src/hotspot/share/logging/logFileOutput.cpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "jvm.h"
 #include "logging/log.hpp"
 #include "logging/logConfiguration.hpp"
 #include "logging/logFileOutput.hpp"
 #include "memory/allocation.inline.hpp"
 #include "runtime/arguments.hpp"
 #include "runtime/os.inline.hpp"
 #include "utilities/globalDefinitions.hpp"
 #include "utilities/defaultStream.hpp"

 const char* const LogFileOutput::Prefix = "file=";
 const char* const LogFileOutput::FileOpenMode = "a";
 const char* const LogFileOutput::PidFilenamePlaceholder = "%p";
 const char* const LogFileOutput::TimestampFilenamePlaceholder = "%t";
 const char* const LogFileOutput::TimestampFormat = "%Y-%m-%d_%H-%M-%S";
 const char* const LogFileOutput::FileSizeOptionKey = "filesize";
 const char* const LogFileOutput::FileCountOptionKey = "filecount";
 char        LogFileOutput::_pid_str[PidBufferSize];
 char        LogFileOutput::_vm_start_time_str[StartTimeBufferSize];

 LogFileOutput::LogFileOutput(const char* name)
     : LogFileStreamOutput(NULL), _name(os::strdup_check_oom(name, mtLogging)),
       _file_name(NULL), _archive_name(NULL), _archive_name_len(0),
       _rotate_size(DefaultFileSize), _file_count(DefaultFileCount), _is_default_file_count(true),
       _current_size(0), _current_file(0), _rotation_semaphore(1) {
   assert(strstr(name, Prefix) == name, "invalid output name '%s': missing prefix: %s", name, Prefix);
   _file_name = make_file_name(name + strlen(Prefix), _pid_str, _vm_start_time_str);
 }

 void LogFileOutput::set_file_name_parameters(jlong vm_start_time) {
   int res = jio_snprintf(_pid_str, sizeof(_pid_str), "%d", os::current_process_id());
   assert(res > 0, "PID buffer too small");

   struct tm local_time;
   time_t utc_time = vm_start_time / 1000;
   os::localtime_pd(&utc_time, &local_time);
   res = (int)strftime(_vm_start_time_str, sizeof(_vm_start_time_str), TimestampFormat, &local_time);
   assert(res > 0, "VM start time buffer too small.");
 }

 LogFileOutput::~LogFileOutput() {
   if (_stream != NULL) {
     if (fclose(_stream) != 0) {
       jio_fprintf(defaultStream::error_stream(), "Could not close log file '%s' (%s).\n",
                   _file_name, os::strerror(errno));
     }
   }
   os::free(_archive_name);
   os::free(_file_name);
   os::free(const_cast<char*>(_name));
 }

 static size_t parse_value(const char* value_str) {
   char* end;
   unsigned long long value = strtoull(value_str, &end, 10);
   if (!isdigit(*value_str) || end != value_str + strlen(value_str) || value >= SIZE_MAX) {
     return SIZE_MAX;
   }
   return value;
 }

 static bool file_exists(const char* filename) {
   struct stat dummy_stat;
   return os::stat(filename, &dummy_stat) == 0;
 }

 static uint number_of_digits(uint number) {
   return number < 10 ? 1 : (number < 100 ? 2 : 3);
 }

 static bool is_regular_file(const char* filename) {
   struct stat st;
   int ret = os::stat(filename, &st);
   if (ret != 0) {
     return false;
   }
   return (st.st_mode & S_IFMT) == S_IFREG;
 }

 static bool is_fifo_file(const char* filename) {
   struct stat st;
   int ret = os::stat(filename, &st);
   if (ret != 0) {
     return false;
   }
   return S_ISFIFO(st.st_mode);
 }

 // Try to find the next number that should be used for file rotation.
 // Return UINT_MAX on error.
 static uint next_file_number(const char* filename,
                              uint number_of_digits,
                              uint filecount,
                              outputStream* errstream) {
   bool found = false;
   uint next_num = 0;

