My patch that helps when expanding the OpenBSD-cvs-x11 deltas.
Sometimes the files extracted are read-only. Rather than abort out in
a big mess, this patch checks for unwritable files, and chmods them
if you specify the -F (force) flag. - d@

--- ctm/ctm/ctm_pass2.c.orig	Fri Feb 18 16:12:35 2000
+++ ctm/ctm/ctm_pass2.c	Fri Feb 18 16:40:02 2000
@@ -114,6 +114,11 @@
 			    ret |= Exit_NotOK;
 			break;
 		    }
+		    if (-1 == access(name, W_OK)) {
+			fprintf(stderr, "  %s: %s not writable.\n",
+				sp->Key, name);
+			ret |= Exit_Forcible;
+		    }
 		    if (SetTime && getuid() && (getuid() != st.st_uid)) {
 			    fprintf(stderr,
 				"  %s: %s not mine, cannot set time.\n",
--- ctm/ctm/ctm_pass3.c.orig	Fri Feb 18 16:12:30 2000
+++ ctm/ctm/ctm_pass3.c	Fri Feb 18 16:42:36 2000
@@ -176,6 +176,26 @@
 
 	if (Verbose > 0)
 		fprintf(stderr,"> %s %s\n",sp->Key,name);
+	if ((strcmp(sp->Key, "FS") == 0 ||
+	     strcmp(sp->Key, "FN") == 0 ||
+	     strcmp(sp->Key, "FE") == 0) && -1 == access(name, W_OK)) {
+		if (Verbose > 1)
+			fprintf(stderr, "  %s: chmod u+w %s\n", 
+			    sp->Key, name);
+		if (!Force) {
+			warn("%s", name);
+			WRONG
+		}
+		if (-1 == stat(name, &st)) {
+			warn("stat: %s", name);
+			WRONG
+		}
+		if (-1 == chmod(name, st.st_mode | S_IWUSR)) {
+			warn("chmod: %s", name);
+			WRONG
+		}
+	}
+
 	if(!strcmp(sp->Key,"FM") || !strcmp(sp->Key, "FS")) {
 	    i = open(name,O_WRONLY|O_CREAT|O_TRUNC,0666);
 	    if(i < 0) {