blob: b7a5862f7472aceb3c8cece84b4e9578641fe19a [file] [log] [blame]
// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/debug/proc_maps_linux.h"
#include <fcntl.h>
#if defined(OS_LINUX)
#include <inttypes.h>
#include "base/file_util.h"
#include "base/strings/string_split.h"
#if defined(OS_ANDROID)
// Bionic's inttypes.h defines PRI/SCNxPTR as an unsigned long int, which
// is incompatible with Bionic's stdint.h defining uintptr_t as a unsigned int:
#undef SCNxPTR
#define SCNxPTR "x"
namespace base {
namespace debug {
// Scans |proc_maps| starting from |pos| returning true if the gate VMA was
// found, otherwise returns false.
static bool ContainsGateVMA(std::string* proc_maps, size_t pos) {
#if defined(ARCH_CPU_ARM_FAMILY)
// The gate VMA on ARM kernels is the interrupt vectors page.
return proc_maps->find(" [vectors]\n", pos) != std::string::npos;
#elif defined(ARCH_CPU_X86_64)
// The gate VMA on x86 64-bit kernels is the virtual system call page.
return proc_maps->find(" [vsyscall]\n", pos) != std::string::npos;
// Otherwise assume there is no gate VMA in which case we shouldn't
// get duplicate entires.
return false;
bool ReadProcMaps(std::string* proc_maps) {
// seq_file only writes out a page-sized amount on each call. Refer to header
// file for details.
const long kReadSize = sysconf(_SC_PAGESIZE);
int fd = HANDLE_EINTR(open("/proc/self/maps", O_RDONLY));
if (fd == -1) {
DPLOG(ERROR) << "Couldn't open /proc/self/maps";
return false;
file_util::ScopedFD fd_closer(&fd);
while (true) {
// To avoid a copy, resize |proc_maps| so read() can write directly into it.
// Compute |buffer| afterwards since resize() may reallocate.
size_t pos = proc_maps->size();
proc_maps->resize(pos + kReadSize);
void* buffer = &(*proc_maps)[pos];
ssize_t bytes_read = HANDLE_EINTR(read(fd, buffer, kReadSize));
if (bytes_read < 0) {
DPLOG(ERROR) << "Couldn't read /proc/self/maps";
return false;
// ... and don't forget to trim off excess bytes.
proc_maps->resize(pos + bytes_read);
if (bytes_read == 0)
// The gate VMA is handled as a special case after seq_file has finished
// iterating through all entries in the virtual memory table.
// Unfortunately, if additional entries are added at this point in time
// seq_file gets confused and the next call to read() will return duplicate
// entries including the gate VMA again.
// Avoid this by searching for the gate VMA and breaking early.
if (ContainsGateVMA(proc_maps, pos))
return true;
bool ParseProcMaps(const std::string& input,
std::vector<MappedMemoryRegion>* regions_out) {
std::vector<MappedMemoryRegion> regions;
// This isn't async safe nor terribly efficient, but it doesn't need to be at
// this point in time.
std::vector<std::string> lines;
SplitString(input, '\n', &lines);
for (size_t i = 0; i < lines.size(); ++i) {
// Due to splitting on '\n' the last line should be empty.
if (i == lines.size() - 1) {
if (!lines[i].empty())
return false;
MappedMemoryRegion region;
const char* line = lines[i].c_str();
char permissions[5] = {'\0'}; // Ensure NUL-terminated string.
uint8 dev_major = 0;
uint8 dev_minor = 0;
long inode = 0;
int path_index = 0;
// Sample format from man 5 proc:
// address perms offset dev inode pathname
// 08048000-08056000 r-xp 00000000 03:0c 64593 /usr/sbin/gpm
// The final %n term captures the offset in the input string, which is used
// to determine the path name. It *does not* increment the return value.
// Refer to man 3 sscanf for details.
if (sscanf(line, "%" SCNxPTR "-%" SCNxPTR " %4c %llx %hhx:%hhx %ld %n",
&region.start, &region.end, permissions, &region.offset,
&dev_major, &dev_minor, &inode, &path_index) < 7) {
return false;
region.permissions = 0;
if (permissions[0] == 'r')
region.permissions |= MappedMemoryRegion::READ;
else if (permissions[0] != '-')
return false;
if (permissions[1] == 'w')
region.permissions |= MappedMemoryRegion::WRITE;
else if (permissions[1] != '-')
return false;
if (permissions[2] == 'x')
region.permissions |= MappedMemoryRegion::EXECUTE;
else if (permissions[2] != '-')
return false;
if (permissions[3] == 'p')
region.permissions |= MappedMemoryRegion::PRIVATE;
else if (permissions[3] != 's' && permissions[3] != 'S') // Shared memory.
return false;
// Pushing then assigning saves us a string copy.
regions.back().path.assign(line + path_index);
return true;
} // namespace debug
} // namespace base