1 /* ELF strtab with GC and suffix merging support. 2 Copyright 2001, 2002, 2003 Free Software Foundation, Inc. 3 Written by Jakub Jelinek <jakub@redhat.com>. 4 5 This file is part of BFD, the Binary File Descriptor library. 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 2 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, write to the Free Software 19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 20 21 #include "bfd.h" 22 #include "sysdep.h" 23 #include "libbfd.h" 24 #include "elf-bfd.h" 25 #include "hashtab.h" 26 #include "libiberty.h" 27 28 /* An entry in the strtab hash table. */ 29 30 struct elf_strtab_hash_entry 31 { 32 struct bfd_hash_entry root; 33 /* Length of this entry. This includes the zero terminator. */ 34 int len; 35 unsigned int refcount; 36 union { 37 /* Index within the merged section. */ 38 bfd_size_type index; 39 /* Entry this is a suffix of (if len < 0). */ 40 struct elf_strtab_hash_entry *suffix; 41 } u; 42 }; 43 44 /* The strtab hash table. */ 45 46 struct elf_strtab_hash 47 { 48 struct bfd_hash_table table; 49 /* Next available index. */ 50 bfd_size_type size; 51 /* Number of array entries alloced. */ 52 bfd_size_type alloced; 53 /* Final strtab size. */ 54 bfd_size_type sec_size; 55 /* Array of pointers to strtab entries. */ 56 struct elf_strtab_hash_entry **array; 57 }; 58 59 /* Routine to create an entry in a section merge hashtab. */ 60 61 static struct bfd_hash_entry * 62 elf_strtab_hash_newfunc (struct bfd_hash_entry *entry, 63 struct bfd_hash_table *table, 64 const char *string) 65 { 66 /* Allocate the structure if it has not already been allocated by a 67 subclass. */ 68 if (entry == NULL) 69 entry = bfd_hash_allocate (table, sizeof (struct elf_strtab_hash_entry)); 70 if (entry == NULL) 71 return NULL; 72 73 /* Call the allocation method of the superclass. */ 74 entry = bfd_hash_newfunc (entry, table, string); 75 76 if (entry) 77 { 78 /* Initialize the local fields. */ 79 struct elf_strtab_hash_entry *ret; 80 81 ret = (struct elf_strtab_hash_entry *) entry; 82 ret->u.index = -1; 83 ret->refcount = 0; 84 ret->len = 0; 85 } 86 87 return entry; 88 } 89 90 /* Create a new hash table. */ 91 92 struct elf_strtab_hash * 93 _bfd_elf_strtab_init (void) 94 { 95 struct elf_strtab_hash *table; 96 bfd_size_type amt = sizeof (struct elf_strtab_hash); 97 98 table = bfd_malloc (amt); 99 if (table == NULL) 100 return NULL; 101 102 if (! bfd_hash_table_init (&table->table, elf_strtab_hash_newfunc)) 103 { 104 free (table); 105 return NULL; 106 } 107 108 table->sec_size = 0; 109 table->size = 1; 110 table->alloced = 64; 111 amt = sizeof (struct elf_strtab_hasn_entry *); 112 table->array = bfd_malloc (table->alloced * amt); 113 if (table->array == NULL) 114 { 115 free (table); 116 return NULL; 117 } 118 119 table->array[0] = NULL; 120 121 return table; 122 } 123 124 /* Free a strtab. */ 125 126 void 127 _bfd_elf_strtab_free (struct elf_strtab_hash *tab) 128 { 129 bfd_hash_table_free (&tab->table); 130 free (tab->array); 131 free (tab); 132 } 133 134 /* Get the index of an entity in a hash table, adding it if it