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

       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\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.

       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 0.19
       Copyright (C) 2008 Peter Miller

                                                            explain_connect(3)