1 /* Generic string table handling.
2 Copyright (C) 2000, 2001, 2002, 2005 Red Hat, Inc.
3 This file is part of Red Hat elfutils.
4 Written by Ulrich Drepper <drepper@redhat.com>, 2000.
5
6 Red Hat elfutils is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by the
8 Free Software Foundation; version 2 of the License.
9
10 Red Hat elfutils is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
14
15 You should have received a copy of the GNU General Public License along
16 with Red Hat elfutils; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
18
19 In addition, as a special exception, Red Hat, Inc. gives You the
20 additional right to link the code of Red Hat elfutils with code licensed
21 under any Open Source Initiative certified open source license
22 (http://www.opensource.org/licenses/index.php) which requires the
23 distribution of source code with any binary distribution and to
24 distribute linked combinations of the two. Non-GPL Code permitted under
25 this exception must only link to the code of Red Hat elfutils through
26 those well defined interfaces identified in the file named EXCEPTION
27 found in the source code files (the "Approved Interfaces"). The files
28 of Non-GPL Code may instantiate templates or use macros or inline
29 functions from the Approved Interfaces without causing the resulting
30 work to be covered by the GNU General Public License. Only Red Hat,
31 Inc. may make changes or additions to the list of Approved Interfaces.
32 Red Hat's grant of this exception is conditioned upon your not adding
33 any new exceptions. If you wish to add a new Approved Interface or
34 exception, please contact Red Hat. You must obey the GNU General Public
35 License in all respects for all of the Red Hat elfutils code and other
36 code used in conjunction with Red Hat elfutils except the Non-GPL Code
37 covered by this exception. If you modify this file, you may extend this
38 exception to your version of the file, but you are not obligated to do
39 so. If you do not wish to provide this exception without modification,
40 you must delete this exception statement from your version and license
41 this file solely under the GPL without exception.
42
43 Red Hat elfutils is an included package of the Open Invention Network.
44 An included package of the Open Invention Network is a package for which
45 Open Invention Network licensees cross-license their patents. No patent
46 license is granted, either expressly or impliedly, by designation as an
47 included package. Should you wish to participate in the Open Invention
48 Network licensing program, please visit www.openinventionnetwork.com
49 <http://www.openinventionnetwork.com>. */
50
51 #ifdef HAVE_CONFIG_H
52 # include <config.h>
53 #endif
54
55 #include <assert.h>
56 #include <inttypes.h>
57 #include <libelf.h>
58 #include <stddef.h>
59 #include <stdlib.h>
60 #include <string.h>
61 #include <unistd.h>
62 #include <sys/param.h>
63
64 #include "libebl.h"
65
66 #ifndef MIN
67 # define MIN(a, b) ((a) < (b) ? (a) : (b))
68 #endif
69
70
71 struct Ebl_GStrent
72 {
73 const char *string;
74 size_t len;
75 struct Ebl_GStrent *next;
76 struct Ebl_GStrent *left;
77 struct Ebl_GStrent *right;
78 size_t offset;
79 unsigned int width;
80 char reverse[0];
81 };
82
83
84 struct memoryblock
85 {
86 struct memoryblock *next;
87 char memory[0];
88 };
89
90
91 struct Ebl_GStrtab
92 {
93 struct Ebl_GStrent *root;
94 struct memoryblock *memory;
95 char *backp;
96 size_t left;
97 size_t total;
98 unsigned int width;
99 bool nullstr;
100
101 struct Ebl_GStrent null;
102 };
103
104
105 /* Cache for the pagesize. We correct this value a bit so that `malloc'
106 is not allocating more than a page. */
107 static size_t ps;
108
109
110 struct Ebl_GStrtab *
ebl_gstrtabinit(unsigned int width,bool nullstr)111 ebl_gstrtabinit (unsigned int width, bool nullstr)
112 {
113 struct Ebl_GStrtab *ret;
114
115 if (ps == 0)
116 {
