| /* |
| * Copyright 2003-2005 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| * |
| */ |
| |
| #include <unistd.h> |
| #include <sys/procfs.h> |
| #include <search.h> |
| #include <stdlib.h> |
| #include <string.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; |
| struct hsearch_data *hash_table; |
| } symtab_t; |
| |
| // read symbol table from given fd. |
| struct symtab* build_symtab(int fd) { |
| ELF_EHDR ehdr; |
| char *names = NULL; |
| 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; |
| ELF_PHDR* phdr = NULL; |
| |
| 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 = (struct elf_section *) |
| calloc(ehdr.e_shnum * sizeof(struct elf_section), 1); |
| 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) { |
| if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) { |
| goto quit; |
| } |
| } |
| cursct++; |
| } |
| |
| for (cnt = 1; cnt < ehdr.e_shnum; cnt++) { |
| ELF_SHDR *shdr = scn_cache[cnt].c_shdr; |
| |
| if (shdr->sh_type == SHT_SYMTAB) { |
| ELF_SYM *syms; |
| int j, n, rslt; |
| 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 = (struct symtab*)calloc(1, sizeof(struct 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 hcreate_r, hsearch_r and hdestroy_r to |
| // manipulate the hash table. |
| symtab->hash_table = (struct hsearch_data*) calloc(1, sizeof(struct hsearch_data)); |
| rslt = hcreate_r(n, symtab->hash_table); |
| // guarantee(rslt, "unexpected failure: hcreate_r"); |
| |
| // 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 = (char *)malloc(size); |
| 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 = (struct elf_symbol *)calloc(n , sizeof(struct elf_symbol)); |
| |
| // copy symbols info our symtab and enter them info the hash table |
| for (j = 0; j < n; j++, syms++) { |
| ENTRY item, *ret; |
| 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; |
| |
| item.key = sym_name; |
| item.data = (void *)&(symtab->symbols[j]); |
| |
| hsearch_r(item, ENTER, &ret, symtab->hash_table); |
| } |
| } |
| } |
| |
| 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) { |
| hdestroy_r(symtab->hash_table); |
| free(symtab->hash_table); |
| } |
| free(symtab); |
| } |
| |
| uintptr_t search_symbol(struct symtab* symtab, uintptr_t base, |
| const char *sym_name, int *sym_size) { |
| ENTRY item; |
| ENTRY* ret = NULL; |
| |
| // library does not have symbol table |
| if (!symtab || !symtab->hash_table) |
| return (uintptr_t)NULL; |
| |
| item.key = (char*) strdup(sym_name); |
| hsearch_r(item, FIND, &ret, symtab->hash_table); |
| if (ret) { |
| struct elf_symbol * sym = (struct elf_symbol *)(ret->data); |
| uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset); |
| if (sym_size) *sym_size = sym->size; |
| free(item.key); |
| return rslt; |
| } |
| |
| quit: |
| free(item.key); |
| return (uintptr_t) NULL; |
| } |
| |
| 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; |
| } |