gzip.c revision 25b3c049e70834cf33790a28643ab058b507b35c 
1/* Decompression support for libdwfl: zlib (gzip) and/or bzlib (bzip2).
2   Copyright (C) 2009 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4
5   Red Hat elfutils is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by the
7   Free Software Foundation; version 2 of the License.
8
9   Red Hat elfutils is distributed in the hope that it will be useful, but
10   WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   General Public License for more details.
13
14   You should have received a copy of the GNU General Public License along
15   with Red Hat elfutils; if not, write to the Free Software Foundation,
16   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
17
18   In addition, as a special exception, Red Hat, Inc. gives You the
19   additional right to link the code of Red Hat elfutils with code licensed
20   under any Open Source Initiative certified open source license
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25   those well defined interfaces identified in the file named EXCEPTION
26   found in the source code files (the "Approved Interfaces").  The files
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31   Red Hat's grant of this exception is conditioned upon your not adding
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33   exception, please contact Red Hat.  You must obey the GNU General Public
34   License in all respects for all of the Red Hat elfutils code and other
35   code used in conjunction with Red Hat elfutils except the Non-GPL Code
36   covered by this exception.  If you modify this file, you may extend this
37   exception to your version of the file, but you are not obligated to do
38   so.  If you do not wish to provide this exception without modification,
39   you must delete this exception statement from your version and license
40   this file solely under the GPL without exception.
41
42   Red Hat elfutils is an included package of the Open Invention Network.
43   An included package of the Open Invention Network is a package for which
44   Open Invention Network licensees cross-license their patents.  No patent
45   license is granted, either expressly or impliedly, by designation as an
46   included package.  Should you wish to participate in the Open Invention
47   Network licensing program, please visit www.openinventionnetwork.com
48   <http://www.openinventionnetwork.com>.  */
49
50#include "libdwflP.h"
51#include "system.h"
52
53#include <unistd.h>
54
55#ifdef LZMA
56# define USE_INFLATE	1
57# include <lzma.h>
58# define unzip		__libdw_unlzma
59# define DWFL_E_ZLIB	DWFL_E_LZMA
60# define MAGIC		"\xFD" "7zXZ\0" /* XZ file format.  */
61# define MAGIC2		"\x5d\0"	/* Raw LZMA format.  */
62# define Z(what)	LZMA_##what
63# define LZMA_ERRNO	LZMA_PROG_ERROR
64# define z_stream	lzma_stream
65# define inflateInit(z)	lzma_auto_decoder (z, 1 << 30, 0)
66# define do_inflate(z)	lzma_code (z, LZMA_RUN)
67# define inflateEnd(z)	lzma_end (z)
68#elif defined BZLIB
69# define USE_INFLATE	1
70# include <bzlib.h>
71# define unzip		__libdw_bunzip2
72# define DWFL_E_ZLIB	DWFL_E_BZLIB
73# define MAGIC		"BZh"
74# define Z(what)	BZ_##what
75# define BZ_ERRNO	BZ_IO_ERROR
76# define z_stream	bz_stream
77# define inflateInit(z)	BZ2_bzDecompressInit (z, 0, 0)
78# define do_inflate(z)	BZ2_bzDecompress (z)
79# define inflateEnd(z)	BZ2_bzDecompressEnd (z)
80#else
81# define USE_INFLATE	0
82# define crc32		loser_crc32
83# include <zlib.h>
84# define unzip		__libdw_gunzip
85# define MAGIC		"\037\213"
86# define Z(what)	Z_##what
87#endif
88
89#define READ_SIZE		(1 << 20)
90
91/* If this is not a compressed image, return DWFL_E_BADELF.
