gen/backtrace.c

   1 /*
   2  * Copyright (c) 2007, 2008 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 <stdint.h>
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include <string.h>
  32
  33 #include "stack_logging.h"
  34 #include "execinfo.h"
  35
  36 int backtrace(void** buffer, int size) {
  37         extern void _thread_stack_pcs(vm_address_t *buffer, unsigned max, unsigned *nb, unsigned skip);
  38         unsigned int num_frames;
  39         _thread_stack_pcs((vm_address_t*)buffer, size, &num_frames, 1);
  40         while (num_frames >= 1 && buffer[num_frames-1] == NULL) num_frames -= 1;
  41         return num_frames;
  42 }
  43
  44 #if __LP64__
  45 #define _BACKTRACE_FORMAT "%-4d%-35s 0x%016lx %s + %lu"
  46 #define _BACKTRACE_FORMAT_SIZE 82
  47 #else
  48 #define _BACKTRACE_FORMAT "%-4d%-35s 0x%08lx %s + %lu"
  49 #define _BACKTRACE_FORMAT_SIZE 65
  50 #endif
  51
  52
  53 static int _backtrace_snprintf(char* buf, size_t size, int frame, const void* addr, const Dl_info* info) {
  54         char symbuf[19];
  55         const char* image = "???";
  56         const char* symbol = symbuf;
  57
  58         if (info->dli_fname) {
  59                 image = strrchr(info->dli_fname, '/') + 1;
  60                 if (image == NULL) image = info->dli_fname;
  61         }
  62
  63         if (info->dli_sname) {
  64                 symbol = info->dli_sname;
  65         } else {
  66                 snprintf(symbuf, sizeof(symbuf), "0x%lx", (uintptr_t)info->dli_saddr);
  67         }
  68
  69         return snprintf(buf, size,
  70                         _BACKTRACE_FORMAT,
  71                         frame,
  72                         image,
  73                         (uintptr_t)addr,
  74                         symbol,
  75                         (uintptr_t)addr - (uintptr_t)info->dli_saddr) + 1;
  76 }
  77
  78 char** backtrace_symbols(void* const* buffer, int size) {
  79         int i;
  80         size_t total_bytes;
  81         char** result;
  82         char** ptrs;
  83         intptr_t strs;
  84         Dl_info* info = calloc(size, sizeof (Dl_info));
  85
  86         if (info == NULL) return NULL;
  87
  88         // Compute the total size for the block that is returned.
  89         // The block will contain size number of pointers to the
  90         // symbol descriptions.
  91
  92         total_bytes = sizeof(char*) * size;
  93
  94         // Plus each symbol description
  95         for (i = 0 ; i < size; ++i) {
  96                 dladdr(buffer[i], &info[i]);
  97                 total_bytes += _BACKTRACE_FORMAT_SIZE + 1;
  98                 if (info[i].dli_sname) total_bytes += strlen(info[i].dli_sname);
  99         }
 100
 101         result = (char**)malloc(total_bytes);
 102         if (result == NULL) {
 103                 free(info);
 104                 return NULL;
 105         }
 106
 107         // Fill in the array of pointers and append the strings for
 108         // each symbol description.
 109
 110         ptrs = result;
 111         strs = ((intptr_t)result) + sizeof(char*) * size;
 112
 113         for (i = 0; i < size; ++i) {
 114                 ptrs[i] = (char*)strs;
 115                 strs += _backtrace_snprintf((char*)strs, total_bytes, i, buffer[i], &info[i]);
 116         }
 117
 118         free(info);
 119
 120         return result;
 121 }
 122
 123 void backtrace_symbols_fd(void* const* buffer, int size, int fd) {
 124         int i;
 125         char buf[BUFSIZ];
 126         Dl_info info;
 127         struct iovec iov[2];
 128
 129         iov[0].iov_base = buf;
 130
 131         iov[1].iov_base = "\n";
 132         iov[1].iov_len = 1;
 133
 134         for (i = 0; i < size; ++i) {
 135                 memset(&info, 0, sizeof(info));
 136                 dladdr(buffer[i], &info);
 137
 138                 iov[0].iov_len = _backtrace_snprintf(buf, sizeof(buf), i, buffer[i], &info);
 139
 140                 writev(fd, iov, 2);
 141         }
 142 }