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)