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 <grp.h>  // For struct group.
 #include <pcrecpp.h>
 #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_util.h"
 #include "crash-reporter/system_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 kLeaveCoreFile[] = "/root/.leave_core";

 static const char kDefaultLogConfig[] = "/etc/crash_reporter_logs.conf";

 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,
     SystemLogging *logger,
     bool generate_diagnostics) {
   CrashCollector::Initialize(count_crash_function,
                              is_feedback_allowed_function,
                              logger);
   our_path_ = our_path;
   initialized_ = true;
   generate_diagnostics_ = generate_diagnostics;
 }

 UserCollector::~UserCollector() {
 }

 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_);
   logger_->LogInfo("%s user crash handling",
                    enabled ? "Enabling" : "Disabling");
   if (file_util::WriteFile(FilePath(core_pipe_limit_file_),
                            kCorePipeLimit,
                            strlen(kCorePipeLimit)) !=
       static_cast<int>(strlen(kCorePipeLimit))) {
     logger_->LogError("Unable to write %s", core_pipe_limit_file_.c_str());
     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())) {
     logger_->LogError("Unable to write %s", core_pattern_file_.c_str());
     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;
       logger_->LogError("Readlink failed on %s with %d",
                         symlink.value().c_str(), 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)) {
     logger_->LogInfo("GetSymlinkTarget failed - Path %s DirectoryExists: %d",
                      process_path.value().c_str(),
                      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) {
       logger_->LogInfo("stat %s failed: %d %d", exe_path.value().c_str(),
                        stat_result, saved_errno);
     } else {
       logger_->LogInfo("stat %s succeeded: st_mode=%d",
                        exe_path.value().c_str(), buf.st_mode);
     }
     return false;
   }
   *base_name = target.BaseName().value();
   return true;
 }

 bool UserCollector::GetIdFromStatus(const char *prefix,
                                     IdKind kind,
                                     const std::string &status_contents,
                                     int *id) {
   // From fs/proc/array.c:task_state(), this file contains:
   // \nUid:\t<uid>\t<euid>\t<suid>\t<fsuid>\n
   std::vector<std::string> status_lines;
   SplitString(status_contents, '\n', &status_lines);
   std::vector<std::string>::iterator line_iterator;
   for (line_iterator = status_lines.begin();
        line_iterator != status_lines.end();
        ++line_iterator) {
     if (line_iterator->find(prefix) == 0)
       break;
   }
   if (line_iterator == status_lines.end()) {
     return false;
   }
   std::string id_substring = line_iterator->substr(strlen(prefix),
                                                    std::string::npos);
   std::vector<std::string> ids;
   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;
 }

 void UserCollector::EnqueueCollectionErrorLog(pid_t pid,
                                               const std::string &exec) {
   FilePath crash_path;
   logger_->LogInfo("Writing conversion problems as separate crash report.");
   if (!GetCreatedCrashDirectoryByEuid(0, &crash_path, NULL)) {
     logger_->LogError("Could not even get log directory; out of space?");
     return;
   }
   std::string dump_basename = FormatDumpBasename(exec, time(NULL), pid);
   std::string error_log = logger_->get_accumulator();
   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);
   WriteCrashMetaData(meta_path, exec, log_path.value());
 }

 bool UserCollector::CopyOffProcFiles(pid_t pid,
                                      const FilePath &container_dir) {
   if (!file_util::CreateDirectory(container_dir)) {
     logger_->LogError("Could not create %s",
                       container_dir.value().c_str());
     return false;
   }
   FilePath process_path = GetProcessPath(pid);
   if (!file_util::PathExists(process_path)) {
     logger_->LogError("Path %s does not exist", process_path.value().c_str());
     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]))) {
       logger_->LogError("Could not copy %s file", proc_files[i]);
       return false;
     }
   }
   return true;
 }

