explain_getpeername(3)

NAME
explain_getpeername - explain getpeername(2) errors

SYNOPSIS
#include <libexplain/getpeername.h>

const char *explain_getpeername(int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size);
const char *explain_errno_getpeername(int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size);
void explain_message_getpeername(char *message, int message_size, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size);
void explain_message_errno_getpeername(char *message, int message_size, int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size);

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

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

The explain_getpeername function is used to obtain an explanation of an error returned by the getpeername(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:
    struct sockaddr sock_addr;
    socklen_t sock_addr_len = sizeof(sock_addr);
    if (getpeername(fildes, &sock_addr, &sock_addr_size) < 0)
    {
        fprintf(stderr, "%s\n", explain_getpeername(fildes,
            &sock_addr, &sock_addr_size));
        exit(EXIT_FAILURE);
    }

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

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

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

sock_addr_size
    The original sock_addr_size, exactly as passed to the getpeername(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_getpeername
const char *explain_errno_getpeername(int errnum, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size);

The explain_errno_getpeername function is used to obtain an explanation of an error returned by the getpeername(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:
    struct sockaddr sock_addr;
    socklen_t sock_addr_len = sizeof(sock_addr);
    if (getpeername(fildes, &sock_addr, &sock_addr_size) < 0)
    {
        int err = errno;
        fprintf(stderr, "%s\n", explain_errno_getpeername(err,
            fildes, &sock_addr, &sock_addr_size));
        exit(EXIT_FAILURE);
    }

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

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 getpeername(2) system call.

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

sock_addr_size
    The original sock_addr_size, exactly as passed to the getpeername(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_getpeername
void explain_message_getpeername(char *message, int message_size, int fildes, struct sockaddr *sock_addr, socklen_t *sock_addr_size);

The explain_message_getpeername function may be used to obtain an explanation of an error returned by the getpeername(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:
    struct sockaddr sock_addr;
    socklen_t sock_addr_len = sizeof(sock_addr);
    if (getpeername(fildes, &sock_addr, &sock_addr_size) < 0)
    {
        char message[3000];
        explain_message_getpeername(message, sizeof(message),
            fildes, &sock_addr, &sock_addr_size);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

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

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 getpeername(2) system call.

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

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

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

The explain_message_errno_getpeername function may be used to obtain an explanation of an error returned by the getpeername(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:
    struct sockaddr sock_addr;
    socklen_t sock_addr_len = sizeof(sock_addr);
    if (getpeername(fildes, &sock_addr, &sock_addr_size) < 0)
    {
        int err = errno;
        char message[3000];
        explain_message_errno_getpeername(message, sizeof(message),
            err, fildes, &sock_addr, &sock_addr_size);
        fprintf(stderr, "%s\n", message);
        exit(EXIT_FAILURE);
    }

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

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 getpeername(2) system call.

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

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

SEE ALSO

getpeername(2)
    get name of connected peer socket

explain_getpeername_or_die(3)
    get name of connected peer socket and report errors

COPYRIGHT
libexplain version 1.1
Copyright (C) 2009 Peter Miller