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#include <sys/types.h>
#include <pwd.h>
#include <string.h>
#include <unistd.h>
main(int argc, char *argv[])
{
char buf[4096], *p;
struct passwd *pw;
/* Build the pathname of the virtual system root. */
strcpy(buf, "/OS/");
if (!(p = strrchr(argv[0], '/')))
p = argv[0];
else
p++;
strcat(buf, p);
/* Change the root directory (but leave us where we were!) */
if (chroot(buf) < 0) {
perror(buf);
exit(1);
}
/* Prep the environment for the virtual system. */
if ((pw = getpwuid(getuid()))) {
strcpy(buf, "HOME=");
strcat(buf, pw->pw_dir);
putenv(strdup(buf));
}
/* Drop root privileges. This program must be setuid root to
* do the chroot() but we don't want to execute the command
* specified by the user with any extra privileges!
*/
seteuid(getuid());
setegid(getgid());
/* Execute the given command. If the command name starts with
* a '-' treat it as a login shell - change directory to the
* user's home directory and strip the leading '-' from the
* command to get the filename to execute.
*/
p = argv[1];
if (*p == '-') {
p++;
if (pw && pw->pw_dir)
chdir(pw->pw_dir);
}
execvp(p, argv+1);
perror(p);
exit(1);
}
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