 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) {
     logger_->LogError("Purposefully failing to create spool directory");
     return false;
   }
   if (!file_util::ReadFileToString(process_path.Append("status"),
                                    &status)) {
     logger_->LogError("Could not read status file");
     logger_->LogInfo("Path %s DirectoryExists: %d",
                      process_path.value().c_str(),
                      file_util::DirectoryExists(process_path));
     return false;
   }
   int process_euid;
   if (!GetIdFromStatus(kUserId, kIdEffective, status, &process_euid)) {
     logger_->LogError("Could not find euid in status file");
     return false;
   }
   if (!GetCreatedCrashDirectoryByEuid(process_euid,
                                       crash_file_path,
                                       out_of_capacity)) {
     logger_->LogError("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;
   }

   logger_->LogError("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");
   std::vector<const char *> core2md_arguments;
   core2md_arguments.push_back(kCoreToMinidumpConverterPath);
   core2md_arguments.push_back(core_path.value().c_str());
   core2md_arguments.push_back(procfs_directory.value().c_str());
   core2md_arguments.push_back(minidump_path.value().c_str());

   if (FLAGS_core2md_failure) {
     // To test how core2md errors are propagaged, cause an error
     // by forgetting a required argument.
     core2md_arguments.pop_back();
   }

   int errorlevel = ForkExecAndPipe(core2md_arguments,
                                    output_path.value().c_str());

   std::string output;
   file_util::ReadFileToString(output_path, &output);
   if (errorlevel != 0) {
     logger_->LogError("Problem during %s [result=%d]: %s",
                       kCoreToMinidumpConverterPath,
                       errorlevel,
                       output.c_str());
     return false;
   }

   if (!file_util::PathExists(minidump_path)) {
     logger_->LogError("Minidump file %s was not created",
                       minidump_path.value().c_str());
     return false;
   }
   return true;
 }

 bool UserCollector::ConvertCoreToMinidump(pid_t pid,
                                           const FilePath &container_dir,
                                           const FilePath &core_path,
                                           const FilePath &minidump_path) {
   if (!CopyOffProcFiles(pid, container_dir)) {
     return false;
   }

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

   bool conversion_result = RunCoreToMinidump(
       core_path,
       container_dir,  // procfs directory
       minidump_path,
       container_dir);  // temporary directory

   if (conversion_result) {
     logger_->LogInfo("Stored minidump to %s", minidump_path.value().c_str());
   }

   return conversion_result;
 }

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

   // Directory like /tmp/crash_reporter.1234 which contains the
   // procfs entries and other temporary files used during conversion.
   FilePath container_dir = FilePath("/tmp").Append(
       StringPrintf("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());

   if (!ConvertCoreToMinidump(pid, container_dir, core_path,
                             minidump_path)) {
     logger_->LogInfo("Leaving core file at %s due to conversion error",
                      core_path.value().c_str());
     return false;
   }

   // 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 (!file_util::PathExists(FilePath(kLeaveCoreFile))) {
     file_util::Delete(core_path, false);
   } else {
     logger_->LogInfo("Leaving core file at %s due to developer image",
                      core_path.value().c_str());
   }

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

 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::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)) {
     logger_->LogError("Invalid parameter: --user=%s", crash_attributes.c_str());
     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.
     logger_->LogWarning("Ignoring crash from %s[%d] while filter_in=%s.",
                         exec.c_str(), pid, FLAGS_filter_in.c_str());
     return true;
   }

   bool feedback = is_feedback_allowed_function_();
   const char *handling_string = "handling";
   if (!feedback) {
     handling_string = "ignoring - no consent";
   }

   // 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") {
     feedback = false;
     handling_string = "ignoring - chrome crash";
   }

   logger_->LogWarning("Received crash notification for %s[%d] sig %d (%s)",
                       exec.c_str(), pid, signal, handling_string);

