crash_reporter/user_collector.cc - platform/system/core - Git at Google

 // Copyright (c) 2010 The Chromium OS 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 "crash-reporter/user_collector.h"

 #include <bits/wordsize.h>
 #include <elf.h>
 #include <fcntl.h>
 #include <grp.h>  // For struct group.
 #include <pcrecpp.h>
 #include <pwd.h>  // For struct passwd.
 #include <sys/types.h>  // For getpwuid_r, getgrnam_r, WEXITSTATUS.

 #include <string>
 #include <vector>

 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
 #include "chromeos/process.h"
 #include "chromeos/syslog_logging.h"
 #include "gflags/gflags.h"

 #pragma GCC diagnostic ignored "-Wstrict-aliasing"
 DEFINE_bool(core2md_failure, false, "Core2md failure test");
 DEFINE_bool(directory_failure, false, "Spool directory failure test");
 DEFINE_string(filter_in, "",
               "Ignore all crashes but this for testing");
 #pragma GCC diagnostic error "-Wstrict-aliasing"

 static const char kCollectionErrorSignature[] =
     "crash_reporter-user-collection";
 // This procfs file is used to cause kernel core file writing to
 // instead pipe the core file into a user space process.  See
 // core(5) man page.
 static const char kCorePatternFile[] = "/proc/sys/kernel/core_pattern";
 static const char kCorePipeLimitFile[] = "/proc/sys/kernel/core_pipe_limit";
 // Set core_pipe_limit to 4 so that we can catch a few unrelated concurrent
 // crashes, but finite to avoid infinitely recursing on crash handling.
 static const char kCorePipeLimit[] = "4";
 static const char kCoreToMinidumpConverterPath[] = "/usr/bin/core2md";

 static const char kDefaultLogConfig[] = "/etc/crash_reporter_logs.conf";
 static const char kStatePrefix[] = "State:\t";

 const char *UserCollector::kUserId = "Uid:\t";
 const char *UserCollector::kGroupId = "Gid:\t";

 UserCollector::UserCollector()
     : generate_diagnostics_(false),
       core_pattern_file_(kCorePatternFile),
       core_pipe_limit_file_(kCorePipeLimitFile),
       initialized_(false) {
 }

 void UserCollector::Initialize(
     UserCollector::CountCrashFunction count_crash_function,
     const std::string &our_path,
     UserCollector::IsFeedbackAllowedFunction is_feedback_allowed_function,
     bool generate_diagnostics) {
   CrashCollector::Initialize(count_crash_function,
                              is_feedback_allowed_function);
   our_path_ = our_path;
   initialized_ = true;
   generate_diagnostics_ = generate_diagnostics;
 }

 UserCollector::~UserCollector() {
 }

 std::string UserCollector::GetErrorTypeSignature(ErrorType error_type) const {
   switch (error_type) {
     case kErrorSystemIssue:
       return "system-issue";
     case kErrorReadCoreData:
       return "read-core-data";
     case kErrorUnusableProcFiles:
       return "unusable-proc-files";
     case kErrorInvalidCoreFile:
       return "invalid-core-file";
     case kErrorUnsupported32BitCoreFile:
       return "unsupported-32bit-core-file";
     case kErrorCore2MinidumpConversion:
       return "core2md-conversion";
     default:
       return "";
   }
 }

 std::string UserCollector::GetPattern(bool enabled) const {
   if (enabled) {
     // Combine the three crash attributes into one parameter to try to reduce
     // the size of the invocation line for crash_reporter since the kernel
     // has a fixed-sized (128B) buffer that it will truncate into.  Note that
     // the kernel does not support quoted arguments in core_pattern.
     return StringPrintf("|%s --user=%%p:%%s:%%e", our_path_.c_str());
   } else {
     return "core";
   }
 }

 bool UserCollector::SetUpInternal(bool enabled) {
   CHECK(initialized_);
   LOG(INFO) << (enabled ? "Enabling" : "Disabling") << " user crash handling";

   if (file_util::WriteFile(FilePath(core_pipe_limit_file_),
                            kCorePipeLimit,
                            strlen(kCorePipeLimit)) !=
       static_cast<int>(strlen(kCorePipeLimit))) {
     LOG(ERROR) << "Unable to write " << core_pipe_limit_file_;
     return false;
   }
   std::string pattern = GetPattern(enabled);
   if (file_util::WriteFile(FilePath(core_pattern_file_),
                            pattern.c_str(),
                            pattern.length()) !=
       static_cast<int>(pattern.length())) {
     LOG(ERROR) << "Unable to write " << core_pattern_file_;
     return false;
   }
   return true;
 }

 FilePath UserCollector::GetProcessPath(pid_t pid) {
   return FilePath(StringPrintf("/proc/%d", pid));
 }

 bool UserCollector::GetSymlinkTarget(const FilePath &symlink,
                                      FilePath *target) {
   int max_size = 32;
   scoped_array<char> buffer;
   while (true) {
     buffer.reset(new char[max_size + 1]);
     ssize_t size = readlink(symlink.value().c_str(), buffer.get(), max_size);
     if (size < 0) {
       int saved_errno = errno;
       LOG(ERROR) << "Readlink failed on " << symlink.value() << " with "
                  << saved_errno;
       return false;
     }
     buffer[size] = 0;
     if (size == max_size) {
       // Avoid overflow when doubling.
       if (max_size * 2 > max_size) {
         max_size *= 2;
         continue;
       } else {
         return false;
       }
     }
     break;
   }

