Mercurial > hg > truffle
view agent/src/os/bsd/symtab.c @ 4930:cd239a88b90c
Merge
author | minqi |
---|---|
date | Tue, 14 Feb 2012 20:54:57 -0800 |
parents | 436b4a3231bf |
children | 39432a1cefdd |
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/* * Copyright (c) 2003, 2010, 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 "symtab.h" #include "salibelf.h" // ---------------------------------------------------- // functions for symbol lookups // ---------------------------------------------------- struct elf_section { ELF_SHDR *c_shdr; void *c_data; }; struct elf_symbol { char *name; uintptr_t offset; uintptr_t size; }; typedef struct symtab { char *strs; size_t num_symbols; struct elf_symbol *symbols; DB* hash_table; } symtab_t; // 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(void *); (*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; } void destroy_symtab(struct symtab* symtab) { if (!symtab) return; if (symtab->strs) free(symtab->strs); if (symtab->symbols) free(symtab->symbols); if (symtab->hash_table) { (*symtab->hash_table->close)(symtab->hash_table); } 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) { struct elf_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++) { struct elf_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; }