| 1 | /* ELF strtab with GC and suffix merging support. |
| 2 | Copyright 2001, 2002, 2003, 2005, 2006, 2007 |
| 3 | Free Software Foundation, Inc. |
| 4 | Written by Jakub Jelinek <jakub@redhat.com>. |
| 5 | |
| 6 | This file is part of BFD, the Binary File Descriptor library. |
| 7 | |
| 8 | This program is free software; you can redistribute it and/or modify |
| 9 | it under the terms of the GNU General Public License as published by |
| 10 | the Free Software Foundation; either version 3 of the License, or |
| 11 | (at your option) any later version. |
| 12 | |
| 13 | This program is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
| 18 | You should have received a copy of the GNU General Public License |
| 19 | along with this program; if not, write to the Free Software |
| 20 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 21 | MA 02110-1301, USA. */ |
| 22 | |
| 23 | #include "sysdep.h" |
| 24 | #include "bfd.h" |
| 25 | #include "libbfd.h" |
| 26 | #include "elf-bfd.h" |
| 27 | #include "hashtab.h" |
| 28 | #include "libiberty.h" |
| 29 | |
| 30 | /* An entry in the strtab hash table. */ |
| 31 | |
| 32 | struct elf_strtab_hash_entry |
| 33 | { |
| 34 | struct bfd_hash_entry root; |
| 35 | /* Length of this entry. This includes the zero terminator. */ |
| 36 | int len; |
| 37 | unsigned int refcount; |
| 38 | union { |
| 39 | /* Index within the merged section. */ |
| 40 | bfd_size_type index; |
| 41 | /* Entry this is a suffix of (if len < 0). */ |
| 42 | struct elf_strtab_hash_entry *suffix; |
| 43 | } u; |
| 44 | }; |
| 45 | |
| 46 | /* The strtab hash table. */ |
| 47 | |
| 48 | struct elf_strtab_hash |
| 49 | { |
| 50 | struct bfd_hash_table table; |
| 51 | /* Next available index. */ |
| 52 | bfd_size_type size; |
| 53 | /* Number of array entries alloced. */ |
| 54 | bfd_size_type alloced; |
| 55 | /* Final strtab size. */ |
| 56 | bfd_size_type sec_size; |
| 57 | /* Array of pointers to strtab entries. */ |
| 58 | struct elf_strtab_hash_entry **array; |
| 59 | }; |
| 60 | |
| 61 | /* Routine to create an entry in a section merge hashtab. */ |
| 62 | |
| 63 | static struct bfd_hash_entry * |
| 64 | elf_strtab_hash_newfunc (struct bfd_hash_entry *entry, |
| 65 | struct bfd_hash_table *table, |
| 66 | const char *string) |
| 67 | { |
| 68 | /* Allocate the structure if it has not already been allocated by a |
| 69 | subclass. */ |
| 70 | if (entry == NULL) |
| 71 | entry = bfd_hash_allocate (table, sizeof (struct elf_strtab_hash_entry)); |
| 72 | if (entry == NULL) |
| 73 | return NULL; |
| 74 | |
| 75 | /* Call the allocation method of the superclass. */ |
| 76 | entry = bfd_hash_newfunc (entry, table, string); |
| 77 | |
| 78 | if (entry) |
| 79 | { |
| 80 | /* Initialize the local fields. */ |
| 81 | struct elf_strtab_hash_entry *ret; |
| 82 | |
| 83 | ret = (struct elf_strtab_hash_entry *) entry; |
| 84 | ret->u.index = -1; |
| 85 | ret->refcount = 0; |
| 86 | ret->len = 0; |
| 87 | } |
| 88 | |
| 89 | return entry; |
| 90 | } |
