kc3-lang/gnulib/lib/canon-host.c

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• Hash : e86c5da6
  Author :
  Date : 2018-06-24T16:54:43
  

  canon-host: take GCC9's advice rather than ignoring warning
  
  Pádraig Brady suggested not to ignore this GCC9 advice.
  * lib/canon-host.c: Undo preceding change.
  * lib/canon-host.h: Instead, declare with _GL_ATTRIBUTE_MALLOC.
  

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• lib/canon-host.c

• /* Host name canonicalization
  
     Copyright (C) 2005-2018 Free Software Foundation, Inc.
  
     Written by Derek Price <derek@ximbiot.com>.
  
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 3, or (at your option)
     any later version.
  
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
  
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  
  #include <config.h>
  
  #include "canon-host.h"
  
  #include <string.h>
  #include <netdb.h>
  
  /* Store the last error for the single-threaded version of this function.  */
  static int last_cherror;
  
  /* Single-threaded of wrapper for canon_host_r.  After a NULL return, error
     messages may be retrieved via ch_strerror().  */
  char *
  canon_host (const char *host)
  {
    return canon_host_r (host, &last_cherror);
  }
  
  /* Return a malloc'd string containing the canonical hostname associated with
     HOST, or NULL if a canonical name cannot be determined.  On NULL return,
     if CHERROR is not NULL, set *CHERROR to an error code as returned by
     getaddrinfo().  Use ch_strerror_r() or gai_strerror() to convert a *CHERROR
     value to a string suitable for error messages.
  
     WARNINGS
       HOST must be a string representation of a resolvable name for this host.
       Strings containing an IP address in dotted decimal notation will be
       returned as-is, without further resolution.
  
       The use of the word "canonical" in this context is unfortunate but
       entrenched.  The value returned by this function will be the end result
       of the resolution of any CNAME chains in the DNS.  There may only be one
       such value for any given hostname, though the actual IP address
       referenced by this value and the device using that IP address may each
       actually have any number of such "canonical" hostnames.  See the POSIX
       getaddrinfo spec <http://www.opengroup.org/susv3xsh/getaddrinfo.html">,
       RFC 1034 <https://www.ietf.org/rfc/rfc1034.txt>, & RFC 2181
       <https://www.ietf.org/rfc/rfc2181.txt> for more on what this confusing
       term really refers to. */
  char *
  canon_host_r (char const *host, int *cherror)
  {
    char *retval = NULL;
    static struct addrinfo hints;
    struct addrinfo *res = NULL;
    int status;
  
    hints.ai_flags = AI_CANONNAME;
    status = getaddrinfo (host, NULL, &hints, &res);
    if (!status)
      {
        /* https://lists.gnu.org/r/bug-coreutils/2006-09/msg00300.html
           says Darwin 7.9.0 getaddrinfo returns 0 but sets
           res->ai_canonname to NULL.  */
        retval = strdup (res->ai_canonname ? res->ai_canonname : host);
        if (!retval && cherror)
          *cherror = EAI_MEMORY;
        freeaddrinfo (res);
      }
    else if (cherror)
      *cherror = status;
  
    return retval;
  }
  
  /* Return a string describing the last error encountered by canon_host.  */
  const char *
  ch_strerror (void)
  {
    return gai_strerror (last_cherror);
  }
  

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