libexplain/mount.h File Reference

explain mount(2) errors More...

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

Go to the source code of this file.

Functions
void	explain_mount_or_die (const char *source, const char *target, const char *file_system_type, unsigned long flags, const void *data)
int	explain_mount_on_error (const char *source, const char *target, const char *file_system_type, unsigned long flags, const void *data)
const char *	explain_mount (const char *source, const char *target, const char *file_system_type, unsigned long flags, const void *data) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_mount (int errnum, const char *source, const char *target, const char *file_system_type, unsigned long flags, const void *data) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_mount (char *message, int message_size, const char *source, const char *target, const char *file_system_type, unsigned long flags, const void *data)
void	explain_message_errno_mount (char *message, int message_size, int errnum, const char *source, const char *target, const char *file_system_type, unsigned long flags, const void *data)

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Detailed Description

explain mount(2) errors

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

Definition in file mount.h.

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Function Documentation

const char* explain_errno_mount	(	int	errnum,
		const char *	source,
		const char *	target,
		const char *	file_system_type,
		unsigned long	flags,
		const void *	data
	)

The explain_errno_mount function is used to obtain an explanation of an error returned by the mount(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.
source	The original source, exactly as passed to the mount(2) system call.
target	The original target, exactly as passed to the mount(2) system call.
file_system_type	The original file_system_type, exactly as passed to the mount(2) system call.
flags	The original flags, exactly as passed to the mount(2) system call.
data	The original data, exactly as passed to the mount(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 (mount(source, target, file_system_type, flags, data) < 0)
 {
     int err = errno;
     explain_output_error_and_die("%s", explain_errno_mount(err, source,
         target, file_system_type, flags, data));
 }

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

void explain_message_errno_mount	(	char *	message,
		int	message_size,
		int	errnum,
		const char *	source,
		const char *	target,
		const char *	file_system_type,
		unsigned long	flags,
		const void *	data
	)

The explain_message_errno_mount function is used to obtain an explanation of an error returned by the mount(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.
source	The original source, exactly as passed to the mount(2) system call.
target	The original target, exactly as passed to the mount(2) system call.
file_system_type	The original file_system_type, exactly as passed to the mount(2) system call.
flags	The original flags, exactly as passed to the mount(2) system call.
data	The original data, exactly as passed to the mount(2) system call.

Example:

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

 if (mount(source, target, file_system_type, flags, data) < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_mount(message, sizeof(message), err, source,
         target, file_system_type, flags, data);
     explain_output_error_and_die("%s", message);
 }

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

void explain_message_mount	(	char *	message,
		int	message_size,
		const char *	source,
		const char *	target,
		const char *	file_system_type,
		unsigned long	flags,
		const void *	data
	)

The explain_message_mount function is used to obtain an explanation of an error returned by the mount(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.
source	The original source, exactly as passed to the mount(2) system call.
target	The original target, exactly as passed to the mount(2) system call.
file_system_type	The original file_system_type, exactly as passed to the mount(2) system call.
flags	The original flags, exactly as passed to the mount(2) system call.
data	The original data, exactly as passed to the mount(2) system call.

Example:

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

 if (mount(source, target, file_system_type, flags, data) < 0)
 {
     char message[3000];
     explain_message_mount(message, sizeof(message), source, target,
         file_system_type, flags, data);
     explain_output_error_and_die("%s", message);  * }

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

const char* explain_mount	(	const char *	source,
		const char *	target,
		const char *	file_system_type,
		unsigned long	flags,
		const void *	data
	)

The explain_mount function is used to obtain an explanation of an error returned by the mount(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:

source	The original source, exactly as passed to the mount(2) system call.
target	The original target, exactly as passed to the mount(2) system call.
file_system_type	The original file_system_type, exactly as passed to the mount(2) system call.
flags	The original flags, exactly as passed to the mount(2) system call.
data	The original data, exactly as passed to the mount(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 (mount(source, target, file_system_type, flags, data) < 0)
 {
     explain_output_error_and_die("%s\n", explain_mount(source, target,
         file_system_type, flags, data));
 }

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

int explain_mount_on_error	(	const char *	source,
		const char *	target,
		const char *	file_system_type,
		unsigned long	flags,
		const void *	data
	)

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

Parameters:

source	The source, exactly as to be passed to the mount(2) system call.
target	The target, exactly as to be passed to the mount(2) system call.
file_system_type	The file_system_type, exactly as to be passed to the mount(2) system call.
flags	The flags, exactly as to be passed to the mount(2) system call.
data	The data, exactly as to be passed to the mount(2) system call.

Returns:

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

Example:

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

 if (explain_mount_on_error(source, target, file_system_type, flags, data) <
     0)
 {
     ...cope with error
     ...no need to print error message
 }

void explain_mount_or_die	(	const char *	source,
		const char *	target,
		const char *	file_system_type,
		unsigned long	flags,
		const void *	data
	)

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

Parameters:

source	The source, exactly as to be passed to the mount(2) system call.
target	The target, exactly as to be passed to the mount(2) system call.
file_system_type	The file_system_type, exactly as to be passed to the mount(2) system call.
flags	The flags, exactly as to be passed to the mount(2) system call.
data	The data, exactly as to be passed to the mount(2) system call.

Returns:

This function only returns on success, see mount(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_mount_or_die(source, target, file_system_type, flags, data);