| /* |
| * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include <unistd.h> |
| #include <search.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <db.h> |
| #include <fcntl.h> |
| |
| #include "libproc_impl.h" |
| #include "symtab.h" |
| #ifndef __APPLE__ |
| #include "salibelf.h" |
| #endif // __APPLE__ |
| |
| |
| // ---------------------------------------------------- |
| // functions for symbol lookups |
| // ---------------------------------------------------- |
| |
| typedef struct symtab_symbol { |
| char *name; // name like __ZThread_... |
| uintptr_t offset; // to loaded address |
| uintptr_t size; // size strlen |
| } symtab_symbol; |
| |
| typedef struct symtab { |
| char *strs; // all symbols "__symbol1__'\0'__symbol2__...." |
| size_t num_symbols; |
| DB* hash_table; |
| symtab_symbol* symbols; |
| } symtab_t; |
| |
| #ifdef __APPLE__ |
| |
| void build_search_table(symtab_t *symtab) { |
| int i; |
| for (i = 0; i < symtab->num_symbols; i++) { |
| DBT key, value; |
| key.data = symtab->symbols[i].name; |
| key.size = strlen(key.data) + 1; |
| value.data = &(symtab->symbols[i]); |
| value.size = sizeof(symtab_symbol); |
| (*symtab->hash_table->put)(symtab->hash_table, &key, &value, 0); |
| |
| // check result |
| if (is_debug()) { |
| DBT rkey, rvalue; |
| char* tmp = (char *)malloc(strlen(symtab->symbols[i].name) + 1); |
| strcpy(tmp, symtab->symbols[i].name); |
| rkey.data = tmp; |
| rkey.size = strlen(tmp) + 1; |
| (*symtab->hash_table->get)(symtab->hash_table, &rkey, &rvalue, 0); |
| // we may get a copy back so compare contents |
| symtab_symbol *res = (symtab_symbol *)rvalue.data; |
| if (strcmp(res->name, symtab->symbols[i].name) || |
| res->offset != symtab->symbols[i].offset || |
| res->size != symtab->symbols[i].size) { |
| print_debug("error to get hash_table value!\n"); |
| } |
| free(tmp); |
| } |
| } |
| } |
| |
| // read symbol table from given fd. |
| struct symtab* build_symtab(int fd) { |
| symtab_t* symtab = NULL; |
| int i; |
| mach_header_64 header; |
| off_t image_start; |
| |
| if (!get_arch_off(fd, CPU_TYPE_X86_64, &image_start)) { |
| print_debug("failed in get fat header\n"); |
| return NULL; |
| } |
| lseek(fd, image_start, SEEK_SET); |
| if (read(fd, (void *)&header, sizeof(mach_header_64)) != sizeof(mach_header_64)) { |
| print_debug("reading header failed!\n"); |
| return NULL; |
| } |
| // header |
| if (header.magic != MH_MAGIC_64) { |
| print_debug("not a valid .dylib file\n"); |
| return NULL; |
| } |
| |
| load_command lcmd; |
| symtab_command symtabcmd; |
| nlist_64 lentry; |
| |
| bool lcsymtab_exist = false; |
| |
| long filepos = ltell(fd); |
| for (i = 0; i < header.ncmds; i++) { |
| lseek(fd, filepos, SEEK_SET); |
| if (read(fd, (void *)&lcmd, sizeof(load_command)) != sizeof(load_command)) { |
| print_debug("read load_command failed for file\n"); |
| return NULL; |
| } |
| filepos += lcmd.cmdsize; // next command position |
| if (lcmd.cmd == LC_SYMTAB) { |
| lseek(fd, -sizeof(load_command), SEEK_CUR); |
| lcsymtab_exist = true; |
| break; |
| } |
| } |
| if (!lcsymtab_exist) { |
| print_debug("No symtab command found!\n"); |
| return NULL; |
| } |
| if (read(fd, (void *)&symtabcmd, sizeof(symtab_command)) != sizeof(symtab_command)) { |
| print_debug("read symtab_command failed for file"); |
| return NULL; |
| } |
| symtab = (symtab_t *)malloc(sizeof(symtab_t)); |
| if (symtab == NULL) { |
| print_debug("out of memory: allocating symtab\n"); |
| return NULL; |
| } |
| |
| // create hash table, we use berkeley db to |
| // manipulate the hash table. |
| symtab->hash_table = dbopen(NULL, O_CREAT | O_RDWR, 0600, DB_HASH, NULL); |