   // len is filename + dot + digits + null char
   size_t len = strlen(filename) + number_of_digits + 2;
   char* archive_name = NEW_C_HEAP_ARRAY(char, len, mtLogging);
   char* oldest_name = NEW_C_HEAP_ARRAY(char, len, mtLogging);

   for (uint i = 0; i < filecount; i++) {
     int ret = jio_snprintf(archive_name, len, "%s.%0*u",
                            filename, number_of_digits, i);
     assert(ret > 0 && static_cast<size_t>(ret) == len - 1,
            "incorrect buffer length calculation");

     if (file_exists(archive_name) && !is_regular_file(archive_name)) {
       // We've encountered something that's not a regular file among the
       // possible file rotation targets. Fail immediately to prevent
       // problems later.
       errstream->print_cr("Possible rotation target file '%s' already exists "
                           "but is not a regular file.", archive_name);
       next_num = UINT_MAX;
       break;
     }

     // Stop looking if we find an unused file name
     if (!file_exists(archive_name)) {
       next_num = i;
       found = true;
       break;
     }

     // Keep track of oldest existing log file
     if (!found
         || os::compare_file_modified_times(oldest_name, archive_name) > 0) {
       strcpy(oldest_name, archive_name);
       next_num = i;
       found = true;
     }
   }

   FREE_C_HEAP_ARRAY(char, oldest_name);
   FREE_C_HEAP_ARRAY(char, archive_name);
   return next_num;
 }

 bool LogFileOutput::parse_options(const char* options, outputStream* errstream) {
   if (options == NULL || strlen(options) == 0) {
     return true;
   }
   bool success = true;
   char* opts = os::strdup_check_oom(options, mtLogging);

   char* comma_pos;
   char* pos = opts;
   do {
     comma_pos = strchr(pos, ',');
     if (comma_pos != NULL) {
       *comma_pos = '\0';
     }

     char* equals_pos = strchr(pos, '=');
     if (equals_pos == NULL) {
       errstream->print_cr("Invalid option '%s' for log file output.", pos);
       success = false;
       break;
     }
     char* key = pos;
     char* value_str = equals_pos + 1;
     *equals_pos = '\0';

     if (strcmp(FileCountOptionKey, key) == 0) {
       size_t value = parse_value(value_str);
       if (value > MaxRotationFileCount) {
         errstream->print_cr("Invalid option: %s must be in range [0, %u]",
                             FileCountOptionKey,
                             MaxRotationFileCount);
         success = false;
         break;
       }
       _file_count = static_cast<uint>(value);
       _is_default_file_count = false;
     } else if (strcmp(FileSizeOptionKey, key) == 0) {
       julong value;
       success = Arguments::atojulong(value_str, &value);
       if (!success || (value > SIZE_MAX)) {
         errstream->print_cr("Invalid option: %s must be in range [0, "
                             SIZE_FORMAT "]", FileSizeOptionKey, (size_t)SIZE_MAX);
         success = false;
         break;
       }
       _rotate_size = static_cast<size_t>(value);
     } else {
       errstream->print_cr("Invalid option '%s' for log file output.", key);
       success = false;
       break;
     }
     pos = comma_pos + 1;
   } while (comma_pos != NULL);

   os::free(opts);
   return success;
 }

 bool LogFileOutput::initialize(const char* options, outputStream* errstream) {
   if (!parse_options(options, errstream)) {
     return false;
   }

   bool file_exist = file_exists(_file_name);
   if (file_exist && _is_default_file_count && is_fifo_file(_file_name)) {
     _file_count = 0; // Prevent file rotation for fifo's such as named pipes.
   }

   if (_file_count > 0) {
     // compute digits with filecount - 1 since numbers will start from 0
     _file_count_max_digits = number_of_digits(_file_count - 1);
     _archive_name_len = 2 + strlen(_file_name) + _file_count_max_digits;
     _archive_name = NEW_C_HEAP_ARRAY(char, _archive_name_len, mtLogging);
   }

   log_trace(logging)("Initializing logging to file '%s' (filecount: %u"
                      ", filesize: " SIZE_FORMAT " KiB).",
                      _file_name, _file_count, _rotate_size / K);

   if (_file_count > 0 && file_exist) {
     if (!is_regular_file(_file_name)) {
       errstream->print_cr("Unable to log to file %s with log file rotation: "
                           "%s is not a regular file",
                           _file_name, _file_name);
       return false;
     }
     _current_file = next_file_number(_file_name,
                                      _file_count_max_digits,
                                      _file_count,
                                      errstream);
     if (_current_file == UINT_MAX) {
       return false;
     }
     log_trace(logging)("Existing log file found, saving it as '%s.%0*u'",
                        _file_name, _file_count_max_digits, _current_file);
     archive();
     increment_file_count();
   }