   *target = FilePath(buffer.get());
   return true;
 }

 bool UserCollector::GetExecutableBaseNameFromPid(uid_t pid,
                                                  std::string *base_name) {
   FilePath target;
   FilePath process_path = GetProcessPath(pid);
   FilePath exe_path = process_path.Append("exe");
   if (!GetSymlinkTarget(exe_path, &target)) {
     LOG(INFO) << "GetSymlinkTarget failed - Path " << process_path.value()
               << " DirectoryExists: "
               << file_util::DirectoryExists(process_path);
     // Try to further diagnose exe readlink failure cause.
     struct stat buf;
     int stat_result = stat(exe_path.value().c_str(), &buf);
     int saved_errno = errno;
     if (stat_result < 0) {
       LOG(INFO) << "stat " << exe_path.value() << " failed: " << stat_result
                 << " " << saved_errno;
     } else {
       LOG(INFO) << "stat " << exe_path.value() << " succeeded: st_mode="
                 << buf.st_mode;
     }
     return false;
   }
   *base_name = target.BaseName().value();
   return true;
 }

 bool UserCollector::GetFirstLineWithPrefix(
     const std::vector<std::string> &lines,
     const char *prefix, std::string *line) {
   std::vector<std::string>::const_iterator line_iterator;
   for (line_iterator = lines.begin(); line_iterator != lines.end();
        ++line_iterator) {
     if (line_iterator->find(prefix) == 0) {
       *line = *line_iterator;
       return true;
     }
   }
   return false;
 }

 bool UserCollector::GetIdFromStatus(
     const char *prefix, IdKind kind,
     const std::vector<std::string> &status_lines, int *id) {
   // From fs/proc/array.c:task_state(), this file contains:
   // \nUid:\t<uid>\t<euid>\t<suid>\t<fsuid>\n
   std::string id_line;
   if (!GetFirstLineWithPrefix(status_lines, prefix, &id_line)) {
     return false;
   }
   std::string id_substring = id_line.substr(strlen(prefix), std::string::npos);
   std::vector<std::string> ids;
   base::SplitString(id_substring, '\t', &ids);
   if (ids.size() != kIdMax || kind < 0 || kind >= kIdMax) {
     return false;
   }
   const char *number = ids[kind].c_str();
   char *end_number = NULL;
   *id = strtol(number, &end_number, 10);
   if (*end_number != '\0') {
     return false;
   }
   return true;
 }

 bool UserCollector::GetStateFromStatus(
     const std::vector<std::string> &status_lines, std::string *state) {
   std::string state_line;
   if (!GetFirstLineWithPrefix(status_lines, kStatePrefix, &state_line)) {
     return false;
   }
   *state = state_line.substr(strlen(kStatePrefix), std::string::npos);
   return true;
 }

 void UserCollector::EnqueueCollectionErrorLog(pid_t pid,
                                               ErrorType error_type,
                                               const std::string &exec) {
   FilePath crash_path;
   LOG(INFO) << "Writing conversion problems as separate crash report.";
   if (!GetCreatedCrashDirectoryByEuid(0, &crash_path, NULL)) {
     LOG(ERROR) << "Could not even get log directory; out of space?";
     return;
   }
   std::string dump_basename = FormatDumpBasename(exec, time(NULL), pid);
   std::string error_log = chromeos::GetLog();
   FilePath diag_log_path = GetCrashPath(crash_path, dump_basename, "diaglog");
   if (GetLogContents(FilePath(kDefaultLogConfig), kCollectionErrorSignature,
                      diag_log_path)) {
     // We load the contents of diag_log into memory and append it to
     // the error log.  We cannot just append to files because we need
     // to always create new files to prevent attack.
     std::string diag_log_contents;
     file_util::ReadFileToString(diag_log_path, &diag_log_contents);
     error_log.append(diag_log_contents);
     file_util::Delete(diag_log_path, false);
   }
   FilePath log_path = GetCrashPath(crash_path, dump_basename, "log");
   FilePath meta_path = GetCrashPath(crash_path, dump_basename, "meta");
   // We must use WriteNewFile instead of file_util::WriteFile as we do
   // not want to write with root access to a symlink that an attacker
   // might have created.
   WriteNewFile(log_path, error_log.data(), error_log.length());
   AddCrashMetaData("sig", kCollectionErrorSignature);
   AddCrashMetaData("error_type", GetErrorTypeSignature(error_type));
   WriteCrashMetaData(meta_path, exec, log_path.value());
 }

 bool UserCollector::CopyOffProcFiles(pid_t pid,
                                      const FilePath &container_dir) {
   if (!file_util::CreateDirectory(container_dir)) {
     LOG(ERROR) << "Could not create " << container_dir.value().c_str();
     return false;
   }
   FilePath process_path = GetProcessPath(pid);
   if (!file_util::PathExists(process_path)) {
     LOG(ERROR) << "Path " << process_path.value() << " does not exist";
     return false;
   }
   static const char *proc_files[] = {
     "auxv",
     "cmdline",
     "environ",
     "maps",
     "status"
   };
   for (unsigned i = 0; i < arraysize(proc_files); ++i) {
     if (!file_util::CopyFile(process_path.Append(proc_files[i]),
                              container_dir.Append(proc_files[i]))) {
       LOG(ERROR) << "Could not copy " << proc_files[i] << " file";
       return false;
     }
   }
   return true;
 }

 bool UserCollector::ValidateProcFiles(const FilePath &container_dir) const {
   // Check if the maps file is empty, which could be due to the crashed
   // process being reaped by the kernel before finishing a core dump.
   int64 file_size = 0;
   if (!file_util::GetFileSize(container_dir.Append("maps"), &file_size)) {
     LOG(ERROR) << "Could not get the size of maps file";
     return false;
   }
   if (file_size == 0) {
     LOG(ERROR) << "maps file is empty";
     return false;
   }
   return true;
 }

