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maps_parser.cpp
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363 lines (315 loc) · 11.3 KB
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#include "maps_parser.h"
#include <algorithm>
#include <climits>
#include <cstdlib>
#include <filesystem>
#include <fstream>
#include <regex>
#include <set>
#include <sstream>
#include <stdexcept>
#include <unistd.h>
#include "logging.h"
namespace pystack {
namespace fs = std::filesystem;
// Regex pattern for parsing /proc/pid/maps lines
// Format: start-end permissions offset dev inode pathname
static const std::regex MAPS_REGEXP(
R"(([0-9a-f]+)-([0-9a-f]+)\s+(.{4})\s+([0-9a-f]+)\s+([0-9a-f]+:[0-9a-f]+)\s+(\d+)\s*(.*)?)");
std::vector<VirtualMap>
parseProcMaps(pid_t pid)
{
std::vector<VirtualMap> maps;
std::string maps_path = "/proc/" + std::to_string(pid) + "/maps";
std::ifstream maps_file(maps_path);
if (!maps_file.is_open()) {
throw std::runtime_error("No such process id: " + std::to_string(pid));
}
std::string line;
while (std::getline(maps_file, line)) {
std::smatch match;
if (!std::regex_match(line, match, MAPS_REGEXP)) {
LOG(DEBUG) << "Line cannot be recognized: " << line;
continue;
}
uintptr_t start = std::stoull(match[1].str(), nullptr, 16);
uintptr_t end = std::stoull(match[2].str(), nullptr, 16);
std::string permissions = match[3].str();
unsigned long offset = std::stoul(match[4].str(), nullptr, 16);
std::string device = match[5].str();
unsigned long inode = std::stoul(match[6].str());
std::string pathname = match[7].str();
size_t start_pos = pathname.find_first_not_of(" \t");
if (start_pos != std::string::npos) {
pathname = pathname.substr(start_pos);
} else {
pathname = "";
}
maps.emplace_back(
start,
end,
end - start, // filesize
permissions,
offset,
device,
inode,
pathname);
}
return maps;
}
std::vector<VirtualMap>
parseCoreFileMaps(
const std::vector<CoreVirtualMap>& mapped_files,
const std::vector<CoreVirtualMap>& memory_maps)
{
std::set<std::pair<uintptr_t, uintptr_t>> memory_map_ranges;
for (const auto& map : memory_maps) {
memory_map_ranges.insert({map.start, map.end});
}
std::vector<CoreVirtualMap> missing_mapped_files;
for (const auto& map : mapped_files) {
if (memory_map_ranges.find({map.start, map.end}) == memory_map_ranges.end()) {
missing_mapped_files.push_back(map);
}
}
std::vector<CoreVirtualMap> all_maps;
all_maps.reserve(memory_maps.size() + missing_mapped_files.size());
all_maps.insert(all_maps.end(), memory_maps.begin(), memory_maps.end());
all_maps.insert(all_maps.end(), missing_mapped_files.begin(), missing_mapped_files.end());
std::sort(all_maps.begin(), all_maps.end(), [](const CoreVirtualMap& a, const CoreVirtualMap& b) {
return a.start < b.start;
});
std::set<std::string> missing_map_paths;
for (const auto& map : missing_mapped_files) {
if (!map.path.empty()) {
try {
missing_map_paths.insert(fs::canonical(map.path).string());
} catch (...) {
missing_map_paths.insert(map.path);
}
}
}
std::unordered_map<std::string, std::string> file_maps;
for (const auto& map : memory_maps) {
if (map.path.empty()) {
continue;
}
try {
std::string resolved_path = fs::canonical(map.path).string();
if (missing_map_paths.count(resolved_path)) {
file_maps[resolved_path] = map.path;
}
} catch (...) {
// Ignore errors resolving paths
}
}
std::vector<VirtualMap> result;
result.reserve(all_maps.size());
for (const auto& elem : all_maps) {
std::string path = elem.path;
if (!path.empty()) {
std::string resolved;
try {
resolved = fs::canonical(path).string();
} catch (...) {
resolved = path;
}
auto it = file_maps.find(resolved);
if (it != file_maps.end()) {
path = it->second;
}
}
result.emplace_back(
elem.start,
elem.end,
elem.filesize,
elem.flags,
elem.offset,
elem.device,
elem.inode,
path);
}
return result;
}
static VirtualMap
getBaseMap(const std::vector<VirtualMap>& binary_maps)
{
for (const auto& map : binary_maps) {
if (!map.Path().empty()) {
return map;
}
}
if (!binary_maps.empty()) {
return binary_maps[0];
}
throw std::runtime_error("No maps available");
}
static std::optional<VirtualMap>
getBss(const std::vector<VirtualMap>& elf_maps, uintptr_t load_point)
{
if (elf_maps.empty()) {
return std::nullopt;
}
VirtualMap binary_map = getBaseMap(elf_maps);
if (binary_map.Path().empty()) {
return std::nullopt;
}
SectionInfo bss_info;
if (!getSectionInfo(binary_map.Path(), ".bss", &bss_info)) {
return std::nullopt;
}
uintptr_t start = load_point + bss_info.corrected_addr;
LOG(INFO) << "Determined exact addr of .bss section: " << std::hex << start << " (" << load_point
<< " + " << bss_info.corrected_addr << ")" << std::dec;
unsigned long offset = 0;
const VirtualMap* first_matching_map = nullptr;
for (const auto& map : elf_maps) {
if (map.containsAddr(start)) {