| 91 | |
| 92 | /* Create a new hash table. */ |
| 93 | |
| 94 | struct elf_strtab_hash * |
| 95 | _bfd_elf_strtab_init (void) |
| 96 | { |
| 97 | struct elf_strtab_hash *table; |
| 98 | bfd_size_type amt = sizeof (struct elf_strtab_hash); |
| 99 | |
| 100 | table = bfd_malloc (amt); |
| 101 | if (table == NULL) |
| 102 | return NULL; |
| 103 | |
| 104 | if (!bfd_hash_table_init (&table->table, elf_strtab_hash_newfunc, |
| 105 | sizeof (struct elf_strtab_hash_entry))) |
| 106 | { |
| 107 | free (table); |
| 108 | return NULL; |
| 109 | } |
| 110 | |
| 111 | table->sec_size = 0; |
| 112 | table->size = 1; |
| 113 | table->alloced = 64; |
| 114 | amt = sizeof (struct elf_strtab_hasn_entry *); |
| 115 | table->array = bfd_malloc (table->alloced * amt); |
| 116 | if (table->array == NULL) |
| 117 | { |
| 118 | free (table); |
| 119 | return NULL; |
| 120 | } |
| 121 | |
| 122 | table->array[0] = NULL; |
| 123 | |
| 124 | return table; |
| 125 | } |
| 126 | |
| 127 | /* Free a strtab. */ |
| 128 | |
| 129 | void |
| 130 | _bfd_elf_strtab_free (struct elf_strtab_hash *tab) |
| 131 | { |
| 132 | bfd_hash_table_free (&tab->table); |
| 133 | free (tab->array); |
| 134 | free (tab); |
| 135 | } |
| 136 | |
| 137 | /* Get the index of an entity in a hash table, adding it if it is not |
| 138 | already present. */ |
| 139 | |
| 140 | bfd_size_type |
| 141 | _bfd_elf_strtab_add (struct elf_strtab_hash *tab, |
| 142 | const char *str, |
| 143 | bfd_boolean copy) |
| 144 | { |
| 145 | register struct elf_strtab_hash_entry *entry; |
| 146 | |
| 147 | /* We handle this specially, since we don't want to do refcounting |
| 148 | on it. */ |
| 149 | if (*str == '\0') |
| 150 | return 0; |
| 151 | |
| 152 | BFD_ASSERT (tab->sec_size == 0); |
| 153 | entry = (struct elf_strtab_hash_entry *) |
| 154 | bfd_hash_lookup (&tab->table, str, TRUE, copy); |
| 155 | |
| 156 | if (entry == NULL) |
| 157 | return (bfd_size_type) -1; |
| 158 | |
| 159 | entry->refcount++; |
| 160 | if (entry->len == 0) |
| 161 | { |
| 162 | entry->len = strlen (str) + 1; |
| 163 | /* 2G strings lose. */ |
| 164 | BFD_ASSERT (entry->len > 0); |
| 165 | if (tab->size == tab->alloced) |
| 166 | { |
| 167 | bfd_size_type amt = sizeof (struct elf_strtab_hash_entry *); |
| 168 | tab->alloced *= 2; |
| 169 | tab->array = bfd_realloc (tab->array, tab->alloced * amt); |
| 170 | if (tab->array == NULL) |
| 171 | return (bfd_size_type) -1; |
| 172 | } |
| 173 | |
| 174 | entry->u.index = tab->size++; |
| 175 | tab->array[entry->u.index] = entry; |
| 176 | } |
| 177 | return entry->u.index; |
| 178 | } |
| 179 | |
| 180 | void |
| 181 | _bfd_elf_strtab_addref (struct elf_strtab_hash *tab, bfd_size_type idx) |
| 182 | { |
| 183 | if (idx == 0 || idx == (bfd_size_type) -1) |
| 184 | return; |
| 185 | BFD_ASSERT (tab->sec_size == 0); |
| 186 | BFD_ASSERT (idx < tab->size); |
| 187 | ++tab->array[idx]->refcount; |
| 188 | } |
| 189 | |
| 190 | void |
| 191 | _bfd_elf_strtab_delref (struct elf_strtab_hash *tab, bfd_size_type idx) |
