/*      $OpenBSD: which.c,v 1.27 2019/01/25 00:19:27 millert Exp $      */

/*
 * Copyright (c) 1997 Todd C. Miller <millert@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/stat.h>
#include <sys/sysctl.h>

#include <err.h>
#include <errno.h>
#include <limits.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define PROG_WHICH      1
#define PROG_WHEREIS    2

extern char *__progname;

int findprog(char *, char *, int, int);
static void __dead usage(void);

/*
 * which(1) -- find an executable(s) in the user's path
 * whereis(1) -- find an executable(s) in the default user path
 *
 * Return values:
 *      0 - all executables found
 *      1 - some found, some not
 *      2 - none found
 */

int
main(int argc, char *argv[])
{
        char *path;
        size_t n;
        int ch, allmatches = 0, notfound = 0, progmode = PROG_WHICH;

        while ((ch = getopt(argc, argv, "a")) != -1)
                switch (ch) {
                case 'a':
                        allmatches = 1;
                        break;
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (argc == 0)
                usage();

        if (strcmp(__progname, "whereis") == 0) {
                progmode = PROG_WHEREIS;
                path = _PATH_STDPATH;
        } else {
                if ((path = getenv("PATH")) == NULL || *path == '\0')
                        path = _PATH_DEFPATH;
        }

        /* To make access(2) do what we want */
        if (setgid(getegid()))
                err(1, "Can't set gid to %u", getegid());
        if (setuid(geteuid()))
                err(1, "Can't set uid to %u", geteuid());

        if (pledge("stdio rpath", NULL) == -1)
                err(2, "pledge");

        for (n = 0; n < argc; n++)
                if (findprog(argv[n], path, progmode, allmatches) == 0)
                        notfound++;

        return ((notfound == 0) ? 0 : ((notfound == argc) ? 2 : 1));
}

int
findprog(char *prog, char *path, int progmode, int allmatches)
{
        char *p, filename[PATH_MAX];
        int len, rval = 0;
        struct stat sbuf;
        char *pathcpy;

        /* Special case if prog contains '/' */
        if (strchr(prog, '/')) {
                if ((stat(prog, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
                    access(prog, X_OK) == 0) {
                        (void)puts(prog);
                        return (1);
                } else {
                        warnx("%s: Command not found.", prog);
                        return (0);
                }
        }

        if ((path = strdup(path)) == NULL)
                err(1, "strdup");
        pathcpy = path;

        while ((p = strsep(&pathcpy, ":")) != NULL) {
                if (*p == '\0')
                        p = ".";

                len = strlen(p);
                while (len > 0 && p[len-1] == '/')
                        p[--len] = '\0';        /* strip trailing '/' */

                len = snprintf(filename, sizeof(filename), "%s/%s", p, prog);
                if (len < 0 || len >= sizeof(filename)) {
                        warnc(ENAMETOOLONG, "%s/%s", p, prog);
                        free(path);
                        return (0);
                }
                if ((stat(filename, &sbuf) == 0) && S_ISREG(sbuf.st_mode) &&
                    access(filename, X_OK) == 0) {
                        (void)puts(filename);
                        rval = 1;
                        if (!allmatches) {
                                free(path);
                                return (rval);
                        }
                }
        }
        (void)free(path);

        /* whereis(1) is silent on failure. */
        if (!rval && progmode != PROG_WHEREIS)
                warnx("%s: Command not found.", prog);
        return (rval);
}

static void __dead
usage(void)
{
        (void)fprintf(stderr, "usage: %s [-a] name ...\n", __progname);
        exit(1);
}