first_matching_map = ↦
break;
}
}
if (!first_matching_map) {
return std::nullopt;
}
offset = first_matching_map->Offset() + (start - first_matching_map->Start());
return VirtualMap(
start,
start + bss_info.size,
bss_info.size,
"", // flags
offset, // offset
"", // device
0, // inode
""); // path
}
ProcessMemoryMapInfo
parseMapInformation(
const std::string& binary,
const std::vector<VirtualMap>& maps,
const std::unordered_map<std::string, uintptr_t>* load_point_by_module)
{
std::unordered_map<std::string, std::vector<VirtualMap>> maps_by_library;
std::string current_lib;
std::unordered_map<std::string, uintptr_t> computed_load_points;
if (!load_point_by_module) {
for (const auto& map : maps) {
if (!map.Path().empty()) {
std::string name = fs::path(map.Path()).filename().string();
if (computed_load_points.find(name) == computed_load_points.end()) {
computed_load_points[name] = map.Start();
} else {
computed_load_points[name] = std::min(computed_load_points[name], map.Start());
}
}
}
load_point_by_module = &computed_load_points;
}
for (const auto& memory_range : maps) {
std::string path_name;
if (!memory_range.Path().empty()) {
path_name = fs::path(memory_range.Path()).filename().string();
current_lib = path_name;
} else {
path_name = current_lib;
}
maps_by_library[path_name].push_back(memory_range);
}
std::string binary_name = fs::path(binary).filename().string();
auto python_it = maps_by_library.find(binary_name);
if (python_it == maps_by_library.end()) {
// Construct error message with available maps
std::ostringstream available;
for (const auto& map : maps) {
if (!map.Path().empty() && map.Path().find(".so") == std::string::npos) {
available << map.Path() << ", ";
}
}
std::string available_str = available.str();
if (available_str.length() >= 2) {
available_str = available_str.substr(0, available_str.length() - 2);
}
throw std::runtime_error(
"Unable to find maps for the executable " + binary
+ ". Available executable maps: " + available_str);
}
const std::vector<VirtualMap>& binary_maps = python_it->second;
VirtualMap python = getBaseMap(binary_maps);
LOG(INFO) << "python binary first map found: " << python.Path();
std::optional<VirtualMap> libpython;
const std::vector<VirtualMap>* elf_maps = nullptr;
std::string libpython_name;
std::vector<std::string> libpython_binaries;
for (const auto& [lib_name, _] : maps_by_library) {
if (lib_name.find("libpython") != std::string::npos) {
libpython_binaries.push_back(lib_name);
}
}
uintptr_t load_point = 0;
if (libpython_binaries.size() > 1) {
throw std::runtime_error(
"Unexpectedly found multiple libpython in process: "
+ std::to_string(libpython_binaries.size()));
} else if (libpython_binaries.size() == 1) {
libpython_name = libpython_binaries[0];
const auto& libpython_maps = maps_by_library[libpython_name];
elf_maps = &libpython_maps;
auto load_it = load_point_by_module->find(libpython_name);
load_point = (load_it != load_point_by_module->end()) ? load_it->second : UINTPTR_MAX;
libpython = getBaseMap(libpython_maps);
LOG(INFO) << libpython_name << " first map found: " << libpython->Path();
} else {
LOG(INFO) << "Process does not have a libpython.so, reading from binary";
elf_maps = &binary_maps;
auto load_it = load_point_by_module->find(binary_name);
load_point = (load_it != load_point_by_module->end()) ? load_it->second : UINTPTR_MAX;
}
std::optional<VirtualMap> heap;
auto heap_it = maps_by_library.find("[heap]");
if (heap_it != maps_by_library.end() && !heap_it->second.empty()) {
heap = heap_it->second.front();
LOG(INFO) << "Heap map found";
}
std::optional<VirtualMap> bss = getBss(*elf_maps, load_point);
if (!bss) {
for (const auto& map : *elf_maps) {
if (map.Path().empty() && map.Flags().find('r') != std::string::npos) {
bss = map;
break;
}
}
}
if (bss) {
LOG(INFO) << "bss map found";
}
return ProcessMemoryMapInfo{heap, bss, python, libpython};
}
ProcessMemoryMapInfo
parseMapInformationForProcess(pid_t pid, const std::vector<VirtualMap>& maps)
{
std::string exe_link = "/proc/" + std::to_string(pid) + "/exe";
char exe_path[PATH_MAX];
ssize_t len = readlink(exe_link.c_str(), exe_path, sizeof(exe_path) - 1);
if (len == -1) {
throw std::runtime_error("Failed to read /proc/" + std::to_string(pid) + "/exe");
}
exe_path[len] = '\0';
return parseMapInformation(exe_path, maps);
}
std::optional<std::string>
getThreadName(pid_t pid, pid_t tid)
{
std::string comm_path = "/proc/" + std::to_string(pid) + "/task/" + std::to_string(tid) + "/comm";
std::ifstream comm_file(comm_path);
if (!comm_file.is_open()) {
return std::nullopt;
}
std::string name;
std::getline(comm_file, name);
size_t end = name.find_last_not_of(" \t\n\r");
if (end != std::string::npos) {
name = name.substr(0, end + 1);
}
return name;
}
} // namespace pystack