Re: Don't allow "rm -rf /"

[Theo Buehler]

On Sun, Aug 23, 2015 at 07:38:15AM -0400, Ted Unangst wrote:
> Theo Buehler wrote:
> > @@ -401,9 +401,10 @@ checkdot(char **argv)
> >             else
> >                     p = *t;
> >  
> > -           if (ISDOT(p)) {
> > +           if (ISDOT(p) || *p == '\0') {
> >                     if (!complained++)
> > -                           warnx("\".\" and \"..\" may not be removed");
> > +                           warnx("\"/\", \".\" and \"..\" may not be "
> > +                               "removed");
> >                     eval = 1;
> >                     for (save = t; (t[0] = t[1]) != NULL; ++t)
> >                             continue;
> > 
> 
> I think separate error messages are appriate. The one about dots should not be
> cluttered with this.

Do I miss something simpler?

Index: bin/rm/rm.1
===================================================================
RCS file: /var/cvs/src/bin/rm/rm.1,v
retrieving revision 1.37
diff -u -p -r1.37 rm.1
--- bin/rm/rm.1 25 May 2014 19:07:36 -0000      1.37
+++ bin/rm/rm.1 22 Aug 2015 21:49:02 -0000
@@ -102,6 +102,7 @@ The
 utility removes symbolic links, not the files referenced by the links.
 .Pp
 It is an error to attempt to remove the files
+.Dq / ,
 .Dq \&.
 or
 .Dq .. .
Index: bin/rm/rm.c
===================================================================
RCS file: /var/cvs/src/bin/rm/rm.c,v
retrieving revision 1.30
diff -u -p -r1.30 rm.c
--- bin/rm/rm.c 16 Jan 2015 06:39:32 -0000      1.30
+++ bin/rm/rm.c 23 Aug 2015 11:52:28 -0000
@@ -54,7 +54,7 @@ extern char *__progname;
 int dflag, eval, fflag, iflag, Pflag, stdin_ok;
 
 int    check(char *, char *, struct stat *);
-void   checkdot(char **);
+void   checkdotorslash(char **);
 void   rm_file(char **);
 int    rm_overwrite(char *, struct stat *);
 int    pass(int, off_t, char *, size_t);
@@ -105,7 +105,7 @@ main(int argc, char *argv[])
        if (argc < 1 && fflag == 0)
                usage();
 
-       checkdot(argv);
+       checkdotorslash(argv);
 
        if (*argv) {
                stdin_ok = isatty(STDIN_FILENO);
@@ -383,12 +383,12 @@ check(char *path, char *name, struct sta
  */
 #define ISDOT(a)       ((a)[0] == '.' && (!(a)[1] || ((a)[1] == '.' && 
!(a)[2])))
 void
-checkdot(char **argv)
+checkdotorslash(char **argv)
 {
        char *p, **save, **t;
-       int complained;
+       int dotcomplained, slashcomplained;
 
-       complained = 0;
+       dotcomplained = slashcomplained = 0;
        for (t = argv; *t;) {
                /* strip trailing slashes */
                p = strrchr (*t, '\0');
@@ -402,14 +402,20 @@ checkdot(char **argv)
                        p = *t;
 
                if (ISDOT(p)) {
-                       if (!complained++)
+                       if (!dotcomplained++)
                                warnx("\".\" and \"..\" may not be removed");
-                       eval = 1;
-                       for (save = t; (t[0] = t[1]) != NULL; ++t)
-                               continue;
-                       t = save;
-               } else
+               } else if (*p == '\0') {
+                       if (!slashcomplained++)
+                               warnx("\"/\" may not be removed");
+               } else {
                        ++t;
+                       continue;
+               }
+
+               eval = 1;
+               for (save = t; (t[0] = t[1]) != NULL; ++t)
+                       continue;
+               t = save;
        }
 }