   _stream = os::fopen(_file_name, FileOpenMode);
   if (_stream == NULL) {
     errstream->print_cr("Error opening log file '%s': %s",
                         _file_name, strerror(errno));
     return false;
   }

   if (_file_count == 0 && is_regular_file(_file_name)) {
     log_trace(logging)("Truncating log file");
     os::ftruncate(os::get_fileno(_stream), 0);
   }

   return true;
 }

 int LogFileOutput::write(const LogDecorations& decorations, const char* msg) {
   if (_stream == NULL) {
     // An error has occurred with this output, avoid writing to it.
     return 0;
   }

   _rotation_semaphore.wait();
   int written = LogFileStreamOutput::write(decorations, msg);
   _current_size += written;

   if (should_rotate()) {
     rotate();
   }
   _rotation_semaphore.signal();

   return written;
 }

 int LogFileOutput::write(LogMessageBuffer::Iterator msg_iterator) {
   if (_stream == NULL) {
     // An error has occurred with this output, avoid writing to it.
     return 0;
   }

   _rotation_semaphore.wait();
   int written = LogFileStreamOutput::write(msg_iterator);
   _current_size += written;

   if (should_rotate()) {
     rotate();
   }
   _rotation_semaphore.signal();

   return written;
 }

 void LogFileOutput::archive() {
   assert(_archive_name != NULL && _archive_name_len > 0, "Rotation must be configured before using this function.");
   int ret = jio_snprintf(_archive_name, _archive_name_len, "%s.%0*u",
                          _file_name, _file_count_max_digits, _current_file);
   assert(ret >= 0, "Buffer should always be large enough");

   // Attempt to remove possibly existing archived log file before we rename.
   // Don't care if it fails, we really only care about the rename that follows.
   remove(_archive_name);

   // Rename the file from ex hotspot.log to hotspot.log.2
   if (rename(_file_name, _archive_name) == -1) {
     jio_fprintf(defaultStream::error_stream(), "Could not rename log file '%s' to '%s' (%s).\n",
                 _file_name, _archive_name, os::strerror(errno));
   }
 }

 void LogFileOutput::force_rotate() {
   if (_file_count == 0) {
     // Rotation not possible
     return;
   }
   _rotation_semaphore.wait();
   rotate();
   _rotation_semaphore.signal();
 }

 void LogFileOutput::rotate() {

   if (fclose(_stream)) {
     jio_fprintf(defaultStream::error_stream(), "Error closing file '%s' during log rotation (%s).\n",
                 _file_name, os::strerror(errno));
   }

   // Archive the current log file
   archive();

   // Open the active log file using the same stream as before
   _stream = os::fopen(_file_name, FileOpenMode);
   if (_stream == NULL) {
     jio_fprintf(defaultStream::error_stream(), "Could not reopen file '%s' during log rotation (%s).\n",
                 _file_name, os::strerror(errno));
     return;
   }

   // Reset accumulated size, increase current file counter, and check for file count wrap-around.
   _current_size = 0;
   increment_file_count();
 }

 char* LogFileOutput::make_file_name(const char* file_name,
                                     const char* pid_string,
                                     const char* timestamp_string) {
   char* result = NULL;

   // Lets start finding out if we have any %d and/or %t in the name.
   // We will only replace the first occurrence of any placeholder
   const char* pid = strstr(file_name, PidFilenamePlaceholder);
   const char* timestamp = strstr(file_name, TimestampFilenamePlaceholder);

   if (pid == NULL && timestamp == NULL) {
     // We found no place-holders, return the simple filename
     return os::strdup_check_oom(file_name, mtLogging);
   }

   // At least one of the place-holders were found in the file_name
   const char* first = "";
   size_t first_pos = SIZE_MAX;
   size_t first_replace_len = 0;

   const char* second = "";
   size_t second_pos = SIZE_MAX;
   size_t second_replace_len = 0;

