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unxz.c revision 1.4 
      1 
      2 #include <stdarg.h>
      3 #include <errno.h>
      4 #include <stdio.h>
      5 #include <unistd.h>
      6 #include <lzma.h>
      7 
      8 static off_t
      9 unxz(int i, int o, char *pre, size_t prelen, off_t *bytes_in)
     10 {
     11 	lzma_stream strm = LZMA_STREAM_INIT;
     12 	static const int flags = LZMA_TELL_UNSUPPORTED_CHECK|LZMA_CONCATENATED;
     13 	lzma_ret ret;
     14 	lzma_action action = LZMA_RUN;
     15 	off_t bytes_out, bp;
     16 	uint8_t ibuf[BUFSIZ];
     17 	uint8_t obuf[BUFSIZ];
     18 
     19 	if (bytes_in == NULL)
     20 		bytes_in = &bp;
     21 
     22 	strm.next_in = ibuf;
     23 	memcpy(ibuf, pre, prelen);
     24 	strm.avail_in = read(i, ibuf + prelen, sizeof(ibuf) - prelen);
     25 	if (strm.avail_in == (size_t)-1)
     26 		maybe_err("read failed");
     27 	strm.avail_in += prelen;
     28 	*bytes_in = strm.avail_in;
     29 
     30 	if ((ret = lzma_stream_decoder(&strm, UINT64_MAX, flags)) != LZMA_OK)
     31 		maybe_errx("Can't initialize decoder (%d)", ret);
     32 
     33 	strm.next_out = NULL;
     34 	strm.avail_out = 0;
     35 	if ((ret = lzma_code(&strm, LZMA_RUN)) != LZMA_OK)
     36 		maybe_errx("Can't read headers (%d)", ret);
     37 
     38 	bytes_out = 0;
     39 	strm.next_out = obuf;
     40 	strm.avail_out = sizeof(obuf);
     41 
     42 	for (;;) {
     43 		if (strm.avail_in == 0) {
     44 			strm.next_in = ibuf;
     45 			strm.avail_in = read(i, ibuf, sizeof(ibuf));
     46 			switch (strm.avail_in) {
     47 			case (size_t)-1:
     48 				maybe_err("read failed");
     49 				/*NOTREACHED*/
     50 			case 0:
     51 				action = LZMA_FINISH;
     52 				break;
     53 			default:
     54 				*bytes_in += strm.avail_in;
     55 				break;
     56 			}
     57 		}
     58 
     59 		ret = lzma_code(&strm, action);
     60 
     61 		// Write and check write error before checking decoder error.
     62 		// This way as much data as possible gets written to output
     63 		// even if decoder detected an error.
     64 		if (strm.avail_out == 0 || ret != LZMA_OK) {
     65 			const size_t write_size = sizeof(obuf) - strm.avail_out;
     66 
     67 			if (write(o, obuf, write_size) != (ssize_t)write_size)
     68 				maybe_err("write failed");
     69 
     70 			strm.next_out = obuf;
     71 			strm.avail_out = sizeof(obuf);
     72 			bytes_out += write_size;
     73 		}
     74 
     75 		if (ret != LZMA_OK) {
     76 			if (ret == LZMA_STREAM_END) {
     77 				// Check that there's no trailing garbage.
     78 				if (strm.avail_in != 0 || read(i, ibuf, 1))
     79 					ret = LZMA_DATA_ERROR;
     80 				else {
     81 					lzma_end(&strm);
     82 					return bytes_out;
     83 				}
     84 			}
     85 
     86 			const char *msg;
     87 			switch (ret) {
     88 			case LZMA_MEM_ERROR:
     89 				msg = strerror(ENOMEM);
     90 				break;
     91 
     92 			case LZMA_FORMAT_ERROR:
     93 				msg = "File format not recognized";
     94 				break;
     95 
     96 			case LZMA_OPTIONS_ERROR:
     97 				// FIXME: Better message?
     98 				msg = "Unsupported compression options";
     99 				break;
    100 
    101 			case LZMA_DATA_ERROR:
    102 				msg = "File is corrupt";
    103 				break;
    104 
    105 			case LZMA_BUF_ERROR:
    106 				msg = "Unexpected end of input";
    107 				break;
    108 
    109 			case LZMA_MEMLIMIT_ERROR:
    110 				msg = "Reached memory limit";
    111 				break;
    112 
    113 			default:
    114 				maybe_errx("Unknown error (%d)", ret);
    115 				break;
    116 			}
    117 			maybe_errx("%s", msg);
    118 
    119 		}
    120 	}
    121 }
    122