Colony » Colony Scout

/*-

 * 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>

#include <assert.h>

#include <errno.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <limits.h>

#include <paths.h>

#include <unistd.h>

extern char **environ;

int

execvp(const char *name, char * const *argv)

{

        const char **memp;

        int cnt;

        size_t lp, ln = 0;

        int eacces = 0;

        unsigned int etxtbsy = 0;

        char buf[PATH_MAX];

        const char *bp, *path, *p;

        /* "" is not a valid filename; check this before traversing PATH. */

        if (name[0] == '\0') {

                errno = ENOENT;

                goto done;

        }

        /* 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;

        ln = strlen(name);

        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))

                        continue;

                memcpy(buf, p, lp);

                buf[lp] = '/';

                memcpy(buf + lp + 1, name, ln);

                buf[lp + ln + 1] = '\0';

retry:                (void)execve(bp, argv, environ);

                switch (errno) {

                case EACCES:

                        eacces = 1;

                        break;

                case ENOTDIR:

                case ENOENT:

                        break;

                case ENOEXEC:

                        for (cnt = 0; argv[cnt] != NULL; ++cnt)

                                continue;

                        if ((memp = (const char **)(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, (char * const *)memp,

                            environ);

                        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);

}