1 /* ELF 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 #include <system.h>
66
67 #ifndef MIN
68 # define MIN(a, b) ((a) < (b) ? (a) : (b))
69 #endif
70
71
72 struct Ebl_Strent
73 {
74 const char *string;
75 size_t len;
76 struct Ebl_Strent *next;
77 struct Ebl_Strent *left;
78 struct Ebl_Strent *right;
79 size_t offset;
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_Strtab
92 {
93 struct Ebl_Strent *root;
94 struct memoryblock *memory;
95 char *backp;
96 size_t left;
97 size_t total;
98 bool nullstr;
99
100 struct Ebl_Strent null;
101 };
102
103
104 /* Cache for the pagesize. We correct this value a bit so that `malloc'
105 is not allocating more than a page. */
106 static size_t ps;
107
108
109 struct Ebl_Strtab *
ebl_strtabinit(bool nullstr)110 ebl_strtabinit (bool nullstr)
111 {
112 if (ps == 0)
113 {
114 ps = sysconf (_SC_PAGESIZE) - 2 * sizeof (void *);
115 assert (sizeof (struct memoryblock) < ps);
116 }
117
118 struct Ebl_Strtab *ret
119 = (struct Ebl_Strtab *) calloc (1, sizeof (struct Ebl_Strtab));
120 if (ret != NULL)
121 {
122 ret->nullstr = nullstr;
123
124 if (nullstr)
125 {
126 ret->null.len = 1;
127 ret->null.string = "";
128 }
129 }
130
131 return ret;
132 }
133
134
135 static int
morememory(struct Ebl_Strtab * st,size_t len)136 morememory (struct Ebl_Strtab *st, size_t len)
137 {
138 if (len < ps)
139 len = ps;
140
141 struct memoryblock *newmem = (struct memoryblock *) malloc (len);
142 if (newmem == NULL)
143 return 1;
144
145 newmem->next = st->memory;
146 st->memory = newmem;
147 st->backp = newmem->memory;
148 st->left = len - offsetof (struct memoryblock, memory);
149
150 return 0;
151 }
152
153
154 void
ebl_strtabfree(struct Ebl_Strtab * st)155 ebl_strtabfree (struct Ebl_Strtab *st)
156 {
157 struct memoryblock *mb = st->memory;
158
159 while (mb != NULL)
160 {
161 void *old = mb;
162 mb = mb->next;
163 free (old);
164 }
165
166 free (st);
167 }
168
169
170 static struct Ebl_Strent *
newstring(struct Ebl_Strtab * st,const char * str,size_t len)171 newstring (struct Ebl_Strtab *st, const char *str, size_t len)
172 {
173 /* Compute the amount of padding needed to make the structure aligned. */
174 size_t align = ((__alignof__ (struct Ebl_Strent)
175 - (((uintptr_t) st->backp)
176 & (__alignof__ (struct Ebl_Strent) - 1)))
177 & (__alignof__ (struct Ebl_Strent) - 1));
178
179 /* Make sure there is enough room in the memory block. */
180 if (st->left < align + sizeof (struct Ebl_Strent) + len)
181 {
182 if (morememory (st, sizeof (struct Ebl_Strent) + len))
183 return NULL;
184
185 align = 0;
186 }
187
188 /* Create the reserved string. */
189 struct Ebl_Strent *newstr = (struct Ebl_Strent *) (st->backp + align);
190 newstr->string = str;
191 newstr->len = len;
192 newstr->next = NULL;
193 newstr->left = NULL;
194 newstr->right = NULL;
195 newstr->offset = 0;
196 for (int i = len - 2; i >= 0; --i)
197 newstr->reverse[i] = str[len - 2 - i];
198 newstr->reverse[len - 1] = '\0';
199 st->backp += align + sizeof (struct Ebl_Strent) + len;
200 st->left -= align + sizeof (struct Ebl_Strent) + len;
201
202 return newstr;
203 }
204
205
206 /* XXX This function should definitely be rewritten to use a balancing
207 tree algorith (AVL, red-black trees). For now a simple, correct
208 implementation is enough. */
209 static struct Ebl_Strent **
searchstring(struct Ebl_Strent ** sep,struct Ebl_Strent * newstr)210 searchstring (struct Ebl_Strent **sep, struct Ebl_Strent *newstr)
211 {
212 /* More strings? */
213 if (*sep == NULL)
214 {
215 *sep = newstr;
216 return sep;
217 }
218
219 /* Compare the strings. */
220 int cmpres = memcmp ((*sep)->reverse, newstr->reverse,
221 MIN ((*sep)->len, newstr->len) - 1);
222 if (cmpres == 0)
223 /* We found a matching string. */
224 return sep;
225 else if (cmpres > 0)
226 return searchstring (&(*sep)->left, newstr);
227 else
228 return searchstring (&(*sep)->right, newstr);
229 }
230
231
232 /* Add new string. The actual string is assumed to be permanent. */
233 struct Ebl_Strent *
ebl_strtabadd(struct Ebl_Strtab * st,const char * str,size_t len)234 ebl_strtabadd (struct Ebl_Strtab *st, const char *str, size_t len)
