decoder_machO.cpp revision 3526:3b01d0321dfa
1/* 2 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25#include "precompiled.hpp" 26 27#ifdef __APPLE__ 28#include "decoder_machO.hpp" 29 30#include <cxxabi.h> 31#include <mach-o/loader.h> 32#include <mach-o/nlist.h> 33 34 35bool MachODecoder::demangle(const char* symbol, char *buf, int buflen) { 36 int status; 37 char* result; 38 size_t size = (size_t)buflen; 39 // Don't pass buf to __cxa_demangle. In case of the 'buf' is too small, 40 // __cxa_demangle will call system "realloc" for additional memory, which 41 // may use different malloc/realloc mechanism that allocates 'buf'. 42 if ((result = abi::__cxa_demangle(symbol, NULL, NULL, &status)) != NULL) { 43 jio_snprintf(buf, buflen, "%s", result); 44 // call c library's free 45 ::free(result); 46 return true; 47 } 48 return false; 49} 50 51bool MachODecoder::decode(address addr, char *buf, 52 int buflen, int *offset, const void *mach_base) { 53 struct symtab_command * symt = (struct symtab_command *) 54 mach_find_command((struct mach_header_64 *)mach_base, LC_SYMTAB); 55 if (symt == NULL) { 56 DEBUG_ONLY(tty->print_cr("no symtab in mach file at 0x%lx", mach_base)); 57 return false; 58 } 59 uint32_t off = symt->symoff; /* symbol table offset (within this mach file) */ 60 uint32_t nsyms = symt->nsyms; /* number of symbol table entries */ 61 uint32_t stroff = symt->stroff; /* string table offset */ 62 uint32_t strsize = symt->strsize; /* string table size in bytes */ 63 64 // iterate through symbol table trying to match our offset 65 66 uint32_t addr_relative = (uintptr_t) mach_base - (uintptr_t) addr; // offset we seek in the symtab 67 void * symtab_addr = (void*) ((uintptr_t) mach_base + off); 68 struct nlist_64 *cur_nlist = (struct nlist_64 *) symtab_addr; 69 struct nlist_64 *last_nlist = cur_nlist; // no size stored in an entry, so keep previously seen nlist 70 71 int32_t found_strx = 0; 72 int32_t found_symval = 0; 73 74 for (uint32_t i=0; i < nsyms; i++) { 75 uint32_t this_value = cur_nlist->n_value; 76 77 if (addr_relative == this_value) { 78 found_strx = cur_nlist->n_un.n_strx; 79 found_symval = this_value; 80 break; 81 } else if (addr_relative > this_value) { 82 // gone past it, use previously seen nlist: 83 found_strx = last_nlist->n_un.n_strx; 84 found_symval = last_nlist->n_value; 85 break; 86 } 87 last_nlist = cur_nlist; 88 cur_nlist = cur_nlist + sizeof(struct nlist_64); 89 } 90 if (found_strx == 0) { 91 return false; 92 } 93 // write the offset: 94 *offset = addr_relative - found_symval; 95 96 // lookup found_strx in the string table 97 char * symname = mach_find_in_stringtable((char*) ((uintptr_t)mach_base + stroff), strsize, found_strx); 98 if (symname) { 99 strncpy(buf, symname, buflen); 100 return true; 101 } 102 DEBUG_ONLY(tty->print_cr("no string or null string found.")); 103 return false; 104} 105 106void* MachODecoder::mach_find_command(struct mach_header_64 * mach_base, uint32_t command_wanted) { 107 // possibly verify it is a mach_header, use magic number. 108 // commands begin immediately after the header. 109 struct load_command *pos = (struct load_command *) mach_base + sizeof(struct mach_header_64); 110 for (uint32_t i = 0; i < mach_base->ncmds; i++) { 111 struct load_command *this_cmd = (struct load_command *) pos; 112 if (this_cmd->cmd == command_wanted) { 113 return pos; 114 } 115 int cmdsize = this_cmd->cmdsize; 116 pos += cmdsize; 117 } 118 return NULL; 119} 120 121char* MachODecoder::mach_find_in_stringtable(char *strtab, uint32_t tablesize, int strx_wanted) { 122 123 if (strx_wanted == 0) { 124 return NULL; 125 } 126 char *strtab_end = strtab + tablesize; 127 128 // find the first string, skip over the space char 129 // (or the four zero bytes we see e.g. in libclient) 130 if (*strtab == ' ') { 131 strtab++; 132 if (*strtab != 0) { 133 DEBUG_ONLY(tty->print_cr("string table has leading space but no following zero.")); 134 return NULL; 135 } 136 strtab++; 137 } else { 138 if ((uint32_t) *strtab != 0) { 139 DEBUG_ONLY(tty->print_cr("string table without leading space or leading int of zero.")); 140 return NULL; 141 } 142 strtab+=4; 143 } 144 // read the real strings starting at index 1 145 int cur_strx = 1; 146 while (strtab < strtab_end) { 147 if (cur_strx == strx_wanted) { 148 return strtab; 149 } 150 // find start of next string 151 while (*strtab != 0) { 152 strtab++; 153 } 154 strtab++; // skip the terminating zero 155 cur_strx++; 156 } 157 DEBUG_ONLY(tty->print_cr("string number %d not found.", strx_wanted)); 158 return NULL; 159} 160 161 162#endif 163 164 165