117 ps = sysconf (_SC_PAGESIZE) - 2 * sizeof (void *);
118 assert (sizeof (struct memoryblock) < ps);
119 }
120
121 ret = (struct Ebl_GStrtab *) calloc (1, sizeof (struct Ebl_GStrtab));
122 if (ret != NULL)
123 {
124 ret->width = width;
125 ret->nullstr = nullstr;
126
127 if (nullstr)
128 {
129 ret->null.len = 1;
130 ret->null.string = (char *) calloc (1, width);
131 }
132 }
133
134 return ret;
135 }
136
137
138 static void
morememory(struct Ebl_GStrtab * st,size_t len)139 morememory (struct Ebl_GStrtab *st, size_t len)
140 {
141 struct memoryblock *newmem;
142
143 if (len < ps)
144 len = ps;
145 newmem = (struct memoryblock *) malloc (len);
146 if (newmem == NULL)
147 abort ();
148
149 newmem->next = st->memory;
150 st->memory = newmem;
151 st->backp = newmem->memory;
152 st->left = len - offsetof (struct memoryblock, memory);
153 }
154
155
156 void
ebl_gstrtabfree(struct Ebl_GStrtab * st)157 ebl_gstrtabfree (struct Ebl_GStrtab *st)
158 {
159 struct memoryblock *mb = st->memory;
160
161 while (mb != NULL)
162 {
163 void *old = mb;
164 mb = mb->next;
165 free (old);
166 }
167
168 if (st->null.string != NULL)
169 free ((char *) st->null.string);
170
171 free (st);
172 }
173
174
175 static struct Ebl_GStrent *
newstring(struct Ebl_GStrtab * st,const char * str,size_t len)176 newstring (struct Ebl_GStrtab *st, const char *str, size_t len)
177 {
178 /* Compute the amount of padding needed to make the structure aligned. */
179 size_t align = ((__alignof__ (struct Ebl_GStrent)
180 - (((uintptr_t) st->backp)
181 & (__alignof__ (struct Ebl_GStrent) - 1)))
182 & (__alignof__ (struct Ebl_GStrent) - 1));
183
184 /* Make sure there is enough room in the memory block. */
185 if (st->left < align + sizeof (struct Ebl_GStrent) + len * st->width)
186 {
187 morememory (st, sizeof (struct Ebl_GStrent) + len * st->width);
188 align = 0;
189 }
190
191 /* Create the reserved string. */
192 struct Ebl_GStrent *newstr = (struct Ebl_GStrent *) (st->backp + align);
193 newstr->string = str;
194 newstr->len = len;
195 newstr->width = st->width;
196 newstr->next = NULL;
197 newstr->left = NULL;
198 newstr->right = NULL;
199 newstr->offset = 0;
200 for (int i = len - 2; i >= 0; --i)
201 for (int j = st->width - 1; j >= 0; --j)
202 newstr->reverse[i * st->width + j] = str[(len - 2 - i) * st->width + j];
203 for (size_t j = 0; j < st->width; ++j)
204 newstr->reverse[(len - 1) * st->width + j] = '\0';
205 st->backp += align + sizeof (struct Ebl_GStrent) + len * st->width;
206 st->left -= align + sizeof (struct Ebl_GStrent) + len * st->width;
207
208 return newstr;
209 }
210
211
212 /* XXX This function should definitely be rewritten to use a balancing
213 tree algorith (AVL, red-black trees). For now a simple, correct
214 implementation is enough. */
215 static struct Ebl_GStrent **
searchstring(struct Ebl_GStrent ** sep,struct Ebl_GStrent * newstr)216 searchstring (struct Ebl_GStrent **sep, struct Ebl_GStrent *newstr)
217 {
218 int cmpres;
219
220 /* More strings? */
221 if (*sep == NULL)
222 {
223 *sep = newstr;
224 return sep;
225 }
226
227 /* Compare the strings. */
228 cmpres = memcmp ((*sep)->reverse, newstr->reverse,
229 (MIN ((*sep)->len, newstr->len) - 1) * (*sep)->width);
230 if (cmpres == 0)
231 /* We found a matching string. */
232 return sep;
233 else if (cmpres > 0)
234 return searchstring (&(*sep)->left, newstr);
235 else
236 return searchstring (&(*sep)->right, newstr);
237 }
238
239
240 /* Add new string. The actual string is assumed to be permanent. */
241 struct Ebl_GStrent *
ebl_gstrtabadd(struct Ebl_GStrtab * st,const char * str,size_t len)242 ebl_gstrtabadd (struct Ebl_GStrtab *st, const char *str, size_t len)
243 {
244 struct Ebl_GStrent *newstr;
245 struct Ebl_GStrent **sep;
246
247 /* Compute the string length if the caller doesn't know it. */
248 if (len == 0)
249 {
250 size_t j;
251
252 do
253 for (j = 0; j < st->width; ++j)
254 if (str[len * st->width + j] != '\0')
255 break;
256 while (j == st->width && ++len);
