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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 0.19
       Copyright (C) 2009 Peter Miller

                                                        explain_getpeername(3)