libexplain/snprintf.c File Reference

#include <libexplain/ac/errno.h>
#include <libexplain/ac/stdio.h>
#include <libexplain/buffer/errno/snprintf.h>
#include <libexplain/common_message_buffer.h>
#include <libexplain/snprintf.h>

Go to the source code of this file.

Functions
const char *	explain_snprintf (char *data, size_t data_size, const char *format,...)
const char *	explain_errno_snprintf (int errnum, char *data, size_t data_size, const char *format,...)
void	explain_message_snprintf (char *message, int message_size, char *data, size_t data_size, const char *format,...)
void	explain_message_errno_snprintf (char *message, int message_size, int errnum, char *data, size_t data_size, const char *format,...)

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Function Documentation

const char* explain_errno_snprintf	(	int	errnum,
		char *	data,
		size_t	data_size,
		const char *	format,
			...
	)

The explain_errno_snprintf function is used to obtain an explanation of an error returned by the snprintf(3) system call. The least the message will contain is the value of strerror(errnum), but usually it will do much better, and indicate the underlying cause in more detail.

Parameters:

errnum	The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is necessary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno.
data	The original data, exactly as passed to the snprintf(3) system call.
data_size	The original data_size, exactly as passed to the snprintf(3) system call.
format	The original format, exactly as passed to the snprintf(3) system call.

Returns:

The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

Note:

This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

Example:

This function is intended to be used in a fashion similar to the following example:

 errno = EINVAL;
 int result = snprintf(data, data_size, format, ...);
 if (result < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_snprintf(err, data, data_size,
         format, ...));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_snprintf_or_die function.

Definition at line 49 of file snprintf.c.

void explain_message_errno_snprintf	(	char *	message,
		int	message_size,
		int	errnum,
		char *	data,
		size_t	data_size,
		const char *	format,
			...
	)

Definition at line 85 of file snprintf.c.

void explain_message_snprintf	(	char *	message,
		int	message_size,
		char *	data,
		size_t	data_size,
		const char *	format,
			...
	)

Definition at line 69 of file snprintf.c.

const char* explain_snprintf	(	char *	data,
		size_t	data_size,
		const char *	format,
			...
	)

The explain_snprintf function is used to obtain an explanation of an error returned by the snprintf(3) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

The errno global variable will be used to obtain the error value to be decoded.

Parameters:

data	The original data, exactly as passed to the snprintf(3) system call.
data_size	The original data_size, exactly as passed to the snprintf(3) system call.
format	The original format, exactly as passed to the snprintf(3) system call.

Returns:

The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

Note:

This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

Example:

This function is intended to be used in a fashion similar to the following example:

 errno = EINVAL;
 int result = snprintf(data, data_size, format, ...);
 if (result < 0)
 {
     fprintf(stderr, "%s\n", explain_snprintf(data, data_size, format, ...));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_snprintf_or_die function.

Definition at line 28 of file snprintf.c.