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. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD: src/lib/libc/gen/nlist.c,v 1.12.2.1 2001/07/11 23:59:09 obrien Exp $ 30 * 31 * @(#)nlist.c 8.1 (Berkeley) 6/4/93 32 */ 33 34 #include "namespace.h" 35 #include <sys/param.h> 36 #include <sys/mman.h> 37 #include <sys/stat.h> 38 #include <sys/file.h> 39 40 #include <errno.h> 41 #include <a.out.h> 42 #include <stdio.h> 43 #include <string.h> 44 #include <unistd.h> 45 #include "un-namespace.h" 46 47 #define _NLIST_DO_AOUT 48 #define _NLIST_DO_ELF 49 50 #ifdef _NLIST_DO_ELF 51 #include <machine/elf.h> 52 #include <elf-hints.h> 53 #endif 54 55 int __fdnlist(int, struct nlist *); 56 int __aout_fdnlist(int, struct nlist *); 57 int __elf_fdnlist(int, struct nlist *); 58 59 int 60 nlist(const char *name, struct nlist *list) 61 { 62 int fd, n; 63 64 fd = _open(name, O_RDONLY | O_CLOEXEC, 0); 65 if (fd < 0) 66 return (-1); 67 n = __fdnlist(fd, list); 68 _close(fd); 69 return (n); 70 } 71 72 static struct nlist_handlers { 73 int (*fn)(int fd, struct nlist *list); 74 } nlist_fn[] = { 75 #ifdef _NLIST_DO_AOUT 76 { __aout_fdnlist }, 77 #endif 78 #ifdef _NLIST_DO_ELF 79 { __elf_fdnlist }, 80 #endif 81 }; 82 83 int 84 __fdnlist(int fd, struct nlist *list) 85 { 86 int n = -1; 87 size_t i; 88 89 for (i = 0; i < NELEM(nlist_fn); i++) { 90 n = (nlist_fn[i].fn)(fd, list); 91 if (n != -1) 92 break; 93 } 94 return (n); 95 } 96 97 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 98 99 #ifdef _NLIST_DO_AOUT 100 int 101 __aout_fdnlist(int fd, struct nlist *list) 102 { 103 struct nlist *p, *symtab; 104 caddr_t strtab, a_out_mmap; 105 off_t stroff, symoff; 106 u_long symsize; 107 int nent; 108 struct exec * exec; 109 struct stat st; 110 111 /* check that file is at least as large as struct exec! */ 112 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec))) 113 return (-1); 114 115 /* Check for files too large to mmap. */ 116 if (st.st_size > SIZE_T_MAX) { 117 errno = EFBIG; 118 return (-1); 119 } 120 121 /* 122 * Map the whole a.out file into our address space. 123 * We then find the string table withing this area. 124 * We do not just mmap the string table, as it probably 125 * does not start at a page boundary - we save ourselves a 126 * lot of nastiness by mmapping the whole file. 127 * 128 * This gives us an easy way to randomly access all the strings, 129 * without making the memory allocation permanent as with 130 * malloc/free (i.e., munmap will return it to the system). 131 */ 132 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0); 133 if (a_out_mmap == MAP_FAILED) 134 return (-1); 135 136 exec = (struct exec *)a_out_mmap; 137 if (N_BADMAG(*exec)) { 138 munmap(a_out_mmap, (size_t)st.st_size); 139 return (-1); 140 } 141 142 symoff = N_SYMOFF(*exec); 143 symsize = exec->a_syms; 144 stroff = symoff + symsize; 145 146 /* find the string table in our mmapped area */ 147 strtab = a_out_mmap + stroff; 148 symtab = (struct nlist *)(a_out_mmap + symoff); 149 150 /* 151 * clean out any left-over information for all valid entries. 152 * Type and value defined to be 0 if not found; historical 153 * versions cleared other and desc as well. Also figure out 154 * the largest string length so don't read any more of the 155 * string table than we have to. 156 * 157 * XXX clearing anything other than n_type and n_value violates 158 * the semantics given in the man page. 159 */ 160 nent = 0; 161 for (p = list; !ISLAST(p); ++p) { 162 p->n_type = 0; 163 p->n_other = 0; 164 p->n_desc = 0; 165 p->n_value = 0; 166 ++nent; 167 } 168 169 while (symsize > 0) { 170 int soff; 171 172 symsize-= sizeof(struct nlist); 173 soff = symtab->n_un.n_strx; 174 175 176 if (soff != 0 && (symtab->n_type & N_STAB) == 0) 177 for (p = list; !ISLAST(p); p++) 178 if (!strcmp(&strtab[soff], p->n_un.n_name)) { 179 p->n_value = symtab->n_value; 180 p->n_type = symtab->n_type; 181 p->n_desc = symtab->n_desc; 182 p->n_other = symtab->n_other; 183 if (--nent <= 0) 184 break; 185 } 186 symtab++; 187 } 188 munmap(a_out_mmap, (size_t)st.st_size); 189 return (nent); 190 } 191 #endif 192 193 #ifdef _NLIST_DO_ELF 194 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 195 196 /* 197 * __elf_is_okay__ - Determine if ehdr really 198 * is ELF and valid for the target platform. 199 * 200 * WARNING: This is NOT a ELF ABI function and 201 * as such it's use should be restricted. 202 */ 203 static int 204 __elf_is_okay__(Elf_Ehdr *ehdr) 205 { 206 int retval = 0; 207 /* 208 * We need to check magic, class size, endianess, 209 * and version before we look at the rest of the 210 * Elf_Ehdr structure. These few elements are 211 * represented in a machine independant fashion. 