explain_connect(3) Library Functions Manual explain_connect(3)
NAME
explain_connect - explain connect(2) errors
SYNOPSIS
#include <libexplain/connect.h>
const char *explain_connect(int fildes, const struct sockaddr *serv_addr, int serv_addr_size);
const char *explain_errno_connect(int errnum, int fildes, const struct sockaddr *serv_addr, int serv_addr_size);
void explain_message_connect(char *message, int message_size, int fildes, const struct sockaddr *serv_addr, int serv_addr_size);
void explain_message_errno_connect(char *message, int message_size, int errnum, int fildes, const struct sockaddr *serv_addr, int
serv_addr_size);
DESCRIPTION
These functions may be used to obtain explanations for errors returned by the connect(2) system call.
explain_connect
const char *explain_connect(int fildes, const struct sockaddr *serv_addr, int serv_addr_size);
The explain_connect function is used to obtain an explanation of an error returned by the connect(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 (connect(fildes, serv_addr, serv_addr_size) < 0)
{
fprintf(stderr, "%s
", explain_connect(fildes, serv_addr,
serv_addr_size));
exit(EXIT_FAILURE);
}
fildes The original fildes, exactly as passed to the connect(2) system call.
serv_addr
The original serv_addr, exactly as passed to the connect(2) system call.
serv_addr_size
The original serv_addr_size, exactly as passed to the connect(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_connect
const char *explain_errno_connect(int errnum, int fildes, const struct sockaddr *serv_addr, int serv_addr_size);
The explain_errno_connect function is used to obtain an explanation of an error returned by the connect(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 (connect(fildes, serv_addr, serv_addr_size) < 0)
{
int err = errno;
fprintf(stderr, "%s
", explain_errno_connect(err,
fildes, serv_addr, serv_addr_size));
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.
fildes The original fildes, exactly as passed to the connect(2) system call.
serv_addr
The original serv_addr, exactly as passed to the connect(2) system call.
serv_addr_size
The original serv_addr_size, exactly as passed to the connect(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_connect
void explain_message_connect(char *message, int message_size, int fildes, const struct sockaddr *serv_addr, int serv_addr_size);
The explain_message_connect function may be used to obtain an explanation of an error returned by the connect(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 (connect(fildes, serv_addr, serv_addr_size) < 0)
{
char message[3000];
explain_message_connect(message, sizeof(message),
fildes, serv_addr, serv_addr_size);
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.
fildes The original fildes, exactly as passed to the connect(2) system call.
serv_addr
The original serv_addr, exactly as passed to the connect(2) system call.
serv_addr_size
The original serv_addr_size, exactly as passed to the connect(2) system call.
explain_message_errno_connect
void explain_message_errno_connect(char *message, int message_size, int errnum, int fildes, const struct sockaddr *serv_addr, int
serv_addr_size);
The explain_message_errno_connect function may be used to obtain an explanation of an error returned by the connect(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 (connect(fildes, serv_addr, serv_addr_size) < 0)
{
int err = errno;
char message[3000];
explain_message_errno_connect(message, sizeof(message), err,
fildes, serv_addr, serv_addr_size);
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.
fildes The original fildes, exactly as passed to the connect(2) system call.
serv_addr
The original serv_addr, exactly as passed to the connect(2) system call.
serv_addr_size
The original serv_addr_size, exactly as passed to the connect(2) system call.
SEE ALSO
connect(2)
initiate a connection on a socket
explain_connect_or_die(3)
initiate a connection on a socket and report errors
COPYRIGHT
libexplain version 0.52
Copyright (C) 2008 Peter Miller
explain_connect(3)