1 /* $NetBSD: symtab.c,v 1.2 2013/08/29 15:01:57 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 #include <stdlib.h> 33 #include <stdio.h> 34 #include <string.h> 35 #include <stdint.h> 36 #include <err.h> 37 #include <dlfcn.h> 38 39 #if 1 40 #include "private_libelf.h" 41 #else 42 #include <libelf.h> 43 #include <gelf.h> 44 #endif 45 #ifndef ELF_ST_BIND 46 #define ELF_ST_BIND(x) ((x) >> 4) 47 #endif 48 #ifndef ELF_ST_TYPE 49 #define ELF_ST_TYPE(x) (((unsigned int)x) & 0xf) 50 #endif 51 52 53 #include "symtab.h" 54 55 struct symbol { 56 char *st_name; 57 uintptr_t st_value; 58 uintptr_t st_info; 59 }; 60 61 struct symtab { 62 size_t nsymbols; 63 struct symbol *symbols; 64 }; 65 66 static int 67 address_compare(const void *a, const void *b) 68 { 69 const struct symbol *sa = a; 70 const struct symbol *sb = b; 71 return (int)(intmax_t)(sa->st_value - sb->st_value); 72 } 73 74 void 75 symtab_destroy(symtab_t *s) 76 { 77 if (s == NULL) 78 return; 79 for (size_t i = 0; i < s->nsymbols; i++) 80 free(s->symbols[i].st_name); 81 free(s->symbols); 82 free(s); 83 } 84 85 symtab_t * 86 symtab_create(int fd, int bind, int type) 87 { 88 Elf *elf; 89 symtab_t *st; 90 Elf_Scn *scn = NULL; 91 92 if (elf_version(EV_CURRENT) == EV_NONE) { 93 warnx("Elf Library is out of date."); 94 return NULL; 95 } 96 97 elf = elf_begin(fd, ELF_C_READ, NULL); 98 if (elf == NULL) { 99 warnx("Error opening elf file: %s", elf_errmsg(elf_errno())); 100 return NULL; 101 } 102 st = calloc(1, sizeof(*st)); 103 if (st == NULL) { 104 warnx("Error allocating symbol table"); 105 elf_end(elf); 106 return NULL; 107 } 108 109 while ((scn = elf_nextscn(elf, scn)) != NULL) { 110 GElf_Shdr shdr; 111 Elf_Data *edata; 112 size_t ns; 113 struct symbol *s; 114 115 if (gelf_getshdr(scn, &shdr) == NULL) 116 goto out; /* XXX prevent use of uninitialized */ 117 if(shdr.sh_type != SHT_SYMTAB) 118 continue; 119 120 edata = elf_getdata(scn, NULL); 121 ns = shdr.sh_size / shdr.sh_entsize; 122 s = calloc(ns, sizeof(*s)); 123 if (s == NULL) { 124 warn("Cannot allocate %zu symbols", ns); 125 goto out; 126 } 127 st->symbols = s; 128 129 for (size_t i = 0; i < ns; i++) { 130 GElf_Sym sym; 131 if (gelf_getsym(edata, (int)i, &sym) == NULL) 132 goto out; /* XXX prevent uninitialized */ 133 134 if (bind != -1 && 135 (unsigned)bind != ELF_ST_BIND(sym.st_info)) 136 continue; 137 138 if (type != -1 && 139 (unsigned)type != ELF_ST_TYPE(sym.st_info)) 140 continue; 141 142 s->st_value = sym.st_value; 143 s->st_info = sym.st_info; 144 s->st_name = strdup( 145 elf_strptr(elf, shdr.sh_link, sym.st_name)); 146 if (s->st_name == NULL) 147 goto out; 148 s++; 149 } 150 st->nsymbols = s - st->symbols; 151 if (st->nsymbols == 0) { 152 warnx("No symbols found"); 153 goto out; 154 } 155 qsort(st->symbols, st->nsymbols, sizeof(*st->symbols), 156 address_compare); 157 elf_end(elf); 158 return st; 159 } 160 out: 161 symtab_destroy(st); 162 elf_end(elf); 163 return NULL; 164 } 165 166 167 int 168 symtab_find(const symtab_t *st, const void *p, Dl_info *dli) 169 { 170 struct symbol *s = st->symbols; 171 size_t ns = st->nsymbols; 172 size_t hi = ns; 173 size_t lo = 0; 174 size_t mid = ns / 2; 175 uintptr_t dd, sd, me = (uintptr_t)p; 176 177 for (;;) { 178 if (s[mid].st_value < me) 179 lo = mid; 180 else if (s[mid].st_value > me) 181 hi = mid; 182 else 183 break; 184 if (hi - lo == 1) { 185 mid = lo; 186 break; 187 } 188 mid = (hi + lo) / 2; 189 } 190 dd = me - (uintptr_t)dli->dli_saddr; 191 sd = me - s[mid].st_value; 192 if (dd > sd) { 193 dli->dli_saddr = (void *)s[mid].st_value; 194 dli->dli_sname = s[mid].st_name; 195 } 196 return 1; 197 } 198