   // If we found a %p, then setup our variables accordingly
   if (pid != NULL) {
     if (timestamp == NULL || pid < timestamp) {
       first = pid_string;
       first_pos = pid - file_name;
       first_replace_len = strlen(PidFilenamePlaceholder);
     } else {
       second = pid_string;
       second_pos = pid - file_name;
       second_replace_len = strlen(PidFilenamePlaceholder);
     }
   }

   if (timestamp != NULL) {
     if (pid == NULL || timestamp < pid) {
       first = timestamp_string;
       first_pos = timestamp - file_name;
       first_replace_len = strlen(TimestampFilenamePlaceholder);
     } else {
       second = timestamp_string;
       second_pos = timestamp - file_name;
       second_replace_len = strlen(TimestampFilenamePlaceholder);
     }
   }

   size_t first_len = strlen(first);
   size_t second_len = strlen(second);

   // Allocate the new buffer, size it to hold all we want to put in there +1.
   size_t result_len =  strlen(file_name) + first_len - first_replace_len + second_len - second_replace_len;
   result = NEW_C_HEAP_ARRAY(char, result_len + 1, mtLogging);

   // Assemble the strings
   size_t file_name_pos = 0;
   size_t i = 0;
   while (i < result_len) {
     if (file_name_pos == first_pos) {
       // We are in the range of the first placeholder
       strcpy(result + i, first);
       // Bump output buffer position with length of replacing string
       i += first_len;
       // Bump source buffer position to skip placeholder
       file_name_pos += first_replace_len;
     } else if (file_name_pos == second_pos) {
       // We are in the range of the second placeholder
       strcpy(result + i, second);
       i += second_len;
       file_name_pos += second_replace_len;
     } else {
       // Else, copy char by char of the original file
       result[i] = file_name[file_name_pos++];
       i++;
     }
   }
   // Add terminating char
   result[result_len] = '\0';
   return result;
 }

 void LogFileOutput::describe(outputStream *out) {
   LogOutput::describe(out);
   out->print(" ");

   out->print("filecount=%u,filesize=" SIZE_FORMAT "%s", _file_count,
              byte_size_in_proper_unit(_rotate_size),
              proper_unit_for_byte_size(_rotate_size));
 }
	/*
	* Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*
	*/
	#include "precompiled.hpp"
	#include "jvm.h"
	#include "logging/log.hpp"
	#include "logging/logConfiguration.hpp"
	#include "logging/logFileOutput.hpp"
	#include "memory/allocation.inline.hpp"
	#include "runtime/arguments.hpp"
	#include "runtime/os.inline.hpp"
	#include "utilities/globalDefinitions.hpp"
	#include "utilities/defaultStream.hpp"

	const char* const LogFileOutput::Prefix = "file=";
	const char* const LogFileOutput::FileOpenMode = "a";
	const char* const LogFileOutput::PidFilenamePlaceholder = "%p";
	const char* const LogFileOutput::TimestampFilenamePlaceholder = "%t";
	const char* const LogFileOutput::TimestampFormat = "%Y-%m-%d_%H-%M-%S";
	const char* const LogFileOutput::FileSizeOptionKey = "filesize";
	const char* const LogFileOutput::FileCountOptionKey = "filecount";
	char LogFileOutput::_pid_str[PidBufferSize];
	char LogFileOutput::_vm_start_time_str[StartTimeBufferSize];

	LogFileOutput::LogFileOutput(const char* name)
	: LogFileStreamOutput(NULL), _name(os::strdup_check_oom(name, mtLogging)),
	_file_name(NULL), _archive_name(NULL), _archive_name_len(0),
	_rotate_size(DefaultFileSize), _file_count(DefaultFileCount), _is_default_file_count(true),
	_current_size(0), _current_file(0), _rotation_semaphore(1) {
	assert(strstr(name, Prefix) == name, "invalid output name '%s': missing prefix: %s", name, Prefix);
	_file_name = make_file_name(name + strlen(Prefix), _pid_str, _vm_start_time_str);
	}

	void LogFileOutput::set_file_name_parameters(jlong vm_start_time) {
	int res = jio_snprintf(_pid_str, sizeof(_pid_str), "%d", os::current_process_id());
	assert(res > 0, "PID buffer too small");

	struct tm local_time;
	time_t utc_time = vm_start_time / 1000;
	os::localtime_pd(&utc_time, &local_time);
	res = (int)strftime(_vm_start_time_str, sizeof(_vm_start_time_str), TimestampFormat, &local_time);
	assert(res > 0, "VM start time buffer too small.");
	}

