bool success = true;
+
+ // Try to decompress all files.
+ for (int i = 1; i < argc; ++i) {
+ if (!init_decoder(&strm)) {
+ // Decoder initialization failed. There's no point
+ // to retry it so we need to exit.
+ success = false;
+ break;
+ }
+
+ FILE *infile = fopen(argv[i], "rb");
+
+ if (infile == NULL) {
+ fprintf(stderr, "%s: Error opening the "
+ "input file: %s\n",
+ argv[i], strerror(errno));
+ success = false;
+ } else {
+ success &= decompress(&strm, argv[i], infile, stdout);
+ fclose(infile);
+ }
+ }
+
+ // Free the memory allocated for the decoder. This only needs to be
+ // done after the last file.
+ lzma_end(&strm);
+
+ if (fclose(stdout)) {
+ fprintf(stderr, "Write error: %s\n", strerror(errno));
+ success = false;
+ }
+
+ return success ? EXIT_SUCCESS : EXIT_FAILURE;
+}
diff --git a/doc/examples/03_compress_custom.c b/doc/examples/03_compress_custom.c
new file mode 100644
index 00000000..51abbb17
--- /dev/null
+++ b/doc/examples/03_compress_custom.c
@@ -0,0 +1,193 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file 03_compress_custom.c
+/// \brief Compress in multi-call mode using x86 BCJ and LZMA2
+///
+/// Usage: ./03_compress_custom < INFILE > OUTFILE
+///
+/// Example: ./03_compress_custom < foo > foo.xz
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <lzma.h>
+
+
+static bool
+init_encoder(lzma_stream *strm)
+{
+ // Use the default preset (6) for LZMA2.
+ //
+ // The lzma_options_lzma structure and the lzma_lzma_preset() function
+ // are declared in lzma/lzma.h (src/liblzma/api/lzma/lzma.h in the
+ // source package or e.g. /usr/include/lzma/lzma.h depending on
+ // the install prefix).
+ lzma_options_lzma opt_lzma2;
+ if (lzma_lzma_preset(&opt_lzma2, LZMA_PRESET_DEFAULT)) {
+ // It should never fail because the default preset
+ // (and presets 0-9 optionally with LZMA_PRESET_EXTREME)
+ // are supported by all stable liblzma versions.
+ //
+ // (The encoder initialization later in this function may
+ // still fail due to unsupported preset *if* the features
+ // required by the preset have been disabled at build time,
+ // but no-one does such things except on embedded systems.)
+ fprintf(stderr, "Unsupported preset, possibly a bug\n");
+ return false;
+ }
+
+ // Now we could customize the LZMA2 options if we wanted. For example,
+ // we could set the the dictionary size (opt_lzma2.dict_size) to
+ // something else than the default (8 MiB) of the default preset.
+ // See lzma/lzma.h for details of all LZMA2 options.
+ //
+ // The x86 BCJ filter will try to modify the x86 instruction stream so
+ // that LZMA2 can compress it better. The x86 BCJ filter doesn't need
+ // any options so it will be set to NULL below.
+ //
+ // Construct the filter chain. The uncompressed data goes first to
+ // the first filter in the array, in this case the x86 BCJ filter.
+ // The array is always terminated by setting .id = LZMA_VLI_UNKNOWN.
+ //
+ // See lzma/filter.h for more information about the lzma_filter
+ // structure.
+ lzma_filter filters[] = {
+ { .id = LZMA_FILTER_X86, .options = NULL },
+ { .id = LZMA_FILTER_LZMA2, .options = &opt_lzma2 },
+ { .id = LZMA_VLI_UNKNOWN, .options = NULL },
+ };
+
+ // Initialize the encoder using the custom filter chain.
