microlog

A simple customizable logging library implemented in C99.

Table of Contents

• microlog
  • Table of Contents
  • Usage
    • ulog_set_quiet(bool enable)
    • ulog_set_level(int level)
    • Advanced Functions
      • ulog_add_fp(FILE *fp, int level)
      • ulog_add_callback(ulog_LogFn fn, void *udata, int level)
      • ulog_set_lock(ulog_LockFn fn, void *udata)
      • const char* ulog_level_string(int level)
    • Customization
      • Customization defines
  • License
  • Credits

Usage

The library can be linked as a CMake project or can be added manually: ulog.c and ulog.h should be dropped into an existing project and compiled along with it.

The library provides 6 function-like macros for logging:

log_trace(const char *fmt, ...);
log_debug(const char *fmt, ...);
log_info(const char *fmt, ...);
log_warn(const char *fmt, ...);
log_error(const char *fmt, ...);
log_fatal(const char *fmt, ...);

Each function takes a printf format string followed by additional arguments:

log_trace("Hello %s", "world")

Resulting in a line with the given format printed to stderr:

20:18:26 TRACE src/main.c:11: Hello world

ulog_set_quiet(bool enable)

Quiet-mode can be enabled by passing true to the ulog_set_quiet( function. While this mode is enabled the library will not output anything to stderr, but will continue to write to files and callbacks if any are set.

ulog_set_level(int level)

The current logging level can be set by using the ulog_set_level() function. All logs below the given level will not be written to stderr. By default the level is LOG_TRACE, such that nothing is ignored.

Advanced Functions

ulog_add_fp(FILE *fp, int level)

One or more file pointers where the log will be written can be provided to the library by using the ulog_add_fp() function. The data written to the file output is of the following format:

2047-03-11 20:18:26 TRACE src/main.c:11: Hello world

Any messages below the given level are ignored. If the library failed to add a file pointer a value less-than-zero is returned.

ulog_add_callback(ulog_LogFn fn, void *udata, int level)

One or more callback functions which are called with the log data can be provided to the library by using the ulog_add_callback() function. A callback function is passed a ulog_Event structure containing the line number, filename, fmt string, va printf va_list, level and the given udata.

ulog_set_lock(ulog_LockFn fn, void *udata)

If the log will be written to from multiple threads a lock function can be set. The function is passed the boolean true if the lock should be acquired or false if the lock should be released and the given udata value.

const char* ulog_level_string(int level)

Returns the name of the given log level as a string.

Customization

Customization defines

• ULOG_USE_COLOR - Use ANSI color escape codes when printing.
• ULOG_HIDE_FILE_STRING - Hide the file name and line number.
• ULOG_SHORT_LEVEL_STRINGS - Use short level strings, e.g. "T" for "TRACE", "I" for "INFO".
• HAVE_ULOG_CFG_H - Use a custom configuration file.
• ULOG_HAVE_TIME - Print the time in the log messages. Requires implementation of long unsigned ulog_get_time(void)

You can use the defines in the compiler options, e.g. -DULOG_USE_COLOR. Or you can provide -DHAVE_ULOG_CFG_H to your compiler and the options in ulog_cfg.h - a custom configuration file.

License

This library is free software; you can redistribute it and/or modify it under the terms of the MIT license. See LICENSE for details.

Credits

Based on https://github.com/rxi/log.c.git