/*-
 * 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.
 *
 * @(#)exec.c   8.1 (Berkeley) 6/4/93
 * $FreeBSD: src/lib/libc/gen/exec.c,v 1.25 2008/06/23 05:22:06 ed Exp $
 */

#include "namespace.h"
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <paths.h>

#include <stdarg.h>
#include "un-namespace.h"
#include "libc_private.h"

extern char **environ;

int
execl(const char *name, const char *arg, ...)
{
        va_list ap;
        const char **argv;
        int n;

        va_start(ap, arg);
        n = 1;
        while (va_arg(ap, char *) != NULL)
                n++;
        va_end(ap);
        argv = alloca((n + 1) * sizeof(*argv));
        if (argv == NULL) {
                errno = ENOMEM;
                return (-1);
        }
        va_start(ap, arg);
        n = 1;
        argv[0] = arg;
        while ((argv[n] = va_arg(ap, const char *)) != NULL)
                n++;
        va_end(ap);
        return (_execve(name, __DECONST(char **, argv),
                        __DECONST(char **, environ)));
}

int
execle(const char *name, const char *arg, ...)
{
        va_list ap;
        const char **argv, **envp;
        int n;

        va_start(ap, arg);
        n = 1;
        while (va_arg(ap, char *) != NULL)
                n++;
        va_end(ap);
        argv = alloca((n + 1) * sizeof(*argv));
        if (argv == NULL) {
                errno = ENOMEM;
                return (-1);
        }
        va_start(ap, arg);
        n = 1;
        argv[0] = arg;
        while ((argv[n] = va_arg(ap, const char *)) != NULL)
                n++;
        envp = va_arg(ap, const char **);
        va_end(ap);
        return (_execve(name, __DECONST(char **, argv),
                        __DECONST(char **, envp)));
}

int
execlp(const char *name, const char *arg, ...)
{
        va_list ap;
        const char **argv;
        int n;

        va_start(ap, arg);
        n = 1;
        while (va_arg(ap, char *) != NULL)
                n++;
        va_end(ap);
        argv = alloca((n + 1) * sizeof(*argv));
        if (argv == NULL) {
                errno = ENOMEM;
                return (-1);
        }
        va_start(ap, arg);
        n = 1;
        argv[0] = arg;
        while ((argv[n] = va_arg(ap, const char *)) != NULL)
                n++;
        va_end(ap);
        return (execvp(name, __DECONST(char **, argv)));
}

int
execv(const char *name, char * const *argv)
{
        _execve(name, argv, environ);
        return (-1);
}

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

static int
execvPe(const char *name, const char *path, char * const *argv,
        char * const *envp)
{
        const char **memp;
        int cnt;
        size_t lp, ln;
        int eacces, save_errno;
        const char *bp, *p;
        char *cur, buf[MAXPATHLEN];
        struct stat sb;

        eacces = 0;

        /* If it's an absolute or relative path name, it's easy. */
        if (strchr(name, '/')) {
                bp = name;
                cur = NULL;
                goto retry;
        }
        bp = buf;

        /* If it's an empty path name, fail in the usual POSIX way. */
        if (*name == '\0') {
                errno = ENOENT;
                return (-1);
        }

        cur = alloca(strlen(path) + 1);
        if (cur == NULL) {
                errno = ENOMEM;
                return (-1);
        }
        strcpy(cur, path);
        while ((p = strsep(&cur, ":")) != NULL) {
                /*
                 * It's a SHELL path -- double, leading and trailing colons
                 * mean the current directory.
                 */
                if (*p == '\0') {
                        p = ".";
                        lp = 1;
                } else
                        lp = strlen(p);
                ln = strlen(name);

                /*
                 * 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)) {
                        _write(STDERR_FILENO, "execvP: ", 8);
                        _write(STDERR_FILENO, p, lp);
                        _write(STDERR_FILENO, ": path too long\n", 16);
                        continue;
                }
                bcopy(p, buf, lp);
                buf[lp] = '/';
                bcopy(name, buf + lp + 1, ln);
                buf[lp + ln + 1] = '\0';
retry:
                _execve(bp, argv, envp);
                switch (errno) {
                case E2BIG:
                        goto done;
                case ELOOP:
                case ENAMETOOLONG:
                case ENOENT:
                        break;
                case ENOEXEC:
                        for (cnt = 0; argv[cnt]; ++cnt)
                                ;
                        memp = alloca((cnt + 2) * sizeof(char *));
                        if (memp == NULL) {
                                /* errno = ENOMEM; XXX override ENOEXEC? */
                                goto done;
                        }
                        memp[0] = "sh";
                        memp[1] = bp;
                        bcopy(argv + 1, memp + 2, cnt * sizeof(char *));
                        _execve(_PATH_BSHELL, __DECONST(char **, memp), envp);
                        goto done;
                case ENOMEM:
                        goto done;
                case ENOTDIR:
                        break;
                case ETXTBSY:
                        /*
                         * We used to retry here, but sh(1) doesn't.
                         */
                        goto done;
                default:
                        /*
                         * EACCES may be for an inaccessible directory or
                         * a non-executable file.  Call stat() to decide
                         * which.  This also handles ambiguities for EFAULT
                         * and EIO, and undocumented errors like ESTALE.
                         * We hope that the race for a stat() is unimportant.
                         */
                        save_errno = errno;
                        if (stat(bp, &sb) != 0)
                                break;
                        if (save_errno == EACCES) {
                                eacces = 1;
                                continue;
                        }
                        errno = save_errno;
                        goto done;
                }
        }
        if (eacces)
                errno = EACCES;
        else
                errno = ENOENT;
done:
        return (-1);
}

int
execvP(const char *name, const char *path, char * const argv[])
{
        return execvPe(name, path, argv, environ);
}

int
_execvpe(const char *name, char * const argv[], char * const envp[])
{
        const char *path;

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

        return (execvPe(name, path, argv, envp));
}