slog2fa()

Log a printf-style string in a slog2 buffer

Synopsis:

#include <sys/slog2.h>

int slog2fa( slog2_buffer_t buffer,
             uint16_t code,
             uint8_t severity,
             const char* format, ... );

Arguments:

buffer

The handle of the buffer you want to log the message in, or NULL to use the default buffer that you specified earlier with slog2_set_default_buffer().

code

A user-specified code that you want to be associated with the message. The slog2 system doesn't interpret this code in any way.

severity

The severity level of this log item; one of:

SLOG2_SHUTDOWN
SLOG2_CRITICAL
SLOG2_ERROR
SLOG2_WARNING
SLOG2_NOTICE
SLOG2_INFO
SLOG2_DEBUG1
SLOG2_DEBUG2

For more information, see the entry for slog2_register().

format

A printf-formatted character string used to define the log message.

Additional arguments

An argument vector that specifies the arguments for the format string. You must use the appropriate SLOG2_FA_*() helper macro for parameters, as described below. The last parameter in the vector must be SLOG2_FA_END.

Library:

libslog2

Use the -l slog2 option to qcc to link against this library.

Description:

The slog2fa() function a printf-style format string along with its arguments specified in the argument vector. This function uses special formatting macros to ensure that va_args() doesn't trigger any interrupts. The format string isn't decoded before writing; it must be decoded during the time of the read.

Note: If you're specifying a string with %s, the size must include the NULL character.

You can use the following macros to build the parameters to slog2fa:

SLOG2_FA_UNSIGNED( x )
SLOG2_FA_SIGNED( x )
SLOG2_FA_CHAR( x )
SLOG2_FA_FLOAT( x )
SLOG2_FA_DOUBLE( x )
SLOG2_FA_STRING( x )
SLOG2_FA_END — you must end the list with this macro

For example:

int8_t some_number = -1;

slog2fa( ..., "string:%s, some_number:%d", SLOG2_FA_STRING( "Hello world" ),
                                           SLOG2_FA_SIGNED( some_number ),
                                           SLOG2_FA_END );

Returns:

0 on success, or -1 if an error occurred.

Errors:

EBUSY: The logger couldn't obtain a buffer within the number of retries that you specified when you registered the buffer set; see slog2_register().
EFAULT: You specified NULL for buffer, but there's no default buffer.
EINVAL: The format string is invalid.
ENOMEM: The resulting packet size would be greater than the maximum packet size allowed.
EPERM: The process hasn't registered with slog2.

Examples:

See slog2_register().

Classification:

QNX Neutrino

Safety:
Cancellation point	No
Interrupt handler	Read the Caveats
Signal handler	Yes
Thread	Yes

Caveats:

Don't use double or float arguments in an interrupt handler, unless your code is compiled to use software floating-point emulation.