Lightweight (single header file) C module implementing logging. The only dependency is the stdio.h providing fprintf().

The module provides 5 logging macros: error, warn, info, debug, and trace. There is no fatal level. If you want to fatal, then you should probably panic.

The macros do not have popular log_ prefix. Why? Because the names are quite self explanatory. There is no need to clutter the code with the extra log_ prefix. The warn macro conflicts with the warn() function from the err.h. However, let's be honest, no one uses err.h as the functions it provides are pretty much useless.

The module is not thread safe. If you want thread safety, then you must implement it on your own.

Simply copy the log.h file to your project.

The module is statically configurable during the compilation time. There are 5 following configuration macros (alphabetical order):

• LOG_COLOR - if defined, log level will be printed in color. If you don't like the default colors simply edit proper macros in the log.h file.
• LOG_LEVEL - log level. Valid values are:
  • 0 - no logs.
  • 1 - only errors.
  • 2 - errors and warnings.
  • 3 - errors, warnings, and infos.
  • 4 - errors, warnings, infos and debugs,
  • 5 - errors, warnings, infos, debugs, and traces.
• LOG_PREFIX - optional logging prefix. If defined in the Makefile or command line, remember to double quote, for example, -DLOG_PREFIX="\"your prefix:\""
• LOG_STREAM - stream for logging. The default one is stderr.
• LOG_TIME - if defined, the log will include the time. The time format is custom format. The user must provide implementation for the struct log_time log_time(void); function. For more details check the documentation in the log.h file.

The configuration can also be done per source file scope, which is sometimes desired, especially for the LOG_PREFIX. In such a case simply configure the module before include. Example:

#define LOG_PREFIX "my_prefix: "
#define LOG_LEVEL 5
#include "log.h"

Check main.c file.