| 0,0 → 1,237 |
|---|
| /* |
| * Copyright (c) 2008 Jiri Svoboda |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * - The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** @addtogroup rtld rtld |
| * @brief |
| * @{ |
| */ |
| /** |
| * @file |
| */ |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include <rtld.h> |
| #include <symbol.h> |
| #include <elf.h> |
| |
| /* |
| * Hash tables are 32-bit (elf_word) even for 64-bit ELF files. |
| */ |
| static elf_word elf_hash(const unsigned char *name) |
| { |
| elf_word h = 0, g; |
| |
| while (*name) { |
| h = (h << 4) + *name++; |
| g = h & 0xf0000000; |
| if (g != 0) h ^= g >> 24; |
| h &= ~g; |
| } |
| |
| return h; |
| } |
| |
| static elf_symbol_t *def_find_in_module(char *name, module_t *m) |
| { |
| elf_symbol_t *sym_table; |
| elf_symbol_t *s, *sym; |
| elf_word nbucket; |
| elf_word nchain; |
| elf_word i; |
| char *s_name; |
| elf_word bucket; |
| |
| DPRINTF("def_find_in_module('%s', %s)\n", name, m->dyn.soname); |
| |
| sym_table = m->dyn.sym_tab; |
| nbucket = m->dyn.hash[0]; |
| nchain = m->dyn.hash[1]; |
| |
| bucket = elf_hash((unsigned char *)name) % nbucket; |
| i = m->dyn.hash[2 + bucket]; |
| |
| sym = NULL; |
| while (i != STN_UNDEF) { |
| s = &sym_table[i]; |
| s_name = m->dyn.str_tab + s->st_name; |
| |
| if (str_cmp(name, s_name) == 0) { |
| sym = s; |
| break; |
| } |
| |
| i = m->dyn.hash[2 + nbucket + i]; |
| } |
| |
| if (!sym) |
| return NULL; /* Not found */ |
| |
| if (sym->st_shndx == SHN_UNDEF) { |
| /* Not a definition */ |
| return NULL; |
| } |
| |
| return sym; /* Found */ |
| } |
| |
| /** Find the definition of a symbol in a module and its deps. |
| * |
| * Search the module dependency graph is breadth-first, beginning |
| * from the module @a start. Thus, @start and all its dependencies |
| * get searched. |
| * |
| * @param name Name of the symbol to search for. |
| * @param start Module in which to start the search.. |
| * @param mod (output) Will be filled with a pointer to the module |
| * that contains the symbol. |
| */ |
| elf_symbol_t *symbol_bfs_find(char *name, module_t *start, module_t **mod) |
| { |
| module_t *m, *dm; |
| elf_symbol_t *sym, *s; |
| link_t queue_head; |
| size_t i; |
| |
| /* |
| * Do a BFS using the queue_link and bfs_tag fields. |
| * Vertices (modules) are tagged the moment they are inserted |
| * into the queue. This prevents from visiting the same vertex |
| * more times in case of circular dependencies. |
| */ |
| |
| /* Mark all vertices (modules) as unvisited */ |
| modules_untag(); |
| |
| /* Insert root (the program) into the queue and tag it */ |
| list_initialize(&queue_head); |
| start->bfs_tag = true; |
| list_append(&start->queue_link, &queue_head); |
| |
| /* If the symbol is found, it will be stored in 'sym' */ |
| sym = NULL; |
| |
| /* While queue is not empty */ |
| while (!list_empty(&queue_head)) { |
| /* Pop first element from the queue */ |
| m = list_get_instance(queue_head.next, module_t, queue_link); |
| list_remove(&m->queue_link); |
| |
| s = def_find_in_module(name, m); |
| if (s != NULL) { |
| /* Symbol found */ |
| sym = s; |
| *mod = m; |
| break; |
| } |
| |
| /* |
| * Insert m's untagged dependencies into the queue |
| * and tag them. |
| */ |
| for (i = 0; i < m->n_deps; ++i) { |
| dm = m->deps[i]; |
| |
| if (dm->bfs_tag == false) { |
| dm->bfs_tag = true; |
| list_append(&dm->queue_link, &queue_head); |
| } |
| } |
| } |
| |
| /* Empty the queue so that we leave it in a clean state */ |
| while (!list_empty(&queue_head)) |
| list_remove(queue_head.next); |
| |
| if (!sym) { |
| printf("Error, symbol '%s' not found anywhere\n", name); |
| exit(1); |
| return NULL; /* Not found */ |
| } |
| |
| return sym; /* Symbol found */ |
| } |
| |
| |
| /** Find the definition of a symbol.. |
| * |
| * By definition in System V ABI, if module origin has the flag DT_SYMBOLIC, |
| * origin is searched first. Otherwise, or if the symbol hasn't been found, |
| * the module dependency graph is searched breadth-first, beginning |
| * from the executable program. |
| * |
| * @param name Name of the symbol to search for. |
| * @param origin Module in which the dependency originates. |
| * @param mod (output) Will be filled with a pointer to the module |
| * that contains the symbol. |
| */ |
| elf_symbol_t *symbol_def_find(char *name, module_t *origin, module_t **mod) |
| { |
| module_t *m, *dm; |
| elf_symbol_t *sym, *s; |
| link_t queue_head; |
| size_t i; |
| |
| if (origin->dyn.symbolic) { |
| /* |
| * Origin module has a DT_SYMBOLIC flag. |
| * Try this module first |
| */ |
| s = def_find_in_module(name, origin); |
| if (s != NULL) { |
| /* Found */ |
| *mod = origin; |
| return s; |
| } |
| } |
| |
| /* Not DT_SYMBOLIC or no match. Now try other locations. */ |
| |
| if (runtime_env->program) { |
| /* Program is dynamic -- start with program as root. */ |
| return symbol_bfs_find(name, runtime_env->program, mod); |
| } else { |
| /* Program is static -- start with @a origin as root. */ |
| return symbol_bfs_find(name, origin, mod); |
| } |
| } |
| |
| uintptr_t symbol_get_addr(elf_symbol_t *sym, module_t *m) |
| { |
| if (sym->st_shndx == SHN_ABS) { |
| /* Do not add bias to absolute symbols */ |
| return sym->st_value; |
| } else { |
| return sym->st_value + m->bias; |
| } |
| } |
| |
| /** @} |
| */ |