 UserCollector::ErrorType UserCollector::ValidateCoreFile(
     const FilePath &core_path) const {
   int fd = HANDLE_EINTR(open(core_path.value().c_str(), O_RDONLY));
   if (fd < 0) {
     LOG(ERROR) << "Could not open core file " << core_path.value();
     return kErrorInvalidCoreFile;
   }

   char e_ident[EI_NIDENT];
   bool read_ok = file_util::ReadFromFD(fd, e_ident, sizeof(e_ident));
   HANDLE_EINTR(close(fd));
   if (!read_ok) {
     LOG(ERROR) << "Could not read header of core file";
     return kErrorInvalidCoreFile;
   }

   if (e_ident[EI_MAG0] != ELFMAG0 || e_ident[EI_MAG1] != ELFMAG1 ||
       e_ident[EI_MAG2] != ELFMAG2 || e_ident[EI_MAG3] != ELFMAG3) {
     LOG(ERROR) << "Invalid core file";
     return kErrorInvalidCoreFile;
   }

 #if __WORDSIZE == 64
   // TODO(benchan, mkrebs): Remove this check once core2md can
   // handles both 32-bit and 64-bit ELF on a 64-bit platform.
   if (e_ident[EI_CLASS] == ELFCLASS32) {
     LOG(ERROR) << "Conversion of 32-bit core file on 64-bit platform is "
                << "currently not supported";
     return kErrorUnsupported32BitCoreFile;
   }
 #endif

   return kErrorNone;
 }

 bool UserCollector::GetCreatedCrashDirectory(pid_t pid,
                                              FilePath *crash_file_path,
                                              bool *out_of_capacity) {
   FilePath process_path = GetProcessPath(pid);
   std::string status;
   if (FLAGS_directory_failure) {
     LOG(ERROR) << "Purposefully failing to create spool directory";
     return false;
   }
   if (!file_util::ReadFileToString(process_path.Append("status"),
                                    &status)) {
     LOG(ERROR) << "Could not read status file";
     LOG(INFO) << "Path " << process_path.value() << " DirectoryExists: "
               << file_util::DirectoryExists(process_path);
     return false;
   }

   std::vector<std::string> status_lines;
   base::SplitString(status, '\n', &status_lines);

   std::string process_state;
   if (!GetStateFromStatus(status_lines, &process_state)) {
     LOG(ERROR) << "Could not find process state in status file";
     return false;
   }
   LOG(INFO) << "State of crashed process [" << pid << "]: " << process_state;

   int process_euid;
   if (!GetIdFromStatus(kUserId, kIdEffective, status_lines, &process_euid)) {
     LOG(ERROR) << "Could not find euid in status file";
     return false;
   }
   if (!GetCreatedCrashDirectoryByEuid(process_euid,
                                       crash_file_path,
                                       out_of_capacity)) {
     LOG(ERROR) << "Could not create crash directory";
     return false;
   }
   return true;
 }

 bool UserCollector::CopyStdinToCoreFile(const FilePath &core_path) {
   // Copy off all stdin to a core file.
   FilePath stdin_path("/dev/fd/0");
   if (file_util::CopyFile(stdin_path, core_path)) {
     return true;
   }

   LOG(ERROR) << "Could not write core file";
   // If the file system was full, make sure we remove any remnants.
   file_util::Delete(core_path, false);
   return false;
 }

 bool UserCollector::RunCoreToMinidump(const FilePath &core_path,
                                       const FilePath &procfs_directory,
                                       const FilePath &minidump_path,
                                       const FilePath &temp_directory) {
   FilePath output_path = temp_directory.Append("output");
   chromeos::ProcessImpl core2md;
   core2md.RedirectOutput(output_path.value());
   core2md.AddArg(kCoreToMinidumpConverterPath);
   core2md.AddArg(core_path.value());
   core2md.AddArg(procfs_directory.value());

   if (!FLAGS_core2md_failure) {
     core2md.AddArg(minidump_path.value());
   } else {
     // To test how core2md errors are propagaged, cause an error
     // by forgetting a required argument.
   }

   int errorlevel = core2md.Run();

   std::string output;
   file_util::ReadFileToString(output_path, &output);
   if (errorlevel != 0) {
     LOG(ERROR) << "Problem during " << kCoreToMinidumpConverterPath
                << " [result=" << errorlevel << "]: " << output;
     return false;
   }

   if (!file_util::PathExists(minidump_path)) {
     LOG(ERROR) << "Minidump file " << minidump_path.value()
                << " was not created";
     return false;
   }
   return true;
 }

 UserCollector::ErrorType UserCollector::ConvertCoreToMinidump(
     pid_t pid,
     const FilePath &container_dir,
     const FilePath &core_path,
     const FilePath &minidump_path) {
   // If proc files are unuable, we continue to read the core file from stdin,
   // but only skip the core-to-minidump conversion, so that we may still use
   // the core file for debugging.
   bool proc_files_usable =
       CopyOffProcFiles(pid, container_dir) && ValidateProcFiles(container_dir);

   if (!CopyStdinToCoreFile(core_path)) {
     return kErrorReadCoreData;
   }

   if (!proc_files_usable) {
     LOG(INFO) << "Skipped converting core file to minidump due to "
               << "unusable proc files";
     return kErrorUnusableProcFiles;
   }

   ErrorType error = ValidateCoreFile(core_path);
   if (error != kErrorNone) {
     return error;
   }

   if (!RunCoreToMinidump(core_path,
                          container_dir,  // procfs directory
                          minidump_path,
                          container_dir)) {  // temporary directory
     return kErrorCore2MinidumpConversion;
   }

