flash: close files (c.f. #256)

artiq/frontend/artiq_flash.py

@@ -97,7 +97,8 @@ def main():
         elif action == "gateware":
             bin = os.path.join(opts.dir, "top.bin")
             if not os.access(bin, os.R_OK):
-                bin = tempfile.mkstemp()[1]
+                bin_handle, bin = tempfile.mkstemp()
+                bin_handle.close()
                 bit = os.path.join(opts.dir, "top.bit")
                 conv = True
             prog.append("jtagspi_program {} 0x{:x}".format(

artiq/frontend/bit2bin.py

@@ -60,7 +60,8 @@ def bit2bin(bit, bin, flip=False):
             d = bitfile.read(l)
             if flip:
                 d = flip32(d)
-            open(bin, "wb").write(d)
+            with open(bin, "wb") as f:
+                f.write(d)
         else:
             d = bitfile.read(*struct.unpack(">H", bitfile.read(2)))
             print("Unexpected key: ", key, d)