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 1.6 2005/04/26 08:21:34 joerg Exp $ 35 * 36 * @(#)nlist.c 8.1 (Berkeley) 6/4/93 37 */ 38 39 #include "namespace.h" 40 #include <sys/param.h> 41 #include <sys/mman.h> 42 #include <sys/stat.h> 43 #include <sys/file.h> 44 45 #include <errno.h> 46 #include <a.out.h> 47 #include <stdio.h> 48 #include <string.h> 49 #include <unistd.h> 50 #include "un-namespace.h" 51 52 #define _NLIST_DO_AOUT 53 #define _NLIST_DO_ELF 54 55 #ifdef _NLIST_DO_ELF 56 #include <machine/elf.h> 57 #include <elf-hints.h> 58 #endif 59 60 int __fdnlist(int, struct nlist *); 61 int __aout_fdnlist(int, struct nlist *); 62 int __elf_fdnlist(int, struct nlist *); 63 64 int 65 nlist(const char *name, 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 _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(int fd, struct nlist *list) 90 { 91 int n = -1; 92 size_t i; 93 94 for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) { 95 n = (nlist_fn[i].fn)(fd, list); 96 if (n != -1) 97 break; 98 } 99 return (n); 100 } 101 102 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 103 104 #ifdef _NLIST_DO_AOUT 105 int 106 __aout_fdnlist(int fd, struct nlist *list) 107 { 108 struct nlist *p, *symtab; 109 caddr_t strtab, a_out_mmap; 110 off_t stroff, symoff; 111 u_long symsize; 112 int nent; 113 struct exec * exec; 114 struct stat st; 115 116 /* check that file is at least as large as struct exec! */ 117 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec))) 118 return (-1); 119 120 /* Check for files too large to mmap. */ 121 if (st.st_size > SIZE_T_MAX) { 122 errno = EFBIG; 123 return (-1); 124 } 125 126 /* 127 * Map the whole a.out file into our address space. 128 * We then find the string table withing this area. 129 * We do not just mmap the string table, as it probably 130 * does not start at a page boundary - we save ourselves a 131 * lot of nastiness by mmapping the whole file. 132 * 133 * This gives us an easy way to randomly access all the strings, 134 * without making the memory allocation permanent as with 135 * malloc/free (i.e., munmap will return it to the system). 136 */ 137 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0); 138 if (a_out_mmap == MAP_FAILED) 139 return (-1); 140 141 exec = (struct exec *)a_out_mmap; 142 if (N_BADMAG(*exec)) { 143 munmap(a_out_mmap, (size_t)st.st_size); 144 return (-1); 145 } 146 147 symoff = N_SYMOFF(*exec); 148 symsize = exec->a_syms; 149 stroff = symoff + symsize; 150 151 /* find the string table in our mmapped area */ 152 strtab = a_out_mmap + stroff; 153 symtab = (struct nlist *)(a_out_mmap + symoff); 154 155 /* 156 * clean out any left-over information for all valid entries. 157 * Type and value defined to be 0 if not found; historical 158 * versions cleared other and desc as well. Also figure out 159 * the largest string length so don't read any more of the 160 * string table than we have to. 161 * 162 * XXX clearing anything other than n_type and n_value violates 163 * the semantics given in the man page. 164 */ 165 nent = 0; 166 for (p = list; !ISLAST(p); ++p) { 167 p->n_type = 0; 168 p->n_other = 0; 169 p->n_desc = 0; 170 p->n_value = 0; 171 ++nent; 172 } 173 174 while (symsize > 0) { 175 int soff; 176 177 symsize-= sizeof(struct nlist); 178 soff = symtab->n_un.n_strx; 179 180 181 if (soff != 0 && (symtab->n_type & N_STAB) == 0) 182 for (p = list; !ISLAST(p); p++) 183 if (!strcmp(&strtab[soff], p->n_un.n_name)) { 184 p->n_value = symtab->n_value; 185 p->n_type = symtab->n_type; 186 p->n_desc = symtab->n_desc; 187 p->n_other = symtab->n_other; 188 if (--nent <= 0) 189 break; 190 } 191 symtab++; 192 } 193 munmap(a_out_mmap, (size_t)st.st_size); 194 return (nent); 195 } 196 #endif 197 198 #ifdef _NLIST_DO_ELF 199 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 200 201 /* 202 * __elf_is_okay__ - Determine if ehdr really 203 * is ELF and valid for the target platform. 204 * 205 * WARNING: This is NOT a ELF ABI function and 206 * as such it's use should be restricted. 207 */ 208 static int 209 __elf_is_okay__(Elf_Ehdr *ehdr) 210 { 211 int retval = 0; 212 /* 213 * We need to check magic, class size, endianess, 214 * and version before we look at the rest of the 215 * Elf_Ehdr structure. These few elements are 216 * represented in a machine independant fashion. 