/logmod

A lightweight modular C logging library

Primary LanguageCMIT LicenseMIT

LogMod

LogMod is a simple logging module for C applications. It provides functionality to initialize a logging context, retrieve loggers, and log messages with different severity levels.

Features

  • Initialize logging context with application ID and logger table.
  • Retrieve or create loggers by context ID.
  • Log messages with different severity levels (TRACE, DEBUG, INFO, WARN, ERROR, FATAL).
  • Optionally log messages to a file.

Installation

To use LogMod in your project, include the logmod.h header file and link against the logmod.c source file.

Usage

Initialization

To initialize the logging context, use the logmod_init function:

#include "logmod.h"

struct logmod logmod;
struct logmod_logger table[5];

logmod_err code = logmod_init(&logmod, "APPLICATION_ID", table, 5);
if (code != LOGMOD_OK) {
    // Handle error
}

Retrieving Loggers

To retrieve or create a logger by context ID, use the logmod_logger_get function:

struct logmod_logger *LOGMOD_LOGGER = logmod_logger_get(&logmod, "CONTEXT_ID");
if (LOGMOD_LOGGER == NULL) {
    // Handle error
}

The logger is stored in the LOGMOD_LOGGER variable, which is a macro created to ensure ANSI C compatibility.

Logging Messages

To log messages with different severity levels, use provided macros:

LOGMOD_TRACE(("This is a trace message"));
LOGMOD_DEBUG(("This is a debug message"));
LOGMOD_INFO(("This is an info message"));
LOGMOD_WARN(("This is a warning message"));
LOGMOD_ERROR(("This is an error message"));
LOGMOD_FATAL(("This is a fatal message"));

Using printf Formatters

LogMod supports formatted logging messages similar to printf. Here are some examples:

int value = 42;
const char *name = "example";

LOGMOD_INFO(("Integer value: %d", value));
LOGMOD_DEBUG(("String value: %s", name));
LOGMOD_WARN(("Combined values: %s = %d", name, value));

These macros allow you to include variable data in your log messages, making them more informative and useful for debugging.

Cleanup

To clean up the logging context, use the logmod_cleanup function:

logmod_cleanup(&logmod);

API Reference

logmod_init

logmod_err logmod_init(struct logmod *logmod, const char *const app_id, struct logmod_logger table[], unsigned length);

Initializes the logging context with the specified application ID and logger table.

  • logmod: Pointer to the logging context structure.
  • app_id: Application ID string.
  • table: Logger table array.
  • length: Length of the logger table array.

Returns LOGMOD_OK on success, or an error code on failure.

logmod_cleanup

logmod_err logmod_cleanup(struct logmod *logmod);

Cleans up the logging context.

  • logmod: Pointer to the logging context structure. Returns LOGMOD_OK on success

logmod_logger_get

struct logmod_logger *logmod_logger_get(struct logmod *logmod, const char *const context_id);

Retrieves or creates a logger by context ID.

  • logmod: Pointer to the logging context structure.
  • context_id: Context ID string. Returns a pointer to the logger, or NULL on failure. Note: The variable MUST be called LOGMOD_LOGGER (which is a macro created to ensure ANSI C compatibility).

logmod_logger_set_lock

logmod_err logmod_logger_set_lock(struct logmod_logger *logger, void (*lock)(int should_lock));

Sets the lock function for the specified logger.

  • logger: Pointer to the logger structure.
  • lock: Lock function pointer.

logmod_logger_set_options

logmod_err logmod_logger_set_options(struct logmod_logger *logger, struct logmod_logger_options options);

Sets the options for the logger.

  • logger: Pointer to the logger structure.
  • options: Logger options structure.

logmod_logger_set_quiet

logmod_err logmod_logger_set_quiet(struct logmod_logger *logger, int quiet);

Sets the quiet mode for the logger.

  • logger: Pointer to the logger structure.
  • quiet: Quiet mode flag. Returns LOGMOD_OK on success.

logmod_logger_set_logfile

logmod_err logmod_logger_set_logfile(struct logmod_logger *logger, char *logfile);

Sets the logfile for the logger.

  • logger: Pointer to the logger structure.
  • logfile: Logfile path string. Returns LOGMOD_OK on success.

_logmod_log

logmod_err _logmod_log(struct logmod_logger *logger, const char *fmt, ...);

Logs a message with the specified logger and format string.

  • logger: Pointer to the logger structure.
  • fmt: Format string for the message. Returns LOGMOD_OK on success, or an error code on failure.

License

This project is licensed under the MIT License - see the LICENSE file for details.