1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD: src/lib/libc/gen/nlist.c,v 1.12.2.1 2001/07/11 23:59:09 obrien Exp $ 34 * $DragonFly: src/lib/libc/gen/nlist.c,v 1.4 2004/06/06 15:05:55 hmp Exp $ 35 * 36 * @(#)nlist.c 8.1 (Berkeley) 6/4/93 37 */ 38 39 #include <sys/param.h> 40 #include <sys/mman.h> 41 #include <sys/stat.h> 42 #include <sys/file.h> 43 44 #include <errno.h> 45 #include <a.out.h> 46 #include <stdio.h> 47 #include <string.h> 48 #include <unistd.h> 49 50 #define _NLIST_DO_AOUT 51 #define _NLIST_DO_ELF 52 53 #ifdef _NLIST_DO_ELF 54 #include <machine/elf.h> 55 #include <elf-hints.h> 56 #endif 57 58 int __fdnlist (int, struct nlist *); 59 int __aout_fdnlist (int, struct nlist *); 60 int __elf_fdnlist (int, struct nlist *); 61 62 int 63 nlist(name, list) 64 const char *name; 65 struct nlist *list; 66 { 67 int fd, n; 68 69 fd = _open(name, O_RDONLY, 0); 70 if (fd < 0) 71 return (-1); 72 n = __fdnlist(fd, list); 73 (void)_close(fd); 74 return (n); 75 } 76 77 static struct nlist_handlers { 78 int (*fn) (int fd, struct nlist *list); 79 } nlist_fn[] = { 80 #ifdef _NLIST_DO_AOUT 81 { __aout_fdnlist }, 82 #endif 83 #ifdef _NLIST_DO_ELF 84 { __elf_fdnlist }, 85 #endif 86 }; 87 88 int 89 __fdnlist(fd, list) 90 int fd; 91 struct nlist *list; 92 { 93 int n = -1, i; 94 95 for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) { 96 n = (nlist_fn[i].fn)(fd, list); 97 if (n != -1) 98 break; 99 } 100 return (n); 101 } 102 103 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 104 105 #ifdef _NLIST_DO_AOUT 106 int 107 __aout_fdnlist(fd, list) 108 int fd; 109 struct nlist *list; 110 { 111 struct nlist *p, *symtab; 112 caddr_t strtab, a_out_mmap; 113 off_t stroff, symoff; 114 u_long symsize; 115 int nent; 116 struct exec * exec; 117 struct stat st; 118 119 /* check that file is at least as large as struct exec! */ 120 if ((fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec))) 121 return (-1); 122 123 /* Check for files too large to mmap. */ 124 if (st.st_size > SIZE_T_MAX) { 125 errno = EFBIG; 126 return (-1); 127 } 128 129 /* 130 * Map the whole a.out file into our address space. 131 * We then find the string table withing this area. 132 * We do not just mmap the string table, as it probably 133 * does not start at a page boundary - we save ourselves a 134 * lot of nastiness by mmapping the whole file. 135 * 136 * This gives us an easy way to randomly access all the strings, 137 * without making the memory allocation permanent as with 138 * malloc/free (i.e., munmap will return it to the system). 139 */ 140 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0); 141 if (a_out_mmap == MAP_FAILED) 142 return (-1); 143 144 exec = (struct exec *)a_out_mmap; 145 if (N_BADMAG(*exec)) { 146 munmap(a_out_mmap, (size_t)st.st_size); 147 return (-1); 148 } 149 150 symoff = N_SYMOFF(*exec); 151 symsize = exec->a_syms; 152 stroff = symoff + symsize; 153 154 /* find the string table in our mmapped area */ 155 strtab = a_out_mmap + stroff; 156 symtab = (struct nlist *)(a_out_mmap + symoff); 157 158 /* 159 * clean out any left-over information for all valid entries. 160 * Type and value defined to be 0 if not found; historical 161 * versions cleared other and desc as well. Also figure out 162 * the largest string length so don't read any more of the 163 * string table than we have to. 164 * 165 * XXX clearing anything other than n_type and n_value violates 166 * the semantics given in the man page. 167 */ 168 nent = 0; 169 for (p = list; !ISLAST(p); ++p) { 170 p->n_type = 0; 171 p->n_other = 0; 172 p->n_desc = 0; 173 p->n_value = 0; 174 ++nent; 175 } 176 177 while (symsize > 0) { 178 int soff; 179 180 symsize-= sizeof(struct nlist); 181 soff = symtab->n_un.n_strx; 182 183 184 if (soff != 0 && (symtab->n_type & N_STAB) == 0) 185 for (p = list; !ISLAST(p); p++) 186 if (!strcmp(&strtab[soff], p->n_un.n_name)) { 187 p->n_value = symtab->n_value; 188 p->n_type = symtab->n_type; 189 p->n_desc = symtab->n_desc; 190 p->n_other = symtab->n_other; 191 if (--nent <= 0) 192 break; 193 } 194 symtab++; 195 } 196 munmap(a_out_mmap, (size_t)st.st_size); 197 return (nent); 198 } 199 #endif 200 201 #ifdef _NLIST_DO_ELF 202 static void elf_sym_to_nlist (struct nlist *, Elf_Sym *, Elf_Shdr *, int); 203 204 /* 205 * __elf_is_okay__ - Determine if ehdr really 206 * is ELF and valid for the target platform. 207 * 208 * WARNING: This is NOT a ELF ABI function and 209 * as such it's use should be restricted. 210 */ 211 int 212 __elf_is_okay__(ehdr) 213 Elf_Ehdr *ehdr; 214 { 215 int retval = 0; 216 /* 217 * We need to check magic, class size, endianess, 218 * and version before we look at the rest of the 219 * Elf_Ehdr structure. These few elements are 220 * represented in a machine independant fashion. 