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+/*
+ * 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;
+}
+