py/objarray: Fix array.append so it doesn't extend if append fails.

dpgeorge · dpgeorge · commit 04d5e644fcf4 · 2016-04-07T09:03:33.000+01:00
Addresses issue adafruit#1965.
diff --git a/py/objarray.c b/py/objarray.c
@@ -336,7 +336,9 @@ STATIC mp_obj_t array_append(mp_obj_t self_in, mp_obj_t arg) {
         self->items = m_renew(byte, self->items, item_sz * self->len, item_sz * (self->len + self->free));
         mp_seq_clear(self->items, self->len + 1, self->len + self->free, item_sz);
     }
-    mp_binary_set_val_array(self->typecode, self->items, self->len++, arg);
+    mp_binary_set_val_array(self->typecode, self->items, self->len, arg);
+    // only update length/free if set succeeded
+    self->len++;
     self->free--;
     return mp_const_none; // return None, as per CPython
 }
diff --git a/tests/basics/bytearray_append.py b/tests/basics/bytearray_append.py
@@ -0,0 +1,15 @@
+# test bytearray.append method
+
+a = bytearray(4)
+print(a)
+
+# append should append a single byte
+a.append(2)
+print(a)
+
+# a should not be modified if append fails
+try:
+    a.append(None)
+except TypeError:
+    print('TypeError')
+print(a)

Original file line number	Diff line number	Diff line change
`@@ -336,7 +336,9 @@ STATIC mp_obj_t array_append(mp_obj_t self_in, mp_obj_t arg) {`
`336`	`336`	`self->items = m_renew(byte, self->items, item_sz * self->len, item_sz * (self->len + self->free));`
`337`	`337`	`mp_seq_clear(self->items, self->len + 1, self->len + self->free, item_sz);`
`338`	`338`	`}`
`339`		`- mp_binary_set_val_array(self->typecode, self->items, self->len++, arg);`
	`339`	`+ mp_binary_set_val_array(self->typecode, self->items, self->len, arg);`
	`340`	`+ // only update length/free if set succeeded`
	`341`	`+ self->len++;`
`340`	`342`	`self->free--;`
`341`	`343`	`return mp_const_none; // return None, as per CPython`
`342`	`344`	`}`