212 */ 213 if (IS_ELF(*ehdr) && 214 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 215 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 216 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 217 218 /* Now check the machine dependant header */ 219 if (ehdr->e_machine == ELF_TARG_MACH && 220 ehdr->e_version == ELF_TARG_VER) 221 retval = 1; 222 } 223 return retval; 224 } 225 226 int 227 __elf_fdnlist(int fd, struct nlist *list) 228 { 229 struct nlist *p; 230 Elf_Off symoff = 0, symstroff = 0; 231 Elf_Word symsize = 0, symstrsize = 0; 232 Elf_Sword cc, i; 233 int nent = -1; 234 int errsave; 235 Elf_Sym sbuf[1024]; 236 Elf_Sym *s; 237 Elf_Ehdr ehdr; 238 char *strtab = NULL; 239 Elf_Shdr *shdr = NULL; 240 Elf_Word shdr_size; 241 void *base; 242 struct stat st; 243 244 /* Make sure obj is OK */ 245 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 246 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 247 !__elf_is_okay__(&ehdr) || 248 _fstat(fd, &st) < 0) 249 return (-1); 250 251 /* calculate section header table size */ 252 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 253 254 #ifndef __x86_64__ 255 /* Make sure it's not too big to mmap */ 256 if (shdr_size > SIZE_T_MAX) { 257 errno = EFBIG; 258 return (-1); 259 } 260 #endif 261 262 /* mmap section header table */ 263 base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd, 264 (off_t)ehdr.e_shoff); 265 if (base == MAP_FAILED) 266 return (-1); 267 shdr = (Elf_Shdr *)base; 268 269 /* 270 * Find the symbol table entry and it's corresponding 271 * string table entry. Version 1.1 of the ABI states 272 * that there is only one symbol table but that this 273 * could change in the future. 274 */ 275 for (i = 0; i < ehdr.e_shnum; i++) { 276 if (shdr[i].sh_type == SHT_SYMTAB) { 277 symoff = shdr[i].sh_offset; 278 symsize = shdr[i].sh_size; 279 symstroff = shdr[shdr[i].sh_link].sh_offset; 280 symstrsize = shdr[shdr[i].sh_link].sh_size; 281 break; 282 } 283 } 284 285 #ifndef __x86_64__ 286 /* Check for files too large to mmap. */ 287 if (symstrsize > SIZE_T_MAX) { 288 errno = EFBIG; 289 goto done; 290 } 291 #endif 292 293 /* 294 * Map string table into our address space. This gives us 295 * an easy way to randomly access all the strings, without 296 * making the memory allocation permanent as with malloc/free 297 * (i.e., munmap will return it to the system). 298 */ 299 base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd, 300 (off_t)symstroff); 301 if (base == MAP_FAILED) 302 goto done; 303 strtab = (char *)base; 304 305 /* 306 * clean out any left-over information for all valid entries. 307 * Type and value defined to be 0 if not found; historical 308 * versions cleared other and desc as well. Also figure out 309 * the largest string length so don't read any more of the 310 * string table than we have to. 311 * 312 * XXX clearing anything other than n_type and n_value violates 313 * the semantics given in the man page. 314 */ 315 nent = 0; 316 for (p = list; !ISLAST(p); ++p) { 317 p->n_type = 0; 318 p->n_other = 0; 319 p->n_desc = 0; 320 p->n_value = 0; 321 ++nent; 322 } 323 324 /* Don't process any further if object is stripped. */ 325 if (symoff == 0) 326 goto done; 327 328 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 329 nent = -1; 330 goto done; 331 } 332 333 while (symsize > 0 && nent > 0) { 334 cc = MIN(symsize, sizeof(sbuf)); 335 if (_read(fd, sbuf, cc) != cc) 336 break; 337 symsize -= cc; 338 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 339 char *name; 340 struct nlist *p_local; 341 342 name = strtab + s->st_name; 343 if (name[0] == '\0') 344 continue; 345 for (p_local = list; !ISLAST(p_local); p_local++) { 346 if ((p_local->n_un.n_name[0] == '_' && 347 strcmp(name, p_local->n_un.n_name+1) == 0) 348 || strcmp(name, p_local->n_un.n_name) == 0) { 349 elf_sym_to_nlist(p_local, s, shdr, 350 ehdr.e_shnum); 351 if (--nent <= 0) 352 break; 353 } 354 } 355 } 356 } 357 done: 358 errsave = errno; 359 if (strtab != NULL) 360 munmap(strtab, symstrsize); 361 if (shdr != NULL) 362 munmap(shdr, shdr_size); 363 errno = errsave; 364 return (nent); 365 } 366 367 /* 368 * Convert an Elf_Sym into an nlist structure. This fills in only the 369 * n_value and n_type members. 370 */ 371 static void 372 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum) 373 { 374 nl->n_value = s->st_value; 375 376 switch (s->st_shndx) { 377 case SHN_UNDEF: 378 case SHN_COMMON: 379 nl->n_type = N_UNDF; 380 break; 381 case SHN_ABS: 382 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 383 N_FN : N_ABS; 384 break; 385 default: 386 if (s->st_shndx >= shnum) 387 nl->n_type = N_UNDF; 388 else { 389 Elf_Shdr *sh = shdr + s->st_shndx; 390 391 nl->n_type = sh->sh_type == SHT_PROGBITS ? 392 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 393 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 394 } 395 break; 396 } 397 398 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 399 ELF_ST_BIND(s->st_info) == STB_WEAK) 400 nl->n_type |= N_EXT; 401 } 402 #endif /* _NLIST_DO_ELF */ 403