log.c

A simple logging library implemented in C99

Usage

log.c and log.h should be dropped into an existing project and compiled along with it. The library provides 6 function-like macros for logging:

Semihosting Support

When using this library on embedded ARM targets, semihosting is supported for output. To enable semihosting in OpenOCD, add the following to your configuration:

arm semihosting enable

This allows log messages to be displayed through the debugger when running on hardware.

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

log_set_quiet(bool enable)

Quiet-mode can be enabled by passing true to the log_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.

log_set_level(int level)

The current logging level can be set by using the log_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.

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.

log_set_lock(log_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* log_level_string(int level)

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

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.