libexplain/sleep.h File Reference

explain sleep(3) errors More...

#include <libexplain/gcc_attributes.h>
#include <libexplain/large_file_support.h>

Go to the source code of this file.

Functions
unsigned int	explain_sleep_or_die (unsigned int seconds)
unsigned int	explain_sleep_on_error (unsigned int seconds)
const char *	explain_sleep (unsigned int seconds) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_sleep (int errnum, unsigned int seconds) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_sleep (char *message, int message_size, unsigned int seconds)
void	explain_message_errno_sleep (char *message, int message_size, int errnum, unsigned int seconds)

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Detailed Description

explain sleep(3) errors

These functions may be used to obtain explanations for errors returned by the sleep(3) system call.

Definition in file sleep.h.

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Function Documentation

const char* explain_errno_sleep	(	int	errnum,
		unsigned int	seconds
	)

The explain_errno_sleep function is used to obtain an explanation of an error returned by the sleep(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.
seconds	The original seconds, exactly as passed to the sleep(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:

 unsigned int result = sleep(seconds);
 if (result < 0)
 {
     int err = errno;
     explain_output_error_and_die("%s", explain_errno_sleep(err, seconds));
 }

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

void explain_message_errno_sleep	(	char *	message,
		int	message_size,
		int	errnum,
		unsigned int	seconds
	)

The explain_message_errno_sleep function is used to obtain an explanation of an error returned by the sleep(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:

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.
seconds	The original seconds, exactly as passed to the sleep(3) system call.

Example:

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

 unsigned int result = sleep(seconds);
 if (result < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_sleep(message, sizeof(message), err, seconds);
     explain_output_error_and_die("%s", message);
 }

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

void explain_message_sleep	(	char *	message,
		int	message_size,
		unsigned int	seconds
	)

The explain_message_sleep function is used to obtain an explanation of an error returned by the sleep(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.

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.
seconds	The original seconds, exactly as passed to the sleep(3) system call.

Example:

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

 unsigned int result = sleep(seconds);
 if (result < 0)
 {
     char message[3000];
     explain_message_sleep(message, sizeof(message), seconds);
     explain_output_error_and_die("%s", message);  * }

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

const char* explain_sleep

(

unsigned int

seconds

)

The explain_sleep function is used to obtain an explanation of an error returned by the sleep(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:

seconds

The original seconds, exactly as passed to the sleep(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:

 unsigned int result = sleep(seconds);
 if (result < 0)
 {
     explain_output_error_and_die("%s\n", explain_sleep(seconds));
 }

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

unsigned int explain_sleep_on_error

(

unsigned int

seconds

)

The explain_sleep_on_error function is used to call the sleep(3) system call. On failure an explanation will be printed to stderr, obtained from the explain_sleep(3) function.

Parameters:

seconds

The seconds, exactly as to be passed to the sleep(3) system call.

Returns:

The value returned by the wrapped sleep(3) system call.

Example:

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

 unsigned int result = explain_sleep_on_error(seconds);
 if (result < 0)
 {
     ...cope with error
     ...no need to print error message
 }

unsigned int explain_sleep_or_die

(

unsigned int

seconds

)

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

Parameters:

seconds

The seconds, exactly as to be passed to the sleep(3) system call.

Returns:

This function only returns on success, see sleep(3) 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:

 unsigned int result = explain_sleep_or_die(seconds);