ulog

A simple, cross platform, and thread safe logging library written in C99.

Supported platforms are Windows and all Unix systems supporting at least POSIX 2001 (Linux, macOS, BSDs, ...).

Usage

Setup

To use the single file header library simply drop ulog.h into your source directory and include it.

#include "ulog.h"

You will need to specify a file to hold the implementation. Do so by defining ULOG_IMPLEMENTATION prior to including ulog.h in one of your .c files.

#define ULOG_IMPLEMENTATION
#include "ulog.h"

Options

There are multiple compile time configuration parameters that can be set. You may either do this by specifying a #define in your source code prior to ULOG_IMPLEMENTATION or via a compiler directive.

• ULOG_LOG_LEVEL specifies the minimum log level. Available log levels are: ULOG_TRACE, ULOG_DEBUG, ULOG_INFO, ULOG_WARN, ULOG_ERROR, ULOG_FATAL. The default is ULOG_TRACE. Logging can be disabled by specifying ULOG_OFF.
• ULOG_PRINT_ERRNO specifies whether or not to print errno from <stderr.h>. Set 0 to not print, 1 to print. The default is 0.

#define ULOG_LOG_LEVEL ULOG_TRACE
#define ULOG_PRINT_ERRNO 0
#define ULOG_IMPLEMENTATION
#include "ulog.h"

Logging

Use the following functions to log a message. All of these functions are thread safe. They are also blocking due to the locking of the output file, so make sure to not use them in critical sections.

ulog_trace("trace message");
ulog_debug("debug message");
ulog_info("info message");
ulog_warn("warn message");
ulog_error("error message");
ulog_fatal("fatal message");

Depending on ULOG_LOG_LEVEL set during compilation some of these messages will be silenced.

All of the function accept a formatting string akin to printf.

ulog_trace("trace message %d %d", 4, 2);

Example

#define ULOG_IMPLEMENTATION
#include "ulog.h"

int
main(void)
{
	ulog_trace("trace message");
	ulog_debug("debug message");
	ulog_info("info message");
	ulog_warn("warn message");
	ulog_error("error message");
	ulog_fatal("fatal message");

	return 0;
}

Which will output:

TRACE <example.c:7>: trace message
DEBUG <example.c:8>: debug message
INFO <example.c:9>: info message
WARN <example.c:10>: warn message
ERROR <example.c:11>: error message
FATAL <example.c:12>: fatal message

License

zlib license, see LICENSE for more details.