From patchwork Sat Mar  3 16:28:45 2018
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Subject: D2586: cext: refactor cleanup code in bdiff()
From: phabricator <phabricator@mercurial-scm.org>
X-Patchwork-Id: 28787
Message-Id: <differential-rev-PHID-DREV-v37ohdp45iubrktlqtcy-req@phab.mercurial-scm.org>
To: mercurial-devel@mercurial-scm.org
Date: Sat, 3 Mar 2018 16:28:45 +0000

indygreg created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  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.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2586

AFFECTED FILES
  mercurial/cext/bdiff.c

CHANGE DETAILS




To: indygreg, #hg-reviewers
Cc: mercurial-devel

diff --git a/mercurial/cext/bdiff.c b/mercurial/cext/bdiff.c
--- a/mercurial/cext/bdiff.c
+++ b/mercurial/cext/bdiff.c
@@ -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;
 }
 
 /*