| if (symtab->hash_table == NULL) |
| goto quit; |
| |
| symtab->num_symbols = symtabcmd.nsyms; |
| symtab->symbols = (symtab_symbol *)malloc(sizeof(symtab_symbol) * symtab->num_symbols); |
| symtab->strs = (char *)malloc(sizeof(char) * symtabcmd.strsize); |
| if (symtab->symbols == NULL || symtab->strs == NULL) { |
| print_debug("out of memory: allocating symtab.symbol or symtab.strs\n"); |
| goto quit; |
| } |
| lseek(fd, image_start + symtabcmd.symoff, SEEK_SET); |
| for (i = 0; i < symtab->num_symbols; i++) { |
| if (read(fd, (void *)&lentry, sizeof(nlist_64)) != sizeof(nlist_64)) { |
| print_debug("read nlist_64 failed at %i\n", i); |
| goto quit; |
| } |
| symtab->symbols[i].offset = lentry.n_value; |
| symtab->symbols[i].size = lentry.n_un.n_strx; // index |
| } |
| |
| // string table |
| lseek(fd, image_start + symtabcmd.stroff, SEEK_SET); |
| int size = read(fd, (void *)(symtab->strs), symtabcmd.strsize * sizeof(char)); |
| if (size != symtabcmd.strsize * sizeof(char)) { |
| print_debug("reading string table failed\n"); |
| goto quit; |
| } |
| |
| for (i = 0; i < symtab->num_symbols; i++) { |
| symtab->symbols[i].name = symtab->strs + symtab->symbols[i].size; |
| if (i > 0) { |
| // fix size |
| symtab->symbols[i - 1].size = symtab->symbols[i].size - symtab->symbols[i - 1].size; |
| print_debug("%s size = %d\n", symtab->symbols[i - 1].name, symtab->symbols[i - 1].size); |
| |
| } |
| |
| if (i == symtab->num_symbols - 1) { |
| // last index |
| symtab->symbols[i].size = |
| symtabcmd.strsize - symtab->symbols[i].size; |
| print_debug("%s size = %d\n", symtab->symbols[i].name, symtab->symbols[i].size); |
| } |
| } |
| |
| // build a hashtable for fast query |
| build_search_table(symtab); |
| return symtab; |
| quit: |
| if (symtab) destroy_symtab(symtab); |
| return NULL; |
| } |
| |
| #else // __APPLE__ |
| |
| struct elf_section { |
| ELF_SHDR *c_shdr; |
| void *c_data; |
| }; |
| |
| // read symbol table from given fd. |
| struct symtab* build_symtab(int fd) { |
| ELF_EHDR ehdr; |
| struct symtab* symtab = NULL; |
| |
| // Reading of elf header |
| struct elf_section *scn_cache = NULL; |
| int cnt = 0; |
| ELF_SHDR* shbuf = NULL; |
| ELF_SHDR* cursct = NULL; |
| ELF_PHDR* phbuf = NULL; |
| int symtab_found = 0; |
| int dynsym_found = 0; |
| uint32_t symsection = SHT_SYMTAB; |
| |
| uintptr_t baseaddr = (uintptr_t)-1; |
| |
| lseek(fd, (off_t)0L, SEEK_SET); |
| if (! read_elf_header(fd, &ehdr)) { |
| // not an elf |
| return NULL; |
| } |
| |
| // read ELF header |
| if ((shbuf = read_section_header_table(fd, &ehdr)) == NULL) { |
| goto quit; |
| } |
| |
| baseaddr = find_base_address(fd, &ehdr); |
| |
| scn_cache = calloc(ehdr.e_shnum, sizeof(*scn_cache)); |
| if (scn_cache == NULL) { |
| goto quit; |
| } |
| |
| for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) { |
| scn_cache[cnt].c_shdr = cursct; |
| if (cursct->sh_type == SHT_SYMTAB || |
| cursct->sh_type == SHT_STRTAB || |
| cursct->sh_type == SHT_DYNSYM) { |
| if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) { |
| goto quit; |
| } |
| } |
| |
| if (cursct->sh_type == SHT_SYMTAB) |
| symtab_found++; |
| |
| if (cursct->sh_type == SHT_DYNSYM) |
| dynsym_found++; |
| |
| cursct++; |
| } |
| |
| if (!symtab_found && dynsym_found) |
| symsection = SHT_DYNSYM; |
| |
| for (cnt = 1; cnt < ehdr.e_shnum; cnt++) { |
| ELF_SHDR *shdr = scn_cache[cnt].c_shdr; |
| |
| if (shdr->sh_type == symsection) { |
| ELF_SYM *syms; |
| int j, n; |
| size_t size; |
| |
| // FIXME: there could be multiple data buffers associated with the |
| // same ELF section. Here we can handle only one buffer. See man page |
| // for elf_getdata on Solaris. |