| 192 | { |
| 193 | if (idx == 0 || idx == (bfd_size_type) -1) |
| 194 | return; |
| 195 | BFD_ASSERT (tab->sec_size == 0); |
| 196 | BFD_ASSERT (idx < tab->size); |
| 197 | BFD_ASSERT (tab->array[idx]->refcount > 0); |
| 198 | --tab->array[idx]->refcount; |
| 199 | } |
| 200 | |
| 201 | void |
| 202 | _bfd_elf_strtab_clear_all_refs (struct elf_strtab_hash *tab) |
| 203 | { |
| 204 | bfd_size_type idx; |
| 205 | |
| 206 | for (idx = 1; idx < tab->size; ++idx) |
| 207 | tab->array[idx]->refcount = 0; |
| 208 | } |
| 209 | |
| 210 | bfd_size_type |
| 211 | _bfd_elf_strtab_size (struct elf_strtab_hash *tab) |
| 212 | { |
| 213 | return tab->sec_size ? tab->sec_size : tab->size; |
| 214 | } |
| 215 | |
| 216 | bfd_size_type |
| 217 | _bfd_elf_strtab_offset (struct elf_strtab_hash *tab, bfd_size_type idx) |
| 218 | { |
| 219 | struct elf_strtab_hash_entry *entry; |
| 220 | |
| 221 | if (idx == 0) |
| 222 | return 0; |
| 223 | BFD_ASSERT (idx < tab->size); |
| 224 | BFD_ASSERT (tab->sec_size); |
| 225 | entry = tab->array[idx]; |
| 226 | BFD_ASSERT (entry->refcount > 0); |
| 227 | entry->refcount--; |
| 228 | return tab->array[idx]->u.index; |
| 229 | } |
| 230 | |
| 231 | bfd_boolean |
| 232 | _bfd_elf_strtab_emit (register bfd *abfd, struct elf_strtab_hash *tab) |
| 233 | { |
| 234 | bfd_size_type off = 1, i; |
| 235 | |
| 236 | if (bfd_bwrite ("", 1, abfd) != 1) |
| 237 | return FALSE; |
| 238 | |
| 239 | for (i = 1; i < tab->size; ++i) |
| 240 | { |
| 241 | register const char *str; |
| 242 | register unsigned int len; |
| 243 | |
| 244 | BFD_ASSERT (tab->array[i]->refcount == 0); |
| 245 | len = tab->array[i]->len; |
| 246 | if ((int) len < 0) |
| 247 | continue; |
| 248 | |
| 249 | str = tab->array[i]->root.string; |
| 250 | if (bfd_bwrite (str, len, abfd) != len) |
| 251 | return FALSE; |
| 252 | |
| 253 | off += len; |
| 254 | } |
| 255 | |
| 256 | BFD_ASSERT (off == tab->sec_size); |
| 257 | return TRUE; |
| 258 | } |
| 259 | |
| 260 | /* Compare two elf_strtab_hash_entry structures. Called via qsort. */ |
| 261 | |
| 262 | static int |
| 263 | strrevcmp (const void *a, const void *b) |
| 264 | { |
| 265 | struct elf_strtab_hash_entry *A = *(struct elf_strtab_hash_entry **) a; |
| 266 | struct elf_strtab_hash_entry *B = *(struct elf_strtab_hash_entry **) b; |
| 267 | unsigned int lenA = A->len; |
| 268 | unsigned int lenB = B->len; |
| 269 | const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1; |
| 270 | const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1; |
| 271 | int l = lenA < lenB ? lenA : lenB; |
| 272 | |
| 273 | while (l) |
| 274 | { |
| 275 | if (*s != *t) |
| 276 | return (int) *s - (int) *t; |
| 277 | s--; |
| 278 | t--; |
| 279 | l--; |
| 280 | } |
| 281 | return lenA - lenB; |
| 282 | } |
| 283 | |
| 284 | static inline int |
| 285 | is_suffix (const struct elf_strtab_hash_entry *A, |
| 286 | const struct elf_strtab_hash_entry *B) |
| 287 | { |
| 288 | if (A->len <= B->len) |
