# HG changeset patch
# User Gregory Szorc <gregory.szorc@gmail.com>
# Date 1520093983 18000
# Node ID b864f4536ca883145a38386a5c383bb8874e091b
# Parent  2f7a3c90c0d7d409325afc533be8bbd7b993b2ae
cext: refactor cleanup code in bdiff()

A future commit will need to introduce additional cleanup code.

We refactor the cleanup code to check NULL before calling free().
We also initialize these variables as NULL.

We set the out of memory exception explicitly, so we can just return
result.

Differential Revision: https://phab.mercurial-scm.org/D2586

diff -r 2f7a3c90c0d7 -r b864f4536ca8 mercurial/cext/bdiff.c
--- a/mercurial/cext/bdiff.c	Fri Mar 02 07:13:33 2018 +0530
+++ b/mercurial/cext/bdiff.c	Sat Mar 03 11:19:43 2018 -0500
@@ -62,11 +62,11 @@
 {
 	char *sa, *sb, *rb, *ia, *ib;
 	PyObject *result = NULL;
-	struct bdiff_line *al, *bl;
+	struct bdiff_line *al = NULL, *bl = NULL;
 	struct bdiff_hunk l, *h;
 	int an, bn, count;
 	Py_ssize_t len = 0, la, lb, li = 0, lcommon = 0, lmax;
-	PyThreadState *_save;
+	PyThreadState *_save = NULL;
 
 	l.next = NULL;
 
@@ -89,12 +89,16 @@
 
 	an = bdiff_splitlines(sa + lcommon, la - lcommon, &al);
 	bn = bdiff_splitlines(sb + lcommon, lb - lcommon, &bl);
-	if (!al || !bl)
-		goto nomem;
+	if (!al || !bl) {
+		PyErr_NoMemory();
+		goto cleanup;
+	}
 
 	count = bdiff_diff(al, an, bl, bn, &l);
-	if (count < 0)
-		goto nomem;
+	if (count < 0) {
+		PyErr_NoMemory();
+		goto cleanup;
+	}
 
 	/* calculate length of output */
 	la = lb = 0;
@@ -110,7 +114,7 @@
 	result = PyBytes_FromStringAndSize(NULL, len);
 
 	if (!result)
-		goto nomem;
+		goto cleanup;
 
 	/* build binary patch */
 	rb = PyBytes_AsString(result);
@@ -130,13 +134,19 @@
 		lb = h->b2;
 	}
 
-nomem:
+cleanup:
 	if (_save)
 		PyEval_RestoreThread(_save);
-	free(al);
-	free(bl);
-	bdiff_freehunks(l.next);
-	return result ? result : PyErr_NoMemory();
+	if (al) {
+		free(al);
+	}
+	if (bl) {
+		free(bl);
+	}
+	if (l.next) {
+		bdiff_freehunks(l.next);
+	}
+	return result;
 }
 
 /*