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