1/* 2 * Copyright (c) 2011, 2017, 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 "prims/jvm.h" 29#include "decoder_machO.hpp" 30 31#include <cxxabi.h> 32#include <mach-o/loader.h> 33#include <mach-o/nlist.h> 34 35 36bool MachODecoder::demangle(const char* symbol, char *buf, int buflen) { 37 int status; 38 char* result; 39 size_t size = (size_t)buflen; 40 // Don't pass buf to __cxa_demangle. In case of the 'buf' is too small, 41 // __cxa_demangle will call system "realloc" for additional memory, which 42 // may use different malloc/realloc mechanism that allocates 'buf'. 43 if ((result = abi::__cxa_demangle(symbol, NULL, NULL, &status)) != NULL) { 44 jio_snprintf(buf, buflen, "%s", result); 45 // call c library's free 46 ::free(result); 47 return true; 48 } 49 return false; 50} 51 52bool MachODecoder::decode(address addr, char *buf, 53 int buflen, int *offset, const void *mach_base) { 54 struct symtab_command * symt = (struct symtab_command *) 55 mach_find_command((struct mach_header_64 *)mach_base, LC_SYMTAB); 56 if (symt == NULL) { 57 DEBUG_ONLY(tty->print_cr("no symtab in mach file at 0x%lx", p2i(mach_base))); 58 return false; 59 } 60 uint32_t off = symt->symoff; /* symbol table offset (within this mach file) */ 61 uint32_t nsyms = symt->nsyms; /* number of symbol table entries */ 62 uint32_t stroff = symt->stroff; /* string table offset */ 63 uint32_t strsize = symt->strsize; /* string table size in bytes */ 64 65 // iterate through symbol table trying to match our offset 66 67 uint32_t addr_relative = (uintptr_t) mach_base - (uintptr_t) addr; // offset we seek in the symtab 68 void * symtab_addr = (void*) ((uintptr_t) mach_base + off); 69 struct nlist_64 *cur_nlist = (struct nlist_64 *) symtab_addr; 70 struct nlist_64 *last_nlist = cur_nlist; // no size stored in an entry, so keep previously seen nlist 71 72 int32_t found_strx = 0; 73 int32_t found_symval = 0; 74 75 for (uint32_t i=0; i < nsyms; i++) { 76 uint32_t this_value = cur_nlist->n_value; 77 78 if (addr_relative == this_value) { 79 found_strx = cur_nlist->n_un.n_strx; 80 found_symval = this_value; 81 break; 82 } else if (addr_relative > this_value) { 83 // gone past it, use previously seen nlist: 84 found_strx = last_nlist->n_un.n_strx; 85 found_symval = last_nlist->n_value; 86 break; 87 } 88 last_nlist = cur_nlist; 89 cur_nlist = cur_nlist + sizeof(struct nlist_64); 90 } 91 if (found_strx == 0) { 92 return false; 93 } 94 // write the offset: 95 *offset = addr_relative - found_symval; 96 97 // lookup found_strx in the string table 98 char * symname = mach_find_in_stringtable((char*) ((uintptr_t)mach_base + stroff), strsize, found_strx); 99 if (symname) { 100 strncpy(buf, symname, buflen); 101 buf[buflen - 1] = '\0'; 102 return true; 103 } 104 DEBUG_ONLY(tty->print_cr("no string or null string found.")); 105 return false; 106} 107 108void* MachODecoder::mach_find_command(struct mach_header_64 * mach_base, uint32_t command_wanted) { 109 // possibly verify it is a mach_header, use magic number. 110 // commands begin immediately after the header. 111 struct load_command *pos = (struct load_command *) mach_base + sizeof(struct mach_header_64); 112 for (uint32_t i = 0; i < mach_base->ncmds; i++) { 113 struct load_command *this_cmd = (struct load_command *) pos; 114 if (this_cmd->cmd == command_wanted) { 115 return pos; 116 } 117 int cmdsize = this_cmd->cmdsize; 118 pos += cmdsize; 119 } 120 return NULL; 121} 122 123char* MachODecoder::mach_find_in_stringtable(char *strtab, uint32_t tablesize, int strx_wanted) { 124 125 if (strx_wanted == 0) { 126 return NULL; 127 } 128 char *strtab_end = strtab + tablesize; 129 130 // find the first string, skip over the space char 131 // (or the four zero bytes we see e.g. in libclient) 132 if (*strtab == ' ') { 133 strtab++; 134 if (*strtab != 0) { 135 DEBUG_ONLY(tty->print_cr("string table has leading space but no following zero.")); 136 return NULL; 137 } 138 strtab++; 139 } else { 140 if ((uint32_t) *strtab != 0) { 141 DEBUG_ONLY(tty->print_cr("string table without leading space or leading int of zero.")); 142 return NULL; 143 } 144 strtab+=4; 145 } 146 // read the real strings starting at index 1 147 int cur_strx = 1; 148 while (strtab < strtab_end) { 149 if (cur_strx == strx_wanted) { 150 return strtab; 151 } 152 // find start of next string 153 while (*strtab != 0) { 154 strtab++; 155 } 156 strtab++; // skip the terminating zero 157 cur_strx++; 158 } 159 DEBUG_ONLY(tty->print_cr("string number %d not found.", strx_wanted)); 160 return NULL; 161} 162 163 164#endif 165 166 167