/*      $NetBSD: execvp.c,v 1.32 2024/01/20 14:52:47 christos Exp $     */

/*-
 * Copyright (c) 1991, 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.
 * 3. 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.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)exec.c      8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: execvp.c,v 1.32 2024/01/20 14:52:47 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <unistd.h>
#include <paths.h>
#include "reentrant.h"
#include "extern.h"

#ifdef __weak_alias
__weak_alias(execvp,_execvp)
__weak_alias(execvpe,_execvpe)
#endif

int
execvpe(const char *name, char * const *argv, char * const * envp)
{
        const char **memp;
        int cnt;
        size_t lp, ln;
        int eacces = 0;
        unsigned int etxtbsy = 0;
        char buf[PATH_MAX];
        const char *bp, *path, *p;

        _DIAGASSERT(name != NULL);

        /* "" is not a valid filename; check this before traversing PATH. */
        if (name[0] == '\0') {
                errno = ENOENT;
                goto done;
        }
        ln = strlen(name);
        /* If it's an absolute or relative path name, it's easy. */
        if (strchr(name, '/')) {
                bp = name;
                path = "";
                goto retry;
        }
        bp = buf;

        /* Get the path we're searching. */
        if (!(path = getenv("PATH")))
                path = _PATH_DEFPATH;

        do {
                /* Find the end of this path element. */
                for (p = path; *path != 0 && *path != ':'; path++)
                        continue;
                /*
                 * It's a SHELL path -- double, leading and trailing colons
                 * mean the current directory.
                 */
                if (p == path) {
                        p = ".";
                        lp = 1;
                } else
                        lp = path - p;

                /*
                 * If the path is too long complain.  This is a possible
                 * security issue; given a way to make the path too long
                 * the user may execute the wrong program.
                 */
                if (lp + ln + 2 > sizeof(buf)) {
                        (void)write(STDERR_FILENO, "execvp: ", 8);
                        (void)write(STDERR_FILENO, p, lp);
                        (void)write(STDERR_FILENO, ": path too long\n", 16);
                        continue;
                }
                memcpy(buf, p, lp);
                buf[lp] = '/';
                memcpy(buf + lp + 1, name, ln);
                buf[lp + ln + 1] = '\0';

retry:          (void)execve(bp, argv, envp);
                switch (errno) {
                case EACCES:
                        eacces = 1;
                        break;
                case ENOTDIR:
                case ENOENT:
                        break;
                case ENOEXEC:
                        for (cnt = 0; argv[cnt] != NULL; ++cnt)
                                continue;
                        /*
                         * we can't use malloc here because, if we are doing
                         * vfork+exec, it leaks memory in the parent.
                         */
                        if ((memp = alloca((cnt + 2) * sizeof(*memp))) == NULL)
                                goto done;
                        memp[0] = _PATH_BSHELL;
                        memp[1] = bp;
                        (void)memcpy(&memp[2], &argv[1], cnt * sizeof(*memp));
                        (void)execve(_PATH_BSHELL, __UNCONST(memp), envp);
                        goto done;
                case ETXTBSY:
                        if (etxtbsy < 3)
                                (void)sleep(++etxtbsy);
                        goto retry;
                default:
                        goto done;
                }
        } while (*path++ == ':');       /* Otherwise, *path was NUL */
        if (eacces)
                errno = EACCES;
        else if (!errno)
                errno = ENOENT;
done:
        return (-1);
}

int
execvp(const char *name, char * const *argv)
{
        return execvpe(name, argv, environ);
}