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freebsd/lib/libc/gen/check_utility_compat.c
Garrett Wollman c9885518de Create a small library function, check_utility_compat(3), to determine
whether a named utility should behave in FreeBSD 4.x-compatible mode
or in a standard mode (default standard).  The configuration is done
malloc(3)-style, with either an environment variable or a symlink.

Update expr(1) to use this new interface.
2002-10-28 00:15:43 +00:00

76 lines
2.4 KiB
C

/*
* Copyright 2002 Massachusetts Institute of Technology
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby
* granted, provided that both the above copyright notice and this
* permission notice appear in all copies, that both the above
* copyright notice and this permission notice appear in all
* supporting documentation, and that the name of M.I.T. not be used
* in advertising or publicity pertaining to distribution of the
* software without specific, written prior permission. M.I.T. makes
* no representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied
* warranty.
*
* THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
* ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
* SHALL M.I.T. 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* I din't use "namespace.h" here because none of the relevant utilities
* are threaded, so I'm not concerned about cancellation points or other
* niceties.
*/
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifndef LINE_MAX
#define LINE_MAX _POSIX2_LINE_MAX
#endif
#define _PATH_UTIL_COMPAT "/etc/compat-FreeBSD-4-util"
#define _ENV_UTIL_COMPAT "_COMPAT_FreeBSD_4"
int
check_utility_compat(const char *utility)
{
char buf[LINE_MAX];
char *p, *bp;
int len;
if ((p = getenv(_ENV_UTIL_COMPAT)) != NULL) {
strlcpy(buf, p, sizeof buf);
} else {
if ((len = readlink(_PATH_UTIL_COMPAT, buf, sizeof buf)) < 0)
return 0;
if (len > sizeof buf)
len = sizeof buf;
buf[len] = '\0';
}
if (buf[0] == '\0')
return 1;
bp = buf;
while ((p = strsep(&bp, ",")) != NULL) {
if (strcmp(p, utility) == 0)
return 1;
}
return 0;
}