   LOG(INFO) << "Stored minidump to " << minidump_path.value();
   return kErrorNone;
 }

 UserCollector::ErrorType UserCollector::ConvertAndEnqueueCrash(
     int pid, const std::string &exec, bool *out_of_capacity) {
   FilePath crash_path;
   if (!GetCreatedCrashDirectory(pid, &crash_path, out_of_capacity)) {
     LOG(ERROR) << "Unable to find/create process-specific crash path";
     return kErrorSystemIssue;
   }

   // Directory like /tmp/crash_reporter/1234 which contains the
   // procfs entries and other temporary files used during conversion.
   FilePath container_dir(StringPrintf("/tmp/crash_reporter/%d", pid));
   // Delete a pre-existing directory from crash reporter that may have
   // been left around for diagnostics from a failed conversion attempt.
   // If we don't, existing files can cause forking to fail.
   file_util::Delete(container_dir, true);
   std::string dump_basename = FormatDumpBasename(exec, time(NULL), pid);
   FilePath core_path = GetCrashPath(crash_path, dump_basename, "core");
   FilePath meta_path = GetCrashPath(crash_path, dump_basename, "meta");
   FilePath minidump_path = GetCrashPath(crash_path, dump_basename, "dmp");
   FilePath log_path = GetCrashPath(crash_path, dump_basename, "log");

   if (GetLogContents(FilePath(kDefaultLogConfig), exec, log_path))
     AddCrashMetaData("log", log_path.value());

   ErrorType error_type =
       ConvertCoreToMinidump(pid, container_dir, core_path, minidump_path);
   if (error_type != kErrorNone) {
     LOG(INFO) << "Leaving core file at " << core_path.value()
               << " due to conversion error";
     return error_type;
   }

   // Here we commit to sending this file.  We must not return false
   // after this point or we will generate a log report as well as a
   // crash report.
   WriteCrashMetaData(meta_path,
                      exec,
                      minidump_path.value());

   if (!IsDeveloperImage()) {
     file_util::Delete(core_path, false);
   } else {
     LOG(INFO) << "Leaving core file at " << core_path.value()
               << " due to developer image";
   }

   file_util::Delete(container_dir, true);
   return kErrorNone;
 }

 bool UserCollector::ParseCrashAttributes(const std::string &crash_attributes,
                                          pid_t *pid, int *signal,
                                          std::string *kernel_supplied_name) {
   pcrecpp::RE re("(\\d+):(\\d+):(.*)");
   return re.FullMatch(crash_attributes, pid, signal, kernel_supplied_name);
 }

 bool UserCollector::ShouldDump(bool has_owner_consent,
                                bool is_developer,
                                bool handle_chrome_crashes,
                                const std::string &exec,
                                std::string *reason) {
   reason->clear();

   // Treat Chrome crashes as if the user opted-out.  We stop counting Chrome
   // crashes towards user crashes, so user crashes really mean non-Chrome
   // user-space crashes.
   if ((exec == "chrome" || exec == "supplied_chrome") &&
       !handle_chrome_crashes) {
     *reason = "ignoring - chrome crash";
     return false;
   }

   // For developer builds, we always want to keep the crash reports unless
   // we're testing the crash facilities themselves.  This overrides
   // feedback.  Crash sending still obeys consent.
   if (is_developer) {
     *reason = "developer build - not testing - always dumping";
     return true;
   }

   if (!has_owner_consent) {
     *reason = "ignoring - no consent";
     return false;
   }

   *reason = "handling";
   return true;
 }

 bool UserCollector::HandleCrash(const std::string &crash_attributes,
                                 const char *force_exec) {
   CHECK(initialized_);
   int pid = 0;
   int signal = 0;
   std::string kernel_supplied_name;

   if (!ParseCrashAttributes(crash_attributes, &pid, &signal,
                             &kernel_supplied_name)) {
     LOG(ERROR) << "Invalid parameter: --user=" <<  crash_attributes;
     return false;
   }

   std::string exec;
   if (force_exec) {
     exec.assign(force_exec);
   } else if (!GetExecutableBaseNameFromPid(pid, &exec)) {
     // If we cannot find the exec name, use the kernel supplied name.
     // We don't always use the kernel's since it truncates the name to
     // 16 characters.
     exec = StringPrintf("supplied_%s", kernel_supplied_name.c_str());
   }

   // Allow us to test the crash reporting mechanism successfully even if
   // other parts of the system crash.
   if (!FLAGS_filter_in.empty() &&
       (FLAGS_filter_in == "none" ||
        FLAGS_filter_in != exec)) {
     // We use a different format message to make it more obvious in tests
     // which crashes are test generated and which are real.
     LOG(WARNING) << "Ignoring crash from " << exec << "[" << pid << "] while "
                  << "filter_in=" << FLAGS_filter_in << ".";
     return true;
   }

   std::string reason;
   bool dump = ShouldDump(is_feedback_allowed_function_(),
                          IsDeveloperImage(),
                          ShouldHandleChromeCrashes(),
                          exec,
                          &reason);

   LOG(WARNING) << "Received crash notification for " << exec << "[" << pid
                << "] sig " << signal << " (" << reason << ")";

   if (dump) {
     count_crash_function_();

     if (generate_diagnostics_) {
       bool out_of_capacity = false;
       ErrorType error_type =
           ConvertAndEnqueueCrash(pid, exec, &out_of_capacity);
       if (error_type != kErrorNone) {
         if (!out_of_capacity)
           EnqueueCollectionErrorLog(pid, error_type, exec);
         return false;
       }
     }
   }

   return true;
 }
	// Copyright (c) 2010 The Chromium OS 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 "crash-reporter/user_collector.h"

	#include <bits/wordsize.h>
	#include <elf.h>
	#include <fcntl.h>
	#include <grp.h> // For struct group.
	#include <pcrecpp.h>
	#include <pwd.h> // For struct passwd.
	#include <sys/types.h> // For getpwuid_r, getgrnam_r, WEXITSTATUS.

