Add rm-on-fail to the hexpatch script, allowing more confidence that repeated make invocations will not accidentally succeed

Makefile

@@ -218,8 +218,7 @@ $(DEPSDIR)/slice.insert.deps: Makefile
 # Generate a working file with any known patches applied
 %.img: %.img.orig
 	cp --reflink=auto $< $@
-	./scripts/hexpatch.pl $@ $@.d/*.patch
-# FIXME - want --rm_on_fail semantics here
+	./scripts/hexpatch.pl --rm_on_fail $@ $@.d/*.patch
 
 # using both __DIR and __FL2 is a hack to get around needing to quote the
 # DOS path separator.  It feels like there should be a better way if I put
@@ -262,7 +261,7 @@ GETELTORITO := ./scripts/geteltorito
 # extract the DOS boot image from an iso (and fix it up so qemu can boot it)
 %.img: %.iso
 	$(GETELTORITO) -o $@ $<
-	./scripts/hexpatch.pl $@ fix-hdd-image-`stat -c %s $@`.patch
+	./scripts/hexpatch.pl --rm_on_fail $@ fix-hdd-image-`stat -c %s $@`.patch
 	$(call build_info,$<.bat)
 
 # $1 is the lenovo named iso

scripts/hexpatch.pl

@@ -20,7 +20,7 @@ sub usage() {
     print("patching the right file\n");
     print("\n");
     print("Usage:\n");
-    print("    hexpatch.pl binaryfile patchfile [patchfile...]\n");
+    print("    hexpatch.pl [--rm_on_fail] binaryfile patchfile [patchfile...]\n");
     print("\n");
     exit(1);
 }
@@ -167,7 +167,21 @@ sub apply_patch {
     }
 }
 
+sub rm_on_fail {
+    my ($bool, $filename) = @_;
+
+    if ($bool) {
+        unlink($filename);
+    }
+}
+
 sub main() {
+    my $rm_on_fail;
+    if (defined($ARGV[0]) && $ARGV[0] eq "--rm_on_fail") {
+        $rm_on_fail=1;
+        shift @ARGV;
+    }
+
     my $binaryfile = shift @ARGV;
     if (!defined($binaryfile) or !defined($ARGV[0])) {
         usage();
@@ -193,11 +207,13 @@ sub main() {
 
         if (!defined($db)) {
             warn("Cannot read $patchfile\n");
+            rm_on_fail($rm_on_fail,$binaryfile);
             exit(1);
         }
 
         if (!verify_context($db,$fh)) {
             warn("The binaryfile does not match the context bytes from $patchfile\n");
+            rm_on_fail($rm_on_fail,$binaryfile);
             exit(1);
         }