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 (at) 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. */ 105 static size_t ps; 106 /* We correct this value a bit so that `malloc' is not allocating more 107 than a page. */ 108 #define MALLOC_OVERHEAD (2 * sizeof (void *)) 109 110 111 struct Ebl_Strtab * 112 ebl_strtabinit (bool nullstr) 113 { 114 if (ps == 0) 115 { 116 ps = sysconf (_SC_PAGESIZE); 117 assert (sizeof (struct memoryblock) < ps - MALLOC_OVERHEAD); 118 } 119 120 struct Ebl_Strtab *ret 121 = (struct Ebl_Strtab *) calloc (1, sizeof (struct Ebl_Strtab)); 122 if (ret != NULL) 123 { 124 ret->nullstr = nullstr; 125 126 if (nullstr) 127 { 128 ret->null.len = 1; 129 ret->null.string = ""; 130 } 131 } 132 133 return ret; 134 } 135 136 137 static int 138 morememory (struct Ebl_Strtab *st, size_t len) 139 { 140 size_t overhead = offsetof (struct memoryblock, memory); 141 len += overhead + MALLOC_OVERHEAD; 142 143 /* Allocate nearest multiple of pagesize >= len. */ 144 len = ((len / ps) + (len % ps != 0)) * ps - MALLOC_OVERHEAD; 145 146 struct memoryblock *newmem = (struct memoryblock *) malloc (len); 147 if (newmem == NULL) 148 return 1; 149 150 newmem->next = st->memory; 151 st->memory = newmem; 152 st->backp = newmem->memory; 153 st->left = len - overhead; 154 155 return 0; 156 } 157 158 159 void 160 ebl_strtabfree (struct Ebl_Strtab *st) 161 { 162 struct memoryblock *mb = st->memory; 163 164 while (mb != NULL) 165 { 166 void *old = mb; 167 mb = mb->next; 168 free (old); 169 } 170 171 free (st); 172 } 173 174 175 static struct Ebl_Strent * 176 newstring (struct Ebl_Strtab *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_Strent) 180 - (((uintptr_t) st->backp) 181 & (__alignof__ (struct Ebl_Strent) - 1))) 182 & (__alignof__ (struct Ebl_Strent) - 1)); 183 184 /* Make sure there is enough room in the memory block. */ 185 if (st->left < align + sizeof (struct Ebl_Strent) + len) 186 { 187 if (morememory (st, sizeof (struct Ebl_Strent) + len)) 188 return NULL; 189 190 align = 0; 191 } 192 193 /* Create the reserved string. */ 194 struct Ebl_Strent *newstr = (struct Ebl_Strent *) (st->backp + align); 195 newstr->string = str; 196 newstr->len = len; 197 newstr->next = NULL; 198 newstr->left = NULL; 199 newstr->right = NULL; 200 newstr->offset = 0; 201 for (int i = len - 2; i >= 0; --i) 202 newstr->reverse[i] = str[len - 2 - i]; 203 newstr->reverse[len - 1] = '\0'; 204 st->backp += align + sizeof (struct Ebl_Strent) + len; 205 st->left -= align + sizeof (struct Ebl_Strent) + len; 206 207 return newstr; 208 } 209 210 211 /* XXX This function should definitely be rewritten to use a balancing 212 tree algorith (AVL, red-black trees). For now a simple, correct 213 implementation is enough. */ 214 static struct Ebl_Strent ** 215 searchstring (struct Ebl_Strent **sep, struct Ebl_Strent *newstr) 216 { 217 /* More strings? */ 218 if (*sep == NULL) 219 { 220 *sep = newstr; 221 return sep; 222 } 223 224 /* Compare the strings. */ 225 int cmpres = memcmp ((*sep)->reverse, newstr->reverse, 226 MIN ((*sep)->len, newstr->len) - 1); 227 if (cmpres == 0) 228 /* We found a matching string. */ 229 return sep; 230 else if (cmpres > 0) 231 return searchstring (&(*sep)->left, newstr); 232 else 233 return searchstring (&(*sep)->right, newstr); 234 } 235 236 237 /* Add new string. The actual string is assumed to be permanent. */ 238 struct Ebl_Strent * 239 ebl_strtabadd (struct Ebl_Strtab *st, const char *str, size_t len) 240 { 241 /* Compute the string length if the caller doesn't know it. */ 242 if (len == 0) 243 len = strlen (str) + 1; 244 245 /* Make sure all "" strings get offset 0 but only if the table was 246 created with a special null entry in mind. */ 