1 files changed, 53 insertions, 0 deletions
diff --git a/system/memory/mozalloc/mozalloc_oom.cpp b/system/memory/mozalloc/mozalloc_oom.cpp
new file mode 100644
index 000000000..820888cdb
--- /dev/null
+++ b/system/memory/mozalloc/mozalloc_oom.cpp
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: sw=4 ts=4 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/mozalloc_abort.h"
+#include "mozilla/mozalloc_oom.h"
+#include "mozilla/Assertions.h"
+
+static mozalloc_oom_abort_handler gAbortHandler;
+
+#define OOM_MSG_LEADER "out of memory: 0x"
+#define OOM_MSG_DIGITS "0000000000000000" // large enough for 2^64
+#define OOM_MSG_TRAILER " bytes requested"
+#define OOM_MSG_FIRST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) - 1
+#define OOM_MSG_LAST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) + \
+                                  sizeof(OOM_MSG_DIGITS) - 3
+
+static const char *hex = "0123456789ABCDEF";
+
+void
+mozalloc_handle_oom(size_t size)
+{
+    char oomMsg[] = OOM_MSG_LEADER OOM_MSG_DIGITS OOM_MSG_TRAILER;
+    size_t i;
+
+    // NB: this is handle_oom() stage 1, which simply aborts on OOM.
+    // we might proceed to a stage 2 in which an attempt is made to
+    // reclaim memory
+
+    if (gAbortHandler)
+        gAbortHandler(size);
+
+    static_assert(OOM_MSG_FIRST_DIGIT_OFFSET > 0,
+                  "Loop below will never terminate (i can't go below 0)");
+
+    // Insert size into the diagnostic message using only primitive operations
+    for (i = OOM_MSG_LAST_DIGIT_OFFSET;
+         size && i >= OOM_MSG_FIRST_DIGIT_OFFSET; i--) {
+      oomMsg[i] = hex[size % 16];
+      size /= 16;
+    }
+
+    mozalloc_abort(oomMsg);
+}
+
+void
+mozalloc_set_oom_abort_handler(mozalloc_oom_abort_handler handler)
+{
+    gAbortHandler = handler;
+}