1 /* $NetBSD: symtab.c,v 1.1 2012/05/26 22:02:29 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2012 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Christos Zoulas. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 #include <sys/cdefs.h> 32 __RCSID("$NetBSD: symtab.c,v 1.1 2012/05/26 22:02:29 christos Exp $"); 33 34 #include <stdlib.h> 35 #include <stdio.h> 36 #include <string.h> 37 #include <err.h> 38 #include <dlfcn.h> 39 40 #include <libelf.h> 41 #include <gelf.h> 42 #ifndef ELF_ST_BIND 43 #define ELF_ST_BIND(x) ((x) >> 4) 44 #endif 45 #ifndef ELF_ST_TYPE 46 #define ELF_ST_TYPE(x) (((unsigned int)x) & 0xf) 47 #endif 48 49 50 #include "symtab.h" 51 52 struct symbol { 53 char *st_name; 54 uintptr_t st_value; 55 uintptr_t st_info; 56 }; 57 58 struct symtab { 59 size_t nsymbols; 60 struct symbol *symbols; 61 }; 62 63 static int 64 address_compare(const void *a, const void *b) 65 { 66 const struct symbol *sa = a; 67 const struct symbol *sb = b; 68 return (int)(intmax_t)(sa->st_value - sb->st_value); 69 } 70 71 void 72 symtab_destroy(symtab_t *s) 73 { 74 if (s == NULL) 75 return; 76 for (size_t i = 0; i < s->nsymbols; i++) 77 free(s->symbols[i].st_name); 78 free(s->symbols); 79 free(s); 80 } 81 82 symtab_t * 83 symtab_create(int fd, int bind, int type) 84 { 85 Elf *elf; 86 symtab_t *st; 87 Elf_Scn *scn = NULL; 88 89 if (elf_version(EV_CURRENT) == EV_NONE) { 90 warnx("Elf Library is out of date."); 91 return NULL; 92 } 93 94 elf = elf_begin(fd, ELF_C_READ, NULL); 95 if (elf == NULL) { 96 warnx("Error opening elf file: %s", elf_errmsg(elf_errno())); 97 return NULL; 98 } 99 st = calloc(1, sizeof(*st)); 100 if (st == NULL) { 101 warnx("Error allocating symbol table"); 102 elf_end(elf); 103 return NULL; 104 } 105 106 while ((scn = elf_nextscn(elf, scn)) != NULL) { 107 GElf_Shdr shdr; 108 Elf_Data *edata; 109 size_t ns; 110 struct symbol *s; 111 112 gelf_getshdr(scn, &shdr); 113 if(shdr.sh_type != SHT_SYMTAB) 114 continue; 115 116 edata = elf_getdata(scn, NULL); 117 ns = shdr.sh_size / shdr.sh_entsize; 118 s = calloc(ns, sizeof(*s)); 119 if (s == NULL) { 120 warn("Cannot allocate %zu symbols", ns); 121 goto out; 122 } 123 st->symbols = s; 124 125 for (size_t i = 0; i < ns; i++) { 126 GElf_Sym sym; 127 gelf_getsym(edata, (int)i, &sym); 128 129 if (bind != -1 && 130 (unsigned)bind != ELF_ST_BIND(sym.st_info)) 131 continue; 132 133 if (type != -1 && 134 (unsigned)type != ELF_ST_TYPE(sym.st_info)) 135 continue; 136 137 s->st_value = sym.st_value; 138 s->st_info = sym.st_info; 139 s->st_name = strdup( 140 elf_strptr(elf, shdr.sh_link, sym.st_name)); 141 if (s->st_name == NULL) 142 goto out; 143 s++; 144 } 145 st->nsymbols = s - st->symbols; 146 if (st->nsymbols == 0) { 147 warnx("No symbols found"); 148 goto out; 149 } 150 qsort(st->symbols, st->nsymbols, sizeof(*st->symbols), 151 address_compare); 152 elf_end(elf); 153 return st; 154 } 155 out: 156 symtab_destroy(st); 157 elf_end(elf); 158 return NULL; 159 } 160 161 162 int 163 symtab_find(const symtab_t *st, const void *p, Dl_info *dli) 164 { 165 struct symbol *s = st->symbols; 166 size_t ns = st->nsymbols; 167 size_t hi = ns; 168 size_t lo = 0; 169 size_t mid = ns / 2; 170 uintptr_t dd, sd, me = (uintptr_t)p; 171 172 for (;;) { 173 if (s[mid].st_value < me) 174 lo = mid; 175 else if (s[mid].st_value > me) 176 hi = mid; 177 else 178 break; 179 if (hi - lo == 1) { 180 mid = lo; 181 break; 182 } 183 mid = (hi + lo) / 2; 184 } 185 dd = me - (uintptr_t)dli->dli_saddr; 186 sd = me - s[mid].st_value; 187 if (dd > sd) { 188 dli->dli_saddr = (void *)s[mid].st_value; 189 dli->dli_sname = s[mid].st_name; 190 } 191 return 1; 192 } 193