The Dlog API provides functions for sending log output.

Required Header

#include <dlog.h>

Overview

Sending log message to circular buffer. Dlog APIs include Priority and Tag. By using priority and Tag, we can easily filtered messages what we want to see.

priority

priority level indicates the urgency of log message

Priority	Description
DLOG_DEBUG	Debug message. - Log message which developer want to check.
DLOG_INFO	Information message - Normal operational messages. above of this priority will always be logged.
DLOG_WARN	Warning messages - Not an error, but indication that an error will occur if action is not taken.
DLOG_ERROR	Error message - Indicate error.

Macro example for useful usage

The Dlog APIs can be used by defining own macros. The macros can be defined like below examples. Thus, developers can use appropriate method as a matter of convenience.

#undef LOG_TAG
#define LOG_TAG "APP_TAG"

#define LOGI(fmt, arg...) \
    ({ do { \
        dlog_print(DLOG_INFO, LOG_TAG, "%s: %s(%d) > " fmt, __MODULE__, __func__, __LINE__, ##arg); \
    } while (0); })
#define LOGW(fmt, arg...) \
    ({ do { \
        dlog_print(DLOG_WARN, LOG_TAG, "%s: %s(%d) > " fmt, __MODULE__, __func__, __LINE__, ##arg); \
    } while (0); })
#define LOGE(fmt, arg...) \
    ({ do { \
        dlog_print(DLOG_ERROR, LOG_TAG, "%s: %s(%d) > " fmt, __MODULE__, __func__, __LINE__, ##arg); \
    } while (0); })

dlogutil CLI

dlogutil is a utility that can be utilized to read stored logs.

The most rudimentary way to use it is to run it with no parameters; it then prints all stored logs to the standard output and awaits more.

Parameters exist to change behaviour:

PARAM	DESCRIPTION
-s	Set default filter to *:s (see later for details)
-f filename	Output to given file instead of stdout
-r kbytes	Rotate log file every this many kilobytes.
-n files	Keep this many old rotations
-v	Set log output format.
-b buffer	Select another buffer
-c	Clear the selected buffers
-d	Exit when no more logs are currently available
-t count	Similar to -d, except only print this many logs from the end
-g	Get the size of selected buffers instead of printing logs
-h, --help	Show help info
--dumpfile file	Parse a binary file generated by the logger daemon

Additionally, you can specify filters. Filters go behind the parameters and are used to decide which logs are shown.
Each log line has priority and a tag. Filters are specified in the format TAG[:PRIO]. Only logs with given tags and priorities are shown.
You can specify * as the tag to match anything. Beware: only a single asterisk works that way, asterisk is not otherwise expanded. For example, "T*G" filter will NOT match "TAG", only literal "T*G".
If you don't specify any filter, it defaults to *:I
If you specify just * as the tag, without priority, its priority defaults to D
If you specify any other tag without priority, the priority defaults to V

dlogutil allows you to specify buffers. These are:

NAME	REMARKS
main	the default, for general platform logging
system	for system logs
radio	for radio logs
apps	for applications
kmsg	a copy of kernel messages (dmesg)

There are also priorities to be specified. These are one letter abbreviations of the following levels:

LEVEL	DESCRIPTION
V	verbose
D	debug
I	info
W	warning
E	error
F	fatal
S	silent

Formats, and what they look like:

NAME	SPECIFICATION	EXAMPLE
brief	PRI/TAG(PID): MSG	E/TEST_APP(123): FOO
process	PRI(PID) MSG (TAG)	E(123) FOO (TEST_APP)
tag	PRI/TAG: MSG	E/TEST_APP: FOO
thread	PRI('P'PID, 'T'TID) MSG	E(P123, T456) FOO
raw	MSG	FOO
time	REALTIME PRI/TAG(PID): MSG	12-31 23:59:59.999 +0200 E/TEST_APP(123): FOO
threadtime	REALTIME PRI/TAG('P'PID, 'T'TID): MSG	12-31 23:59:59.999 +0200 E/TEST_APP(P123, T456): FOO
kerneltime	BOOTTIME PRI/TAG('P'PID, 'T'TID): MSG	0.123 E/TEST_APP(P123, T456): FOO
long	[REALTIME PRI/TAG 'P'PID, 'T'TID] MSG	[12-31 23:59:59.999 +0200 E/TEST_APP P123, T456] FOO

Functions
int	dlog_print (log_priority prio, const char tag, const char fmt,...)
	Sends log with priority and tag.
int	dlog_vprint (log_priority prio, const char tag, const char fmt, va_list ap)
	Sends log with priority, tag, and va_list.

Enumeration Type Documentation

enum dlog_error_e

Enumeration for Dlog Error.

Since :: 2.3

Enumerator:

DLOG_ERROR_NONE	Successful
DLOG_ERROR_INVALID_PARAMETER	Invalid parameter
DLOG_ERROR_NOT_PERMITTED	Operation not permitted

enum log_priority

Enumeration for log priority values in ascending priority order.

Since :: 2.3

Enumerator:

DLOG_UNKNOWN	Keep this always at the start
DLOG_DEFAULT	Default
DLOG_VERBOSE	Verbose
DLOG_DEBUG	Debug
DLOG_INFO	Info
DLOG_WARN	Warning
DLOG_ERROR	Error
DLOG_FATAL	Fatal
DLOG_SILENT	Silent
DLOG_PRIO_MAX	Keep this always at the end.

Function Documentation

int dlog_print	(	log_priority	prio,
		const char *	tag,
		const char *	fmt,
			...
	)

Sends log with priority and tag.

for application.

Since :: 2.3

Parameters:

[in]	prio	priority level of type log_priority
[in]	tag	tag - a null-terminated string
[in]	fmt	format string - same as printf

Returns:: On success, the function returns the number of bytes written. On error, a negative errno-style error code

Return values:

DLOG_ERROR_INVALID_PARAMETER	Invalid parameter
DLOG_ERROR_NOT_PERMITTED	Operation not permitted

Precondition:: none

Postcondition:: none

See also:: dlog_vprint

#include<dlog.h>
int main(void)
{
    int integer = 21;
    char string[] = "test dlog";

    dlog_print(DLOG_INFO, "USR_TAG", "test dlog");
    dlog_print(DLOG_INFO, "USR_TAG", "%s, %d", string, integer);
    return 0;
}

int dlog_vprint	(	log_priority	prio,
		const char *	tag,
		const char *	fmt,
		va_list	ap
	)

Sends log with priority, tag, and va_list.