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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\n", 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  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;
                  fprintf(stderr, "%s\n", 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
               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.

       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\n", 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\n", 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
               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.

       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 0.19
       Copyright (C) 2008 Peter Miller

                                                             explain_socket(3)