NAME

       explain_getaddrinfo - explain getaddrinfo(3) errors

SYNOPSIS

       #include <libexplain/getaddrinfo.h>
       const char *explain_errcode_getaddrinfo(int errnum, const char *node, const char *service,
       const struct addrinfo *hints, struct addrinfo **res);
       void explain_message_errcode_getaddrinfo(char  *message,  int  message_size,  int  errnum,
       const  char  *node,  const  char  *service,  const struct addrinfo *hints, struct addrinfo
       **res);

DESCRIPTION

       These  functions  may  be  used  to  obtain  explanations  for  errors  returned  by   the
       getaddrinfo(3) system call.

   explain_errcode_getaddrinfo
       const char *explain_errcode_getaddrinfo(int errnum, const char *node, const char *service,
       const struct addrinfo *hints, struct addrinfo **res);

       The explain_errcode_getaddrinfo function is used to obtain  an  explanation  of  an  error
       returned  by  the  getaddrinfo(3)  system call.  The least the message will contain is the
       value of gai_strerror(errcode), 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:
              int errcode = getaddrinfo(node, service, hints, res);
              if (errncode == GAI_SYSTEM)
                  errcode = errno;
              if (errcode)
              {
                  fprintf(stderr, "%s\n", explain_errcode_getaddrinfo(errcode,
                      node, service, hints, res));
                  exit(EXIT_FAILURE);
              }

       The above code example is available as the explain_getaddrinfo_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.

       node    The original node, exactly as passed to the getaddrinfo(3) system call.

       service The original service, exactly as passed to the getaddrinfo(3) system call.

       hints   The original hints, exactly as passed to the getaddrinfo(3) system call.

       res     The original res, exactly as passed to the getaddrinfo(3) 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_errno_getaddrinfo
       void explain_message_errno_getaddrinfo(char *message, int message_size, int errnum,  const
       char *node, const char *service, const struct addrinfo *hints, struct addrinfo **res);

       The  explain_message_errno_getaddrinfo function may be used to obtain an explanation of an
       error returned by the getaddrinfo(3) 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:
              int errcode = getaddrinfo(node, service, hints, res);
              if (errnode == EAI_SYSTEM)
                  errcode = errno;
              if (errcode)
              {
                  char message[3000];
                  explain_message_errcode_getaddrinfo(message, sizeof(message),
                      errcode, node, service, hints, res);
                  fprintf(stderr, "%s\n", message);
                  exit(EXIT_FAILURE);
              }

       The above code example is  available  pre‐packaged  as  the  explain_getaddrinfo_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.

       node    The original node, exactly as passed to the getaddrinfo(3) system call.

       service The original service, exactly as passed to the getaddrinfo(3) system call.

       hints   The original hints, exactly as passed to the getaddrinfo(3) system call.

       res     The original res, exactly as passed to the getaddrinfo(3) system call.

SEE ALSO

       getaddrinfo(3)
               network address and

       explain_getaddrinfo_or_die(3)
               network address and and report errors

COPYRIGHT

       libexplain version 1.4
       Copyright (C) 2008 Peter Miller

                                                                           explain_getaddrinfo(3)