explain_accept4(3)

NAME
explain_accept4 - explain accept4(2) errors

SYNOPSIS
#include <libexplain/accept4.h>

const char *explain_accept4(int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags);
const char *explain_errno_accept4(int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags);
void explain_message_accept4(char *message, int message_size, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags);
void explain_message_errno_accept4(char *message, int message_size, int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags);

DESCRIPTION
These functions may be used to obtain explanations for errors returned by the accept4(2) system call.

  explain_accept4
const char *explain_accept4(int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags);

The explain_accept4 function is used to obtain an explanation of an error returned by the accept4(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.

fildes
    The original fildes, exactly as passed to the accept4(2) system call.

sock_addr
    The original sock_addr, exactly as passed to the accept4(2) system call.

sock_addr_size
    The original sock_addr_size, exactly as passed to the accept4(2) system call.

flags
    The original flags, exactly as passed to the accept4(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:
    int result = accept4(fildes, sock_addr, sock_addr_size, flags);
    if (result < 0)
    {
    fprintf(stderr, "%s\n", explain_accept4(fildes, sock_addr, sock_addr_size, flags));
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_accept4_or_die(3) function.

  explain_errno_accept4
const char *explain_errno_accept4(int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags);

The explain_errno_accept4 function is used to obtain an explanation of an error returned by the accept4(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.

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.

fildes
    The original fildes, exactly as passed to the accept4(2) system call.

sock_addr
    The original sock_addr, exactly as passed to the accept4(2) system call.

sock_addr_size
    The original sock_addr_size, exactly as passed to the accept4(2) system call.

flags
    The original flags, exactly as passed to the accept4(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:
    int result = accept4(fildes, sock_addr, sock_addr_size, flags);
    if (result < 0)
    {
        int err = errno;
    fprintf(stderr, "%s\n", explain_errno_accept4(err, fildes, sock_addr, sock_addr_size, flags));
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_accept4_or_die(3) function.

  explain_message_accept4
void explain_message_accept4(char *message, int message_size, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags);

The explain_message_accept4 function is used to obtain an explanation of an error returned by the accept4(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.

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 accept4(2) system call.

sock_addr
    The original sock_addr, exactly as passed to the accept4(2) system call.

sock_addr_size
    The original sock_addr_size, exactly as passed to the accept4(2) system call.

flags
    The original flags, exactly as passed to the accept4(2) system call.

Example: This function is intended to be used in a fashion similar to the following example:
    int result = accept4(fildes, sock_addr, sock_addr_size, flags);
    if (result < 0)
    {
        char message[3000];
    explain_message_accept4(message, sizeof(message), fildes, sock_addr, sock_addr_size, flags);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_accept4_or_die(3) function.

  explain_message_errno_accept4
void explain_message_errno_accept4(char *message, int message_size, int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size, int flags);

The explain_message_errno_accept4 function is used to obtain an explanation of an error returned by the accept4(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.

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.

fildes
    The original fildes, exactly as passed to the accept4(2) system call.

sock_addr
    The original sock_addr, exactly as passed to the accept4(2) system call.

sock_addr_size
    The original sock_addr_size, exactly as passed to the accept4(2) system call.

flags
    The original flags, exactly as passed to the accept4(2) system call.

Example: This function is intended to be used in a fashion similar to the following example:
    int result = accept4(fildes, sock_addr, sock_addr_size, flags);
    if (result < 0)
    {
        int err = errno;
        char message[3000];
    explain_message_errno_accept4(message, sizeof(message), err, fildes, sock_addr, sock_addr_size, flags);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

The above code example is available pre-packaged as the explain_accept4_or_die(3) function.

SEE ALSO

accept4(2)
    accept a connection on a socket

explain_accept4_or_die(3)
    accept a connection on a socket and report errors

COPYRIGHT
libexplain version
Copyright (C) 2009 Peter Miller