/*      $NetBSD: posix_spawnp.c,v 1.5 2024/11/11 06:49:31 martin Exp $  */

/*-
 * Copyright (c) 2011 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Martin Husemann <martin@NetBSD.org>.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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)
__RCSID("$NetBSD: posix_spawnp.c,v 1.5 2024/11/11 06:49:31 martin Exp $");
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"

#include <assert.h>
#include <errno.h>
#include <paths.h>
#include <spawn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>


int posix_spawnp(pid_t * __restrict pid, const char * __restrict file,
    const posix_spawn_file_actions_t *fa,
    const posix_spawnattr_t * __restrict sa,
    char * const *__restrict cav, char * const *__restrict env)
{
        char fpath[FILENAME_MAX];
        const char *path, *p;
        size_t lp, ln;
        int err;

        _DIAGASSERT(file != NULL);

        /* "" is not a valid filename; check this before traversing PATH. */
        if (file[0] == '\0')
                return ENOENT;

        /*
         * If there is a / in the name, fall straight through to posix_spawn().
         */
        if (strchr(file, '/') != NULL)
                return posix_spawn(pid, file, fa, sa, cav, env);

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

        /*
         * Find an executable image with the given name in the PATH
         */

        ln = strlen(file);
        err = 0;
        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 = (size_t)(path - p);

                /*
                 * Once we gain chdir/fchdir file actions, this will need
                 * serious work, as we must treat "." relative to the
                 * target of the (final) chdir performed.
                 *
                 * Fortunately, that day is yet to come.
                 */

                /*
                 * 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(fpath)) {
                        (void)write(STDERR_FILENO, "posix_spawnp: ", 14);
                        (void)write(STDERR_FILENO, p, lp);
                        (void)write(STDERR_FILENO, ": path too long\n", 16);
                        continue;
                }
                memcpy(fpath, p, lp);
                fpath[lp] = '/';
                memcpy(fpath + lp + 1, file, ln);
                fpath[lp + ln + 1] = '\0';

                /*
                 * It would be nice (much better) to try posix_spawn()
                 * here, using the current fpath as the filename, but
                 * there's no guarantee that it is safe to execute it
                 * twice (the file actions may screw us) so that we
                 * cannot do.   This test is weak, barely even adequate.
                 * but unless we are forced into making posix_spawmp()
                 * become a system call (with PATH as an arg, or an array
                 * of possible paths to try, based upon PATH and file)
                 * we really have no better method.
                 */
                if (access(fpath, X_OK) == 0)
                        break;

                if (err == 0)
                        err = errno;

                fpath[0] = '\0';


        } while (*path++ == ':');       /* Otherwise, *path was NUL */

        if (fpath[0] == '\0')
                return err;

        /*
         * Use posix_spawn() with the found binary
         */
        return posix_spawn(pid, fpath, fa, sa, cav, env);
}