libexplain/fchmod.h File Reference

explain fchmod(2) errors More...

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

Go to the source code of this file.

Functions
void	explain_fchmod_or_die (int fildes, mode_t mode)
int	explain_fchmod_on_error (int fildes, mode_t mode)
const char *	explain_fchmod (int fildes, mode_t mode) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_fchmod (int errnum, int fildes, mode_t mode) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_fchmod (char *message, int message_size, int fildes, mode_t mode)
void	explain_message_errno_fchmod (char *message, int message_size, int errnum, int fildes, mode_t mode)

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Detailed Description

explain fchmod(2) errors

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

Definition in file fchmod.h.

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Function Documentation

const char* explain_errno_fchmod	(	int	errnum,
		int	fildes,
		mode_t	mode
	)

The explain_errno_fchmod function is used to obtain an explanation of an error returned by the fchmod(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.
fildes	The original fildes, exactly as passed to the fchmod(2) system call.
mode	The original mode, exactly as passed to the fchmod(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:

 if (fchmod(fildes, mode) < 0)
 {
     int err = errno;
     explain_output_error_and_die("%s", explain_errno_fchmod(err, fildes,
         mode));
 }

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

const char* explain_fchmod	(	int	fildes,
		mode_t	mode
	)

The explain_fchmod function is used to obtain an explanation of an error returned by the fchmod(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:

fildes	The original fildes, exactly as passed to the fchmod(2) system call.
mode	The original mode, exactly as passed to the fchmod(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:

 if (fchmod(fildes, mode) < 0)
 {
     explain_output_error_and_die("%s\n", explain_fchmod(fildes, mode));
 }

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

int explain_fchmod_on_error	(	int	fildes,
		mode_t	mode
	)

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

Parameters:

fildes	The fildes, exactly as to be passed to the fchmod(2) system call.
mode	The mode, exactly as to be passed to the fchmod(2) system call.

Returns:

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

Example:

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

 if (explain_fchmod_on_error(fildes, mode) < 0)
 {
     ...cope with error
     ...no need to print error message
 }

void explain_fchmod_or_die	(	int	fildes,
		mode_t	mode
	)

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

Parameters:

fildes	The fildes, exactly as to be passed to the fchmod(2) system call.
mode	The mode, exactly as to be passed to the fchmod(2) system call.

Returns:

This function only returns on success, see fchmod(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:

 explain_fchmod_or_die(fildes, mode);

void explain_message_errno_fchmod	(	char *	message,
		int	message_size,
		int	errnum,
		int	fildes,
		mode_t	mode
	)

The explain_message_errno_fchmod function is used to obtain an explanation of an error returned by the fchmod(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.
fildes	The original fildes, exactly as passed to the fchmod(2) system call.
mode	The original mode, exactly as passed to the fchmod(2) system call.

Example:

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

 if (fchmod(fildes, mode) < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_fchmod(message, sizeof(message), err, fildes,
         mode);
     explain_output_error_and_die("%s", message);
 }

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

void explain_message_fchmod	(	char *	message,
		int	message_size,
		int	fildes,
		mode_t	mode
	)

The explain_message_fchmod function is used to obtain an explanation of an error returned by the fchmod(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.
fildes	The original fildes, exactly as passed to the fchmod(2) system call.
mode	The original mode, exactly as passed to the fchmod(2) system call.

Example:

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

 if (fchmod(fildes, mode) < 0)
 {
     char message[3000];
     explain_message_fchmod(message, sizeof(message), fildes, mode);
     explain_output_error_and_die("%s", message);  * }

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