	#include <string>
	#include <vector>

	#include "base/file_util.h"
	#include "base/logging.h"
	#include "base/string_split.h"
	#include "base/string_util.h"
	#include "chromeos/process.h"
	#include "chromeos/syslog_logging.h"
	#include "gflags/gflags.h"

	#pragma GCC diagnostic ignored "-Wstrict-aliasing"
	DEFINE_bool(core2md_failure, false, "Core2md failure test");
	DEFINE_bool(directory_failure, false, "Spool directory failure test");
	DEFINE_string(filter_in, "",
	"Ignore all crashes but this for testing");
	#pragma GCC diagnostic error "-Wstrict-aliasing"

	static const char kCollectionErrorSignature[] =
	"crash_reporter-user-collection";
	// This procfs file is used to cause kernel core file writing to
	// instead pipe the core file into a user space process. See
	// core(5) man page.
	static const char kCorePatternFile[] = "/proc/sys/kernel/core_pattern";
	static const char kCorePipeLimitFile[] = "/proc/sys/kernel/core_pipe_limit";
	// Set core_pipe_limit to 4 so that we can catch a few unrelated concurrent
	// crashes, but finite to avoid infinitely recursing on crash handling.
	static const char kCorePipeLimit[] = "4";
	static const char kCoreToMinidumpConverterPath[] = "/usr/bin/core2md";

	static const char kDefaultLogConfig[] = "/etc/crash_reporter_logs.conf";
	static const char kStatePrefix[] = "State:\t";

	const char *UserCollector::kUserId = "Uid:\t";
	const char *UserCollector::kGroupId = "Gid:\t";

	UserCollector::UserCollector()
	: generate_diagnostics_(false),
	core_pattern_file_(kCorePatternFile),
	core_pipe_limit_file_(kCorePipeLimitFile),
	initialized_(false) {
	}

	void UserCollector::Initialize(
	UserCollector::CountCrashFunction count_crash_function,
	const std::string &our_path,
	UserCollector::IsFeedbackAllowedFunction is_feedback_allowed_function,
	bool generate_diagnostics) {
	CrashCollector::Initialize(count_crash_function,
	is_feedback_allowed_function);
	our_path_ = our_path;
	initialized_ = true;
	generate_diagnostics_ = generate_diagnostics;
	}

	UserCollector::~UserCollector() {
	}

	std::string UserCollector::GetErrorTypeSignature(ErrorType error_type) const {
	switch (error_type) {
	case kErrorSystemIssue:
	return "system-issue";
	case kErrorReadCoreData:
	return "read-core-data";
	case kErrorUnusableProcFiles:
	return "unusable-proc-files";
	case kErrorInvalidCoreFile:
	return "invalid-core-file";
	case kErrorUnsupported32BitCoreFile:
	return "unsupported-32bit-core-file";
	case kErrorCore2MinidumpConversion:
	return "core2md-conversion";
	default:
	return "";
	}
	}

	std::string UserCollector::GetPattern(bool enabled) const {
	if (enabled) {
	// Combine the three crash attributes into one parameter to try to reduce
	// the size of the invocation line for crash_reporter since the kernel
	// has a fixed-sized (128B) buffer that it will truncate into. Note that
	// the kernel does not support quoted arguments in core_pattern.
	return StringPrintf("\|%s --user=%%p:%%s:%%e", our_path_.c_str());
	} else {
	return "core";
	}
	}

	bool UserCollector::SetUpInternal(bool enabled) {
	CHECK(initialized_);
	LOG(INFO) << (enabled ? "Enabling" : "Disabling") << " user crash handling";

	if (file_util::WriteFile(FilePath(core_pipe_limit_file_),
	kCorePipeLimit,
	strlen(kCorePipeLimit)) !=
	static_cast<int>(strlen(kCorePipeLimit))) {
	LOG(ERROR) << "Unable to write " << core_pipe_limit_file_;
	return false;
	}
	std::string pattern = GetPattern(enabled);
	if (file_util::WriteFile(FilePath(core_pattern_file_),
	pattern.c_str(),
	pattern.length()) !=
	static_cast<int>(pattern.length())) {
	LOG(ERROR) << "Unable to write " << core_pattern_file_;
	return false;
	}
	return true;
	}

	FilePath UserCollector::GetProcessPath(pid_t pid) {
	return FilePath(StringPrintf("/proc/%d", pid));
	}

	bool UserCollector::GetSymlinkTarget(const FilePath &symlink,
	FilePath *target) {
	int max_size = 32;
	scoped_array<char> buffer;
	while (true) {
	buffer.reset(new char[max_size + 1]);
	ssize_t size = readlink(symlink.value().c_str(), buffer.get(), max_size);
	if (size < 0) {
	int saved_errno = errno;
	LOG(ERROR) << "Readlink failed on " << symlink.value() << " with "
	<< saved_errno;
	return false;
	}
	buffer[size] = 0;
	if (size == max_size) {
	// Avoid overflow when doubling.
	if (max_size * 2 > max_size) {
	max_size *= 2;
	continue;
	} else {
	return false;
	}
	}
	break;
	}