92   If we uncompressed it into *WHOLE, *WHOLE_SIZE, return DWFL_E_NOERROR.
93   Otherwise return an error for bad compressed data or I/O failure.
94   If we return an error after reading the first part of the file,
95   leave that portion malloc'd in *WHOLE, *WHOLE_SIZE.  If *WHOLE
96   is not null on entry, we'll use it in lieu of repeating a read.  */
97
98Dwfl_Error internal_function
99unzip (int fd, off64_t start_offset,
100       void *mapped, size_t mapped_size,
101       void **whole, size_t *whole_size)
102{
103  void *buffer = NULL;
104  size_t size = 0;
105  inline bool bigger_buffer (size_t start)
106  {
107    size_t more = size ? size * 2 : start;
108    char *b = realloc (buffer, more);
109    while (unlikely (b == NULL) && more >= size + 1024)
110      b = realloc (buffer, more -= 1024);
111    if (unlikely (b == NULL))
112      return false;
113    buffer = b;
114    size = more;
115    return true;
116  }
117  inline void smaller_buffer (size_t end)
118  {
119    buffer = realloc (buffer, end) ?: end == 0 ? NULL : buffer;
120    size = end;
121  }
122
123  void *input_buffer = NULL;
124  off_t input_pos = 0;
125
126  inline Dwfl_Error fail (Dwfl_Error failure)
127  {
128    if (input_pos == (off_t) mapped_size)
129      *whole = input_buffer;
130    else
131      {
132	free (input_buffer);
133	*whole = NULL;
134      }
135    free (buffer);
136    return failure;
137  }
138
139  inline Dwfl_Error zlib_fail (int result)
140  {
141    switch (result)
142      {
143      case Z (MEM_ERROR):
144	return fail (DWFL_E_NOMEM);
145      case Z (ERRNO):
146	return fail (DWFL_E_ERRNO);
147      default:
148	return fail (DWFL_E_ZLIB);
149      }
150  }
151
152  if (mapped == NULL)
153    {
154      if (*whole == NULL)
155	{
156	  input_buffer = malloc (READ_SIZE);
157	  if (unlikely (input_buffer == NULL))
158	    return DWFL_E_NOMEM;
159
160	  ssize_t n = pread_retry (fd, input_buffer, READ_SIZE, start_offset);
161	  if (unlikely (n < 0))
162	    return zlib_fail (Z (ERRNO));
163
164	  input_pos = n;
165	  mapped = input_buffer;
166	  mapped_size = n;
167	}
168      else
169	{
170	  input_buffer = *whole;
171	  input_pos = mapped_size = *whole_size;
172	}
173    }
174
175#define NOMAGIC(magic) \
176  (mapped_size <= sizeof magic || memcmp (mapped, magic, sizeof magic - 1))
177
178  /* First, look at the header.  */
179  if (NOMAGIC (MAGIC)
180#ifdef MAGIC2
181      && NOMAGIC (MAGIC2)
182#endif
183      )
184    /* Not a compressed file.  */
185    return DWFL_E_BADELF;
186
187#if USE_INFLATE
188
189  /* This style actually only works with bzlib and liblzma.
190     The stupid zlib interface has nothing to grok the
191     gzip file headers except the slow gzFile interface.  */
192
193  z_stream z = { .next_in = mapped, .avail_in = mapped_size };
194  int result = inflateInit (&z);
195  if (result != Z (OK))
196    {
197      inflateEnd (&z);
198      return zlib_fail (result);
199    }
200
201  do
202    {
203      if (z.avail_in == 0 && input_buffer != NULL)
204	{
205	  ssize_t n = pread_retry (fd, input_buffer, READ_SIZE,
206				   start_offset + input_pos);
207	  if (unlikely (n < 0))
208	    {
209	      inflateEnd (&z);
210	      return zlib_fail (Z (ERRNO));
211	    }
212	  z.next_in = input_buffer;
213	  z.avail_in = n;
214	  input_pos += n;
215	}
216      if (z.avail_out == 0)
217	{
218	  ptrdiff_t pos = (void *) z.next_out - buffer;
219	  if (!bigger_buffer (z.avail_in))
220	    {
221	      result = Z (MEM_ERROR);
222	      break;
223	    }
224	  z.next_out = buffer + pos;
225	  z.avail_out = size - pos;
226	}
227    }
228  while ((result = do_inflate (&z)) == Z (OK));
229
230#ifdef BZLIB
231  uint64_t total_out = (((uint64_t) z.total_out_hi32 << 32)
232			| z.total_out_lo32);
233  smaller_buffer (total_out);
234#else
235  smaller_buffer (z.total_out);
236#endif
237
238  inflateEnd (&z);
239
240  if (result != Z (STREAM_END))
241    return zlib_fail (result);
242
243#else  /* gzip only.  */
244
245  /* Let the decompression library read the file directly.  */
246
247  gzFile zf;
248  Dwfl_Error open_stream (void)
249  {
250    int d = dup (fd);
251    if (unlikely (d < 0))
252      return DWFL_E_BADELF;
253    if (start_offset != 0)
254      {
255	off64_t off = lseek (d, start_offset, SEEK_SET);
256	if (off != start_offset)
257	  {
258	    close (d);
259	    return DWFL_E_BADELF;
260	  }
261      }
262    zf = gzdopen (d, "r");
263    if (unlikely (zf == NULL))
264      {
265	close (d);
266	return zlib_fail (Z (MEM_ERROR));
267      }
268
269    /* From here on, zlib will close D.  */
270
271    return DWFL_E_NOERROR;
272  }
273
274  Dwfl_Error result = open_stream ();
275
276  if (result == DWFL_E_NOERROR && gzdirect (zf))
277    {
278      gzclose (zf);
279      return fail (DWFL_E_BADELF);
280    }
281
282  if (result != DWFL_E_NOERROR)
283    return fail (result);
284
285  ptrdiff_t pos = 0;
286  while (1)
287    {
288      if (!bigger_buffer (1024))
289	{
290	  gzclose (zf);
291	  return zlib_fail (Z (MEM_ERROR));
292	}
293      int n = gzread (zf, buffer + pos, size - pos);
294      if (n < 0)
295	{
296	  int code;
297	  gzerror (zf, &code);
298	  gzclose (zf);
299	  return zlib_fail (code);
300	}
301      if (n == 0)
302	break;
303      pos += n;
304    }
305
306  gzclose (zf);
307  smaller_buffer (pos);
308#endif
309
310  free (input_buffer);
311
312  *whole = buffer;
313  *whole_size = size;
314
315  return DWFL_E_NOERROR;
316}
317