glibc/misc/getusershell.c

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/*
* Copyright (c) 1985, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getusershell.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/param.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdio_ext.h>
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#include <ctype.h>
#include <stdlib.h>
#include <unistd.h>
#include <paths.h>
/*
* Local shells should NOT be added here. They should be added in
* /etc/shells.
*/
static const char *okshells[] = { _PATH_BSHELL, _PATH_CSHELL, NULL };
static char **curshell, **shells, *strings;
static char **initshells __P((void));
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/*
* Get a list of shells from _PATH_SHELLS, if it exists.
*/
char *
getusershell()
{
char *ret;
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if (curshell == NULL)
curshell = initshells();
ret = *curshell;
if (ret != NULL)
curshell++;
return (ret);
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}
void
endusershell()
{
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if (shells != NULL)
free(shells);
shells = NULL;
if (strings != NULL)
free(strings);
strings = NULL;
curshell = NULL;
}
void
setusershell()
{
curshell = initshells();
}
static char **
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initshells()
{
register char **sp, *cp;
register FILE *fp;
struct stat64 statb;
int flen;
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if (shells != NULL)
free(shells);
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shells = NULL;
if (strings != NULL)
free(strings);
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strings = NULL;
if ((fp = fopen(_PATH_SHELLS, "r")) == NULL)
return (char **) okshells;
if (fstat64(fileno(fp), &statb) == -1) {
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(void)fclose(fp);
return (char **) okshells;
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}
if ((strings = malloc((u_int)statb.st_size + 1)) == NULL) {
(void)fclose(fp);
return (char **) okshells;
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}
shells = calloc((unsigned)statb.st_size / 3, sizeof (char *));
if (shells == NULL) {
(void)fclose(fp);
free(strings);
strings = NULL;
return (char **) okshells;
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}
/* No threads using this stream. */
__fsetlocking (fp, FSETLOCKING_BYCALLER);
sp = shells;
cp = strings;
flen = statb.st_size;
while (fgets_unlocked(cp, flen - (cp - strings), fp) != NULL) {
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while (*cp != '#' && *cp != '/' && *cp != '\0')
cp++;
if (*cp == '#' || *cp == '\0')
continue;
*sp++ = cp;
while (!isspace(*cp) && *cp != '#' && *cp != '\0')
cp++;
*cp++ = '\0';
}
*sp = NULL;
(void)fclose(fp);
return (shells);
}