fexec.c

/*-
 * Copyright (c) 2003 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matthias Scheler.
 *
 * 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.
 */

#define _BSD_SOURCE     /* for vfork and chroot */
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "xbps_api_impl.h"

static int
pfcexec(struct xbps_handle *xhp, const char *file, const char **argv)
{
        pid_t child;
        int status;

        child = vfork();
        switch (child) {
        case 0:
                /*
                 * If rootdir != / and uid==0 and bin/sh exists,
                 * change root directory and exec command.
                 */
                if (strcmp(xhp->rootdir, "/")) {
                        if (geteuid() == 0 && access("bin/sh", X_OK) == 0) {
                                if (chroot(xhp->rootdir) == 0) {
                                        if (chdir("/") == -1)
                                                _exit(129);
                                }
                        }
                }
                (void)execv(file, __UNCONST(argv));
                _exit(127);
                /* NOTREACHED */
        case -1:
                return -1;
        }

        while (waitpid(child, &status, 0) < 0) {
                if (errno != EINTR)
                        return -1;
        }

        if (!WIFEXITED(status))
                return -1;

        return WEXITSTATUS(status);
}

static int
vfcexec(struct xbps_handle *xhp, const char *arg, va_list ap)
{
        const char **argv;
        size_t argv_size, argc;
        int retval;

        argv_size = 16;
        if ((argv = malloc(argv_size * sizeof(*argv))) == NULL) {
                errno = ENOMEM;
                return -1;
        }

        argv[0] = arg;
        argc = 1;

        do {
                if (argc == argv_size) {
                        argv_size *= 2;
                        argv = realloc(argv, argv_size * sizeof(*argv));
                        if (argv == NULL) {
                                errno = ENOMEM;
                                return -1;
                        }
                }

                arg = va_arg(ap, const char *);
                argv[argc++] = arg;

        } while (arg != NULL);

        retval = pfcexec(xhp, argv[0], argv);
        free(argv);

        return retval;
}

int HIDDEN
xbps_file_exec(struct xbps_handle *xhp, const char *arg, ...)
{
        va_list ap;
        int     result;

        va_start(ap, arg);
        result = vfcexec(xhp, arg, ap);
        va_end(ap);

        return result;
}