Add safety checking to mpatch

mercurial/mpatch.c

@@ -39,18 +39,26 b' struct flist {'
 
 static struct flist *lalloc(int size)
 {
-	struct flist *a;
+	struct flist *a = NULL;
 
 	a = malloc(sizeof(struct flist));
-	a->head = a->tail = a->base = malloc(sizeof(struct frag) * size);
+	if (a) {
+		a->base = malloc(sizeof(struct frag) * size);
+		if (!a->base)
+			free(a);
+		else
+			a->head = a->tail = a->base;
+	}
 	return a;
 }
 
 static void lfree(struct flist *a)
 {
+	if (a) {
 	free(a->base);
 	free(a);
 }
+}
 
 static int lsize(struct flist *a)
 {
@@ -144,13 +152,16 b' static int discard(struct flist *src, in'
    this deletes a and b and returns the resultant list. */
 static struct flist *combine(struct flist *a, struct flist *b)
 {
-	struct flist *c;
-	struct frag *bh = b->head, *ct;
+	struct flist *c = NULL;
+	struct frag *bh, *ct;
 	int offset = 0, post;
 
+	if (a && b)
 	c = lalloc((lsize(a) + lsize(b)) * 2);
 
-	while (bh != b->tail) {
+	if (c) {
+
+		for (bh = b->head; bh != b->tail; bh++) {
 		/* save old hunks */
 		offset = gather(c, a, bh->start, offset);
 
@@ -164,13 +175,14 b' static struct flist *combine(struct flis'
 		ct->len = bh->len;
 		ct->data = bh->data;
 		c->tail++;
-		bh++;
 		offset = post;
 	}
 
 	/* hold on to tail from a */
 	memcpy(c->tail, a->head, sizeof(struct frag) * lsize(a));
 	c->tail += lsize(a);
+	}
+
 	lfree(a);
 	lfree(b);
 	return c;
@@ -242,6 +254,8 b' static struct flist *fold(PyObject *bins'
 	if (start + 1 == end) {
 		/* trivial case, output a decoded list */
 		PyObject *tmp = PyList_GetItem(bins, start);
+		if (!tmp)
+			return NULL;
 		return decode(PyString_AsString(tmp), PyString_Size(tmp));
 	}
 
@@ -259,7 +273,7 b' patches(PyObject *self, PyObject *args)'
 	char *in, *out;
 	int len, outlen;
 
-	if (!PyArg_ParseTuple(args, "OO:mpatch", &text, &bins))
+	if (!PyArg_ParseTuple(args, "SO:mpatch", &text, &bins))
 		return NULL;
 
 	len = PyList_Size(bins);
@@ -270,13 +284,18 b' patches(PyObject *self, PyObject *args)'
 	}
 
 	patch = fold(bins, 0, len);
+	if (!patch)
+		return PyErr_NoMemory();
+
 	outlen = calcsize(PyString_Size(text), patch);
 	result = PyString_FromStringAndSize(NULL, outlen);
+	if (result) {
 	in = PyString_AsString(text);
 	out = PyString_AsString(result);
 	apply(out, in, PyString_Size(text), patch);
+	}
+
 	lfree(patch);
-
 	return result;
 }