symbol_table.c revision 501edd29b823ce1301d2effdd3a9e4b6e2b20b76
1501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown/* 2501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * Copyright (C) 2011 The Android Open Source Project 3501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * 4501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * Licensed under the Apache License, Version 2.0 (the "License"); 5501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * you may not use this file except in compliance with the License. 6501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * You may obtain a copy of the License at 7501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * 8501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * http://www.apache.org/licenses/LICENSE-2.0 9501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * 10501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * Unless required by applicable law or agreed to in writing, software 11501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * distributed under the License is distributed on an "AS IS" BASIS, 12501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * See the License for the specific language governing permissions and 14501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown * limitations under the License. 15501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown */ 16501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 17501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#define LOG_TAG "Corkscrew" 18501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown//#define LOG_NDEBUG 0 19501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 20501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <corkscrew/symbol_table.h> 21501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 22501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <stdlib.h> 23501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <fcntl.h> 24501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <string.h> 25501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <sys/stat.h> 26501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <sys/mman.h> 27501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <sys/exec_elf.h> 28501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown#include <cutils/log.h> 29501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 30501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown// Compare function for qsort 31501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownstatic int qcompar(const void *a, const void *b) { 32501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const symbol_t* asym = (const symbol_t*)a; 33501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const symbol_t* bsym = (const symbol_t*)b; 34501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (asym->start > bsym->start) return 1; 35501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (asym->start < bsym->start) return -1; 36501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return 0; 37501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 38501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 39501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown// Compare function for bsearch 40501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownstatic int bcompar(const void *key, const void *element) { 41501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown uintptr_t addr = *(const uintptr_t*)key; 42501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown const symbol_t* symbol = (const symbol_t*)element; 43501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (addr < symbol->start) return -1; 44501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (addr >= symbol->end) return 1; 45501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return 0; 46501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 47501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 48501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownsymbol_table_t* load_symbol_table(const char *filename) { 49501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown symbol_table_t* table = NULL; 50501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 51501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown int fd = open(filename, O_RDONLY); 52501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (fd < 0) { 53501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown goto out; 54501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 55501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 56501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown struct stat sb; 57501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (fstat(fd, &sb)) { 58501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown goto out_close; 59501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 60501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 61501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown size_t length = sb.st_size; 62501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown char* base = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0); 63501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (base == MAP_FAILED) { 64501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown goto out_close; 65501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 66501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 67501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // Parse the file header 68501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown Elf32_Ehdr *hdr = (Elf32_Ehdr*)base; 69501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (!IS_ELF(*hdr)) { 70501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown goto out_close; 71501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 72501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown Elf32_Shdr *shdr = (Elf32_Shdr*)(base + hdr->e_shoff); 73501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 74501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // Search for the dynamic symbols section 75501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown int sym_idx = -1; 76501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown int dynsym_idx = -1; 77501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (Elf32_Half i = 0; i < hdr->e_shnum; i++) { 78501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (shdr[i].sh_type == SHT_SYMTAB) { 79501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown sym_idx = i; 80501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 81501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (shdr[i].sh_type == SHT_DYNSYM) { 82501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown dynsym_idx = i; 83501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 84501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 85501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (dynsym_idx == -1 && sym_idx == -1) { 86501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown goto out_unmap; 87501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 88501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 89501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table = malloc(sizeof(symbol_table_t)); 90501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if(!table) { 91501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown goto out_unmap; 92501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 93501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->num_symbols = 0; 94501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 95501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown Elf32_Sym *dynsyms = NULL; 96501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown int dynnumsyms = 0; 97501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown char *dynstr = NULL; 98501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (dynsym_idx != -1) { 99501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown dynsyms = (Elf32_Sym*)(base + shdr[dynsym_idx].sh_offset); 100501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown dynnumsyms = shdr[dynsym_idx].sh_size / shdr[dynsym_idx].sh_entsize; 101501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown int dynstr_idx = shdr[dynsym_idx].sh_link; 102501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown dynstr = base + shdr[dynstr_idx].sh_offset; 103501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 