	*target = FilePath(buffer.get());
	return true;
	}

	bool UserCollector::GetExecutableBaseNameFromPid(uid_t pid,
	std::string *base_name) {
	FilePath target;
	FilePath process_path = GetProcessPath(pid);
	FilePath exe_path = process_path.Append("exe");
	if (!GetSymlinkTarget(exe_path, &target)) {
	LOG(INFO) << "GetSymlinkTarget failed - Path " << process_path.value()
	<< " DirectoryExists: "
	<< file_util::DirectoryExists(process_path);
	// Try to further diagnose exe readlink failure cause.
	struct stat buf;
	int stat_result = stat(exe_path.value().c_str(), &buf);
	int saved_errno = errno;
	if (stat_result < 0) {
	LOG(INFO) << "stat " << exe_path.value() << " failed: " << stat_result
	<< " " << saved_errno;
	} else {
	LOG(INFO) << "stat " << exe_path.value() << " succeeded: st_mode="
	<< buf.st_mode;
	}
	return false;
	}
	*base_name = target.BaseName().value();
	return true;
	}

	bool UserCollector::GetFirstLineWithPrefix(
	const std::vector<std::string> &lines,
	const char prefix, std::string line) {
	std::vector<std::string>::const_iterator line_iterator;
	for (line_iterator = lines.begin(); line_iterator != lines.end();
	++line_iterator) {
	if (line_iterator->find(prefix) == 0) {
	line = line_iterator;
	return true;
	}
	}
	return false;
	}

	bool UserCollector::GetIdFromStatus(
	const char *prefix, IdKind kind,
	const std::vector<std::string> &status_lines, int *id) {
	// From fs/proc/array.c:task_state(), this file contains:
	// \nUid:\t<uid>\t<euid>\t<suid>\t<fsuid>\n
	std::string id_line;
	if (!GetFirstLineWithPrefix(status_lines, prefix, &id_line)) {
	return false;
	}
	std::string id_substring = id_line.substr(strlen(prefix), std::string::npos);
	std::vector<std::string> ids;
	base::SplitString(id_substring, '\t', &ids);
	if (ids.size() != kIdMax \|\| kind < 0 \|\| kind >= kIdMax) {
	return false;
	}
	const char *number = ids[kind].c_str();
	char *end_number = NULL;
	*id = strtol(number, &end_number, 10);
	if (*end_number != '\0') {
	return false;
	}
	return true;
	}

	bool UserCollector::GetStateFromStatus(
	const std::vector<std::string> &status_lines, std::string *state) {
	std::string state_line;
	if (!GetFirstLineWithPrefix(status_lines, kStatePrefix, &state_line)) {
	return false;
	}
	*state = state_line.substr(strlen(kStatePrefix), std::string::npos);
	return true;
	}

	void UserCollector::EnqueueCollectionErrorLog(pid_t pid,
	ErrorType error_type,
	const std::string &exec) {
	FilePath crash_path;
	LOG(INFO) << "Writing conversion problems as separate crash report.";
	if (!GetCreatedCrashDirectoryByEuid(0, &crash_path, NULL)) {
	LOG(ERROR) << "Could not even get log directory; out of space?";
	return;
	}
	std::string dump_basename = FormatDumpBasename(exec, time(NULL), pid);
	std::string error_log = chromeos::GetLog();
	FilePath diag_log_path = GetCrashPath(crash_path, dump_basename, "diaglog");
	if (GetLogContents(FilePath(kDefaultLogConfig), kCollectionErrorSignature,
	diag_log_path)) {
	// We load the contents of diag_log into memory and append it to
	// the error log. We cannot just append to files because we need
	// to always create new files to prevent attack.
	std::string diag_log_contents;
	file_util::ReadFileToString(diag_log_path, &diag_log_contents);
	error_log.append(diag_log_contents);
	file_util::Delete(diag_log_path, false);
	}
	FilePath log_path = GetCrashPath(crash_path, dump_basename, "log");
	FilePath meta_path = GetCrashPath(crash_path, dump_basename, "meta");
	// We must use WriteNewFile instead of file_util::WriteFile as we do
	// not want to write with root access to a symlink that an attacker
	// might have created.
	WriteNewFile(log_path, error_log.data(), error_log.length());
	AddCrashMetaData("sig", kCollectionErrorSignature);
	AddCrashMetaData("error_type", GetErrorTypeSignature(error_type));
	WriteCrashMetaData(meta_path, exec, log_path.value());
	}

	bool UserCollector::CopyOffProcFiles(pid_t pid,
	const FilePath &container_dir) {
	if (!file_util::CreateDirectory(container_dir)) {
	LOG(ERROR) << "Could not create " << container_dir.value().c_str();
	return false;
	}
	FilePath process_path = GetProcessPath(pid);
	if (!file_util::PathExists(process_path)) {
	LOG(ERROR) << "Path " << process_path.value() << " does not exist";
	return false;
	}
	static const char *proc_files[] = {
	"auxv",
	"cmdline",
	"environ",
	"maps",
	"status"
	};
	for (unsigned i = 0; i < arraysize(proc_files); ++i) {
	if (!file_util::CopyFile(process_path.Append(proc_files[i]),
	container_dir.Append(proc_files[i]))) {
	LOG(ERROR) << "Could not copy " << proc_files[i] << " file";
	return false;
	}
	}
	return true;
	}

	bool UserCollector::ValidateProcFiles(const FilePath &container_dir) const {
	// Check if the maps file is empty, which could be due to the crashed
	// process being reaped by the kernel before finishing a core dump.
	int64 file_size = 0;
	if (!file_util::GetFileSize(container_dir.Append("maps"), &file_size)) {
	LOG(ERROR) << "Could not get the size of maps file";
	return false;
	}
	if (file_size == 0) {
	LOG(ERROR) << "maps file is empty";
	return false;
	}
	return true;
	}