257 }
258
259 /* Make sure all "" strings get offset 0 but only if the table was
260 created with a special null entry in mind. */
261 if (len == 1 && st->null.string != NULL)
262 return &st->null;
263
264 /* Allocate memory for the new string and its associated information. */
265 newstr = newstring (st, str, len);
266
267 /* Search in the array for the place to insert the string. If there
268 is no string with matching prefix and no string with matching
269 leading substring, create a new entry. */
270 sep = searchstring (&st->root, newstr);
271 if (*sep != newstr)
272 {
273 /* This is not the same entry. This means we have a prefix match. */
274 if ((*sep)->len > newstr->len)
275 {
276 struct Ebl_GStrent *subs;
277
278 /* Check whether we already know this string. */
279 for (subs = (*sep)->next; subs != NULL; subs = subs->next)
280 if (subs->len == newstr->len)
281 {
282 /* We have an exact match with a substring. Free the memory
283 we allocated. */
284 st->left += (st->backp - (char *) newstr) * st->width;
285 st->backp = (char *) newstr;
286
287 return subs;
288 }
289
290 /* We have a new substring. This means we don't need the reverse
291 string of this entry anymore. */
292 st->backp -= newstr->len;
293 st->left += newstr->len;
294
295 newstr->next = (*sep)->next;
296 (*sep)->next = newstr;
297 }
298 else if ((*sep)->len != newstr->len)
299 {
300 /* When we get here it means that the string we are about to
301 add has a common prefix with a string we already have but
302 it is longer. In this case we have to put it first. */
303 st->total += newstr->len - (*sep)->len;
304 newstr->next = *sep;
305 newstr->left = (*sep)->left;
306 newstr->right = (*sep)->right;
307 *sep = newstr;
308 }
309 else
310 {
311 /* We have an exact match. Free the memory we allocated. */
312 st->left += (st->backp - (char *) newstr) * st->width;
313 st->backp = (char *) newstr;
314
315 newstr = *sep;
316 }
317 }
318 else
319 st->total += newstr->len;
320
321 return newstr;
322 }
323
324
325 static void
copystrings(struct Ebl_GStrent * nodep,char ** freep,size_t * offsetp)326 copystrings (struct Ebl_GStrent *nodep, char **freep, size_t *offsetp)
327 {
328 struct Ebl_GStrent *subs;
329
330 if (nodep->left != NULL)
331 copystrings (nodep->left, freep, offsetp);
332
333 /* Process the current node. */
334 nodep->offset = *offsetp;
335 *freep = (char *) mempcpy (*freep, nodep->string, nodep->len * nodep->width);
336 *offsetp += nodep->len * nodep->width;
337
338 for (subs = nodep->next; subs != NULL; subs = subs->next)
339 {
340 assert (subs->len < nodep->len);
341 subs->offset = nodep->offset + (nodep->len - subs->len) * nodep->width;
342 assert (subs->offset != 0 || subs->string[0] == '\0');
343 }
344
345 if (nodep->right != NULL)
346 copystrings (nodep->right, freep, offsetp);
347 }
348
349
350 void
ebl_gstrtabfinalize(struct Ebl_GStrtab * st,Elf_Data * data)351 ebl_gstrtabfinalize (struct Ebl_GStrtab *st, Elf_Data *data)
352 {
353 size_t copylen;
354 char *endp;
355 size_t nulllen = st->nullstr ? st->width : 0;
356
357 /* Fill in the information. */
358 data->d_buf = malloc (st->total + nulllen);
359 if (data->d_buf == NULL)
360 abort ();
361
362 /* The first byte must always be zero if we created the table with a
363 null string. */
364 if (st->nullstr)
365 memset (data->d_buf, '\0', st->width);
366
367 data->d_type = ELF_T_BYTE;
368 data->d_size = st->total + nulllen;
369 data->d_off = 0;
370 data->d_align = 1;
371 data->d_version = EV_CURRENT;
372
373 /* Now run through the tree and add all the string while also updating
374 the offset members of the elfstrent records. */
375 endp = (char *) data->d_buf + nulllen;
376 copylen = nulllen;
377 copystrings (st->root, &endp, ©len);
378 assert (copylen == st->total * st->width + nulllen);
379 }
380
381
382 size_t
ebl_gstrtaboffset(struct Ebl_GStrent * se)383 ebl_gstrtaboffset (struct Ebl_GStrent *se)
384 {
385 return se->offset;
386 }
387