	LogFileOutput::~LogFileOutput() {
	if (_stream != NULL) {
	if (fclose(_stream) != 0) {
	jio_fprintf(defaultStream::error_stream(), "Could not close log file '%s' (%s).\n",
	_file_name, os::strerror(errno));
	}
	}
	os::free(_archive_name);
	os::free(_file_name);
	os::free(const_cast<char*>(_name));
	}

	static size_t parse_value(const char* value_str) {
	char* end;
	unsigned long long value = strtoull(value_str, &end, 10);
	if (!isdigit(*value_str) \|\| end != value_str + strlen(value_str) \|\| value >= SIZE_MAX) {
	return SIZE_MAX;
	}
	return value;
	}

	static bool file_exists(const char* filename) {
	struct stat dummy_stat;
	return os::stat(filename, &dummy_stat) == 0;
	}

	static uint number_of_digits(uint number) {
	return number < 10 ? 1 : (number < 100 ? 2 : 3);
	}

	static bool is_regular_file(const char* filename) {
	struct stat st;
	int ret = os::stat(filename, &st);
	if (ret != 0) {
	return false;
	}
	return (st.st_mode & S_IFMT) == S_IFREG;
	}

	static bool is_fifo_file(const char* filename) {
	struct stat st;
	int ret = os::stat(filename, &st);
	if (ret != 0) {
	return false;
	}
	return S_ISFIFO(st.st_mode);
	}

	// Try to find the next number that should be used for file rotation.
	// Return UINT_MAX on error.
	static uint next_file_number(const char* filename,
	uint number_of_digits,
	uint filecount,
	outputStream* errstream) {
	bool found = false;
	uint next_num = 0;

	// len is filename + dot + digits + null char
	size_t len = strlen(filename) + number_of_digits + 2;
	char* archive_name = NEW_C_HEAP_ARRAY(char, len, mtLogging);
	char* oldest_name = NEW_C_HEAP_ARRAY(char, len, mtLogging);

	for (uint i = 0; i < filecount; i++) {
	int ret = jio_snprintf(archive_name, len, "%s.%0*u",
	filename, number_of_digits, i);
	assert(ret > 0 && static_cast<size_t>(ret) == len - 1,
	"incorrect buffer length calculation");

	if (file_exists(archive_name) && !is_regular_file(archive_name)) {
	// We've encountered something that's not a regular file among the
	// possible file rotation targets. Fail immediately to prevent
	// problems later.
	errstream->print_cr("Possible rotation target file '%s' already exists "
	"but is not a regular file.", archive_name);
	next_num = UINT_MAX;
	break;
	}

	// Stop looking if we find an unused file name
	if (!file_exists(archive_name)) {
	next_num = i;
	found = true;
	break;
	}

	// Keep track of oldest existing log file
	if (!found
	\|\| os::compare_file_modified_times(oldest_name, archive_name) > 0) {
	strcpy(oldest_name, archive_name);
	next_num = i;
	found = true;
	}
	}

	FREE_C_HEAP_ARRAY(char, oldest_name);
	FREE_C_HEAP_ARRAY(char, archive_name);
	return next_num;
	}

	bool LogFileOutput::parse_options(const char* options, outputStream* errstream) {
	if (options == NULL \|\| strlen(options) == 0) {
	return true;
	}
	bool success = true;
	char* opts = os::strdup_check_oom(options, mtLogging);

	char* comma_pos;
	char* pos = opts;
	do {
	comma_pos = strchr(pos, ',');
	if (comma_pos != NULL) {
	*comma_pos = '\0';
	}

	char* equals_pos = strchr(pos, '=');
	if (equals_pos == NULL) {
	errstream->print_cr("Invalid option '%s' for log file output.", pos);
	success = false;
	break;
	}
	char* key = pos;
	char* value_str = equals_pos + 1;
	*equals_pos = '\0';

