1 /*
2 * Copyright (c) 2011, 2014, 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
35 bool 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
51 bool 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", p2i(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 buf[buflen - 1] = '\0';
101 return true;
102 }
103 DEBUG_ONLY(tty->print_cr("no string or null string found."));
104 return false;
105 }
106
107 void* MachODecoder::mach_find_command(struct mach_header_64 * mach_base, uint32_t command_wanted) {
108 // possibly verify it is a mach_header, use magic number.
109 // commands begin immediately after the header.
110 struct load_command *pos = (struct load_command *) mach_base + sizeof(struct mach_header_64);
111 for (uint32_t i = 0; i < mach_base->ncmds; i++) {
112 struct load_command *this_cmd = (struct load_command *) pos;
113 if (this_cmd->cmd == command_wanted) {
114 return pos;
115 }
116 int cmdsize = this_cmd->cmdsize;
117 pos += cmdsize;
118 }
119 return NULL;
120 }
121
122 char* MachODecoder::mach_find_in_stringtable(char *strtab, uint32_t tablesize, int strx_wanted) {
123
124 if (strx_wanted == 0) {
125 return NULL;
126 }
127 char *strtab_end = strtab + tablesize;
128
129 // find the first string, skip over the space char
130 // (or the four zero bytes we see e.g. in libclient)
131 if (*strtab == ' ') {
132 strtab++;
133 if (*strtab != 0) {
134 DEBUG_ONLY(tty->print_cr("string table has leading space but no following zero."));
135 return NULL;
136 }
137 strtab++;
138 } else {
139 if ((uint32_t) *strtab != 0) {
140 DEBUG_ONLY(tty->print_cr("string table without leading space or leading int of zero."));
141 return NULL;
142 }
143 strtab+=4;
144 }
145 // read the real strings starting at index 1
146 int cur_strx = 1;
147 while (strtab < strtab_end) {
148 if (cur_strx == strx_wanted) {
149 return strtab;
150 }
151 // find start of next string
152 while (*strtab != 0) {
153 strtab++;
154 }
155 strtab++; // skip the terminating zero
156 cur_strx++;
157 }
158 DEBUG_ONLY(tty->print_cr("string number %d not found.", strx_wanted));
159 return NULL;
160 }
161
162
163 #endif
164
165