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[binutils.git] / bfd / elf-strtab.c
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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>.
6 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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. */
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"
30 /* An entry in the strtab hash table. */
32 struct elf_strtab_hash_entry
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;
46 /* The strtab hash table. */
48 struct elf_strtab_hash
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;
61 /* Routine to create an entry in a section merge hashtab. */
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)
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;
75 /* Call the allocation method of the superclass. */
76 entry = bfd_hash_newfunc (entry, table, string);
78 if (entry)
80 /* Initialize the local fields. */
81 struct elf_strtab_hash_entry *ret;
83 ret = (struct elf_strtab_hash_entry *) entry;
84 ret->u.index = -1;
85 ret->refcount = 0;
86 ret->len = 0;
89 return entry;
92 /* Create a new hash table. */
94 struct elf_strtab_hash *
95 _bfd_elf_strtab_init (void)
97 struct elf_strtab_hash *table;
98 bfd_size_type amt = sizeof (struct elf_strtab_hash);
100 table = bfd_malloc (amt);
101 if (table == NULL)
102 return NULL;
104 if (!bfd_hash_table_init (&table->table, elf_strtab_hash_newfunc,
105 sizeof (struct elf_strtab_hash_entry)))
107 free (table);
108 return NULL;
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)
118 free (table);
119 return NULL;
122 table->array[0] = NULL;
124 return table;
127 /* Free a strtab. */
129 void
130 _bfd_elf_strtab_free (struct elf_strtab_hash *tab)
132 bfd_hash_table_free (&tab->table);
133 free (tab->array);
134 free (tab);
137 /* Get the index of an entity in a hash table, adding it if it is not
138 already present. */
140 bfd_size_type
141 _bfd_elf_strtab_add (struct elf_strtab_hash *tab,
142 const char *str,
143 bfd_boolean copy)
145 register struct elf_strtab_hash_entry *entry;
147 /* We handle this specially, since we don't want to do refcounting
148 on it. */
149 if (*str == '\0')
150 return 0;
152 BFD_ASSERT (tab->sec_size == 0);
153 entry = (struct elf_strtab_hash_entry *)
154 bfd_hash_lookup (&tab->table, str, TRUE, copy);
156 if (entry == NULL)
157 return (bfd_size_type) -1;
159 entry->refcount++;
160 if (entry->len == 0)
162 entry->len = strlen (str) + 1;
163 /* 2G strings lose. */
164 BFD_ASSERT (entry->len > 0);
165 if (tab->size == tab->alloced)
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;
174 entry->u.index = tab->size++;
175 tab->array[entry->u.index] = entry;
177 return entry->u.index;
180 void
181 _bfd_elf_strtab_addref (struct elf_strtab_hash *tab, bfd_size_type idx)
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;
190 void
191 _bfd_elf_strtab_delref (struct elf_strtab_hash *tab, bfd_size_type idx)
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;
201 void
202 _bfd_elf_strtab_clear_all_refs (struct elf_strtab_hash *tab)
204 bfd_size_type idx;
206 for (idx = 1; idx < tab->size; ++idx)
207 tab->array[idx]->refcount = 0;
210 bfd_size_type
211 _bfd_elf_strtab_size (struct elf_strtab_hash *tab)
213 return tab->sec_size ? tab->sec_size : tab->size;
216 bfd_size_type
217 _bfd_elf_strtab_offset (struct elf_strtab_hash *tab, bfd_size_type idx)
219 struct elf_strtab_hash_entry *entry;
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;
231 bfd_boolean
232 _bfd_elf_strtab_emit (register bfd *abfd, struct elf_strtab_hash *tab)
234 bfd_size_type off = 1, i;
236 if (bfd_bwrite ("", 1, abfd) != 1)
237 return FALSE;
239 for (i = 1; i < tab->size; ++i)
241 register const char *str;
242 register unsigned int len;
244 BFD_ASSERT (tab->array[i]->refcount == 0);
245 len = tab->array[i]->len;
246 if ((int) len < 0)
247 continue;
249 str = tab->array[i]->root.string;
250 if (bfd_bwrite (str, len, abfd) != len)
251 return FALSE;
253 off += len;
256 BFD_ASSERT (off == tab->sec_size);
257 return TRUE;
260 /* Compare two elf_strtab_hash_entry structures. Called via qsort. */
262 static int
263 strrevcmp (const void *a, const void *b)
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;
273 while (l)
275 if (*s != *t)
276 return (int) *s - (int) *t;
277 s--;
278 t--;
279 l--;
281 return lenA - lenB;
284 static inline int
285 is_suffix (const struct elf_strtab_hash_entry *A,
286 const struct elf_strtab_hash_entry *B)
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;
293 return memcmp (A->root.string + (A->len - B->len),
294 B->root.string, B->len - 1) == 0;
297 /* This function assigns final string table offsets for used strings,
298 merging strings matching suffixes of longer strings if possible. */
300 void
301 _bfd_elf_strtab_finalize (struct elf_strtab_hash *tab)
303 struct elf_strtab_hash_entry **array, **a, *e;
304 bfd_size_type size, amt;
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;
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;
318 for (i = 1, a = array; i < tab->size; ++i)
320 e = tab->array[i];
321 if (e->refcount)
323 *a++ = e;
324 /* Adjust the length to not include the zero terminator. */
325 e->len -= 1;
327 else
328 e->len = 0;
331 size = a - array;
332 if (size != 0)
334 qsort (array, size, sizeof (struct elf_strtab_hash_entry *), strrevcmp);
336 /* Loop over the sorted array and merge suffixes. Start from the
337 end because we want eg.
339 s1 -> "d"
340 s2 -> "bcd"
341 s3 -> "abcd"
343 to end up as
345 s3 -> "abcd"
346 s2 _____^
347 s1 _______^
349 ie. we don't want s1 pointing into the old s2. */
350 e = *--a;
351 e->len += 1;
352 while (--a >= array)
354 struct elf_strtab_hash_entry *cmp = *a;
356 cmp->len += 1;
357 if (is_suffix (e, cmp))
359 cmp->u.suffix = e;
360 cmp->len = -cmp->len;
362 else
363 e = cmp;
367 alloc_failure:
368 if (array)
369 free (array);
371 /* Assign positions to the strings we want to keep. */
372 size = 1;
373 for (i = 1; i < tab->size; ++i)
375 e = tab->array[i];
376 if (e->refcount && e->len > 0)
378 e->u.index = size;
379 size += e->len;
383 tab->sec_size = size;
385 /* Adjust the rest. */
386 for (i = 1; i < tab->size; ++i)
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);