explain_socket(3) Library Functions Manual explain_socket(3)
NAME
explain_socket - explain socket(2) errors
SYNOPSIS
#include <libexplain/socket.h>
const char *explain_socket(int domain, int type, int protocol);
const char *explain_errno_socket(int errnum, int domain, int type, int protocol);
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);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by the socket(2) system call.
explain_socket
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:
if (socket(domain, type, protocol) < 0)
{
fprintf(stderr, "%s
", explain_socket(domain, type, protocol));
exit(EXIT_FAILURE);
}
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.
explain_errno_socket
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 mes-
sage 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:
if (socket(domain, type, protocol) < 0)
{
int err = errno;
fprintf(stderr, "%s
", explain_errno_socket(err,
domain, type, protocol));
exit(EXIT_FAILURE);
}
errnum The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is neces-
sary 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.
explain_message_socket
void explain_message_socket(char *message, int message_size, int domain, int type, int protocol);
The explain_message_socket function may be 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:
if (socket(domain, type, protocol) < 0)
{
char message[3000];
explain_message_socket(message, sizeof(message), domain, type, protocol);
fprintf(stderr, "%s
", message);
exit(EXIT_FAILURE);
}
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.
explain_message_errno_socket
void explain_message_errno_socket(char *message, int message_size, int errnum, int domain, int type, int protocol);
The explain_message_errno_socket function may be 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:
if (socket(domain, type, protocol) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_socket(message, sizeof(message), err,
domain, type, protocol);
fprintf(stderr, "%s
", message);
exit(EXIT_FAILURE);
}
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 neces-
sary 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.
SEE ALSO
socket(2)
create an endpoint for communication
explain_socket_or_die(3)
create an endpoint for communication and report errors
COPYRIGHT
libexplain version 0.52
Copyright (C) 2008 Peter Miller
explain_socket(3)