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 Red Hat elfutils. 4 Written by Ulrich Drepper <drepper (at) redhat.com>, 1998. 5 6 Red Hat elfutils is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by the 8 Free Software Foundation; version 2 of the License. 9 10 Red Hat elfutils is distributed in the hope that it will be useful, but 11 WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 General Public License for more details. 14 15 You should have received a copy of the GNU General Public License along 16 with Red Hat elfutils; if not, write to the Free Software Foundation, 17 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. 18 19 In addition, as a special exception, Red Hat, Inc. gives You the 20 additional right to link the code of Red Hat elfutils with code licensed 21 under any Open Source Initiative certified open source license 22 (http://www.opensource.org/licenses/index.php) which requires the 23 distribution of source code with any binary distribution and to 24 distribute linked combinations of the two. Non-GPL Code permitted under 25 this exception must only link to the code of Red Hat elfutils through 26 those well defined interfaces identified in the file named EXCEPTION 27 found in the source code files (the "Approved Interfaces"). The files 28 of Non-GPL Code may instantiate templates or use macros or inline 29 functions from the Approved Interfaces without causing the resulting 30 work to be covered by the GNU General Public License. Only Red Hat, 31 Inc. may make changes or additions to the list of Approved Interfaces. 32 Red Hat's grant of this exception is conditioned upon your not adding 33 any new exceptions. If you wish to add a new Approved Interface or 34 exception, please contact Red Hat. You must obey the GNU General Public 35 License in all respects for all of the Red Hat elfutils code and other 36 code used in conjunction with Red Hat elfutils except the Non-GPL Code 37 covered by this exception. If you modify this file, you may extend this 38 exception to your version of the file, but you are not obligated to do 39 so. If you do not wish to provide this exception without modification, 40 you must delete this exception statement from your version and license 41 this file solely under the GPL without exception. 42 43 Red Hat elfutils is an included package of the Open Invention Network. 44 An included package of the Open Invention Network is a package for which 45 Open Invention Network licensees cross-license their patents. No patent 46 license is granted, either expressly or impliedly, by designation as an 47 included package. Should you wish to participate in the Open Invention 48 Network licensing program, please visit www.openinventionnetwork.com 49 <http://www.openinventionnetwork.com>. */ 50 51 #ifdef HAVE_CONFIG_H 52 # include <config.h> 53 #endif 54 55 #include <fcntl.h> 56 #include <gelf.h> 57 #include <libelf.h> 58 #include <nlist.h> 59 #include <unistd.h> 60 61 #include "libelfP.h" 62 63 64 struct hashentry 65 { 66 const char *str; 67 GElf_Sym sym; 68 }; 69 #define TYPE struct hashentry 70 /* XXX Use a better hash function some day. */ 71 #define HASHFCT(str, len) INTUSE(elf_hash) (str) 72 #define COMPARE(p1, p2) strcmp ((p1)->str, (p2)->str) 73 #define CLASS static 74 #define PREFIX nlist_ 75 #define xcalloc(n, m) calloc (n, m) 76 #define next_prime(s) __libelf_next_prime (s) 77 #include <fixedsizehash.h> 78 79 80 int 81 nlist (const char *filename, struct nlist *nl) 82 { 83 int fd; 84 Elf *elf; 85 Elf_Scn *scn = NULL; 86 Elf_Scn *symscn = NULL; 87 GElf_Shdr shdr_mem; 88 GElf_Shdr *shdr = NULL; 89 Elf_Data *data; 90 struct nlist_fshash *table; 91 size_t nsyms; 92 size_t cnt; 93 94 /* Open the file. */ 95 fd = open (filename, O_RDONLY); 96 if (fd == -1) 97 { 98 __libelf_seterrno (ELF_E_NOFILE); 99 goto fail; 100 } 101 102 /* For compatibility reasons (`nlist' existed before ELF and libelf) 103 we don't expect the caller to set the ELF version. Do this here 104 if it hasn't happened yet. */ 105 if (__libelf_version_initialized == 0) 106 INTUSE(elf_version) (EV_CURRENT); 107 