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/* Copyright (c) 2001 Neal H Walfield <neal@cs.uml.edu>.
This file is placed into the public domain. Its distribution
is unlimited.
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* NAME
xgethostname - get the host name.
SYNOPSIS
char *xgethostname (void);
DESCRIPTION
The xhostname function is intended to replace gethostname(2), a
function used to access the host name. The old interface is
inflexable given that it assumes the existance of the
MAXHOSTNAMELEN macro, which neither POSIX nor the proposed
Single Unix Specification version 3 guarantee to be defined.
RETURN VALUE
On success, a malloced, null terminated (possibly truncated)
string containing the host name is returned. On failure,
NULL is returned and errno is set.
*/
#include <sys/param.h> /* For MAXHOSTNAMELEN */
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
char *
xgethostname (void)
{
int size = 0;
int addnull = 0;
char *buf;
int err;
#ifdef MAXHOSTNAMELEN
size = MAXHOSTNAMELEN;
addnull = 1;
#else /* MAXHOSTNAMELEN */
#ifdef _SC_HOST_NAME_MAX
size = sysconf (_SC_HOST_NAME_MAX);
addnull = 1;
#endif /* _SC_HOST_NAME_MAX */
if (size <= 0)
size = 256;
#endif /* MAXHOSTNAMELEN */
buf = malloc (size + addnull);
if (! buf)
{
errno = ENOMEM;
return NULL;
}
err = gethostname (buf, size);
while (err == -1 && errno == ENAMETOOLONG)
{
free (buf);
size *= 2;
buf = malloc (size + addnull);
if (! buf)
{
errno = ENOMEM;
return NULL;
}
err = gethostname (buf, size);
}
if (err)
{
if (buf)
free (buf);
errno = err;
return NULL;
}
if (addnull)
buf[size] = '\0';
return buf;
}
#ifdef WANT_TO_TEST_XGETHOSTNAME
#include <stdio.h>
#include <string.h>
int
main (int argc, char *argv[])
{
char *hostname;
hostname = xgethostname ();
if (! hostname)
{
perror ("xgethostname");
return 1;
}
printf ("%s\n", hostname);
free (hostname);
return 0;
}
#endif /* WANT_TO_TEST_XGETHOSTNAME */
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