trivial patch for misleading error message on failed
directory creation.

Notes:
Wed Aug 31 15:04:40 EDT 2005 rsc
    If you run tar to try to extract a file inside
    a directory that cannot be created you used to get:
    
    	% tar xf x.tar
    	tar: can't create x/y: 'x/y' does not exist
    	tar: can't create x/y/a: 'x/y/a' does not exist
    	% 
    
    I fixed the first error, which was tar's fault,
    so now you get:
    
    	% tar xf x.tar
    	tar: can't create x/y: permission denied
    	tar: can't create x/y/a: 'x/y/a' does not exist
    	% 
    
    The second error is the kernel's fault:
    
    	% syscall create x/y/a 0 0
    	syscall: return -1, error:'x/y/a' does not exist
    	% 
    
    Your fix did not make sense to me.  It was second-guessing
    various operations instead of letting the real errors shine
    through.
    
    I will look at fixing the kernel message.
    

Wed Aug 31 15:50:30 EDT 2005 rsc
    I fixed the kernel too.  There is a new /sys/src/9/port/chan.c on sources.
    


Reference: /n/sources/patch/sorry/tar-permission
Date: Tue Aug 30 23:47:17 CES 2005
Signed-off-by: steve@quintile.net
Reviewed-by: rsc

--- /sys/src/cmd/tar.c	Tue Aug 30 23:30:21 2005
+++ /sys/src/cmd/tar.c	Tue Aug 30 23:30:16 2005
@@ -788,20 +788,23 @@
 	f = create(s, OREAD, DMDIR | 0777);
 	if (f >= 0)
 		close(f);
+	if (f < 0)
+		fprint(2, "%s: can't create %s: %r\n", argv0, s);
 	return f;
 }
 
-static void
+static int
 mkpdirs(char *s)
 {
-	int done = 0;
+	int err = 0;
 	char *p = s;
 
-	while (!done && (p = strchr(p + 1, '/')) != nil) {
+	while (!err && (p = strchr(p + 1, '/')) != nil) {
 		*p = '\0';
-		done = (access(s, AEXIST) < 0 && makedir(s) < 0);
+		err = (access(s, AEXIST) < 0 && makedir(s) < 0);
 		*p = '/';
 	}
+	return err;
 }
 
 /* copy a file from the archive into the filesystem */
@@ -854,7 +857,8 @@
 
 				fd = create(fname, rw, mode);
 				if (fd < 0) {
-					mkpdirs(fname);
+					if (mkpdirs(fname) != 0)
+						break;
 					fd = create(fname, rw, mode);
 				}
 				if (fd < 0 &&