235 {
236 /* Compute the string length if the caller doesn't know it. */
237 if (len == 0)
238 len = strlen (str) + 1;
239
240 /* Make sure all "" strings get offset 0 but only if the table was
241 created with a special null entry in mind. */
242 if (len == 1 && st->null.string != NULL)
243 return &st->null;
244
245 /* Allocate memory for the new string and its associated information. */
246 struct Ebl_Strent *newstr = newstring (st, str, len);
247 if (newstr == NULL)
248 return NULL;
249
250 /* Search in the array for the place to insert the string. If there
251 is no string with matching prefix and no string with matching
252 leading substring, create a new entry. */
253 struct Ebl_Strent **sep = searchstring (&st->root, newstr);
254 if (*sep != newstr)
255 {
256 /* This is not the same entry. This means we have a prefix match. */
257 if ((*sep)->len > newstr->len)
258 {
259 /* Check whether we already know this string. */
260 for (struct Ebl_Strent *subs = (*sep)->next; subs != NULL;
261 subs = subs->next)
262 if (subs->len == newstr->len)
263 {
264 /* We have an exact match with a substring. Free the memory
265 we allocated. */
266 st->left += st->backp - (char *) newstr;
267 st->backp = (char *) newstr;
268
269 return subs;
270 }
271
272 /* We have a new substring. This means we don't need the reverse
273 string of this entry anymore. */
274 st->backp -= newstr->len;
275 st->left += newstr->len;
276
277 newstr->next = (*sep)->next;
278 (*sep)->next = newstr;
279 }
280 else if ((*sep)->len != newstr->len)
281 {
282 /* When we get here it means that the string we are about to
283 add has a common prefix with a string we already have but
284 it is longer. In this case we have to put it first. */
285 st->total += newstr->len - (*sep)->len;
286 newstr->next = *sep;
287 newstr->left = (*sep)->left;
288 newstr->right = (*sep)->right;
289 *sep = newstr;
290 }
291 else
292 {
293 /* We have an exact match. Free the memory we allocated. */
294 st->left += st->backp - (char *) newstr;
295 st->backp = (char *) newstr;
296
297 newstr = *sep;
298 }
299 }
300 else
301 st->total += newstr->len;
302
303 return newstr;
304 }
305
306
307 static void
copystrings(struct Ebl_Strent * nodep,char ** freep,size_t * offsetp)308 copystrings (struct Ebl_Strent *nodep, char **freep, size_t *offsetp)
309 {
310 if (nodep->left != NULL)
311 copystrings (nodep->left, freep, offsetp);
312
313 /* Process the current node. */
314 nodep->offset = *offsetp;
315 *freep = (char *) mempcpy (*freep, nodep->string, nodep->len);
316 *offsetp += nodep->len;
317
318 for (struct Ebl_Strent *subs = nodep->next; subs != NULL; subs = subs->next)
319 {
320 assert (subs->len < nodep->len);
321 subs->offset = nodep->offset + nodep->len - subs->len;
322 assert (subs->offset != 0 || subs->string[0] == '\0');
323 }
324
325 if (nodep->right != NULL)
326 copystrings (nodep->right, freep, offsetp);
327 }
328
329
330 void
ebl_strtabfinalize(struct Ebl_Strtab * st,Elf_Data * data)331 ebl_strtabfinalize (struct Ebl_Strtab *st, Elf_Data *data)
332 {
333 size_t nulllen = st->nullstr ? 1 : 0;
334
335 /* Fill in the information. */
336 data->d_buf = malloc (st->total + nulllen);
337 if (data->d_buf == NULL)
338 abort ();
339
340 /* The first byte must always be zero if we created the table with a
341 null string. */
342 if (st->nullstr)
343 *((char *) data->d_buf) = '\0';
344
345 data->d_type = ELF_T_BYTE;
346 data->d_size = st->total + nulllen;
347 data->d_off = 0;
348 data->d_align = 1;
349 data->d_version = EV_CURRENT;
350
351 /* Now run through the tree and add all the string while also updating
352 the offset members of the elfstrent records. */
353 char *endp = (char *) data->d_buf + nulllen;
354 size_t copylen = nulllen;
355 copystrings (st->root, &endp, ©len);
356 assert (copylen == st->total + nulllen);
357 }
358
359
360 size_t
ebl_strtaboffset(struct Ebl_Strent * se)361 ebl_strtaboffset (struct Ebl_Strent *se)
362 {
363 return se->offset;
364 }
365
366
367 const char *
ebl_string(struct Ebl_Strent * se)368 ebl_string (struct Ebl_Strent *se)
369 {
370 assert (se->string != NULL);
371
372 return se->string;
373 }
374