	UserCollector::ErrorType UserCollector::ValidateCoreFile(
	const FilePath &core_path) const {
	int fd = HANDLE_EINTR(open(core_path.value().c_str(), O_RDONLY));
	if (fd < 0) {
	LOG(ERROR) << "Could not open core file " << core_path.value();
	return kErrorInvalidCoreFile;
	}

	char e_ident[EI_NIDENT];
	bool read_ok = file_util::ReadFromFD(fd, e_ident, sizeof(e_ident));
	HANDLE_EINTR(close(fd));
	if (!read_ok) {
	LOG(ERROR) << "Could not read header of core file";
	return kErrorInvalidCoreFile;
	}

	if (e_ident[EI_MAG0] != ELFMAG0 \|\| e_ident[EI_MAG1] != ELFMAG1 \|\|
	e_ident[EI_MAG2] != ELFMAG2 \|\| e_ident[EI_MAG3] != ELFMAG3) {
	LOG(ERROR) << "Invalid core file";
	return kErrorInvalidCoreFile;
	}

	#if __WORDSIZE == 64
	// TODO(benchan, mkrebs): Remove this check once core2md can
	// handles both 32-bit and 64-bit ELF on a 64-bit platform.
	if (e_ident[EI_CLASS] == ELFCLASS32) {
	LOG(ERROR) << "Conversion of 32-bit core file on 64-bit platform is "
	<< "currently not supported";
	return kErrorUnsupported32BitCoreFile;
	}
	#endif

	return kErrorNone;
	}

	bool UserCollector::GetCreatedCrashDirectory(pid_t pid,
	FilePath *crash_file_path,
	bool *out_of_capacity) {
	FilePath process_path = GetProcessPath(pid);
	std::string status;
	if (FLAGS_directory_failure) {
	LOG(ERROR) << "Purposefully failing to create spool directory";
	return false;
	}
	if (!file_util::ReadFileToString(process_path.Append("status"),
	&status)) {
	LOG(ERROR) << "Could not read status file";
	LOG(INFO) << "Path " << process_path.value() << " DirectoryExists: "
	<< file_util::DirectoryExists(process_path);
	return false;
	}

	std::vector<std::string> status_lines;
	base::SplitString(status, '\n', &status_lines);

	std::string process_state;
	if (!GetStateFromStatus(status_lines, &process_state)) {
	LOG(ERROR) << "Could not find process state in status file";
	return false;
	}
	LOG(INFO) << "State of crashed process [" << pid << "]: " << process_state;

	int process_euid;
	if (!GetIdFromStatus(kUserId, kIdEffective, status_lines, &process_euid)) {
	LOG(ERROR) << "Could not find euid in status file";
	return false;
	}
	if (!GetCreatedCrashDirectoryByEuid(process_euid,
	crash_file_path,
	out_of_capacity)) {
	LOG(ERROR) << "Could not create crash directory";
	return false;
	}
	return true;
	}

	bool UserCollector::CopyStdinToCoreFile(const FilePath &core_path) {
	// Copy off all stdin to a core file.
	FilePath stdin_path("/dev/fd/0");
	if (file_util::CopyFile(stdin_path, core_path)) {
	return true;
	}

	LOG(ERROR) << "Could not write core file";
	// If the file system was full, make sure we remove any remnants.
	file_util::Delete(core_path, false);
	return false;
	}

	bool UserCollector::RunCoreToMinidump(const FilePath &core_path,
	const FilePath &procfs_directory,
	const FilePath &minidump_path,
	const FilePath &temp_directory) {
	FilePath output_path = temp_directory.Append("output");
	chromeos::ProcessImpl core2md;
	core2md.RedirectOutput(output_path.value());
	core2md.AddArg(kCoreToMinidumpConverterPath);
	core2md.AddArg(core_path.value());
	core2md.AddArg(procfs_directory.value());

	if (!FLAGS_core2md_failure) {
	core2md.AddArg(minidump_path.value());
	} else {
	// To test how core2md errors are propagaged, cause an error
	// by forgetting a required argument.
	}

	int errorlevel = core2md.Run();

	std::string output;
	file_util::ReadFileToString(output_path, &output);
	if (errorlevel != 0) {
	LOG(ERROR) << "Problem during " << kCoreToMinidumpConverterPath
	<< " [result=" << errorlevel << "]: " << output;
	return false;
	}

	if (!file_util::PathExists(minidump_path)) {
	LOG(ERROR) << "Minidump file " << minidump_path.value()
	<< " was not created";
	return false;
	}
	return true;
	}

	UserCollector::ErrorType UserCollector::ConvertCoreToMinidump(
	pid_t pid,
	const FilePath &container_dir,
	const FilePath &core_path,
	const FilePath &minidump_path) {
	// If proc files are unuable, we continue to read the core file from stdin,
	// but only skip the core-to-minidump conversion, so that we may still use
	// the core file for debugging.
	bool proc_files_usable =
	CopyOffProcFiles(pid, container_dir) && ValidateProcFiles(container_dir);

	if (!CopyStdinToCoreFile(core_path)) {
	return kErrorReadCoreData;
	}

	if (!proc_files_usable) {
	LOG(INFO) << "Skipped converting core file to minidump due to "
	<< "unusable proc files";
	return kErrorUnusableProcFiles;
	}

	ErrorType error = ValidateCoreFile(core_path);
	if (error != kErrorNone) {
	return error;
	}

	if (!RunCoreToMinidump(core_path,
	container_dir, // procfs directory
	minidump_path,
	container_dir)) { // temporary directory
	return kErrorCore2MinidumpConversion;
	}