104501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 105501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown Elf32_Sym *syms = NULL; 106501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown int numsyms = 0; 107501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown char *str = NULL; 108501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (sym_idx != -1) { 109501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown syms = (Elf32_Sym*)(base + shdr[sym_idx].sh_offset); 110501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown numsyms = shdr[sym_idx].sh_size / shdr[sym_idx].sh_entsize; 111501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown int str_idx = shdr[sym_idx].sh_link; 112501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown str = base + shdr[str_idx].sh_offset; 113501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 114501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 115501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown int dynsymbol_count = 0; 116501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (dynsym_idx != -1) { 117501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // Iterate through the dynamic symbol table, and count how many symbols 118501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // are actually defined 119501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (int i = 0; i < dynnumsyms; i++) { 120501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (dynsyms[i].st_shndx != SHN_UNDEF) { 121501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown dynsymbol_count++; 122501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 123501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 124501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 125501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 126501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown size_t symbol_count = 0; 127501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (sym_idx != -1) { 128501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // Iterate through the symbol table, and count how many symbols 129501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // are actually defined 130501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (int i = 0; i < numsyms; i++) { 131501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (syms[i].st_shndx != SHN_UNDEF 132501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown && str[syms[i].st_name] 133501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown && syms[i].st_value 134501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown && syms[i].st_size) { 135501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown symbol_count++; 136501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 137501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 138501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 139501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 140501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // Now, create an entry in our symbol table structure for each symbol... 141501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->num_symbols += symbol_count + dynsymbol_count; 142501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->symbols = malloc(table->num_symbols * sizeof(symbol_t)); 143501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (!table->symbols) { 144501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free(table); 145501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table = NULL; 146501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown goto out_unmap; 147501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 148501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 149501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown size_t symbol_index = 0; 150501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (dynsym_idx != -1) { 151501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // ...and populate them 152501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (int i = 0; i < dynnumsyms; i++) { 153501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (dynsyms[i].st_shndx != SHN_UNDEF) { 154501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->symbols[symbol_index].name = strdup(dynstr + dynsyms[i].st_name); 155501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->symbols[symbol_index].start = dynsyms[i].st_value; 156501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->symbols[symbol_index].end = dynsyms[i].st_value + dynsyms[i].st_size; 157501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown symbol_index += 1; 158501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 159501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 160501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 161501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 162501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (sym_idx != -1) { 163501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // ...and populate them 164501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (int i = 0; i < numsyms; i++) { 165501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (syms[i].st_shndx != SHN_UNDEF 166501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown && str[syms[i].st_name] 167501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown && syms[i].st_value 168501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown && syms[i].st_size) { 169501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->symbols[symbol_index].name = strdup(str + syms[i].st_name); 170501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->symbols[symbol_index].start = syms[i].st_value; 171501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown table->symbols[symbol_index].end = syms[i].st_value + syms[i].st_size; 172501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown symbol_index += 1; 173501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 174501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 175501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 176501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 177501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown // Sort the symbol table entries, so they can be bsearched later 178501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown qsort(table->symbols, table->num_symbols, sizeof(symbol_t), qcompar); 179501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 180501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownout_unmap: 181501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown munmap(base, length); 182501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 183501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownout_close: 184501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown close(fd); 185501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 186501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownout: 187501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return table; 188501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 189501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 190501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownvoid free_symbol_table(symbol_table_t* table) { 191501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (table) { 192501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown for (size_t i = 0; i < table->num_symbols; i++) { 193501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free(table->symbols[i].name); 194501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 195501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free(table->symbols); 196501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown free(table); 197501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown } 198501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 199501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown 200501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brownconst symbol_t* find_symbol(const symbol_table_t* table, uintptr_t addr) { 201501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown if (!table) return NULL; 202501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown return (const symbol_t*)bsearch(&addr, table->symbols, table->num_symbols, 203501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown sizeof(symbol_t), bcompar); 204501edd29b823ce1301d2effdd3a9e4b6e2b20b76Jeff Brown} 205