| 289 | /* B cannot be a suffix of A unless A is equal to B, which is guaranteed |
| 290 | not to be equal by the hash table. */ |
| 291 | return 0; |
| 292 | |
| 293 | return memcmp (A->root.string + (A->len - B->len), |
| 294 | B->root.string, B->len - 1) == 0; |
| 295 | } |
| 296 | |
| 297 | /* This function assigns final string table offsets for used strings, |
| 298 | merging strings matching suffixes of longer strings if possible. */ |
| 299 | |
| 300 | void |
| 301 | _bfd_elf_strtab_finalize (struct elf_strtab_hash *tab) |
| 302 | { |
| 303 | struct elf_strtab_hash_entry **array, **a, *e; |
| 304 | bfd_size_type size, amt; |
| 305 | |
| 306 | /* GCC 2.91.66 (egcs-1.1.2) on i386 miscompiles this function when i is |
| 307 | a 64-bit bfd_size_type: a 64-bit target or --enable-64-bit-bfd. |
| 308 | Besides, indexing with a long long wouldn't give anything but extra |
| 309 | cycles. */ |
| 310 | size_t i; |
| 311 | |
| 312 | /* Sort the strings by suffix and length. */ |
| 313 | amt = tab->size * sizeof (struct elf_strtab_hash_entry *); |
| 314 | array = bfd_malloc (amt); |
| 315 | if (array == NULL) |
| 316 | goto alloc_failure; |
| 317 | |
| 318 | for (i = 1, a = array; i < tab->size; ++i) |
| 319 | { |
| 320 | e = tab->array[i]; |
| 321 | if (e->refcount) |
| 322 | { |
| 323 | *a++ = e; |
| 324 | /* Adjust the length to not include the zero terminator. */ |
| 325 | e->len -= 1; |
| 326 | } |
| 327 | else |
| 328 | e->len = 0; |
| 329 | } |
| 330 | |
| 331 | size = a - array; |
| 332 | if (size != 0) |
| 333 | { |
| 334 | qsort (array, size, sizeof (struct elf_strtab_hash_entry *), strrevcmp); |
| 335 | |
| 336 | /* Loop over the sorted array and merge suffixes. Start from the |
| 337 | end because we want eg. |
| 338 | |
| 339 | s1 -> "d" |
| 340 | s2 -> "bcd" |
| 341 | s3 -> "abcd" |
| 342 | |
| 343 | to end up as |
| 344 | |
| 345 | s3 -> "abcd" |
| 346 | s2 _____^ |
| 347 | s1 _______^ |
| 348 | |
| 349 | ie. we don't want s1 pointing into the old s2. */ |
| 350 | e = *--a; |
| 351 | e->len += 1; |
| 352 | while (--a >= array) |
| 353 | { |
| 354 | struct elf_strtab_hash_entry *cmp = *a; |
| 355 | |
| 356 | cmp->len += 1; |
| 357 | if (is_suffix (e, cmp)) |
| 358 | { |
| 359 | cmp->u.suffix = e; |
| 360 | cmp->len = -cmp->len; |
| 361 | } |
| 362 | else |
| 363 | e = cmp; |
| 364 | } |
| 365 | } |
| 366 | |
| 367 | alloc_failure: |
| 368 | if (array) |
| 369 | free (array); |
| 370 | |
| 371 | /* Assign positions to the strings we want to keep. */ |
| 372 | size = 1; |
| 373 | for (i = 1; i < tab->size; ++i) |
| 374 | { |
| 375 | e = tab->array[i]; |
| 376 | if (e->refcount && e->len > 0) |
| 377 | { |
| 378 | e->u.index = size; |
| 379 | size += e->len; |
| 380 | } |
| 381 | } |
| 382 | |
| 383 | tab->sec_size = size; |
| 384 | |
| 385 | /* Adjust the rest. */ |
| 386 | for (i = 1; i < tab->size; ++i) |
| 387 | { |
| 388 | e = tab->array[i]; |
| 389 | if (e->refcount && e->len < 0) |
| 390 | e->u.index = e->u.suffix->u.index + (e->u.suffix->len + e->len); |
| 391 | } |
| 392 | } |