	LOG(INFO) << "Stored minidump to " << minidump_path.value();
	return kErrorNone;
	}

	UserCollector::ErrorType UserCollector::ConvertAndEnqueueCrash(
	int pid, const std::string &exec, bool *out_of_capacity) {
	FilePath crash_path;
	if (!GetCreatedCrashDirectory(pid, &crash_path, out_of_capacity)) {
	LOG(ERROR) << "Unable to find/create process-specific crash path";
	return kErrorSystemIssue;
	}

	// Directory like /tmp/crash_reporter/1234 which contains the
	// procfs entries and other temporary files used during conversion.
	FilePath container_dir(StringPrintf("/tmp/crash_reporter/%d", pid));
	// Delete a pre-existing directory from crash reporter that may have
	// been left around for diagnostics from a failed conversion attempt.
	// If we don't, existing files can cause forking to fail.
	file_util::Delete(container_dir, true);
	std::string dump_basename = FormatDumpBasename(exec, time(NULL), pid);
	FilePath core_path = GetCrashPath(crash_path, dump_basename, "core");
	FilePath meta_path = GetCrashPath(crash_path, dump_basename, "meta");
	FilePath minidump_path = GetCrashPath(crash_path, dump_basename, "dmp");
	FilePath log_path = GetCrashPath(crash_path, dump_basename, "log");

	if (GetLogContents(FilePath(kDefaultLogConfig), exec, log_path))
	AddCrashMetaData("log", log_path.value());

	ErrorType error_type =
	ConvertCoreToMinidump(pid, container_dir, core_path, minidump_path);
	if (error_type != kErrorNone) {
	LOG(INFO) << "Leaving core file at " << core_path.value()
	<< " due to conversion error";
	return error_type;
	}

	// Here we commit to sending this file. We must not return false
	// after this point or we will generate a log report as well as a
	// crash report.
	WriteCrashMetaData(meta_path,
	exec,
	minidump_path.value());

	if (!IsDeveloperImage()) {
	file_util::Delete(core_path, false);
	} else {
	LOG(INFO) << "Leaving core file at " << core_path.value()
	<< " due to developer image";
	}

	file_util::Delete(container_dir, true);
	return kErrorNone;
	}

	bool UserCollector::ParseCrashAttributes(const std::string &crash_attributes,
	pid_t pid, int signal,
	std::string *kernel_supplied_name) {
	pcrecpp::RE re("(\\d+):(\\d+):(.*)");
	return re.FullMatch(crash_attributes, pid, signal, kernel_supplied_name);
	}

	bool UserCollector::ShouldDump(bool has_owner_consent,
	bool is_developer,
	bool handle_chrome_crashes,
	const std::string &exec,
	std::string *reason) {
	reason->clear();

	// Treat Chrome crashes as if the user opted-out. We stop counting Chrome
	// crashes towards user crashes, so user crashes really mean non-Chrome
	// user-space crashes.
	if ((exec == "chrome" \|\| exec == "supplied_chrome") &&
	!handle_chrome_crashes) {
	*reason = "ignoring - chrome crash";
	return false;
	}

	// For developer builds, we always want to keep the crash reports unless
	// we're testing the crash facilities themselves. This overrides
	// feedback. Crash sending still obeys consent.
	if (is_developer) {
	*reason = "developer build - not testing - always dumping";
	return true;
	}

	if (!has_owner_consent) {
	*reason = "ignoring - no consent";
	return false;
	}

	*reason = "handling";
	return true;
	}

	bool UserCollector::HandleCrash(const std::string &crash_attributes,
	const char *force_exec) {
	CHECK(initialized_);
	int pid = 0;
	int signal = 0;
	std::string kernel_supplied_name;

	if (!ParseCrashAttributes(crash_attributes, &pid, &signal,
	&kernel_supplied_name)) {
	LOG(ERROR) << "Invalid parameter: --user=" << crash_attributes;
	return false;
	}

	std::string exec;
	if (force_exec) {
	exec.assign(force_exec);
	} else if (!GetExecutableBaseNameFromPid(pid, &exec)) {
	// If we cannot find the exec name, use the kernel supplied name.
	// We don't always use the kernel's since it truncates the name to
	// 16 characters.
	exec = StringPrintf("supplied_%s", kernel_supplied_name.c_str());
	}

	// Allow us to test the crash reporting mechanism successfully even if
	// other parts of the system crash.
	if (!FLAGS_filter_in.empty() &&
	(FLAGS_filter_in == "none" \|\|
	FLAGS_filter_in != exec)) {
	// We use a different format message to make it more obvious in tests
	// which crashes are test generated and which are real.
	LOG(WARNING) << "Ignoring crash from " << exec << "[" << pid << "] while "
	<< "filter_in=" << FLAGS_filter_in << ".";
	return true;
	}

	std::string reason;
	bool dump = ShouldDump(is_feedback_allowed_function_(),
	IsDeveloperImage(),
	ShouldHandleChromeCrashes(),
	exec,
	&reason);

	LOG(WARNING) << "Received crash notification for " << exec << "[" << pid
	<< "] sig " << signal << " (" << reason << ")";

	if (dump) {
	count_crash_function_();

	if (generate_diagnostics_) {
	bool out_of_capacity = false;
	ErrorType error_type =
	ConvertAndEnqueueCrash(pid, exec, &out_of_capacity);
	if (error_type != kErrorNone) {
	if (!out_of_capacity)
	EnqueueCollectionErrorLog(pid, error_type, exec);
	return false;
	}
	}
	}

	return true;
	}