kc3-lang/gnulib/lib/xgethostname.c

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• Hash : f30ed230
  Author :
  Date : 2021-04-03T16:07:21
  

  xgethostname: reorganize / simplify
  
  xgethostname and xgetdomainname were essentially copies long
  ago, but they’ve diverged.  Bring them back together again
  by implementing the (rarely used) latter in terms of the former.
  And avoid some unnecessary realloc calls while we’re at it.
  * lib/xgetdomainname.c: Rewrite from scratch so that it merely
  includes xgethostname.c with a few preliminaries.
  * lib/xgethostname.c: Generalize so that it can be included
  from xgetdomainname.c.
  (GETANAME, XGETANAME): New macros.
  (INITIAL_HOSTNAME_LENGTH): Remove.  No need for this parameter.
  Use 100 instead, as few hostnames are longer than that.
  (XGETANAME): Try getting the hostname into the stack first,
  as that avoids a malloc call in the usual case.
  Check for both POSIX-style truncation and SunOS 5.5 bug
  in a cleaner way, by simply checking string length.
  Don’t use x2realloc, which wastes time preserving buffer garbage;
  use xpalloc with NULL instead.  Don’t bother shrinking buffer
  in the very rare case where the hostname is longer than sizeof
  buf; it’s not worth the aggravation.
  * modules/xgetdomainname (Depends-on): Remove free-posix, xalloc.
  Add xgethostname.
  

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• lib/xgethostname.c

• /* xgethostname.c -- return current hostname with unlimited length
  
     Copyright (C) 1992, 1996, 2000-2001, 2003-2006, 2009-2021 Free Software
     Foundation, Inc.
  
     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 of the License, 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/>.  */
  
  /* written by Jim Meyering and Paul Eggert */
  
  #include <config.h>
  
  #ifndef GETANAME
  /* Specification.  */
  # include "xgethostname.h"
  # define GETANAME gethostname
  # define XGETANAME xgethostname
  #endif
  
  #include <stdlib.h>
  #include <errno.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "xalloc.h"
  
  /* Return the current host or domain name in malloc'd storage.
     If malloc fails, exit.
     Upon any other failure, return NULL and set errno.  */
  char *
  XGETANAME (void)
  {
    char buf[100];
    idx_t size = sizeof buf;
    char *name = buf;
    char *alloc = NULL;
  
    while (1)
      {
        /* Use SIZE_1 here rather than SIZE to work around the bug in
           SunOS 5.5's gethostname whereby it NUL-terminates HOSTNAME
           even when the name is as long as the supplied buffer.  */
        idx_t size_1 = size - 1;
        name[size_1] = '\0';
        errno = 0;
        if (GETANAME (name, size_1) == 0)
          {
            /* Check whether the name was possibly truncated; POSIX does not
               specify whether a truncated name is null-terminated.  */
            idx_t actual_size = strlen (name) + 1;
            if (actual_size < size_1)
              return alloc ? alloc : xmemdup (name, actual_size);
            errno = 0;
          }
        free (alloc);
        if (errno != 0 && errno != ENAMETOOLONG && errno != EINVAL
            /* macOS/Darwin does this when SIZE_1 is too small.  */
            && errno != ENOMEM)
          return NULL;
        name = alloc = xpalloc (NULL, &size, 1, -1, 1);
      }
  }
  

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