1 /* Read MiniDebugInfo data from an objfile. 2 3 Copyright (C) 2012-2013 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 #include "defs.h" 21 #include "gdb_bfd.h" 22 #include "gdb_string.h" 23 #include "symfile.h" 24 #include "objfiles.h" 25 #include "gdbcore.h" 26 27 #ifdef HAVE_LIBLZMA 28 29 #include <lzma.h> 30 31 /* Allocator function for LZMA. */ 32 33 static void * 34 alloc_lzma (void *opaque, size_t nmemb, size_t size) 35 { 36 return xmalloc (nmemb * size); 37 } 38 39 /* Free function for LZMA. */ 40 41 static void 42 free_lzma (void *opaque, void *ptr) 43 { 44 xfree (ptr); 45 } 46 47 /* The allocator object for LZMA. Note that 'gdb_lzma_allocator' 48 cannot be const due to the lzma library function prototypes. */ 49 50 static lzma_allocator gdb_lzma_allocator = { alloc_lzma, free_lzma, NULL }; 51 52 /* Custom bfd_openr_iovec implementation to read compressed data from 53 a section. This keeps only the last decompressed block in memory 54 to allow larger data without using to much memory. */ 55 56 struct lzma_stream 57 { 58 /* Section of input BFD from which we are decoding data. */ 59 asection *section; 60 61 /* lzma library decompression state. */ 62 lzma_index *index; 63 64 /* Currently decoded block. */ 65 bfd_size_type data_start; 66 bfd_size_type data_end; 67 gdb_byte *data; 68 }; 69 70 /* bfd_openr_iovec OPEN_P implementation for 71 find_separate_debug_file_in_section. OPEN_CLOSURE is 'asection *' 72 of the section to decompress. 73 74 Return 'struct lzma_stream *' must be freed by caller by xfree, together 75 with its INDEX lzma data. */ 76 77 static void * 78 lzma_open (struct bfd *nbfd, void *open_closure) 79 { 80 asection *section = open_closure; 81 bfd_size_type size, offset; 82 lzma_stream_flags options; 83 gdb_byte footer[LZMA_STREAM_HEADER_SIZE]; 84 gdb_byte *indexdata; 85 lzma_index *index; 86 int ret; 87 uint64_t memlimit = UINT64_MAX; 88 struct lzma_stream *lstream; 89 size_t pos; 90 91 size = bfd_get_section_size (section); 92 offset = section->filepos + size - LZMA_STREAM_HEADER_SIZE; 93 if (size < LZMA_STREAM_HEADER_SIZE 94 || bfd_seek (section->owner, offset, SEEK_SET) != 0 95 || bfd_bread (footer, LZMA_STREAM_HEADER_SIZE, section->owner) 96 != LZMA_STREAM_HEADER_SIZE 97 || lzma_stream_footer_decode (&options, footer) != LZMA_OK 98 || offset < options.backward_size) 99 { 100 bfd_set_error (bfd_error_wrong_format); 101 return NULL; 102 } 103 104 offset -= options.backward_size; 105 indexdata = xmalloc (options.backward_size); 106 index = NULL; 107 pos = 0; 108 if (bfd_seek (section->owner, offset, SEEK_SET) != 0 109 || bfd_bread (indexdata, options.backward_size, section->owner) 110 != options.backward_size 111 || lzma_index_buffer_decode (&index, &memlimit, &gdb_lzma_allocator, 112 indexdata, &pos, options.backward_size) 113 != LZMA_OK 114 || lzma_index_size (index) != options.backward_size) 115 { 116 xfree (indexdata); 117 bfd_set_error (bfd_error_wrong_format); 118 return NULL; 119 } 120 xfree (indexdata); 121 122 lstream = xzalloc (sizeof (struct lzma_stream)); 123 lstream->section = section; 124 lstream->index = index; 125 126 return lstream; 127 } 128 129 /* bfd_openr_iovec PREAD_P implementation for 130 find_separate_debug_file_in_section. Passed STREAM 131 is 'struct lzma_stream *'. */ 132 133 static file_ptr 134 lzma_pread (struct bfd *nbfd, void *stream, void *buf, file_ptr nbytes, 135 file_ptr offset) 136 { 137 struct lzma_stream *lstream = stream; 138 bfd_size_type chunk_size; 139 lzma_index_iter iter; 140 gdb_byte *compressed, *uncompressed; 141 file_ptr block_offset; 142 lzma_filter filters[LZMA_FILTERS_MAX + 1]; 143 lzma_block block; 144 size_t compressed_pos, uncompressed_pos; 145 file_ptr res; 146 147 res = 0; 148 while (nbytes > 0) 149 { 150 if (lstream->data == NULL 151 || lstream->data_start > offset || offset >= lstream->data_end) 152 { 153 asection *section = lstream->section; 154 155 lzma_index_iter_init (&iter, lstream->index); 156 if (lzma_index_iter_locate (&iter, offset)) 157 break; 158 159 compressed = xmalloc (iter.block.total_size); 160 block_offset = section->filepos + iter.block.compressed_file_offset; 161 if (bfd_seek (section->owner, block_offset, SEEK_SET) != 0 162 || bfd_bread (compressed, iter.block.total_size, section->owner) 163 != iter.block.total_size) 164 { 165 xfree (compressed); 166 break; 167 } 168 169 uncompressed = xmalloc (iter.block.uncompressed_size); 170 171 memset (&block, 0, sizeof (block)); 172 block.filters = filters; 173 block.header_size = lzma_block_header_size_decode (compressed[0]); 174 if (lzma_block_header_decode (&block, &gdb_lzma_allocator, compressed) 175 != LZMA_OK) 176 { 177 xfree (compressed); 178 xfree (uncompressed); 179 break; 180 } 181 182 compressed_pos = block.header_size; 183 uncompressed_pos = 0; 184 if (lzma_block_buffer_decode (&block, &gdb_lzma_allocator, 185 compressed, &compressed_pos, 186 iter.block.total_size, 187 uncompressed, &uncompressed_pos, 188 iter.block.uncompressed_size) 189 != LZMA_OK) 190 { 191 xfree (compressed); 192 xfree (uncompressed); 193 break; 194 } 195 196 xfree (compressed); 197 198 xfree (lstream->data); 199 lstream->data = uncompressed; 200 lstream->data_start = iter.block.uncompressed_file_offset; 201 lstream->data_end = (iter.block.uncompressed_file_offset 202 + iter.block.uncompressed_size); 203 } 204 205 chunk_size = min (nbytes, lstream->data_end - offset); 206 memcpy (buf, lstream->data + offset - lstream->data_start, chunk_size); 207 buf = (gdb_byte *) buf + chunk_size; 208 offset += chunk_size; 209 nbytes -= chunk_size; 210 res += chunk_size; 211 } 212 213 return res; 214 } 215 216 /* bfd_openr_iovec CLOSE_P implementation for 217 find_separate_debug_file_in_section. Passed STREAM 218 is 'struct lzma_stream *'. */ 219 220 static int 221 lzma_close (struct bfd *nbfd, 222 void *stream) 223 { 224 struct lzma_stream *lstream = stream; 225 226 lzma_index_end (lstream->index, &gdb_lzma_allocator); 227 xfree (lstream->data); 228 xfree (lstream); 229 230 /* Zero means success. */ 231 return 0; 232 } 233 234 /* bfd_openr_iovec STAT_P implementation for 235 find_separate_debug_file_in_section. Passed STREAM 236 is 'struct lzma_stream *'. */ 237 238 static int 239 lzma_stat (struct bfd *abfd, 240 void *stream, 241 struct stat *sb) 242 { 243 struct lzma_stream *lstream = stream; 244 245 sb->st_size = lzma_index_uncompressed_size (lstream->index); 246 return 0; 247 } 248 249 #endif /* HAVE_LIBLZMA */ 250 251 /* This looks for a xz compressed separate debug info object file embedded 252 in a section called .gnu_debugdata. See 253 http://fedoraproject.org/wiki/Features/MiniDebugInfo 254 or the "Separate Debug Sections" of the manual for details. 255 If we find one we create a iovec based bfd that decompresses the 256 object data on demand. If we don't find one, return NULL. */ 257 258 bfd * 259 find_separate_debug_file_in_section (struct objfile *objfile) 260 { 261 asection *section; 262 bfd *abfd; 263 264 if (objfile->obfd == NULL) 265 return NULL; 266 267 section = bfd_get_section_by_name (objfile->obfd, ".gnu_debugdata"); 268 if (section == NULL) 269 return NULL; 270 271 #ifdef HAVE_LIBLZMA 272 abfd = gdb_bfd_openr_iovec (objfile->name, gnutarget, lzma_open, section, 273 lzma_pread, lzma_close, lzma_stat); 274 if (abfd == NULL) 275 return NULL; 276 277 if (!bfd_check_format (abfd, bfd_object)) 278 { 279 warning (_("Cannot parse .gnu_debugdata section; not a BFD object")); 280 gdb_bfd_unref (abfd); 281 return NULL; 282 } 283 #else 284 warning (_("Cannot parse .gnu_debugdata section; LZMA support was " 285 "disabled at compile time")); 286 abfd = NULL; 287 #endif /* !HAVE_LIBLZMA */ 288 289 return abfd; 290 } 291