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      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 <stdint.h>
     19 #include <sys/types.h>
     20 #include <unistd.h>
     21 
     22 #include <backtrace/backtrace_constants.h>
     23 #include <backtrace/BacktraceMap.h>
     24 #include <log/log.h>
     25 
     26 #include "thread_utils.h"
     27 
     28 BacktraceMap::BacktraceMap(pid_t pid) : pid_(pid) {
     29   if (pid_ < 0) {
     30     pid_ = getpid();
     31   }
     32 }
     33 
     34 BacktraceMap::~BacktraceMap() {
     35 }
     36 
     37 void BacktraceMap::FillIn(uintptr_t addr, backtrace_map_t* map) {
     38   for (BacktraceMap::const_iterator it = begin();
     39        it != end(); ++it) {
     40     if (addr >= it->start && addr < it->end) {
     41       *map = *it;
     42       return;
     43     }
     44   }
     45   *map = {};
     46 }
     47 
     48 bool BacktraceMap::ParseLine(const char* line, backtrace_map_t* map) {
     49   unsigned long int start;
     50   unsigned long int end;
     51   char permissions[5];
     52   int name_pos;
     53 
     54 #if defined(__APPLE__)
     55 // Mac OS vmmap(1) output:
     56 // __TEXT                 0009f000-000a1000 [    8K     8K] r-x/rwx SM=COW  /Volumes/android/dalvik-dev/out/host/darwin-x86/bin/libcorkscrew_test\n
     57 // 012345678901234567890123456789012345678901234567890123456789
     58 // 0         1         2         3         4         5
     59   if (sscanf(line, "%*21c %lx-%lx [%*13c] %3c/%*3c SM=%*3c  %n",
     60              &start, &end, permissions, &name_pos) != 3) {
     61 #else
     62 // Linux /proc/<pid>/maps lines:
     63 // 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so\n
     64 // 012345678901234567890123456789012345678901234567890123456789
     65 // 0         1         2         3         4         5
     66   if (sscanf(line, "%lx-%lx %4s %*x %*x:%*x %*d%n",
     67              &start, &end, permissions, &name_pos) != 3) {
     68 #endif
     69     return false;
     70   }
     71 
     72   map->start = start;
     73   map->end = end;
     74   map->flags = PROT_NONE;
     75   if (permissions[0] == 'r') {
     76     map->flags |= PROT_READ;
     77   }
     78   if (permissions[1] == 'w') {
     79     map->flags |= PROT_WRITE;
     80   }
     81   if (permissions[2] == 'x') {
     82     map->flags |= PROT_EXEC;
     83   }
     84 
     85   while (isspace(line[name_pos])) {
     86     name_pos += 1;
     87   }
     88   map->name = line+name_pos;
     89   if (!map->name.empty() && map->name[map->name.length()-1] == '\n') {
     90     map->name.erase(map->name.length()-1);
     91   }
     92 
     93   ALOGV("Parsed map: start=%p, end=%p, flags=%x, name=%s",
     94         reinterpret_cast<void*>(map->start), reinterpret_cast<void*>(map->end),
     95         map->flags, map->name.c_str());
     96   return true;
     97 }
     98 
     99 bool BacktraceMap::Build() {
    100 #if defined(__APPLE__)
    101   char cmd[sizeof(pid_t)*3 + sizeof("vmmap -w -resident -submap -allSplitLibs -interleaved ") + 1];
    102 #else
    103   char path[sizeof(pid_t)*3 + sizeof("/proc//maps") + 1];
    104 #endif
    105   char line[1024];
    106 
    107 #if defined(__APPLE__)
    108   // cmd is guaranteed to always be big enough to hold this string.
    109   snprintf(cmd, sizeof(cmd), "vmmap -w -resident -submap -allSplitLibs -interleaved %d", pid_);
    110   FILE* fp = popen(cmd, "r");
    111 #else
    112   // path is guaranteed to always be big enough to hold this string.
    113   snprintf(path, sizeof(path), "/proc/%d/maps", pid_);
    114   FILE* fp = fopen(path, "r");
    115 #endif
    116   if (fp == nullptr) {
    117     return false;
    118   }
    119 
    120   while(fgets(line, sizeof(line), fp)) {
    121     backtrace_map_t map;
    122     if (ParseLine(line, &map)) {
    123       maps_.push_back(map);
    124     }
    125   }
    126 #if defined(__APPLE__)
    127   pclose(fp);
    128 #else
    129   fclose(fp);
    130 #endif
    131 
    132   return true;
    133 }
    134 
    135 #if defined(__APPLE__)
    136 // Corkscrew and libunwind don't compile on the mac, so create a generic
    137 // map object.
    138 BacktraceMap* BacktraceMap::Create(pid_t pid, bool uncached) {
    139   BacktraceMap* map = new BacktraceMap(pid);
    140   if (!map->Build()) {
    141     delete map;
    142     return nullptr;
    143   }
    144   return map;
    145 }
    146 #endif
    147