libexplain/mmap.h File Reference

explain mmap(2) errors More...

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

Go to the source code of this file.

Functions
void *	explain_mmap_or_die (void *data, size_t data_size, int prot, int flags, int fildes, off_t offset)
void *	explain_mmap_on_error (void *data, size_t data_size, int prot, int flags, int fildes, off_t offset)
const char *	explain_mmap (void *data, size_t data_size, int prot, int flags, int fildes, off_t offset) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_mmap (int errnum, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_mmap (char *message, int message_size, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset)
void	explain_message_errno_mmap (char *message, int message_size, int errnum, void *data, size_t data_size, int prot, int flags, int fildes, off_t offset)

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Detailed Description

explain mmap(2) errors

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

Definition in file mmap.h.

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Function Documentation

const char* explain_errno_mmap	(	int	errnum,
		void *	data,
		size_t	data_size,
		int	prot,
		int	flags,
		int	fildes,
		off_t	offset
	)

The explain_errno_mmap function is used to obtain an explanation of an error returned by the mmap(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.
data	The original data, exactly as passed to the mmap(2) system call.
data_size	The original data_size, exactly as passed to the mmap(2) system call.
prot	The original prot, exactly as passed to the mmap(2) system call.
flags	The original flags, exactly as passed to the mmap(2) system call.
fildes	The original fildes, exactly as passed to the mmap(2) system call.
offset	The original offset, exactly as passed to the mmap(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:

 void *result = mmap(data, data_size, prot, flags, fildes, offset);
 if (!result)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_mmap(err, data, data_size, prot,
         flags, fildes, offset));
     exit(EXIT_FAILURE);
 }

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

void explain_message_errno_mmap	(	char *	message,
		int	message_size,
		int	errnum,
		void *	data,
		size_t	data_size,
		int	prot,
		int	flags,
		int	fildes,
		off_t	offset
	)

The explain_message_errno_mmap function is used to obtain an explanation of an error returned by the mmap(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.
data	The original data, exactly as passed to the mmap(2) system call.
data_size	The original data_size, exactly as passed to the mmap(2) system call.
prot	The original prot, exactly as passed to the mmap(2) system call.
flags	The original flags, exactly as passed to the mmap(2) system call.
fildes	The original fildes, exactly as passed to the mmap(2) system call.
offset	The original offset, exactly as passed to the mmap(2) system call.

Example:

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

 void *result = mmap(data, data_size, prot, flags, fildes, offset);
 if (!result)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_mmap(message, sizeof(message), err, data,
         data_size, prot, flags, fildes, offset);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

void explain_message_mmap	(	char *	message,
		int	message_size,
		void *	data,
		size_t	data_size,
		int	prot,
		int	flags,
		int	fildes,
		off_t	offset
	)

The explain_message_mmap function is used to obtain an explanation of an error returned by the mmap(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.
data	The original data, exactly as passed to the mmap(2) system call.
data_size	The original data_size, exactly as passed to the mmap(2) system call.
prot	The original prot, exactly as passed to the mmap(2) system call.
flags	The original flags, exactly as passed to the mmap(2) system call.
fildes	The original fildes, exactly as passed to the mmap(2) system call.
offset	The original offset, exactly as passed to the mmap(2) system call.

Example:

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

 void *result = mmap(data, data_size, prot, flags, fildes, offset);
 if (!result)
 {
     char message[3000];
     explain_message_mmap(message, sizeof(message), data, data_size, prot,
         flags, fildes, offset);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

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

const char* explain_mmap	(	void *	data,
		size_t	data_size,
		int	prot,
		int	flags,
		int	fildes,
		off_t	offset
	)

The explain_mmap function is used to obtain an explanation of an error returned by the mmap(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:

data	The original data, exactly as passed to the mmap(2) system call.
data_size	The original data_size, exactly as passed to the mmap(2) system call.
prot	The original prot, exactly as passed to the mmap(2) system call.
flags	The original flags, exactly as passed to the mmap(2) system call.
fildes	The original fildes, exactly as passed to the mmap(2) system call.
offset	The original offset, exactly as passed to the mmap(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:

 void *result = mmap(data, data_size, prot, flags, fildes, offset);
 if (!result)
 {
     fprintf(stderr, "%s\n", explain_mmap(data, data_size, prot, flags,
         fildes, offset));
     exit(EXIT_FAILURE);
 }

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

void* explain_mmap_on_error	(	void *	data,
		size_t	data_size,
		int	prot,
		int	flags,
		int	fildes,
		off_t	offset
	)

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

Parameters:

data	The data, exactly as to be passed to the mmap(2) system call.
data_size	The data_size, exactly as to be passed to the mmap(2) system call.
prot	The prot, exactly as to be passed to the mmap(2) system call.
flags	The flags, exactly as to be passed to the mmap(2) system call.
fildes	The fildes, exactly as to be passed to the mmap(2) system call.
offset	The offset, exactly as to be passed to the mmap(2) system call.

Returns:

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

Example:

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

 void *result = explain_mmap_on_error(data, data_size, prot, flags, fildes,
     offset);
 if (!result)
 {
     ...cope with error
     ...no need to print error message
 }

void* explain_mmap_or_die	(	void *	data,
		size_t	data_size,
		int	prot,
		int	flags,
		int	fildes,
		off_t	offset
	)

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

Parameters:

data	The data, exactly as to be passed to the mmap(2) system call.
data_size	The data_size, exactly as to be passed to the mmap(2) system call.
prot	The prot, exactly as to be passed to the mmap(2) system call.
flags	The flags, exactly as to be passed to the mmap(2) system call.
fildes	The fildes, exactly as to be passed to the mmap(2) system call.
offset	The offset, exactly as to be passed to the mmap(2) system call.

Returns:

This function only returns on success, see mmap(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_mmap_or_die(data, data_size, prot, flags, fildes, offset);