libexplain/wait3.h File Reference

explain wait3(2) errors More...

#include <libexplain/gcc_attributes.h>

Go to the source code of this file.

Functions
int	explain_wait3_or_die (int *status, int options, struct rusage *rusage)
int	explain_wait3_on_error (int *status, int options, struct rusage *rusage) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_wait3 (int *status, int options, struct rusage *rusage) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_wait3 (int errnum, int *status, int options, struct rusage *rusage) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_wait3 (char *message, int message_size, int *status, int options, struct rusage *rusage)
void	explain_message_errno_wait3 (char *message, int message_size, int errnum, int *status, int options, struct rusage *rusage)

---

Detailed Description

explain wait3(2) errors

Definition in file wait3.h.

---

Function Documentation

const char* explain_errno_wait3	(	int	errnum,
		int *	status,
		int	options,
		struct rusage *	rusage
	)

The explain_errno_wait3 function is used to obtain an explanation of an error returned by the wait3(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:

 pid_t pid = wait3(status, options, rusage);
 if (pid < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_wait3(err, status, options,
         rusage));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_wait3_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.
status	The original status, exactly as passed to the wait3(2) system call.
options	The original options, exactly as passed to the wait3(2) system call.
rusage	The original rusage, exactly as passed to the wait3(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.

void explain_message_errno_wait3	(	char *	message,
		int	message_size,
		int	errnum,
		int *	status,
		int	options,
		struct rusage *	rusage
	)

The explain_message_errno_wait3 function is used to obtain an explanation of an error returned by the wait3(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:

 pid_t pid = wait3(status, options, rusage);
 if (pid < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_wait3(message, sizeof(message), err, status,
         options, rusage);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_wait3_or_die function.

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.
status	The original status, exactly as passed to the wait3(2) system call.
options	The original options, exactly as passed to the wait3(2) system call.
rusage	The original rusage, exactly as passed to the wait3(2) system call.

void explain_message_wait3	(	char *	message,
		int	message_size,
		int *	status,
		int	options,
		struct rusage *	rusage
	)

The explain_message_wait3 function is used to obtain an explanation of an error returned by the wait3(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.

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

 pid_t pid = wait3(status, options, rusage);
 if (pid < 0)
 {
     char message[3000];
     explain_message_wait3(message, sizeof(message), status, options,
         rusage);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_wait3_or_die function.

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.
status	The original status, exactly as passed to the wait3(2) system call.
options	The original options, exactly as passed to the wait3(2) system call.
rusage	The original rusage, exactly as passed to the wait3(2) system call.

const char* explain_wait3	(	int *	status,
		int	options,
		struct rusage *	rusage
	)

The explain_wait3 function is used to obtain an explanation of an error returned by the wait3(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.

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

 pid_t pid = wait3(status, options, rusage);
 if (pid < 0)
 {
     fprintf(stderr, "%s\n", explain_wait3(status, options, rusage));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_wait3_or_die function.

Parameters:

status	The original status, exactly as passed to the wait3(2) system call.
options	The original options, exactly as passed to the wait3(2) system call.
rusage	The original rusage, exactly as passed to the wait3(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.

int explain_wait3_on_error	(	int *	status,
		int	options,
		struct rusage *	rusage
	)

The explain_wait3_on_error function is used to call the wait3(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_wait3(3) function.

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

 pid_t pid = explain_wait3_on_error(status, options, rusage);
 if (pid < 0)
 {
     ...cope with error
     ...no need to print error message
 }

Parameters:

status	The status, exactly as to be passed to the wait3(2) system call.
options	The options, exactly as to be passed to the wait3(2) system call.
rusage	The rusage, exactly as to be passed to the wait3(2) system call.

Returns:

The value returned by the wrapped wait3(2) system call.

int explain_wait3_or_die	(	int *	status,
		int	options,
		struct rusage *	rusage
	)

The explain_wait3_or_die function is used to call the wait3(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_wait3(3) function, and then the process terminates by calling exit(EXIT_FAILURE).

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

 pid_t pid = explain_wait3_or_die(status, options, rusage);

Parameters:

status	The status, exactly as to be passed to the wait3(2) system call.
options	The options, exactly as to be passed to the wait3(2) system call.
rusage	The rusage, exactly as to be passed to the wait3(2) system call.

Returns:

This function only returns on success. On failure, prints an explanation and exits, it does not return.