libexplain/time.h File Reference

explain time(2) errors More...

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

Go to the source code of this file.

Functions
time_t	explain_time_or_die (time_t *t)
time_t	explain_time_on_error (time_t *t) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_time (time_t *t) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_time (int errnum, time_t *t) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_time (char *message, int message_size, time_t *t)
void	explain_message_errno_time (char *message, int message_size, int errnum, time_t *t)

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Detailed Description

explain time(2) errors

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

Definition in file time.h.

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Function Documentation

const char* explain_errno_time	(	int	errnum,
		time_t *	t
	)

The explain_errno_time function is used to obtain an explanation of an error returned by the time(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.
t	The original t, exactly as passed to the time(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:

 time_t result = time(t);
 if (result < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_time(err, t));
     exit(EXIT_FAILURE);
 }

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

void explain_message_errno_time	(	char *	message,
		int	message_size,
		int	errnum,
		time_t *	t
	)

The explain_message_errno_time function is used to obtain an explanation of an error returned by the time(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.
t	The original t, exactly as passed to the time(2) system call.

Example:

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

 time_t result = time(t);
 if (result < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_time(message, sizeof(message), err, t);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

void explain_message_time	(	char *	message,
		int	message_size,
		time_t *	t
	)

The explain_message_time function is used to obtain an explanation of an error returned by the time(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.
t	The original t, exactly as passed to the time(2) system call.

Example:

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

 time_t result = time(t);
 if (result < 0)
 {
     char message[3000];
     explain_message_time(message, sizeof(message), t);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

const char* explain_time

(

time_t *

t

)

The explain_time function is used to obtain an explanation of an error returned by the time(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:

t	The original t, exactly as passed to the time(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:

 time_t result = time(t);
 if (result < 0)
 {
     fprintf(stderr, "%s\n", explain_time(t));
     exit(EXIT_FAILURE);
 }

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

time_t explain_time_on_error

(

time_t *

t

)

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

Parameters:

t	The t, exactly as to be passed to the time(2) system call.

Returns:

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

Example:

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

 time_t result = explain_time_on_error(t);
 if (result < 0)
 {
     ...cope with error
     ...no need to print error message
 }

time_t explain_time_or_die

(

time_t *

t

)

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

Parameters:

t	The t, exactly as to be passed to the time(2) system call.

Returns:

This function only returns on success, see time(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:

 time_t result = explain_time_or_die(t);