   // For developer builds, we always want to keep the crash reports unless
   // we're testing the crash facilities themselves.
   if (file_util::PathExists(FilePath(kLeaveCoreFile)) &&
       !IsCrashTestInProgress()) {
     feedback = true;
   }

   if (feedback) {
     count_crash_function_();

     if (generate_diagnostics_) {
       bool out_of_capacity = false;
       bool convert_and_enqueue_result =
           ConvertAndEnqueueCrash(pid, exec, &out_of_capacity);
       if (!convert_and_enqueue_result) {
         if (!out_of_capacity)
           EnqueueCollectionErrorLog(pid, 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 <grp.h> // For struct group.
	#include <pcrecpp.h>
	#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_util.h"
	#include "crash-reporter/system_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 kLeaveCoreFile[] = "/root/.leave_core";

	static const char kDefaultLogConfig[] = "/etc/crash_reporter_logs.conf";

	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,
	SystemLogging *logger,
	bool generate_diagnostics) {
	CrashCollector::Initialize(count_crash_function,
	is_feedback_allowed_function,
	logger);
	our_path_ = our_path;
	initialized_ = true;
	generate_diagnostics_ = generate_diagnostics;
	}

	UserCollector::~UserCollector() {
	}

	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_);
	logger_->LogInfo("%s user crash handling",
	enabled ? "Enabling" : "Disabling");
	if (file_util::WriteFile(FilePath(core_pipe_limit_file_),
	kCorePipeLimit,
	strlen(kCorePipeLimit)) !=
	static_cast<int>(strlen(kCorePipeLimit))) {
	logger_->LogError("Unable to write %s", core_pipe_limit_file_.c_str());
	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())) {
	logger_->LogError("Unable to write %s", core_pattern_file_.c_str());
	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;
	logger_->LogError("Readlink failed on %s with %d",
	symlink.value().c_str(), 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)) {
	logger_->LogInfo("GetSymlinkTarget failed - Path %s DirectoryExists: %d",
	process_path.value().c_str(),
	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) {
	logger_->LogInfo("stat %s failed: %d %d", exe_path.value().c_str(),
	stat_result, saved_errno);
	} else {
	logger_->LogInfo("stat %s succeeded: st_mode=%d",
	exe_path.value().c_str(), buf.st_mode);
	}
	return false;
	}
	*base_name = target.BaseName().value();
	return true;
	}

	bool UserCollector::GetIdFromStatus(const char *prefix,
	IdKind kind,
	const std::string &status_contents,
	int *id) {
	// From fs/proc/array.c:task_state(), this file contains:
	// \nUid:\t<uid>\t<euid>\t<suid>\t<fsuid>\n
	std::vector<std::string> status_lines;
	SplitString(status_contents, '\n', &status_lines);
	std::vector<std::string>::iterator line_iterator;
	for (line_iterator = status_lines.begin();
	line_iterator != status_lines.end();
	++line_iterator) {
	if (line_iterator->find(prefix) == 0)
	break;
	}
	if (line_iterator == status_lines.end()) {
	return false;
	}
	std::string id_substring = line_iterator->substr(strlen(prefix),
	std::string::npos);
	std::vector<std::string> ids;
	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;
	}

	void UserCollector::EnqueueCollectionErrorLog(pid_t pid,
	const std::string &exec) {
	FilePath crash_path;
	logger_->LogInfo("Writing conversion problems as separate crash report.");
	if (!GetCreatedCrashDirectoryByEuid(0, &crash_path, NULL)) {
	logger_->LogError("Could not even get log directory; out of space?");
	return;
	}
	std::string dump_basename = FormatDumpBasename(exec, time(NULL), pid);
	std::string error_log = logger_->get_accumulator();
	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);
	WriteCrashMetaData(meta_path, exec, log_path.value());
	}

	bool UserCollector::CopyOffProcFiles(pid_t pid,
	const FilePath &container_dir) {
	if (!file_util::CreateDirectory(container_dir)) {
	logger_->LogError("Could not create %s",
	container_dir.value().c_str());
	return false;
	}
	FilePath process_path = GetProcessPath(pid);
	if (!file_util::PathExists(process_path)) {
	logger_->LogError("Path %s does not exist", process_path.value().c_str());
	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]))) {
	logger_->LogError("Could not copy %s file", proc_files[i]);
	return false;
	}
	}
	return true;
	}

