BacktraceMap.cpp revision f4b0b7971c0333b7331c2f54384af5de0260ae75 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <ctype.h>
18#include <sys/types.h>
19#include <unistd.h>
20
21#include <string>
22#include <vector>
23
24#include <backtrace/backtrace_constants.h>
25#include <backtrace/BacktraceMap.h>
26#include <log/log.h>
27
28#include "thread_utils.h"
29#include "BacktraceImpl.h"
30
31BacktraceMap::BacktraceMap(pid_t pid) : pid_(pid) {
32  if (pid_ < 0) {
33    pid_ = getpid();
34  }
35}
36
37BacktraceMap::~BacktraceMap() {
38}
39
40const backtrace_map_t* BacktraceMap::Find(uintptr_t addr) {
41  for (BacktraceMap::const_iterator it = begin();
42       it != end(); ++it) {
43    if (addr >= it->start && addr < it->end) {
44      return &*it;
45    }
46  }
47  return NULL;
48}
49
50bool BacktraceMap::ParseLine(const char* line, backtrace_map_t* map) {
51  unsigned long int start;
52  unsigned long int end;
53  char permissions[5];
54  int name_pos;
55
56#if defined(__APPLE__)
57// Mac OS vmmap(1) output:
58// __TEXT                 0009f000-000a1000 [    8K     8K] r-x/rwx SM=COW  /Volumes/android/dalvik-dev/out/host/darwin-x86/bin/libcorkscrew_test\n
59// 012345678901234567890123456789012345678901234567890123456789
60// 0         1         2         3         4         5
61  if (sscanf(line, "%*21c %lx-%lx [%*13c] %3c/%*3c SM=%*3c  %n",
62             &start, &end, permissions, &name_pos) != 3) {
63#else
64// Linux /proc/<pid>/maps lines:
65// 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so\n
66// 012345678901234567890123456789012345678901234567890123456789
67// 0         1         2         3         4         5
68  if (sscanf(line, "%lx-%lx %4s %*x %*x:%*x %*d%n",
69             &start, &end, permissions, &name_pos) != 3) {
70#endif
71    return false;
72  }
73
74  map->start = start;
75  map->end = end;
76  map->flags = PROT_NONE;
77  if (permissions[0] == 'r') {
78    map->flags |= PROT_READ;
79  }
80  if (permissions[1] == 'w') {
81    map->flags |= PROT_WRITE;
82  }
83  if (permissions[2] == 'x') {
84    map->flags |= PROT_EXEC;
85  }
86
87  while (isspace(line[name_pos])) {
88    name_pos += 1;
89  }
90  map->name = line+name_pos;
91  if (!map->name.empty() && map->name[map->name.length()-1] == '\n') {
92    map->name.erase(map->name.length()-1);
93  }
94
95  ALOGV("Parsed map: start=%p, end=%p, flags=%x, name=%s",
96        reinterpret_cast<void*>(map->start), reinterpret_cast<void*>(map->end),
97        map->flags, map->name.c_str());
98  return true;
99}
100
101bool BacktraceMap::Build() {
102#if defined(__APPLE__)
103  char cmd[sizeof(pid_t)*3 + sizeof("vmmap -w -resident -submap -allSplitLibs -interleaved ") + 1];
104#else
105  char path[sizeof(pid_t)*3 + sizeof("/proc//maps") + 1];
106#endif
107  char line[1024];
108
109#if defined(__APPLE__)
110  // cmd is guaranteed to always be big enough to hold this string.
111  sprintf(cmd, "vmmap -w -resident -submap -allSplitLibs -interleaved %d", pid_);
112  FILE* fp = popen(cmd, "r");
113#else
114  // path is guaranteed to always be big enough to hold this string.
115  sprintf(path, "/proc/%d/maps", pid_);
116  FILE* fp = fopen(path, "r");
117#endif
118  if (fp == NULL) {
119    return false;
120  }
121
122  while(fgets(line, sizeof(line), fp)) {
123    backtrace_map_t map;
124    if (ParseLine(line, &map)) {
125      maps_.push_back(map);
126    }
127  }
128#if defined(__APPLE__)
129  pclose(fp);
130#else
131  fclose(fp);
132#endif
133
134  return true;
135}
136
137#if defined(__APPLE__)
138// Corkscrew and libunwind don't compile on the mac, so create a generic
139// map object.
140BacktraceMap* BacktraceMap::Create(pid_t pid) {
141  BacktraceMap* map = new BacktraceMap(pid);
142  if (!map->Build()) {
143    delete map;
144    return NULL;
145  }
146  return map;
147}
148#endif
149