libexplain/lchmod.h File Reference

explain lchmod(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_lchmod_or_die (const char *pathname, mode_t mode)
int	explain_lchmod_on_error (const char *pathname, mode_t mode)
const char *	explain_lchmod (const char *pathname, mode_t mode) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_lchmod (int errnum, const char *pathname, mode_t mode) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_lchmod (char *message, int message_size, const char *pathname, mode_t mode)
void	explain_message_errno_lchmod (char *message, int message_size, int errnum, const char *pathname, mode_t mode)

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Detailed Description

explain lchmod(2) errors

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

Definition in file lchmod.h.

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Function Documentation

const char* explain_errno_lchmod	(	int	errnum,
		const char *	pathname,
		mode_t	mode
	)

The explain_errno_lchmod function is used to obtain an explanation of an error returned by the lchmod(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.
pathname	The original pathname, exactly as passed to the lchmod(2) system call.
mode	The original mode, exactly as passed to the lchmod(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 (lchmod(pathname, mode) < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_lchmod(err, pathname, mode));
     exit(EXIT_FAILURE);
 }

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

const char* explain_lchmod	(	const char *	pathname,
		mode_t	mode
	)

The explain_lchmod function is used to obtain an explanation of an error returned by the lchmod(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:

pathname	The original pathname, exactly as passed to the lchmod(2) system call.
mode	The original mode, exactly as passed to the lchmod(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 (lchmod(pathname, mode) < 0)
 {
     fprintf(stderr, "%s\n", explain_lchmod(pathname, mode));
     exit(EXIT_FAILURE);
 }

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

int explain_lchmod_on_error	(	const char *	pathname,
		mode_t	mode
	)

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

Parameters:

pathname	The pathname, exactly as to be passed to the lchmod(2) system call.
mode	The mode, exactly as to be passed to the lchmod(2) system call.

Returns:

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

Example:

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

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

void explain_lchmod_or_die	(	const char *	pathname,
		mode_t	mode
	)

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

Parameters:

pathname	The pathname, exactly as to be passed to the lchmod(2) system call.
mode	The mode, exactly as to be passed to the lchmod(2) system call.

Returns:

This function only returns on success, see lchmod(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_lchmod_or_die(pathname, mode);

void explain_message_errno_lchmod	(	char *	message,
		int	message_size,
		int	errnum,
		const char *	pathname,
		mode_t	mode
	)

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

Example:

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

 if (lchmod(pathname, mode) < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_lchmod(message, sizeof(message), err, pathname,
         mode);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

void explain_message_lchmod	(	char *	message,
		int	message_size,
		const char *	pathname,
		mode_t	mode
	)

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

Example:

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

 if (lchmod(pathname, mode) < 0)
 {
     char message[3000];
     explain_message_lchmod(message, sizeof(message), pathname, mode);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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