	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) {
	logger_->LogError("Purposefully failing to create spool directory");
	return false;
	}
	if (!file_util::ReadFileToString(process_path.Append("status"),
	&status)) {
	logger_->LogError("Could not read status file");
	logger_->LogInfo("Path %s DirectoryExists: %d",
	process_path.value().c_str(),
	file_util::DirectoryExists(process_path));
	return false;
	}
	int process_euid;
	if (!GetIdFromStatus(kUserId, kIdEffective, status, &process_euid)) {
	logger_->LogError("Could not find euid in status file");
	return false;
	}
	if (!GetCreatedCrashDirectoryByEuid(process_euid,
	crash_file_path,
	out_of_capacity)) {
	logger_->LogError("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;
	}

	logger_->LogError("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");
	std::vector<const char *> core2md_arguments;
	core2md_arguments.push_back(kCoreToMinidumpConverterPath);
	core2md_arguments.push_back(core_path.value().c_str());
	core2md_arguments.push_back(procfs_directory.value().c_str());
	core2md_arguments.push_back(minidump_path.value().c_str());

	if (FLAGS_core2md_failure) {
	// To test how core2md errors are propagaged, cause an error
	// by forgetting a required argument.
	core2md_arguments.pop_back();
	}

	int errorlevel = ForkExecAndPipe(core2md_arguments,
	output_path.value().c_str());

	std::string output;
	file_util::ReadFileToString(output_path, &output);
	if (errorlevel != 0) {
	logger_->LogError("Problem during %s [result=%d]: %s",
	kCoreToMinidumpConverterPath,
	errorlevel,
	output.c_str());
	return false;
	}

	if (!file_util::PathExists(minidump_path)) {
	logger_->LogError("Minidump file %s was not created",
	minidump_path.value().c_str());
	return false;
	}
	return true;
	}

	bool UserCollector::ConvertCoreToMinidump(pid_t pid,
	const FilePath &container_dir,
	const FilePath &core_path,
	const FilePath &minidump_path) {
	if (!CopyOffProcFiles(pid, container_dir)) {
	return false;
	}

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

	bool conversion_result = RunCoreToMinidump(
	core_path,
	container_dir, // procfs directory
	minidump_path,
	container_dir); // temporary directory

	if (conversion_result) {
	logger_->LogInfo("Stored minidump to %s", minidump_path.value().c_str());
	}

	return conversion_result;
	}

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

	// Directory like /tmp/crash_reporter.1234 which contains the
	// procfs entries and other temporary files used during conversion.
	FilePath container_dir = FilePath("/tmp").Append(
	StringPrintf("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());

	if (!ConvertCoreToMinidump(pid, container_dir, core_path,
	minidump_path)) {
	logger_->LogInfo("Leaving core file at %s due to conversion error",
	core_path.value().c_str());
	return false;
	}

	// 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 (!file_util::PathExists(FilePath(kLeaveCoreFile))) {
	file_util::Delete(core_path, false);
	} else {
	logger_->LogInfo("Leaving core file at %s due to developer image",
	core_path.value().c_str());
	}

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

	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::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)) {
	logger_->LogError("Invalid parameter: --user=%s", crash_attributes.c_str());
	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.
	logger_->LogWarning("Ignoring crash from %s[%d] while filter_in=%s.",
	exec.c_str(), pid, FLAGS_filter_in.c_str());
	return true;
	}

	bool feedback = is_feedback_allowed_function_();
	const char *handling_string = "handling";
	if (!feedback) {
	handling_string = "ignoring - no consent";
	}

	// 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") {
	feedback = false;
	handling_string = "ignoring - chrome crash";
	}

	logger_->LogWarning("Received crash notification for %s[%d] sig %d (%s)",
	exec.c_str(), pid, signal, handling_string);

	// For developer builds, we always want to keep the crash reports unless
	// we're testing the crash facilities themselves.
	if (file_util::PathExists(FilePath(kLeaveCoreFile)) &&
	!IsCrashTestInProgress()) {
	feedback = true;
	}

	if (feedback) {
	count_crash_function_();

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

	return true;
	}