libexplain/message/lseek.c File Reference

#include <libexplain/ac/errno.h>
#include <libexplain/ac/unistd.h>
#include <libexplain/lseek.h>

Go to the source code of this file.

Functions
void	explain_message_lseek (char *message, int message_size, int fildes, off_t offset, int whence)

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Function Documentation

void explain_message_lseek	(	char *	message,
		int	message_size,
		int	fildes,
		off_t	offset,
		int	whence
	)

The explain_message_lseek function is used to obtain an explanation of an error returned by the lseek(2) 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.

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

Parameters:

message	The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.
message_size	The size in bytes of the location in which to store the returned message.
fildes	The original fildes, exactly as passed to the lseek(2) system call.
offset	The original offset, exactly as passed to the lseek(2) system call.
whence	The original whence, exactly as passed to the lseek(2) system call.

Example:

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

 off_t result = lseek(fildes, offset, whence);
 if (result < 0)
 {
     char message[3000];
     explain_message_lseek(message, sizeof(message), fildes, offset, whence);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

Definition at line 26 of file lseek.c.