diff -r 000000000000 -r 6474c204b198 js/src/jscrashformat.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jscrashformat.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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/. */
+
+#ifndef jscrashformat_h
+#define jscrashformat_h
+
+namespace js {
+namespace crash {
+
+static const int crash_cookie_len = 16;
+static const char crash_cookie[crash_cookie_len] = "*J*S*CRASHDATA*";
+
+/* These values are used for CrashHeader::id. */
+enum {
+    JS_CRASH_STACK_GC = 0x400,
+    JS_CRASH_STACK_ERROR = 0x401,
+    JS_CRASH_RING = 0x800
+};
+
+/*
+ * All the data here will be stored directly in the minidump, so we use
+ * platform-independent types. We also ensure that the size of every field is a
+ * multiple of 8 bytes, to guarantee that they won't be padded.
+ */
+
+struct CrashHeader
+{
+    char cookie[crash_cookie_len];
+
+    /* id of the crash data, chosen from the enum above. */
+    uint64_t id;
+
+    CrashHeader(uint64_t id) : id(id) { memcpy(cookie, crash_cookie, crash_cookie_len); }
+};
+
+struct CrashRegisters
+{
+    uint64_t ip, sp, bp;
+};
+
+static const int crash_buffer_size = 32 * 1024;
+
+struct CrashStack
+{
+    CrashStack(uint64_t id) : header(id) {}
+
+    CrashHeader header;
+    uint64_t snaptime;    /* Unix time when the stack was snapshotted. */
+    CrashRegisters regs;  /* Register contents for the snapshot. */
+    uint64_t stack_base;  /* Base address of stack at the time of snapshot. */
+    uint64_t stack_len;   /* Extent of the stack. */
+    char stack[crash_buffer_size]; /* Contents of the stack. */
+};
+
+struct CrashRing
+{
+    CrashRing(uint64_t id) : header(id), offset(0) { memset(buffer, 0, sizeof(buffer)); }
+
+    CrashHeader header;
+    uint64_t offset; /* Next byte to be written in the buffer. */
+    char buffer[crash_buffer_size];
+};
+
+/* These are the tag values for each entry in the CrashRing. */
+enum {
+    JS_CRASH_TAG_GC = 0x200
+};
+
+} /* namespace crash */
+} /* namespace js */
+
+#endif /* jscrashformat_h */