1/* Extract symbol list from binary. 2 Copyright (C) 1998, 1999, 2000, 2001, 2002, 2005, 2007 Red Hat, Inc. 3 This file is part of elfutils. 4 Written by Ulrich Drepper <drepper@redhat.com>, 1998. 5 6 This file is free software; you can redistribute it and/or modify 7 it under the terms of either 8 9 * the GNU Lesser General Public License as published by the Free 10 Software Foundation; either version 3 of the License, or (at 11 your option) any later version 12 13 or 14 15 * the GNU General Public License as published by the Free 16 Software Foundation; either version 2 of the License, or (at 17 your option) any later version 18 19 or both in parallel, as here. 20 21 elfutils is distributed in the hope that it will be useful, but 22 WITHOUT ANY WARRANTY; without even the implied warranty of 23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 24 General Public License for more details. 25 26 You should have received copies of the GNU General Public License and 27 the GNU Lesser General Public License along with this program. If 28 not, see <http://www.gnu.org/licenses/>. */ 29 30#ifdef HAVE_CONFIG_H 31# include <config.h> 32#endif 33 34#include <fcntl.h> 35#include <gelf.h> 36#include <libelf.h> 37#include <nlist.h> 38#include <unistd.h> 39 40#include "libelfP.h" 41 42 43struct hashentry 44{ 45 const char *str; 46 GElf_Sym sym; 47}; 48#define TYPE struct hashentry 49/* XXX Use a better hash function some day. */ 50#define HASHFCT(str, len) INTUSE(elf_hash) (str) 51#define COMPARE(p1, p2) strcmp ((p1)->str, (p2)->str) 52#define CLASS static 53#define PREFIX nlist_ 54#define xcalloc(n, m) calloc (n, m) 55#define next_prime(s) __libelf_next_prime (s) 56#include <fixedsizehash.h> 57 58 59int 60nlist (const char *filename, struct nlist *nl) 61{ 62 int fd; 63 Elf *elf; 64 Elf_Scn *scn = NULL; 65 Elf_Scn *symscn = NULL; 66 GElf_Shdr shdr_mem; 67 GElf_Shdr *shdr = NULL; 68 Elf_Data *data; 69 struct nlist_fshash *table; 70 size_t nsyms; 71 size_t cnt; 72 73 /* Open the file. */ 74 fd = open (filename, O_RDONLY); 75 if (fd == -1) 76 { 77 __libelf_seterrno (ELF_E_NOFILE); 78 goto fail; 79 } 80 81 /* For compatibility reasons (`nlist' existed before ELF and libelf) 82 we don't expect the caller to set the ELF version. Do this here 83 if it hasn't happened yet. */ 84 if (__libelf_version_initialized == 0) 85 INTUSE(elf_version) (EV_CURRENT); 86 87 /* Now get an ELF descriptor. */ 88 elf = INTUSE(elf_begin) (fd, ELF_C_READ_MMAP, NULL); 89 if (elf == NULL) 90 goto fail_fd; 91 92 /* Find a symbol table. We prefer the real symbol table but if it 93 does not exist use the dynamic symbol table. */ 94 while ((scn = INTUSE(elf_nextscn) (elf, scn)) != NULL) 95 { 96 shdr = INTUSE(gelf_getshdr) (scn, &shdr_mem); 97 if (shdr == NULL) 98 goto fail_close; 99 100 /* That is what we are looking for. */ 101 if (shdr->sh_type == SHT_SYMTAB) 102 { 103 symscn = scn; 104 break; 105 } 106 107 /* Better than nothing. Remember this section. */ 108 if (shdr->sh_type == SHT_DYNSYM) 109 symscn = scn; 110 } 111 112 if (symscn == NULL) 113 /* We haven't found anything. Fail. */ 114 goto fail_close; 115 116 /* Re-get the section header in case we found only the dynamic symbol 117 table. */ 118 if (scn == NULL) 119 