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 34 #if defined(LIBC_SCCS) && !defined(lint) 35 static char sccsid[] = "@(#)nlist.c 8.1 (Berkeley) 6/4/93"; 36 #endif /* LIBC_SCCS and not lint */ 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "namespace.h" 41 #include <sys/param.h> 42 #include <sys/mman.h> 43 #include <sys/stat.h> 44 #include <sys/file.h> 45 #include <arpa/inet.h> 46 47 #include <errno.h> 48 #include <a.out.h> 49 #include <stdio.h> 50 #include <string.h> 51 #include <unistd.h> 52 #include "un-namespace.h" 53 54 #define _NLIST_DO_AOUT 55 #define _NLIST_DO_ELF 56 57 #ifdef _NLIST_DO_ELF 58 #include <machine/elf.h> 59 #include <elf-hints.h> 60 #endif 61 62 int __fdnlist(int, struct nlist *); 63 int __aout_fdnlist(int, struct nlist *); 64 int __elf_fdnlist(int, struct nlist *); 65 66 int 67 nlist(name, list) 68 const char *name; 69 struct nlist *list; 70 { 71 int fd, n; 72 73 fd = _open(name, O_RDONLY, 0); 74 if (fd < 0) 75 return (-1); 76 n = __fdnlist(fd, list); 77 (void)_close(fd); 78 return (n); 79 } 80 81 static struct nlist_handlers { 82 int (*fn)(int fd, struct nlist *list); 83 } nlist_fn[] = { 84 #ifdef _NLIST_DO_AOUT 85 { __aout_fdnlist }, 86 #endif 87 #ifdef _NLIST_DO_ELF 88 { __elf_fdnlist }, 89 #endif 90 }; 91 92 int 93 __fdnlist(fd, list) 94 int fd; 95 struct nlist *list; 96 { 97 int n = -1, i; 98 99 for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) { 100 n = (nlist_fn[i].fn)(fd, list); 101 if (n != -1) 102 break; 103 } 104 return (n); 105 } 106 107 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 108 109 #ifdef _NLIST_DO_AOUT 110 int 111 __aout_fdnlist(fd, list) 112 int fd; 113 struct nlist *list; 114 { 115 struct nlist *p, *symtab; 116 caddr_t strtab, a_out_mmap; 117 off_t stroff, symoff; 118 u_long symsize; 119 int nent; 120 struct exec * exec; 121 struct stat st; 122 123 /* check that file is at least as large as struct exec! */ 124 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec))) 125 return (-1); 126 127 /* Check for files too large to mmap. */ 128 if (st.st_size > SIZE_T_MAX) { 129 errno = EFBIG; 130 return (-1); 131 } 132 133 /* 134 * Map the whole a.out file into our address space. 135 * We then find the string table withing this area. 136 * We do not just mmap the string table, as it probably 137 * does not start at a page boundary - we save ourselves a 138 * lot of nastiness by mmapping the whole file. 139 * 140 * This gives us an easy way to randomly access all the strings, 141 * without making the memory allocation permanent as with 142 * malloc/free (i.e., munmap will return it to the system). 143 */ 144 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0); 145 if (a_out_mmap == MAP_FAILED) 146 return (-1); 147 148 exec = (struct exec *)a_out_mmap; 149 if (N_BADMAG(*exec)) { 150 munmap(a_out_mmap, (size_t)st.st_size); 151 return (-1); 152 } 153 154 symoff = N_SYMOFF(*exec); 155 symsize = exec->a_syms; 156 stroff = symoff + symsize; 157 158 /* find the string table in our mmapped area */ 159 strtab = a_out_mmap + stroff; 160 symtab = (struct nlist *)(a_out_mmap + symoff); 161 162 /* 163 * clean out any left-over information for all valid entries. 164 * Type and value defined to be 0 if not found; historical 165 * versions cleared other and desc as well. Also figure out 166 * the largest string length so don't read any more of the 167 * string table than we have to. 168 * 169 * XXX clearing anything other than n_type and n_value violates 170 * the semantics given in the man page. 171 */ 172 nent = 0; 173 for (p = list; !ISLAST(p); ++p) { 174 p->n_type = 0; 175 p->n_other = 0; 176 p->n_desc = 0; 177 p->n_value = 0; 178 ++nent; 179 } 180 181 while (symsize > 0) { 182 int soff; 183 184 symsize-= sizeof(struct nlist); 185 soff = symtab->n_un.n_strx; 186 187 188 if (soff != 0 && (symtab->n_type & N_STAB) == 0) 189 for (p = list; !ISLAST(p); p++) 190 if (!strcmp(&strtab[soff], p->n_un.n_name)) { 191 p->n_value = symtab->n_value; 192 p->n_type = symtab->n_type; 193 p->n_desc = symtab->n_desc; 194 p->n_other = symtab->n_other; 195 if (--nent <= 0) 196 break; 197 } 198 symtab++; 199 } 200 munmap(a_out_mmap, (size_t)st.st_size); 201 return (nent); 202 } 203 #endif 204 205 #ifdef _NLIST_DO_ELF 206 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 207 208 /* 209 * __elf_is_okay__ - Determine if ehdr really 210 * is ELF and valid for the target platform. 211 * 212 * WARNING: This is NOT an ELF ABI function and 213 * as such its use should be restricted. 214 */ 215 int 216 __elf_is_okay__(ehdr) 217 Elf_Ehdr *ehdr; 218 { 219 int retval = 0; 220 /* 221 * We need to check magic, class size, endianess, 222 * and version before we look at the rest of the 223 * Elf_Ehdr structure. These few elements are 224 * represented in a machine independant fashion. 