87 lines
2.4 KiB
C
87 lines
2.4 KiB
C
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/* xgethostname.c -- return current hostname with unlimited length
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Copyright (C) 1992, 1996, 2000-2001, 2003-2006, 2009-2020 Free Software
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Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* written by Jim Meyering */
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#include <config.h>
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/* Specification. */
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#include "xgethostname.h"
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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include "xalloc.h"
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#ifndef INITIAL_HOSTNAME_LENGTH
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# define INITIAL_HOSTNAME_LENGTH 34
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#endif
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/* Return the current hostname in malloc'd storage.
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If malloc fails, exit.
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Upon any other failure, return NULL and set errno. */
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char *
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xgethostname (void)
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{
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char *hostname = NULL;
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size_t size = INITIAL_HOSTNAME_LENGTH;
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while (1)
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{
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/* Use SIZE_1 here rather than SIZE to work around the bug in
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SunOS 5.5's gethostname whereby it NUL-terminates HOSTNAME
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even when the name is as long as the supplied buffer. */
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size_t size_1;
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hostname = x2realloc (hostname, &size);
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size_1 = size - 1;
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hostname[size_1 - 1] = '\0';
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errno = 0;
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if (gethostname (hostname, size_1) == 0)
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{
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if (! hostname[size_1 - 1])
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break;
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}
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else if (errno != 0 && errno != ENAMETOOLONG && errno != EINVAL
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/* OSX/Darwin does this when the buffer is not large enough */
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&& errno != ENOMEM)
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{
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int saved_errno = errno;
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free (hostname);
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errno = saved_errno;
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return NULL;
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}
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}
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/* Shrink HOSTNAME before returning it. */
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{
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size_t actual_size = strlen (hostname) + 1;
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if (actual_size < size)
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{
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char *shrinked_hostname = realloc (hostname, actual_size);
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if (shrinked_hostname != NULL)
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hostname = shrinked_hostname;
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}
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}
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return hostname;
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}
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