is not 135 already present. */ 136 137 bfd_size_type 138 _bfd_elf_strtab_add (struct elf_strtab_hash *tab, 139 const char *str, 140 bfd_boolean copy) 141 { 142 register struct elf_strtab_hash_entry *entry; 143 144 /* We handle this specially, since we don't want to do refcounting 145 on it. */ 146 if (*str == '\0') 147 return 0; 148 149 BFD_ASSERT (tab->sec_size == 0); 150 entry = (struct elf_strtab_hash_entry *) 151 bfd_hash_lookup (&tab->table, str, TRUE, copy); 152 153 if (entry == NULL) 154 return (bfd_size_type) -1; 155 156 entry->refcount++; 157 if (entry->len == 0) 158 { 159 entry->len = strlen (str) + 1; 160 /* 2G strings lose. */ 161 BFD_ASSERT (entry->len > 0); 162 if (tab->size == tab->alloced) 163 { 164 bfd_size_type amt = sizeof (struct elf_strtab_hash_entry *); 165 tab->alloced *= 2; 166 tab->array = bfd_realloc (tab->array, tab->alloced * amt); 167 if (tab->array == NULL) 168 return (bfd_size_type) -1; 169 } 170 171 entry->u.index = tab->size++; 172 tab->array[entry->u.index] = entry; 173 } 174 return entry->u.index; 175 } 176 177 void 178 _bfd_elf_strtab_addref (struct elf_strtab_hash *tab, bfd_size_type idx) 179 { 180 if (idx == 0 || idx == (bfd_size_type) -1) 181 return; 182 BFD_ASSERT (tab->sec_size == 0); 183 BFD_ASSERT (idx < tab->size); 184 ++tab->array[idx]->refcount; 185 } 186 187 void 188 _bfd_elf_strtab_delref (struct elf_strtab_hash *tab, bfd_size_type idx) 189 { 190 if (idx == 0 || idx == (bfd_size_type) -1) 191 return; 192 BFD_ASSERT (tab->sec_size == 0); 193 BFD_ASSERT (idx < tab->size); 194 BFD_ASSERT (tab->array[idx]->refcount > 0); 195 --tab->array[idx]->refcount; 196 } 197 198 void 199 _bfd_elf_strtab_clear_all_refs (struct elf_strtab_hash *tab) 200 { 201 bfd_size_type idx; 202 203 for (idx = 1; idx < tab->size; ++idx) 204 tab->array[idx]->refcount = 0; 205 } 206 207 bfd_size_type 208 _bfd_elf_strtab_size (struct elf_strtab_hash *tab) 209 { 210 return tab->sec_size ? tab->sec_size : tab->size; 211 } 212 213 bfd_size_type 214 _bfd_elf_strtab_offset (struct elf_strtab_hash *tab, bfd_size_type idx) 215 { 216 struct elf_strtab_hash_entry *entry; 217 218 if (idx == 0) 219 return 0; 220 BFD_ASSERT (idx < tab->size); 221 BFD_ASSERT (tab->sec_size); 222 entry = tab->array[idx]; 223 BFD_ASSERT (entry->refcount > 0); 224 entry->refcount--; 225 return tab->array[idx]->u.index; 226 } 227 228 bfd_boolean 229 _bfd_elf_strtab_emit (register bfd *abfd, struct elf_strtab_hash *tab) 230 { 231 bfd_size_type off = 1, i; 232 233 if (bfd_bwrite ("", 1, abfd) != 1) 234 return FALSE; 235 236 for (i = 1; i < tab->size; ++i) 237 { 238 register const char *str; 239 register unsigned int len; 240 241 BFD_ASSERT (tab->array[i]->refcount == 0); 242 len = tab->array[i]->len; 243 if ((int) len < 0) 244 continue; 245 246 str = tab->array[i]->root.string; 247 if (bfd_bwrite (str, len, abfd) != len) 248 return FALSE; 249 250 off += len; 251 } 252 253 BFD_ASSERT (off == tab->sec_size); 254 return TRUE; 255 } 256 257 /* Compare two elf_strtab_hash_entry structures. Called via qsort. */ 258 259 static int 260 strrevcmp (const void *a, const void *b) 261 { 262 struct elf_strtab_hash_entry *A = *(struct elf_strtab_hash_entry **) a; 263 struct elf_strtab_hash_entry *B = *(struct elf_strtab_hash_entry **) b; 264 unsigned int lenA = A->len; 265 unsigned int lenB = B->len; 266 const unsigned char *s = A->root.string + lenA - 1; 267 const unsigned char *t = B->root.string + lenB - 1; 268 int l = lenA < lenB ? lenA : lenB; 269 270 while (l) 271 { 272 if (*s != *t) 273 return (int) *s - (int) *t; 274 s--; 275 t--; 276 l--; 277 } 278 return lenA - lenB; 279 } 280 281 static inline int 282 is_suffix (const struct elf_strtab_hash_entry *A, 283 const struct elf_strtab_hash_entry *B) 284 { 285 if (A->len <= B->len) 286 /* B cannot be a suffix of A unless A is equal to B, which is guaranteed 287 not to be equal by the hash table. */ 288 return 0; 289 290 return memcmp (A->root.string + (A->len - B->len), 291 B->root.string, B->len - 1) == 0; 292 } 293 294 /* This function assigns final string table offsets for used strings, 295 merging strings matching suffixes of longer strings if possible. */ 296 297 void 298 _bfd_elf_strtab_finalize (struct elf_strtab_hash *tab) 299 { 300 struct elf_strtab_hash_entry **array, **a, *e; 301 bfd_size_type size, amt; 302 303 /* GCC 2.91.66 (egcs-1.1.2) on i386 miscompiles this function when i is 304 a 64-bit bfd_size_type: a 64-bit target or --enable-64-bit-bfd. 305 Besides, indexing with a long long wouldn't give anything but extra 306 cycles. */ 307 size_t i; 308 309 /* Sort the strings by suffix and length. */ 310 amt = tab->size * sizeof (struct elf_strtab_hash_entry *); 311 array = bfd_malloc (amt); 312 if (array == NULL) 313 goto alloc_failure; 314 315 for (i = 1, a = array; i < tab->size; ++i) 316 { 317 e = tab->array[i]; 318 if (e->refcount) 319 { 320 *a++ = e; 321 /* Adjust the length to not include the zero terminator. */ 322 e->len -= 1; 323 } 324 else 325 e->len = 0; 326 } 327 328 size = a - array; 329 if (size != 0) 330 { 331 qsort (array, size, sizeof (struct elf_strtab_hash_entry *), strrevcmp); 332 333 /* Loop over the sorted array and merge suffixes. Start from the 334 end because we want eg. 335 336 s1 -> "d" 337 s2 -> "bcd" 338 s3 -> "abcd" 339 340 to end up as 341 342 s3 -> "abcd" 343 s2 _____^ 344 s1 _______^ 345 346 ie. we don't want s1 pointing into the old s2. */ 347 e = *--a; 348 e->len += 1; 349 while (--a >= array) 350 { 351 struct elf_strtab_hash_entry *cmp = *a; 352 353 cmp->len += 1; 354 if (is_suffix (e, cmp)) 355 { 356 cmp->u.suffix = e; 357 cmp->len = -cmp->len; 358 } 359 else 360 e = cmp; 361 } 362 } 363 364 alloc_failure: 365 if (array) 366 free (array); 367 368 /* Assign positions to the strings we want to keep. */ 369 size = 1; 370 for (i = 1; i < tab->size; ++i) 371 { 372 e = tab->array[i]; 373 if (e->refcount && e->len > 0) 374 { 375 e->u.index = size; 376 size += e->len; 377 } 378 } 379 380 tab->sec_size = size; 381 382 /* Adjust the rest. */ 383 for (i = 1; i < tab->size; ++i) 384 { 385 e = tab->array[i]; 386 if (e->refcount && e->len < 0) 387 e->u.index = e->u.suffix->u.index + (e->u.suffix->len + e->len); 388 } 389 } 390