/*      $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);
}