DOKK / manpages / debian 12 / libexplain-dev / explain_accept4.3.en
explain_accept4(3) Library Functions Manual explain_accept4(3)

explain_accept4 - explain accept4(2) errors

#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);

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

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.

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

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.

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

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.

The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.
The size in bytes of the location in which to store the returned message.
The original fildes, exactly as passed to the accept4(2) system call.
The original sock_addr, exactly as passed to the accept4(2) system call.
The original sock_addr_size, exactly as passed to the accept4(2) system call.
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.

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.

The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.
The size in bytes of the location in which to store the returned message.
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.
The original fildes, exactly as passed to the accept4(2) system call.
The original sock_addr, exactly as passed to the accept4(2) system call.
The original sock_addr_size, exactly as passed to the accept4(2) system call.
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.

accept4(2)
accept a connection on a socket
explain_accept4_or_die(3)
accept a connection on a socket and report errors

libexplain version 1.4
Copyright (C) 2009 Peter Miller