gen/backtrace.c

   1 /*
   2  * Copyright (c) 2007 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <mach/vm_types.h>
  25 #include <sys/uio.h>
  26
  27 #include <dlfcn.h>
  28 #include <stdlib.h>
  29 #include <stdio.h>
  30 #include <string.h>
  31
  32 #include "stack_logging.h"
  33 #include "execinfo.h"
  34
  35 int backtrace(void** buffer, int size) {
  36         extern void _thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb, unsigned skip);
  37         unsigned int num_frames;
  38         _thread_stack_pcs((vm_address_t*)buffer, size, &num_frames, 1);
  39         while (num_frames >= 1 && buffer[num_frames-1] == NULL) num_frames -= 1;
  40         return num_frames;
  41 }
  42
  43 #if __LP64__
  44 #define _BACKTRACE_FORMAT "%-4d%-35s 0x%016x %s + %u"
  45 #define _BACKTRACE_FORMAT_SIZE 82
  46 #else
  47 #define _BACKTRACE_FORMAT "%-4d%-35s 0x%08x %s + %u"
  48 #define _BACKTRACE_FORMAT_SIZE 65
  49 #endif
  50
  51
  52 static int _backtrace_snprintf(char* buf, size_t size, int frame, const void* addr, const Dl_info* info) {
  53         char symbuf[19];
  54         const char* image = "???";
  55         const char* symbol = symbuf;
  56
  57         if (info->dli_fname) {
  58                 image = strrchr(info->dli_fname, '/') + 1;
  59                 if (image == NULL) image = info->dli_fname;
  60         }
  61
  62         if (info->dli_sname) {
  63                 symbol = info->dli_sname;
  64         } else {
  65                 snprintf(symbuf, sizeof(symbuf), "0x%x", info->dli_saddr);
  66         }
  67
  68         return snprintf(buf, size,
  69                         _BACKTRACE_FORMAT,
  70                         frame,
  71                         image,
  72                         addr,
  73                         symbol,
  74                         addr - info->dli_saddr) + 1;
  75 }
  76
  77 char** backtrace_symbols(void* const* buffer, int size) {
  78         int i;
  79         size_t total_bytes;
  80         char** result;
  81         char** ptrs;
  82         intptr_t strs;
  83         Dl_info* info = calloc(size, sizeof (Dl_info));
  84
  85         if (info == NULL) return NULL;
  86
  87         // Compute the total size for the block that is returned.
  88         // The block will contain size number of pointers to the
  89         // symbol descriptions.
  90
  91         total_bytes = sizeof(char*) * size;
  92
  93         // Plus each symbol description
  94         for (i = 0 ; i < size; ++i) {
  95                 dladdr(buffer[i], &info[i]);
  96                 total_bytes += _BACKTRACE_FORMAT_SIZE + 1;
  97                 if (info[i].dli_sname) total_bytes += strlen(info[i].dli_sname);
  98         }
  99
 100         result = (char**)malloc(total_bytes);
 101         if (result == NULL) {
 102                 free(info);
 103                 return NULL;
 104         }
 105
 106         // Fill in the array of pointers and append the strings for
 107         // each symbol description.
 108
 109         ptrs = result;
 110         strs = ((intptr_t)result) + sizeof(char*) * size;
 111
 112         for (i = 0; i < size; ++i) {
 113                 ptrs[i] = (char*)strs;
 114                 strs += _backtrace_snprintf((char*)strs, total_bytes, i, buffer[i], &info[i]);
 115         }
 116
 117         free(info);
 118
 119         return result;
 120 }
 121
 122 void backtrace_symbols_fd(void* const* buffer, int size, int fd) {
 123         int i;
 124         char buf[BUFSIZ];
 125         Dl_info info;
 126         struct iovec iov[2];
 127
 128         iov[0].iov_base = buf;
 129
 130         iov[1].iov_base = "\n";
 131         iov[1].iov_len = 1;
 132
 133         for (i = 0; i < size; ++i) {
 134                 memset(&info, 0, sizeof(info));
 135                 dladdr(buffer[i], &info);
 136
 137                 iov[0].iov_len = _backtrace_snprintf(buf, sizeof(buf), i, buffer[i], &info);
 138
 139                 writev(fd, iov, 2);
 140         }
 141 }