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Diffstat (limited to 'base/debug/proc_maps_linux.cc')
| -rw-r--r-- | base/debug/proc_maps_linux.cc | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/base/debug/proc_maps_linux.cc b/base/debug/proc_maps_linux.cc new file mode 100644 index 0000000000..0bb44b45ac --- /dev/null +++ b/base/debug/proc_maps_linux.cc @@ -0,0 +1,169 @@ +// 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/strings/string_split.h" +#include "build/build_config.h" + +#if defined(OS_LINUX) || defined(OS_ANDROID) +#include <inttypes.h> +#endif + +#if defined(OS_ANDROID) && !defined(__LP64__) +// In 32-bit mode, Bionic's inttypes.h defines PRI/SCNxPTR as an +// unsigned long int, which is incompatible with Bionic's stdint.h +// defining uintptr_t as an unsigned int: +// https://code.google.com/p/android/issues/detail?id=57218 +#undef SCNxPTR +#define SCNxPTR "x" +#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 long kReadSize = 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 + kReadSize); + void* buffer = &(*proc_maps)[pos]; + + ssize_t bytes_read = HANDLE_EINTR(read(fd.get(), buffer, kReadSize)); + 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 + 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 |