217 */ 218 if (IS_ELF(*ehdr) && 219 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 220 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 221 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 222 223 /* Now check the machine dependant header */ 224 if (ehdr->e_machine == ELF_TARG_MACH && 225 ehdr->e_version == ELF_TARG_VER) 226 retval = 1; 227 } 228 return retval; 229 } 230 231 int 232 __elf_fdnlist(int fd, struct nlist *list) 233 { 234 struct nlist *p; 235 Elf_Off symoff = 0, symstroff = 0; 236 Elf_Word symsize = 0, symstrsize = 0; 237 Elf_Sword cc, i; 238 int nent = -1; 239 int errsave; 240 Elf_Sym sbuf[1024]; 241 Elf_Sym *s; 242 Elf_Ehdr ehdr; 243 char *strtab = NULL; 244 Elf_Shdr *shdr = NULL; 245 Elf_Word shdr_size; 246 void *base; 247 struct stat st; 248 249 /* Make sure obj is OK */ 250 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 251 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 252 !__elf_is_okay__(&ehdr) || 253 _fstat(fd, &st) < 0) 254 return (-1); 255 256 /* calculate section header table size */ 257 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 258 259 #ifndef __x86_64__ 260 /* Make sure it's not too big to mmap */ 261 if (shdr_size > SIZE_T_MAX) { 262 errno = EFBIG; 263 return (-1); 264 } 265 #endif 266 267 /* mmap section header table */ 268 base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd, 269 (off_t)ehdr.e_shoff); 270 if (base == MAP_FAILED) 271 return (-1); 272 shdr = (Elf_Shdr *)base; 273 274 /* 275 * Find the symbol table entry and it's corresponding 276 * string table entry. Version 1.1 of the ABI states 277 * that there is only one symbol table but that this 278 * could change in the future. 279 */ 280 for (i = 0; i < ehdr.e_shnum; i++) { 281 if (shdr[i].sh_type == SHT_SYMTAB) { 282 symoff = shdr[i].sh_offset; 283 symsize = shdr[i].sh_size; 284 symstroff = shdr[shdr[i].sh_link].sh_offset; 285 symstrsize = shdr[shdr[i].sh_link].sh_size; 286 break; 287 } 288 } 289 290 #ifndef __x86_64__ 291 /* Check for files too large to mmap. */ 292 if (symstrsize > SIZE_T_MAX) { 293 errno = EFBIG; 294 goto done; 295 } 296 #endif 297 298 /* 299 * Map string table into our address space. This gives us 300 * an easy way to randomly access all the strings, without 301 * making the memory allocation permanent as with malloc/free 302 * (i.e., munmap will return it to the system). 303 */ 304 base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd, 305 (off_t)symstroff); 306 if (base == MAP_FAILED) 307 goto done; 308 strtab = (char *)base; 309 310 /* 311 * clean out any left-over information for all valid entries. 312 * Type and value defined to be 0 if not found; historical 313 * versions cleared other and desc as well. Also figure out 314 * the largest string length so don't read any more of the 315 * string table than we have to. 316 * 317 * XXX clearing anything other than n_type and n_value violates 318 * the semantics given in the man page. 319 */ 320 nent = 0; 321 for (p = list; !ISLAST(p); ++p) { 322 p->n_type = 0; 323 p->n_other = 0; 324 p->n_desc = 0; 325 p->n_value = 0; 326 ++nent; 327 } 328 329 /* Don't process any further if object is stripped. */ 330 if (symoff == 0) 331 goto done; 332 333 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 334 nent = -1; 335 goto done; 336 } 337 338 while (symsize > 0 && nent > 0) { 339 cc = MIN(symsize, sizeof(sbuf)); 340 if (_read(fd, sbuf, cc) != cc) 341 break; 342 symsize -= cc; 343 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 344 char *name; 345 struct nlist *p_local; 346 347 name = strtab + s->st_name; 348 if (name[0] == '\0') 349 continue; 350 for (p_local = list; !ISLAST(p_local); p_local++) { 351 if ((p_local->n_un.n_name[0] == '_' && 352 strcmp(name, p_local->n_un.n_name+1) == 0) 353 || strcmp(name, p_local->n_un.n_name) == 0) { 354 elf_sym_to_nlist(p_local, s, shdr, 355 ehdr.e_shnum); 356 if (--nent <= 0) 357 break; 358 } 359 } 360 } 361 } 362 done: 363 errsave = errno; 364 if (strtab != NULL) 365 munmap(strtab, symstrsize); 366 if (shdr != NULL) 367 munmap(shdr, shdr_size); 368 errno = errsave; 369 return (nent); 370 } 371 372 /* 373 * Convert an Elf_Sym into an nlist structure. This fills in only the 374 * n_value and n_type members. 375 */ 376 static void 377 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum) 378 { 379 nl->n_value = s->st_value; 380 381 switch (s->st_shndx) { 382 case SHN_UNDEF: 383 case SHN_COMMON: 384 nl->n_type = N_UNDF; 385 break; 386 case SHN_ABS: 387 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 388 N_FN : N_ABS; 389 break; 390 default: 391 if (s->st_shndx >= shnum) 392 nl->n_type = N_UNDF; 393 else { 394 Elf_Shdr *sh = shdr + s->st_shndx; 395 396 nl->n_type = sh->sh_type == SHT_PROGBITS ? 397 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 398 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 399 } 400 break; 401 } 402 403 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 404 ELF_ST_BIND(s->st_info) == STB_WEAK) 405 nl->n_type |= N_EXT; 406 } 407 #endif /* _NLIST_DO_ELF */ 408