108 /* Now get an ELF descriptor. */ 109 elf = INTUSE(elf_begin) (fd, ELF_C_READ_MMAP, NULL); 110 if (elf == NULL) 111 goto fail_fd; 112 113 /* Find a symbol table. We prefer the real symbol table but if it 114 does not exist use the dynamic symbol table. */ 115 while ((scn = INTUSE(elf_nextscn) (elf, scn)) != NULL) 116 { 117 shdr = INTUSE(gelf_getshdr) (scn, &shdr_mem); 118 if (shdr == NULL) 119 goto fail_close; 120 121 /* That is what we are looking for. */ 122 if (shdr->sh_type == SHT_SYMTAB) 123 { 124 symscn = scn; 125 break; 126 } 127 128 /* Better than nothing. Remember this section. */ 129 if (shdr->sh_type == SHT_DYNSYM) 130 symscn = scn; 131 } 132 133 if (symscn == NULL) 134 /* We haven't found anything. Fail. */ 135 goto fail_close; 136 137 /* Re-get the section header in case we found only the dynamic symbol 138 table. */ 139 if (scn == NULL) 140 shdr = INTUSE(gelf_getshdr) (symscn, &shdr_mem); 141 /* SHDR->SH_LINK now contains the index of the string section. */ 142 143 /* Get the data for the symbol section. */ 144 data = INTUSE(elf_getdata) (symscn, NULL); 145 if (data == NULL) 146 goto fail_close; 147 148 /* How many symbols are there? */ 149 nsyms = (shdr->sh_size 150 / INTUSE(gelf_fsize) (elf, ELF_T_SYM, 1, data->d_version)); 151 152 /* Create the hash table. */ 153 table = nlist_fshash_init (nsyms); 154 if (table == NULL) 155 { 156 __libelf_seterrno (ELF_E_NOMEM); 157 goto fail_close; 158 } 159 160 /* Iterate over all the symbols in the section. */ 161 for (cnt = 0; cnt < nsyms; ++cnt) 162 { 163 struct hashentry mem; 164 GElf_Sym *sym; 165 166 /* Get the symbol. */ 167 sym = INTUSE(gelf_getsym) (data, cnt, &mem.sym); 168 if (sym == NULL) 169 goto fail_dealloc; 170 171 /* Get the name of the symbol. */ 172 mem.str = INTUSE(elf_strptr) (elf, shdr->sh_link, sym->st_name); 173 if (mem.str == NULL) 174 goto fail_dealloc; 175 176 /* Don't allow zero-length strings. */ 177 if (mem.str[0] == '\0') 178 continue; 179 180 /* And add it to the hash table. Note that we are using the 181 overwrite version. This will ensure that 182 a) global symbols are preferred over local symbols since 183 they are all located at the end 184 b) if there are multiple local symbols with the same name 185 the last one is used. 186 */ 187 (void) nlist_fshash_overwrite (table, mem.str, 0, &mem); 188 } 189 190 /* Now it is time to look for the symbols the user asked for. 191 XXX What is a `null name/null string'? This is what the 192 standard says terminates the list. Is it a null pointer 193 or a zero-length string? We test for both... */ 194 while (nl->n_name != NULL && nl->n_name[0] != '\0') 195 { 196 struct hashentry search; 197 const struct hashentry *found; 198 199 /* Search for a matching entry in the hash table. */ 200 search.str = nl->n_name; 201 found = nlist_fshash_find (table, nl->n_name, 0, &search); 202 203 if (found != NULL) 204 { 205 /* Found it. */ 206 nl->n_value = found->sym.st_value; 207 nl->n_scnum = found->sym.st_shndx; 208 nl->n_type = GELF_ST_TYPE (found->sym.st_info); 209 /* XXX What shall we fill in the next fields? */ 210 nl->n_sclass = 0; 211 nl->n_numaux = 0; 212 } 213 else 214 { 215 /* Not there. */ 216 nl->n_value = 0; 217 nl->n_scnum = 0; 218 nl->n_type = 0; 219 nl->n_sclass = 0; 220 nl->n_numaux = 0; 221 } 222 223 /* Next search request. */ 224 ++nl; 225 } 226 227 /* Free the resources. */ 228 nlist_fshash_fini (table); 229 230 /* We do not need the ELF descriptor anymore. */ 231 (void) INTUSE(elf_end) (elf); 232 233 /* Neither the file descriptor. */ 234 (void) close (fd); 235 236 return 0; 237 238 fail_dealloc: 239 nlist_fshash_fini (table); 240 241 fail_close: 242 /* We do not need the ELF descriptor anymore. */ 243 (void) INTUSE(elf_end) (elf); 244 245 fail_fd: 246 /* Neither the file descriptor. */ 247 (void) close (fd); 248 249 fail: 250 /* We have to set all entries to zero. */ 251 while (nl->n_name != NULL && nl->n_name[0] != '\0') 252 { 253 nl->n_value = 0; 254 nl->n_scnum = 0; 255 nl->n_type = 0; 256 nl->n_sclass = 0; 257 nl->n_numaux = 0; 258 259 /* Next entry. */ 260 ++nl; 261 } 262 263 return -1; 264 } 265