221 */ 222 if (IS_ELF(*ehdr) && 223 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 224 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 225 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 226 227 /* Now check the machine dependant header */ 228 if (ehdr->e_machine == ELF_TARG_MACH && 229 ehdr->e_version == ELF_TARG_VER) 230 retval = 1; 231 } 232 return retval; 233 } 234 235 int 236 __elf_fdnlist(fd, list) 237 int fd; 238 struct nlist *list; 239 { 240 struct nlist *p; 241 Elf_Off symoff = 0, symstroff = 0; 242 Elf_Word symsize = 0, symstrsize = 0; 243 Elf_Sword cc, i; 244 int nent = -1; 245 int errsave; 246 Elf_Sym sbuf[1024]; 247 Elf_Sym *s; 248 Elf_Ehdr ehdr; 249 char *strtab = NULL; 250 Elf_Shdr *shdr = NULL; 251 Elf_Shdr *sh; 252 Elf_Word shdr_size; 253 void *base; 254 struct stat st; 255 256 /* Make sure obj is OK */ 257 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 258 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 259 !__elf_is_okay__(&ehdr) || 260 fstat(fd, &st) < 0) 261 return (-1); 262 263 /* calculate section header table size */ 264 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 265 266 /* Make sure it's not too big to mmap */ 267 if (shdr_size > SIZE_T_MAX) { 268 errno = EFBIG; 269 return (-1); 270 } 271 272 /* mmap section header table */ 273 base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd, 274 (off_t)ehdr.e_shoff); 275 if (base == MAP_FAILED) 276 return (-1); 277 shdr = (Elf_Shdr *)base; 278 279 /* 280 * Find the symbol table entry and it's corresponding 281 * string table entry. Version 1.1 of the ABI states 282 * that there is only one symbol table but that this 283 * could change in the future. 284 */ 285 for (i = 0; i < ehdr.e_shnum; i++) { 286 if (shdr[i].sh_type == SHT_SYMTAB) { 287 symoff = shdr[i].sh_offset; 288 symsize = shdr[i].sh_size; 289 symstroff = shdr[shdr[i].sh_link].sh_offset; 290 symstrsize = shdr[shdr[i].sh_link].sh_size; 291 break; 292 } 293 } 294 295 /* Check for files too large to mmap. */ 296 if (symstrsize > SIZE_T_MAX) { 297 errno = EFBIG; 298 goto done; 299 } 300 /* 301 * Map string table into our address space. This gives us 302 * an easy way to randomly access all the strings, without 303 * making the memory allocation permanent as with malloc/free 304 * (i.e., munmap will return it to the system). 305 */ 306 base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd, 307 (off_t)symstroff); 308 if (base == MAP_FAILED) 309 goto done; 310 strtab = (char *)base; 311 312 /* 313 * clean out any left-over information for all valid entries. 314 * Type and value defined to be 0 if not found; historical 315 * versions cleared other and desc as well. Also figure out 316 * the largest string length so don't read any more of the 317 * string table than we have to. 318 * 319 * XXX clearing anything other than n_type and n_value violates 320 * the semantics given in the man page. 321 */ 322 nent = 0; 323 for (p = list; !ISLAST(p); ++p) { 324 p->n_type = 0; 325 p->n_other = 0; 326 p->n_desc = 0; 327 p->n_value = 0; 328 ++nent; 329 } 330 331 /* Don't process any further if object is stripped. */ 332 if (symoff == 0) 333 goto done; 334 335 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 336 nent = -1; 337 goto done; 338 } 339 340 while (symsize > 0 && nent > 0) { 341 cc = MIN(symsize, sizeof(sbuf)); 342 if (_read(fd, sbuf, cc) != cc) 343 break; 344 symsize -= cc; 345 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 346 char *name; 347 struct nlist *p; 348 349 name = strtab + s->st_name; 350 if (name[0] == '\0') 351 continue; 352 for (p = list; !ISLAST(p); p++) { 353 if ((p->n_un.n_name[0] == '_' && 354 strcmp(name, p->n_un.n_name+1) == 0) 355 || strcmp(name, p->n_un.n_name) == 0) { 356 elf_sym_to_nlist(p, s, shdr, 357 ehdr.e_shnum); 358 if (--nent <= 0) 359 break; 360 } 361 } 362 } 363 } 364 done: 365 errsave = errno; 366 if (strtab != NULL) 367 munmap(strtab, symstrsize); 368 if (shdr != NULL) 369 munmap(shdr, shdr_size); 370 errno = errsave; 371 return (nent); 372 } 373 374 /* 375 * Convert an Elf_Sym into an nlist structure. This fills in only the 376 * n_value and n_type members. 377 */ 378 static void 379 elf_sym_to_nlist(nl, s, shdr, shnum) 380 struct nlist *nl; 381 Elf_Sym *s; 382 Elf_Shdr *shdr; 383 int shnum; 384 { 385 nl->n_value = s->st_value; 386 387 switch (s->st_shndx) { 388 case SHN_UNDEF: 389 case SHN_COMMON: 390 nl->n_type = N_UNDF; 391 break; 392 case SHN_ABS: 393 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 394 N_FN : N_ABS; 395 break; 396 default: 397 if (s->st_shndx >= shnum) 398 nl->n_type = N_UNDF; 399 else { 400 Elf_Shdr *sh = shdr + s->st_shndx; 401 402 nl->n_type = sh->sh_type == SHT_PROGBITS ? 403 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 404 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 405 } 406 break; 407 } 408 409 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 410 ELF_ST_BIND(s->st_info) == STB_WEAK) 411 nl->n_type |= N_EXT; 412 } 413 #endif /* _NLIST_DO_ELF */ 414