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. 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 * 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 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 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 * 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 ** 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 * 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 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 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 361 ebl_strtaboffset (struct Ebl_Strent *se) 362 { 363 return se->offset; 364 } 365 366 367 const char * 368 ebl_string (struct Ebl_Strent *se) 369 { 370 assert (se->string != NULL); 371 372 return se->string; 373 } 374
