Fix export_marks() error handling.

- Don't leak one FILE * on error per export_marks() call. Found with
  cppcheck and reported by Martin Ettl.

- Abort the potentially long for(;idnums.size;) loop on write errors.

- Record error if fprintf() fails for reasons not required to set the
  stream error indicator, such as ENOMEM.

- Add a trailing full-stop to error message when fopen() fails.

Signed-off-by: Matthias Andree <matthias.andree@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-fast-export.c

@@ -428,21 +428,27 @@ static void export_marks(char *file)
 	uint32_t mark;
 	struct object_decoration *deco = idnums.hash;
 	FILE *f;
+	int e = 0;
 
 	f = fopen(file, "w");
 	if (!f)
-		error("Unable to open marks file %s for writing", file);
+		error("Unable to open marks file %s for writing.", file);
 
 	for (i = 0; i < idnums.size; i++) {
 		if (deco->base && deco->base->type == 1) {
 			mark = ptr_to_mark(deco->decoration);
-			fprintf(f, ":%"PRIu32" %s\n", mark,
-				sha1_to_hex(deco->base->sha1));
+			if (fprintf(f, ":%"PRIu32" %s\n", mark,
+				sha1_to_hex(deco->base->sha1)) < 0) {
+			    e = 1;
+			    break;
+			}
 		}
 		deco++;
 	}
 
-	if (ferror(f) || fclose(f))
+	e |= ferror(f);
+	e |= fclose(f);
+	if (e)
 		error("Unable to write marks file %s.", file);
 }