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- // 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>
- #include <stddef.h>
- #include "base/files/file_util.h"
- #include "base/files/scoped_file.h"
- #include "base/logging.h"
- #include "base/strings/string_split.h"
- #include "build/build_config.h"
- #if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID)
- #include <inttypes.h>
- #endif
- 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;
- #else
- // Otherwise assume there is no gate VMA in which case we shouldn't
- // get duplicate entires.
- return false;
- #endif
- }
- 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 size_t read_size = static_cast<size_t>(sysconf(_SC_PAGESIZE));
- base::ScopedFD fd(HANDLE_EINTR(open("/proc/self/maps", O_RDONLY)));
- if (!fd.is_valid()) {
- DPLOG(ERROR) << "Couldn't open /proc/self/maps";
- return false;
- }
- proc_maps->clear();
- 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 + read_size);
- void* buffer = &(*proc_maps)[pos];
- ssize_t bytes_read = HANDLE_EINTR(read(fd.get(), buffer, read_size));
- if (bytes_read < 0) {
- DPLOG(ERROR) << "Couldn't read /proc/self/maps";
- proc_maps->clear();
- return false;
- }
- // ... and don't forget to trim off excess bytes.
- proc_maps->resize(pos + static_cast<size_t>(bytes_read));
- if (bytes_read == 0)
- break;
- // 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))
- break;
- }
- return true;
- }
- bool ParseProcMaps(const std::string& input,
- std::vector<MappedMemoryRegion>* regions_out) {
- CHECK(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", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
- 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()) {
- DLOG(WARNING) << "Last line not empty";
- return false;
- }
- break;
- }
- MappedMemoryRegion region;
- const char* line = lines[i].c_str();
- char permissions[5] = {'\0'}; // Ensure NUL-terminated string.
- uint8_t dev_major = 0;
- uint8_t 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",
- ®ion.start, ®ion.end, permissions, ®ion.offset,
- &dev_major, &dev_minor, &inode, &path_index) < 7) {
- DPLOG(WARNING) << "sscanf failed for line: " << line;
- 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.push_back(region);
- regions.back().path.assign(line + path_index);
- }
- regions_out->swap(regions);
- return true;
- }
- } // namespace debug
- } // namespace base
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