225 */ 226 if (IS_ELF(*ehdr) && 227 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 228 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 229 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 230 231 /* Now check the machine dependant header */ 232 if (ehdr->e_machine == ELF_TARG_MACH && 233 ehdr->e_version == ELF_TARG_VER) 234 retval = 1; 235 } 236 return retval; 237 } 238 239 int 240 __elf_fdnlist(fd, list) 241 int fd; 242 struct nlist *list; 243 { 244 struct nlist *p; 245 Elf_Off symoff = 0, symstroff = 0; 246 Elf_Word symsize = 0, symstrsize = 0; 247 Elf_Sword cc, i; 248 int nent = -1; 249 int errsave; 250 Elf_Sym sbuf[1024]; 251 Elf_Sym *s; 252 Elf_Ehdr ehdr; 253 char *strtab = NULL; 254 Elf_Shdr *shdr = NULL; 255 Elf_Word shdr_size; 256 void *base; 257 struct stat st; 258 259 /* Make sure obj is OK */ 260 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 261 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 262 !__elf_is_okay__(&ehdr) || 263 _fstat(fd, &st) < 0) 264 return (-1); 265 266 /* calculate section header table size */ 267 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 268 269 /* Make sure it's not too big to mmap */ 270 if (shdr_size > SIZE_T_MAX) { 271 errno = EFBIG; 272 return (-1); 273 } 274 275 /* mmap section header table */ 276 base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd, 277 (off_t)ehdr.e_shoff); 278 if (base == MAP_FAILED) 279 return (-1); 280 shdr = (Elf_Shdr *)base; 281 282 /* 283 * Find the symbol table entry and it's corresponding 284 * string table entry. Version 1.1 of the ABI states 285 * that there is only one symbol table but that this 286 * could change in the future. 287 */ 288 for (i = 0; i < ehdr.e_shnum; i++) { 289 if (shdr[i].sh_type == SHT_SYMTAB) { 290 symoff = shdr[i].sh_offset; 291 symsize = shdr[i].sh_size; 292 symstroff = shdr[shdr[i].sh_link].sh_offset; 293 symstrsize = shdr[shdr[i].sh_link].sh_size; 294 break; 295 } 296 } 297 298 /* Check for files too large to mmap. */ 299 if (symstrsize > SIZE_T_MAX) { 300 errno = EFBIG; 301 goto done; 302 } 303 /* 304 * Map string table into our address space. This gives us 305 * an easy way to randomly access all the strings, without 306 * making the memory allocation permanent as with malloc/free 307 * (i.e., munmap will return it to the system). 308 */ 309 base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd, 310 (off_t)symstroff); 311 if (base == MAP_FAILED) 312 goto done; 313 strtab = (char *)base; 314 315 /* 316 * clean out any left-over information for all valid entries. 317 * Type and value defined to be 0 if not found; historical 318 * versions cleared other and desc as well. Also figure out 319 * the largest string length so don't read any more of the 320 * string table than we have to. 321 * 322 * XXX clearing anything other than n_type and n_value violates 323 * the semantics given in the man page. 324 */ 325 nent = 0; 326 for (p = list; !ISLAST(p); ++p) { 327 p->n_type = 0; 328 p->n_other = 0; 329 p->n_desc = 0; 330 p->n_value = 0; 331 ++nent; 332 } 333 334 /* Don't process any further if object is stripped. */ 335 if (symoff == 0) 336 goto done; 337 338 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 339 nent = -1; 340 goto done; 341 } 342 343 while (symsize > 0 && nent > 0) { 344 cc = MIN(symsize, sizeof(sbuf)); 345 if (_read(fd, sbuf, cc) != cc) 346 break; 347 symsize -= cc; 348 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 349 char *name; 350 struct nlist *p; 351 352 name = strtab + s->st_name; 353 if (name[0] == '\0') 354 continue; 355 for (p = list; !ISLAST(p); p++) { 356 if ((p->n_un.n_name[0] == '_' && 357 strcmp(name, p->n_un.n_name+1) == 0) 358 || strcmp(name, p->n_un.n_name) == 0) { 359 elf_sym_to_nlist(p, s, shdr, 360 ehdr.e_shnum); 361 if (--nent <= 0) 362 break; 363 } 364 } 365 } 366 } 367 done: 368 errsave = errno; 369 if (strtab != NULL) 370 munmap(strtab, symstrsize); 371 if (shdr != NULL) 372 munmap(shdr, shdr_size); 373 errno = errsave; 374 return (nent); 375 } 376 377 /* 378 * Convert an Elf_Sym into an nlist structure. This fills in only the 379 * n_value and n_type members. 380 */ 381 static void 382 elf_sym_to_nlist(nl, s, shdr, shnum) 383 struct nlist *nl; 384 Elf_Sym *s; 385 Elf_Shdr *shdr; 386 int shnum; 387 { 388 nl->n_value = s->st_value; 389 390 switch (s->st_shndx) { 391 case SHN_UNDEF: 392 case SHN_COMMON: 393 nl->n_type = N_UNDF; 394 break; 395 case SHN_ABS: 396 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 397 N_FN : N_ABS; 398 break; 399 default: 400 if (s->st_shndx >= shnum) 401 nl->n_type = N_UNDF; 402 else { 403 Elf_Shdr *sh = shdr + s->st_shndx; 404 405 nl->n_type = sh->sh_type == SHT_PROGBITS ? 406 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 407 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 408 } 409 break; 410 } 411 412 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 413 ELF_ST_BIND(s->st_info) == STB_WEAK) 414 nl->n_type |= N_EXT; 415 } 416 #endif /* _NLIST_DO_ELF */ 417