/*      $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 <[email protected]>.
*
* 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);
}