Telodendria/src/include/Log.h

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/*
* Copyright (C) 2022 Jordan Bancino <@jordan:bancino.net>
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
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* included in all copies or portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
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/*
* Log.h: A heavily-modified version of Shlog, a simple C logging
* facility that allows for colorful output, timestamps, and custom
* log levels. This library differs from Shlog in that the naming
* conventions have been updated to be consistent with Telodendria.
*
* Shlog was originally a learning project. It worked well, however,
* and produced elegant logging output, so it was chosen to be the
* main logging mechanism of Telodendria. The original Shlog project
* is now dead; Shlog lives on now only as Telodendria's logging
* mechanism.
*
* In the name of simplicity and portability, I opted to use an
* in-house logging system instead of syslog(), or other system logging
* mechanisms. However, this API could easily be patched to allow
* logging via other mechanisms that support the same features.
*/
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#ifndef TELODENDRIA_LOG_H
#define TELODENDRIA_LOG_H
#include <stdio.h>
#include <stddef.h>
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/*
* There are five log "levels," each one showing more information than
* the previous one. A level of LOG_ERROR shows only errors, while a
* level of LOG_DEBUG shows all output possible.
*/
typedef enum LogLevel
{
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LOG_ERROR,
LOG_WARNING,
LOG_TASK,
LOG_MESSAGE,
LOG_DEBUG
} LogLevel;
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/*
* The possible flags that can be applied to alter the behavior of
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* the logger.
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*/
typedef enum LogFlag
{
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LOG_FLAG_COLOR = (1 << 0) /* Enable color output on TTYs */
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} LogFlag;
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/*
* The log configurations structure in which all settings exist.
* It's not super elegant to pass around a pointer to the logging
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* configuration, but this really is the best way without having a
* global variable. It allows multiple loggers to exist if necessary,
* and makes things more thread safe.
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*/
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typedef struct LogConfig LogConfig;
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/*
* Create a new log configuration on the heap. This will be passed to
* every Log() call after it is configured.
*
* Return: A pointer to a new LogConfig that can be configured and used
* for logging. It should have sane defaults; in other words, you should
* be able to immediately start logging with it.
*/
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extern LogConfig *
LogConfigCreate(void);
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/*
* Free a log configuration. Future attempts to log with the passed
* configuration will fail in an undefined way, such as by hanging the
* process or segfaulting.
*
* Params:
*
* (LogConfig *) The configuration to free. All memory associated with
* configuring the logging mechanism will be
* invalidated.
*/
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extern void
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LogConfigFree(LogConfig *);
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/*
* Set the current log level on the specified log configuration. This
* indicates that only messages at or above this level should be
* logged; all other messages are ignored by the Log() function.
*
* Params:
*
* (LogConfig *) The log configuration to set the log level on.
* (LogLevel) The log level to set.
*/
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extern void
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LogConfigLevelSet(LogConfig *, LogLevel);
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/*
* Indent the log output by two spaces. This can be helpful in
* generating stack traces, or otherwise producing hierarchical output.
* After calling this function, all future log messages using this
* configuration will be indented.
*
* Params:
*
* (LogConfig *) The log configuration to indent.
*/
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extern void
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LogConfigIndent(LogConfig *);
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/*
* Decrease the log output indent by two spaces. This can be helpful in
* generating stack traces, or otherwise producing hierarchical output.
* After calling this function, all future log messages using this
* configuration will be unindented, unless there was no indentation
* to begin with; in that case, this function will do nothing.
*
* Params:
*
* (LogConfig *) The log configuration to unindent.
*/
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extern void
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LogConfigUnindent(LogConfig *);
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/*
* Set the log output indent to an arbitrary amount. This can be helpful
* in generating stack traces, or otherwise producing hierarchical
* output. After calling this function, all future log messages using
* this configuration will be indented by the given amount.
*
* Params:
*
* (LogConfig *) The log configuration to apply the indent to.
*/
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extern void
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LogConfigIndentSet(LogConfig *, size_t);
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extern void
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LogConfigOutputSet(LogConfig *, FILE *);
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extern void
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LogConfigFlagSet(LogConfig *, int);
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extern void
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LogConfigFlagClear(LogConfig *, int);
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extern void
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LogConfigTimeStampFormatSet(LogConfig *, char *);
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/*
* Actually log a message to a console, file, or other output device,
* using the given log configuration. This function is thread-safe; it
* locks a mutex before writing a message, and then unlocks it after
* the message was written. It should therefore work well in
* multithreaded environments, and with multiple different log
* configurations, as each one has its own mutex.
*
* This function only logs messages if they are above the currently
* configured log level. In this way, it is easy to turn some messages
* on and off.
*
* This function is a printf() style function; it takes a format
* string and any number of parameters to format.
*
* Params:
*
* (LogConfig *) The logging configuration.
* (LogLevel) The level of the message to log.
* (const char *) The format string, or a plain message string.
* (...) Any items to map into the format string, printf()
* style.
*/
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extern void
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Log(LogConfig *, LogLevel, const char *,...);
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#endif