libexplain/timerfd_create.h File Reference

explain timerfd_create(2) errors More...

#include <libexplain/gcc_attributes.h>

Go to the source code of this file.

Functions
int	explain_timerfd_create_or_die (int clockid, int flags) LIBEXPLAIN_WARN_UNUSED_RESULT
int	explain_timerfd_create_on_error (int clockid, int flags) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_timerfd_create (int clockid, int flags) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_timerfd_create (int errnum, int clockid, int flags) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_timerfd_create (char *message, int message_size, int clockid, int flags)
void	explain_message_errno_timerfd_create (char *message, int message_size, int errnum, int clockid, int flags)

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Detailed Description

explain timerfd_create(2) errors

These functions may be used to obtain explanations for errors returned by the timerfd_create(2) system call.

Definition in file timerfd_create.h.

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Function Documentation

const char* explain_errno_timerfd_create	(	int	errnum,
		int	clockid,
		int	flags
	)

The explain_errno_timerfd_create function is used to obtain an explanation of an error returned by the timerfd_create(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.

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.
clockid	The original clockid, exactly as passed to the timerfd_create(2) system call.
flags	The original flags, exactly as passed to the timerfd_create(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.

Example:

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

 int result = timerfd_create(clockid, flags);
 if (result < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_timerfd_create(err, clockid,
         flags));
     exit(EXIT_FAILURE);
 }

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

void explain_message_errno_timerfd_create	(	char *	message,
		int	message_size,
		int	errnum,
		int	clockid,
		int	flags
	)

The explain_message_errno_timerfd_create function is used to obtain an explanation of an error returned by the timerfd_create(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.

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.
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.
clockid	The original clockid, exactly as passed to the timerfd_create(2) system call.
flags	The original flags, exactly as passed to the timerfd_create(2) system call.

Example:

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

 int result = timerfd_create(clockid, flags);
 if (result < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_timerfd_create(message, sizeof(message), err,
         clockid, flags);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

void explain_message_timerfd_create	(	char *	message,
		int	message_size,
		int	clockid,
		int	flags
	)

The explain_message_timerfd_create function is used to obtain an explanation of an error returned by the timerfd_create(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.
clockid	The original clockid, exactly as passed to the timerfd_create(2) system call.
flags	The original flags, exactly as passed to the timerfd_create(2) system call.

Example:

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

 int result = timerfd_create(clockid, flags);
 if (result < 0)
 {
     char message[3000];
     explain_message_timerfd_create(message, sizeof(message), clockid,
         flags);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

const char* explain_timerfd_create	(	int	clockid,
		int	flags
	)

The explain_timerfd_create function is used to obtain an explanation of an error returned by the timerfd_create(2) 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:

clockid	The original clockid, exactly as passed to the timerfd_create(2) system call.
flags	The original flags, exactly as passed to the timerfd_create(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.

Example:

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

 int result = timerfd_create(clockid, flags);
 if (result < 0)
 {
     fprintf(stderr, "%s\n", explain_timerfd_create(clockid, flags));
     exit(EXIT_FAILURE);
 }

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

int explain_timerfd_create_on_error	(	int	clockid,
		int	flags
	)

The explain_timerfd_create_on_error function is used to call the timerfd_create(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_timerfd_create(3) function.

Parameters:

clockid	The clockid, exactly as to be passed to the timerfd_create(2) system call.
flags	The flags, exactly as to be passed to the timerfd_create(2) system call.

Returns:

The value returned by the wrapped timerfd_create(2) system call.

Example:

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

 int result = explain_timerfd_create_on_error(clockid, flags);
 if (result < 0)
 {
     ...cope with error
     ...no need to print error message
 }

int explain_timerfd_create_or_die	(	int	clockid,
		int	flags
	)

The explain_timerfd_create_or_die function is used to call the timerfd_create(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_timerfd_create(3) function, and then the process terminates by calling exit(EXIT_FAILURE).

Parameters:

clockid	The clockid, exactly as to be passed to the timerfd_create(2) system call.
flags	The flags, exactly as to be passed to the timerfd_create(2) system call.

Returns:

This function only returns on success, see timerfd_create(2) for more information. On failure, prints an explanation and exits, it does not return.

Example:

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

 int result = explain_timerfd_create_or_die(clockid, flags);