libexplain/errno/select.c File Reference

#include <libexplain/ac/sys/select.h>
#include <libexplain/common_message_buffer.h>
#include <libexplain/select.h>

Go to the source code of this file.

Functions
const char *	explain_errno_select (int errnum, int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)

---

Function Documentation

const char* explain_errno_select	(	int	errnum,
		int	nfds,
		fd_set *	readfds,
		fd_set *	writefds,
		fd_set *	exceptfds,
		struct timeval *	timeout
	)

The explain_errno_select function is used to obtain an explanation of an error returned by the select(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.

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

 if (select(nfds, readfds, writefds, exceptfds, timeout) < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_select(err, nfds, readfds,
         writefds, exceptfds, timeout));
     exit(EXIT_FAILURE);
 }

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

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.
nfds	The original nfds, exactly as passed to the select(2) system call.
readfds	The original readfds, exactly as passed to the select(2) system call.
writefds	The original writefds, exactly as passed to the select(2) system call.
exceptfds	The original exceptfds, exactly as passed to the select(2) system call.
timeout	The original timeout, exactly as passed to the select(2) 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.

Definition at line 26 of file select.c.