	if (strcmp(FileCountOptionKey, key) == 0) {
	size_t value = parse_value(value_str);
	if (value > MaxRotationFileCount) {
	errstream->print_cr("Invalid option: %s must be in range [0, %u]",
	FileCountOptionKey,
	MaxRotationFileCount);
	success = false;
	break;
	}
	_file_count = static_cast<uint>(value);
	_is_default_file_count = false;
	} else if (strcmp(FileSizeOptionKey, key) == 0) {
	julong value;
	success = Arguments::atojulong(value_str, &value);
	if (!success \|\| (value > SIZE_MAX)) {
	errstream->print_cr("Invalid option: %s must be in range [0, "
	SIZE_FORMAT "]", FileSizeOptionKey, (size_t)SIZE_MAX);
	success = false;
	break;
	}
	_rotate_size = static_cast<size_t>(value);
	} else {
	errstream->print_cr("Invalid option '%s' for log file output.", key);
	success = false;
	break;
	}
	pos = comma_pos + 1;
	} while (comma_pos != NULL);

	os::free(opts);
	return success;
	}

	bool LogFileOutput::initialize(const char* options, outputStream* errstream) {
	if (!parse_options(options, errstream)) {
	return false;
	}

	bool file_exist = file_exists(_file_name);
	if (file_exist && _is_default_file_count && is_fifo_file(_file_name)) {
	_file_count = 0; // Prevent file rotation for fifo's such as named pipes.
	}

	if (_file_count > 0) {
	// compute digits with filecount - 1 since numbers will start from 0
	_file_count_max_digits = number_of_digits(_file_count - 1);
	_archive_name_len = 2 + strlen(_file_name) + _file_count_max_digits;
	_archive_name = NEW_C_HEAP_ARRAY(char, _archive_name_len, mtLogging);
	}

	log_trace(logging)("Initializing logging to file '%s' (filecount: %u"
	", filesize: " SIZE_FORMAT " KiB).",
	_file_name, _file_count, _rotate_size / K);

	if (_file_count > 0 && file_exist) {
	if (!is_regular_file(_file_name)) {
	errstream->print_cr("Unable to log to file %s with log file rotation: "
	"%s is not a regular file",
	_file_name, _file_name);
	return false;
	}
	_current_file = next_file_number(_file_name,
	_file_count_max_digits,
	_file_count,
	errstream);
	if (_current_file == UINT_MAX) {
	return false;
	}
	log_trace(logging)("Existing log file found, saving it as '%s.%0*u'",
	_file_name, _file_count_max_digits, _current_file);
	archive();
	increment_file_count();
	}

	_stream = os::fopen(_file_name, FileOpenMode);
	if (_stream == NULL) {
	errstream->print_cr("Error opening log file '%s': %s",
	_file_name, strerror(errno));
	return false;
	}

	if (_file_count == 0 && is_regular_file(_file_name)) {
	log_trace(logging)("Truncating log file");
	os::ftruncate(os::get_fileno(_stream), 0);
	}

	return true;
	}

	int LogFileOutput::write(const LogDecorations& decorations, const char* msg) {
	if (_stream == NULL) {
	// An error has occurred with this output, avoid writing to it.
	return 0;
	}

	_rotation_semaphore.wait();
	int written = LogFileStreamOutput::write(decorations, msg);
	_current_size += written;

	if (should_rotate()) {
	rotate();
	}
	_rotation_semaphore.signal();

	return written;
	}

	int LogFileOutput::write(LogMessageBuffer::Iterator msg_iterator) {
	if (_stream == NULL) {
	// An error has occurred with this output, avoid writing to it.
	return 0;
	}

	_rotation_semaphore.wait();
	int written = LogFileStreamOutput::write(msg_iterator);
	_current_size += written;

	if (should_rotate()) {
	rotate();
	}
	_rotation_semaphore.signal();

	return written;
	}

	void LogFileOutput::archive() {
	assert(_archive_name != NULL && _archive_name_len > 0, "Rotation must be configured before using this function.");
	int ret = jio_snprintf(_archive_name, _archive_name_len, "%s.%0*u",
	_file_name, _file_count_max_digits, _current_file);
	assert(ret >= 0, "Buffer should always be large enough");

	// Attempt to remove possibly existing archived log file before we rename.
	// Don't care if it fails, we really only care about the rename that follows.
	remove(_archive_name);

