libexplain/socket.h File Reference

explain socket(2) errors More...

#include <libexplain/gcc_attributes.h>

Go to the source code of this file.

Functions
int	explain_socket_or_die (int domain, int type, int protocol)
int	explain_socket_on_error (int domain, int type, int protocol) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_socket (int domain, int type, int protocol) LIBEXPLAIN_WARN_UNUSED_RESULT
const char *	explain_errno_socket (int errnum, int domain, int type, int protocol) LIBEXPLAIN_WARN_UNUSED_RESULT
void	explain_message_socket (char *message, int message_size, int domain, int type, int protocol)
void	explain_message_errno_socket (char *message, int message_size, int errnum, int domain, int type, int protocol)

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Detailed Description

explain socket(2) errors

Definition in file socket.h.

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Function Documentation

const char* explain_errno_socket	(	int	errnum,
		int	domain,
		int	type,
		int	protocol
	)

The explain_errno_socket function is used to obtain an explanation of an error returned by the socket(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:

 int fildes = socket(domain, type, protocol);
 if (fildes < 0)
 {
     int err = errno;
     fprintf(stderr, "%s\n", explain_errno_socket(err, domain, type,
         protocol));
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_socket_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.
domain	The original domain, exactly as passed to the socket(2) system call.
type	The original type, exactly as passed to the socket(2) system call.
protocol	The original protocol, exactly as passed to the socket(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_socket	(	char *	message,
		int	message_size,
		int	errnum,
		int	domain,
		int	type,
		int	protocol
	)

The explain_message_errno_socket function is used to obtain an explanation of an error returned by the socket(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:

 int fildes = socket(domain, type, protocol);
 if (fildes < 0)
 {
     int err = errno;
     char message[3000];
     explain_message_errno_socket(message, sizeof(message), err, domain,
         type, protocol);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_socket_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.
domain	The original domain, exactly as passed to the socket(2) system call.
type	The original type, exactly as passed to the socket(2) system call.
protocol	The original protocol, exactly as passed to the socket(2) system call.

void explain_message_socket	(	char *	message,
		int	message_size,
		int	domain,
		int	type,
		int	protocol
	)

The explain_message_socket function is used to obtain an explanation of an error returned by the socket(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:

 int fildes = socket(domain, type, protocol);
 if (fildes < 0)
 {
     char message[3000];
     explain_message_socket(message, sizeof(message), domain, type,
         protocol);
     fprintf(stderr, "%s\n", message);
     exit(EXIT_FAILURE);
 }

The above code example is available pre-packaged as the explain_socket_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.
domain	The original domain, exactly as passed to the socket(2) system call.
type	The original type, exactly as passed to the socket(2) system call.
protocol	The original protocol, exactly as passed to the socket(2) system call.

const char* explain_socket	(	int	domain,
		int	type,
		int	protocol
	)

The explain_socket function is used to obtain an explanation of an error returned by the socket(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:

 int fildes = socket(domain, type, protocol);
 if (fildes < 0)
 {
     fprintf(stderr, "%s\n", explain_socket(domain, type, protocol));
     exit(EXIT_FAILURE);
 }

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

Parameters:

domain	The original domain, exactly as passed to the socket(2) system call.
type	The original type, exactly as passed to the socket(2) system call.
protocol	The original protocol, exactly as passed to the socket(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_socket_on_error	(	int	domain,
		int	type,
		int	protocol
	)

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

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

 int fildes = explain_socket_on_error(domain, type, protocol);
 if (fildes < 0)
 {
     ...cope with error
     ...no need to print error message
 }

Parameters:

domain	The domain, exactly as to be passed to the socket(2) system call.
type	The type, exactly as to be passed to the socket(2) system call.
protocol	The protocol, exactly as to be passed to the socket(2) system call.

Returns:

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

int explain_socket_or_die	(	int	domain,
		int	type,
		int	protocol
	)

The explain_socket_or_die function is used to call the socket(2) system call. On failure an explanation will be printed to stderr, obtained from the explain_socket(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:

 int fildes = explain_socket_or_die(domain, type, protocol);

Parameters:

domain	The domain, exactly as to be passed to the socket(2) system call.
type	The type, exactly as to be passed to the socket(2) system call.
protocol	The protocol, exactly as to be passed to the socket(2) system call.

Returns:

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