shdr = INTUSE(gelf_getshdr) (symscn, &shdr_mem); 120 /* SHDR->SH_LINK now contains the index of the string section. */ 121 122 /* Get the data for the symbol section. */ 123 data = INTUSE(elf_getdata) (symscn, NULL); 124 if (data == NULL) 125 goto fail_close; 126 127 /* How many symbols are there? */ 128 nsyms = (shdr->sh_size 129 / INTUSE(gelf_fsize) (elf, ELF_T_SYM, 1, data->d_version)); 130 131 /* Create the hash table. */ 132 table = nlist_fshash_init (nsyms); 133 if (table == NULL) 134 { 135 __libelf_seterrno (ELF_E_NOMEM); 136 goto fail_close; 137 } 138 139 /* Iterate over all the symbols in the section. */ 140 for (cnt = 0; cnt < nsyms; ++cnt) 141 { 142 struct hashentry mem; 143 GElf_Sym *sym; 144 145 /* Get the symbol. */ 146 sym = INTUSE(gelf_getsym) (data, cnt, &mem.sym); 147 if (sym == NULL) 148 goto fail_dealloc; 149 150 /* Get the name of the symbol. */ 151 mem.str = INTUSE(elf_strptr) (elf, shdr->sh_link, sym->st_name); 152 if (mem.str == NULL) 153 goto fail_dealloc; 154 155 /* Don't allow zero-length strings. */ 156 if (mem.str[0] == '\0') 157 continue; 158 159 /* And add it to the hash table. Note that we are using the 160 overwrite version. This will ensure that 161 a) global symbols are preferred over local symbols since 162 they are all located at the end 163 b) if there are multiple local symbols with the same name 164 the last one is used. 165 */ 166 (void) nlist_fshash_overwrite (table, mem.str, 0, &mem); 167 } 168 169 /* Now it is time to look for the symbols the user asked for. 170 XXX What is a `null name/null string'? This is what the 171 standard says terminates the list. Is it a null pointer 172 or a zero-length string? We test for both... */ 173 while (nl->n_name != NULL && nl->n_name[0] != '\0') 174 { 175 struct hashentry search; 176 const struct hashentry *found; 177 178 /* Search for a matching entry in the hash table. */ 179 search.str = nl->n_name; 180 found = nlist_fshash_find (table, nl->n_name, 0, &search); 181 182 if (found != NULL) 183 { 184 /* Found it. */ 185 nl->n_value = found->sym.st_value; 186 nl->n_scnum = found->sym.st_shndx; 187 nl->n_type = GELF_ST_TYPE (found->sym.st_info); 188 /* XXX What shall we fill in the next fields? */ 189 nl->n_sclass = 0; 190 nl->n_numaux = 0; 191 } 192 else 193 { 194 /* Not there. */ 195 nl->n_value = 0; 196 nl->n_scnum = 0; 197 nl->n_type = 0; 198 nl->n_sclass = 0; 199 nl->n_numaux = 0; 200 } 201 202 /* Next search request. */ 203 ++nl; 204 } 205 206 /* Free the resources. */ 207 nlist_fshash_fini (table); 208 209 /* We do not need the ELF descriptor anymore. */ 210 (void) INTUSE(elf_end) (elf); 211 212 /* Neither the file descriptor. */ 213 (void) close (fd); 214 215 return 0; 216 217 fail_dealloc: 218 nlist_fshash_fini (table); 219 220 fail_close: 221 /* We do not need the ELF descriptor anymore. */ 222 (void) INTUSE(elf_end) (elf); 223 224 fail_fd: 225 /* Neither the file descriptor. */ 226 (void) close (fd); 227 228 fail: 229 /* We have to set all entries to zero. */ 230 while (nl->n_name != NULL && nl->n_name[0] != '\0') 231 { 232 nl->n_value = 0; 233 nl->n_scnum = 0; 234 nl->n_type = 0; 235 nl->n_sclass = 0; 236 nl->n_numaux = 0; 237 238 /* Next entry. */ 239 ++nl; 240 } 241 242 return -1; 243} 244