changeset 38938:dcd395dc98d8

index: remove side-effect from failed nt_new() As pointed out by Yuya in the review of D4108, if realloc() fails, we would end up with an invalid nodetree instance (with nt->nodes set to NULL), which means that if it was later accessed again it would likely segfault. It's probably unlikely that much else happens in the process if it ran out memory, but we should of course do our best to handle it. This patch makes it so we don't update the nodetree in this case. Differential Revision: https://phab.mercurial-scm.org/D4154
author Martin von Zweigbergk <martinvonz@google.com>
date Mon, 06 Aug 2018 09:59:51 -0700
parents f7d8fb2ed8a8
children 53bc73fae1a3
files mercurial/cext/revlog.c
diffstat 1 files changed, 7 insertions(+), 4 deletions(-) [+]
line wrap: on
line diff
--- a/mercurial/cext/revlog.c	Mon Aug 06 22:34:37 2018 -0700
+++ b/mercurial/cext/revlog.c	Mon Aug 06 09:59:51 2018 -0700
@@ -1018,18 +1018,21 @@
 static int nt_new(nodetree *self)
 {
 	if (self->length == self->capacity) {
+		unsigned newcapacity;
+		nodetreenode *newnodes;
 		if (self->capacity >= INT_MAX / (sizeof(nodetreenode) * 2)) {
 			PyErr_SetString(PyExc_MemoryError,
 					"overflow in nt_new");
 			return -1;
 		}
-		self->capacity *= 2;
-		self->nodes = realloc(self->nodes,
-		                      self->capacity * sizeof(nodetreenode));
-		if (self->nodes == NULL) {
+		newcapacity = self->capacity * 2;
+		newnodes = realloc(self->nodes, newcapacity * sizeof(nodetreenode));
+		if (newnodes == NULL) {
 			PyErr_SetString(PyExc_MemoryError, "out of memory");
 			return -1;
 		}
+		self->capacity = newcapacity;
+		self->nodes = newnodes;
 		memset(&self->nodes[self->length], 0,
 		       sizeof(nodetreenode) * (self->capacity - self->length));
 	}