add directory study

study/linux-travel/MINIX-1.5/1.5/Source/commands/su.c

@@ -0,0 +1,54 @@
+/* su - become super-user		Author: Patrick van Kleef */
+
+#include <sys/types.h>
+#include <sgtty.h>
+#include <pwd.h>
+
+main(argc, argv)
+int argc;
+char *argv[];
+{
+  register char *name;
+  char *crypt();
+  char *shell = "/bin/sh";
+  char *shell2 = "/usr/bin/sh";
+  int nr;
+  char password[14];
+  struct sgttyb args;
+  register struct passwd *pwd;
+  struct passwd *getpwnam();
+
+  if (argc > 1)
+	name = argv[1];
+  else
+	name = "root";
+
+  if ((pwd = getpwnam(name)) == 0) {
+	std_err("Unknown id: ");
+	std_err(name);
+	std_err("\n");
+	exit(1);
+  }
+  if (pwd->pw_passwd[0] != '\0' && getuid() != 0) {
+	std_err("Password: ");
+	ioctl(0, TIOCGETP, &args);	/* get parameters */
+	args.sg_flags = args.sg_flags & (~ECHO);
+	ioctl(0, TIOCSETP, &args);
+	nr = read(0, password, 14);
+	password[nr - 1] = 0;
+	std_err("\n");
+	args.sg_flags = args.sg_flags | ECHO;
+	ioctl(0, TIOCSETP, &args);
+	if (strcmp(pwd->pw_passwd, crypt(password, pwd->pw_passwd))) {
+		std_err("Sorry\n");
+		exit(2);
+	}
+  }
+  setgid(pwd->pw_gid);
+  setuid(pwd->pw_uid);
+  if (pwd->pw_shell[0]) shell = pwd->pw_shell;
+  execl(shell, shell, "-i", (char *) 0);
+  execl(shell2, shell2, "-i", (char *) 0);
+  std_err("No shell\n");
+  exit(3);
+}