+ lzma_ret ret = lzma_stream_encoder(strm, filters, LZMA_CHECK_CRC64);
+
+ if (ret == LZMA_OK)
+ return true;
+
+ const char *msg;
+ switch (ret) {
+ case LZMA_MEM_ERROR:
+ msg = "Memory allocation failed";
+ break;
+
+ case LZMA_OPTIONS_ERROR:
+ // We are no longer using a plain preset so this error
+ // message has been edited accordingly compared to
+ // 01_compress_easy.c.
+ msg = "Specified filter chain is not supported";
+ break;
+
+ case LZMA_UNSUPPORTED_CHECK:
+ msg = "Specified integrity check is not supported";
+ break;
+
+ default:
+ msg = "Unknown error, possibly a bug";
+ break;
+ }
+
+ fprintf(stderr, "Error initializing the encoder: %s (error code %u)\n",
+ msg, ret);
+ return false;
+}
+
+
+// This function is identical to the one in 01_compress_easy.c.
+static bool
+compress(lzma_stream *strm, FILE *infile, FILE *outfile)
+{
+ lzma_action action = LZMA_RUN;
+
+ uint8_t inbuf[BUFSIZ];
+ uint8_t outbuf[BUFSIZ];
+
+ strm->next_in = NULL;
+ strm->avail_in = 0;
+ strm->next_out = outbuf;
+ strm->avail_out = sizeof(outbuf);
+
+ while (true) {
+ if (strm->avail_in == 0 && !feof(infile)) {
+ strm->next_in = inbuf;
+ strm->avail_in = fread(inbuf, 1, sizeof(inbuf),
+ infile);
+
+ if (ferror(infile)) {
+ fprintf(stderr, "Read error: %s\n",
+ strerror(errno));
+ return false;
+ }
+
+ if (feof(infile))
+ action = LZMA_FINISH;
+ }
+
+ lzma_ret ret = lzma_code(strm, action);
+
+ if (strm->avail_out == 0 || ret == LZMA_STREAM_END) {
+ size_t write_size = sizeof(outbuf) - strm->avail_out;
+
+ if (fwrite(outbuf, 1, write_size, outfile)
+ != write_size) {
+ fprintf(stderr, "Write error: %s\n",
+ strerror(errno));
+ return false;
+ }
+
+ strm->next_out = outbuf;
+ strm->avail_out = sizeof(outbuf);
+ }
+
+ if (ret != LZMA_OK) {
+ if (ret == LZMA_STREAM_END)
+ return true;
+
+ const char *msg;
+ switch (ret) {
+ case LZMA_MEM_ERROR:
+ msg = "Memory allocation failed";
+ break;
+
+ case LZMA_DATA_ERROR:
+ msg = "File size limits exceeded";
+ break;
+
+ default:
+ msg = "Unknown error, possibly a bug";
+ break;
+ }
+
+ fprintf(stderr, "Encoder error: %s (error code %u)\n",
+ msg, ret);
+ return false;
+ }
+ }
+}
+
+
+extern int
+main(void)
+{
+ lzma_stream strm = LZMA_STREAM_INIT;
+
+ bool success = init_encoder(&strm);
+ if (success)
+ success = compress(&strm, stdin, stdout);
+
+ lzma_end(&strm);
+
+ if (fclose(stdout)) {
+ fprintf(stderr, "Write error: %s\n", strerror(errno));
+ success = false;
+ }
+
+ return success ? EXIT_SUCCESS : EXIT_FAILURE;
+}
diff --git a/doc/examples/Makefile b/doc/examples/Makefile
new file mode 100644
index 00000000..644dc32e
--- /dev/null
+++ b/doc/examples/Makefile
@@ -0,0 +1,23 @@
+#
+# Author: Lasse Collin
+#
+# This file has been put into the public domain.
+# You can do whatever you want with this file.
+#
+
+CC = c99
+CFLAGS = -g
+LDFLAGS = -llzma
+
+PROGS = \
+ 01_compress_easy \
+ 02_decompress \
+ 03_compress_custom
+
+all: $(PROGS)
+
+.c:
+ $(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)
+
+clean:
+ -rm -f $(PROGS)