247 if (len == 1 && st->null.string != NULL) 248 return &st->null; 249 250 /* Allocate memory for the new string and its associated information. */ 251 struct Ebl_Strent *newstr = newstring (st, str, len); 252 if (newstr == NULL) 253 return NULL; 254 255 /* Search in the array for the place to insert the string. If there 256 is no string with matching prefix and no string with matching 257 leading substring, create a new entry. */ 258 struct Ebl_Strent **sep = searchstring (&st->root, newstr); 259 if (*sep != newstr) 260 { 261 /* This is not the same entry. This means we have a prefix match. */ 262 if ((*sep)->len > newstr->len) 263 { 264 /* Check whether we already know this string. */ 265 for (struct Ebl_Strent *subs = (*sep)->next; subs != NULL; 266 subs = subs->next) 267 if (subs->len == newstr->len) 268 { 269 /* We have an exact match with a substring. Free the memory 270 we allocated. */ 271 st->left += st->backp - (char *) newstr; 272 st->backp = (char *) newstr; 273 274 return subs; 275 } 276 277 /* We have a new substring. This means we don't need the reverse 278 string of this entry anymore. */ 279 st->backp -= newstr->len; 280 st->left += newstr->len; 281 282 newstr->next = (*sep)->next; 283 (*sep)->next = newstr; 284 } 285 else if ((*sep)->len != newstr->len) 286 { 287 /* When we get here it means that the string we are about to 288 add has a common prefix with a string we already have but 289 it is longer. In this case we have to put it first. */ 290 st->total += newstr->len - (*sep)->len; 291 newstr->next = *sep; 292 newstr->left = (*sep)->left; 293 newstr->right = (*sep)->right; 294 *sep = newstr; 295 } 296 else 297 { 298 /* We have an exact match. Free the memory we allocated. */ 299 st->left += st->backp - (char *) newstr; 300 st->backp = (char *) newstr; 301 302 newstr = *sep; 303 } 304 } 305 else 306 st->total += newstr->len; 307 308 return newstr; 309 } 310 311 312 static void 313 copystrings (struct Ebl_Strent *nodep, char **freep, size_t *offsetp) 314 { 315 if (nodep->left != NULL) 316 copystrings (nodep->left, freep, offsetp); 317 318 /* Process the current node. */ 319 nodep->offset = *offsetp; 320 *freep = (char *) mempcpy (*freep, nodep->string, nodep->len); 321 *offsetp += nodep->len; 322 323 for (struct Ebl_Strent *subs = nodep->next; subs != NULL; subs = subs->next) 324 { 325 assert (subs->len < nodep->len); 326 subs->offset = nodep->offset + nodep->len - subs->len; 327 assert (subs->offset != 0 || subs->string[0] == '\0'); 328 } 329 330 if (nodep->right != NULL) 331 copystrings (nodep->right, freep, offsetp); 332 } 333 334 335 void 336 ebl_strtabfinalize (struct Ebl_Strtab *st, Elf_Data *data) 337 { 338 size_t nulllen = st->nullstr ? 1 : 0; 339 340 /* Fill in the information. */ 341 data->d_buf = malloc (st->total + nulllen); 342 if (data->d_buf == NULL) 343 abort (); 344 345 /* The first byte must always be zero if we created the table with a 346 null string. */ 347 if (st->nullstr) 348 *((char *) data->d_buf) = '\0'; 349 350 data->d_type = ELF_T_BYTE; 351 data->d_size = st->total + nulllen; 352 data->d_off = 0; 353 data->d_align = 1; 354 data->d_version = EV_CURRENT; 355 356 /* Now run through the tree and add all the string while also updating 357 the offset members of the elfstrent records. */ 358 char *endp = (char *) data->d_buf + nulllen; 359 size_t copylen = nulllen; 360 if (st->root) 361 copystrings (st->root, &endp, ©len); 362 assert (copylen == st->total + nulllen); 363 } 364 365 366 size_t 367 ebl_strtaboffset (struct Ebl_Strent *se) 368 { 369 return se->offset; 370 } 371 372 373 const char * 374 ebl_string (struct Ebl_Strent *se) 375 { 376 assert (se->string != NULL); 377 378 return se->string; 379 } 380