| |
| // guarantee(symtab == NULL, "multiple symtab"); |
| symtab = calloc(1, sizeof(*symtab)); |
| if (symtab == NULL) { |
| goto quit; |
| } |
| // the symbol table |
| syms = (ELF_SYM *)scn_cache[cnt].c_data; |
| |
| // number of symbols |
| n = shdr->sh_size / shdr->sh_entsize; |
| |
| // create hash table, we use berkeley db to |
| // manipulate the hash table. |
| symtab->hash_table = dbopen(NULL, O_CREAT | O_RDWR, 0600, DB_HASH, NULL); |
| // guarantee(symtab->hash_table, "unexpected failure: dbopen"); |
| if (symtab->hash_table == NULL) |
| goto bad; |
| |
| // shdr->sh_link points to the section that contains the actual strings |
| // for symbol names. the st_name field in ELF_SYM is just the |
| // string table index. we make a copy of the string table so the |
| // strings will not be destroyed by elf_end. |
| size = scn_cache[shdr->sh_link].c_shdr->sh_size; |
| symtab->strs = malloc(size); |
| if (symtab->strs == NULL) |
| goto bad; |
| memcpy(symtab->strs, scn_cache[shdr->sh_link].c_data, size); |
| |
| // allocate memory for storing symbol offset and size; |
| symtab->num_symbols = n; |
| symtab->symbols = calloc(n , sizeof(*symtab->symbols)); |
| if (symtab->symbols == NULL) |
| goto bad; |
| |
| // copy symbols info our symtab and enter them info the hash table |
| for (j = 0; j < n; j++, syms++) { |
| DBT key, value; |
| char *sym_name = symtab->strs + syms->st_name; |
| |
| // skip non-object and non-function symbols |
| int st_type = ELF_ST_TYPE(syms->st_info); |
| if ( st_type != STT_FUNC && st_type != STT_OBJECT) |
| continue; |
| // skip empty strings and undefined symbols |
| if (*sym_name == '\0' || syms->st_shndx == SHN_UNDEF) continue; |
| |
| symtab->symbols[j].name = sym_name; |
| symtab->symbols[j].offset = syms->st_value - baseaddr; |
| symtab->symbols[j].size = syms->st_size; |
| |
| key.data = sym_name; |
| key.size = strlen(sym_name) + 1; |
| value.data = &(symtab->symbols[j]); |
| value.size = sizeof(symtab_symbol); |
| (*symtab->hash_table->put)(symtab->hash_table, &key, &value, 0); |
| } |
| } |
| } |
| goto quit; |
| |
| bad: |
| destroy_symtab(symtab); |
| symtab = NULL; |
| |
| quit: |
| if (shbuf) free(shbuf); |
| if (phbuf) free(phbuf); |
| if (scn_cache) { |
| for (cnt = 0; cnt < ehdr.e_shnum; cnt++) { |
| if (scn_cache[cnt].c_data != NULL) { |
| free(scn_cache[cnt].c_data); |
| } |
| } |
| free(scn_cache); |
| } |
| return symtab; |
| } |
| |
| #endif // __APPLE__ |
| |
| void destroy_symtab(symtab_t* symtab) { |
| if (!symtab) return; |
| free(symtab->strs); |
| free(symtab->symbols); |
| free(symtab); |
| } |
| |
| uintptr_t search_symbol(struct symtab* symtab, uintptr_t base, const char *sym_name, int *sym_size) { |
| DBT key, value; |
| int ret; |
| |
| // library does not have symbol table |
| if (!symtab || !symtab->hash_table) { |
| return 0; |
| } |
| |
| key.data = (char*)(uintptr_t)sym_name; |
| key.size = strlen(sym_name) + 1; |
| ret = (*symtab->hash_table->get)(symtab->hash_table, &key, &value, 0); |
| if (ret == 0) { |
| symtab_symbol *sym = value.data; |
| uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset); |
| if (sym_size) *sym_size = sym->size; |
| return rslt; |
| } |
| |
| return 0; |
| } |
| |
| const char* nearest_symbol(struct symtab* symtab, uintptr_t offset, |
| uintptr_t* poffset) { |
| int n = 0; |
| if (!symtab) return NULL; |
| for (; n < symtab->num_symbols; n++) { |
| symtab_symbol* sym = &(symtab->symbols[n]); |
| if (sym->name != NULL && |
| offset >= sym->offset && offset < sym->offset + sym->size) { |
| if (poffset) *poffset = (offset - sym->offset); |
| return sym->name; |
| } |
| } |
| return NULL; |
| } |