	// Rename the file from ex hotspot.log to hotspot.log.2
	if (rename(_file_name, _archive_name) == -1) {
	jio_fprintf(defaultStream::error_stream(), "Could not rename log file '%s' to '%s' (%s).\n",
	_file_name, _archive_name, os::strerror(errno));
	}
	}

	void LogFileOutput::force_rotate() {
	if (_file_count == 0) {
	// Rotation not possible
	return;
	}
	_rotation_semaphore.wait();
	rotate();
	_rotation_semaphore.signal();
	}

	void LogFileOutput::rotate() {

	if (fclose(_stream)) {
	jio_fprintf(defaultStream::error_stream(), "Error closing file '%s' during log rotation (%s).\n",
	_file_name, os::strerror(errno));
	}

	// Archive the current log file
	archive();

	// Open the active log file using the same stream as before
	_stream = os::fopen(_file_name, FileOpenMode);
	if (_stream == NULL) {
	jio_fprintf(defaultStream::error_stream(), "Could not reopen file '%s' during log rotation (%s).\n",
	_file_name, os::strerror(errno));
	return;
	}

	// Reset accumulated size, increase current file counter, and check for file count wrap-around.
	_current_size = 0;
	increment_file_count();
	}

	char* LogFileOutput::make_file_name(const char* file_name,
	const char* pid_string,
	const char* timestamp_string) {
	char* result = NULL;

	// Lets start finding out if we have any %d and/or %t in the name.
	// We will only replace the first occurrence of any placeholder
	const char* pid = strstr(file_name, PidFilenamePlaceholder);
	const char* timestamp = strstr(file_name, TimestampFilenamePlaceholder);

	if (pid == NULL && timestamp == NULL) {
	// We found no place-holders, return the simple filename
	return os::strdup_check_oom(file_name, mtLogging);
	}

	// At least one of the place-holders were found in the file_name
	const char* first = "";
	size_t first_pos = SIZE_MAX;
	size_t first_replace_len = 0;

	const char* second = "";
	size_t second_pos = SIZE_MAX;
	size_t second_replace_len = 0;

	// If we found a %p, then setup our variables accordingly
	if (pid != NULL) {
	if (timestamp == NULL \|\| pid < timestamp) {
	first = pid_string;
	first_pos = pid - file_name;
	first_replace_len = strlen(PidFilenamePlaceholder);
	} else {
	second = pid_string;
	second_pos = pid - file_name;
	second_replace_len = strlen(PidFilenamePlaceholder);
	}
	}

	if (timestamp != NULL) {
	if (pid == NULL \|\| timestamp < pid) {
	first = timestamp_string;
	first_pos = timestamp - file_name;
	first_replace_len = strlen(TimestampFilenamePlaceholder);
	} else {
	second = timestamp_string;
	second_pos = timestamp - file_name;
	second_replace_len = strlen(TimestampFilenamePlaceholder);
	}
	}

	size_t first_len = strlen(first);
	size_t second_len = strlen(second);

	// Allocate the new buffer, size it to hold all we want to put in there +1.
	size_t result_len = strlen(file_name) + first_len - first_replace_len + second_len - second_replace_len;
	result = NEW_C_HEAP_ARRAY(char, result_len + 1, mtLogging);

	// Assemble the strings
	size_t file_name_pos = 0;
	size_t i = 0;
	while (i < result_len) {
	if (file_name_pos == first_pos) {
	// We are in the range of the first placeholder
	strcpy(result + i, first);
	// Bump output buffer position with length of replacing string
	i += first_len;
	// Bump source buffer position to skip placeholder
	file_name_pos += first_replace_len;
	} else if (file_name_pos == second_pos) {
	// We are in the range of the second placeholder
	strcpy(result + i, second);
	i += second_len;
	file_name_pos += second_replace_len;
	} else {
	// Else, copy char by char of the original file
	result[i] = file_name[file_name_pos++];
	i++;
	}
	}
	// Add terminating char
	result[result_len] = '\0';
	return result;
	}

	void LogFileOutput::describe(outputStream *out) {
	LogOutput::describe(out);
	out->print(" ");

	out->print("filecount=%u,filesize=" SIZE_FORMAT "%s", _file_count,
	byte_size_in_proper_unit(_rotate_size),
	proper_unit_for_byte_size(_rotate_size));
	}