From 5159f8f6493bfa3cfb0ee3b1517f4576d4c9d2de Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@twurst.com>
Date: Mon, 16 Nov 2015 18:04:56 +0100
Subject: [PATCH] crypto/secp256k1: raise internal errors as recoverable Go
 panic

---
 crypto/secp256k1/panic_cb.go | 33 +++++++++++++++++++++++++++++++++
 crypto/secp256k1/secp256.go  |  6 ++++++
 2 files changed, 39 insertions(+)
 create mode 100644 crypto/secp256k1/panic_cb.go

diff --git a/crypto/secp256k1/panic_cb.go b/crypto/secp256k1/panic_cb.go
new file mode 100644
index 000000000..e0e9034ee
--- /dev/null
+++ b/crypto/secp256k1/panic_cb.go
@@ -0,0 +1,33 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package secp256k1
+
+import "C"
+import "unsafe"
+
+// Callbacks for converting libsecp256k1 internal faults into
+// recoverable Go panics.
+
+//export secp256k1GoPanicIllegal
+func secp256k1GoPanicIllegal(msg *C.char, data unsafe.Pointer) {
+	panic("illegal argument: " + C.GoString(msg))
+}
+
+//export secp256k1GoPanicError
+func secp256k1GoPanicError(msg *C.char, data unsafe.Pointer) {
+	panic("internal error: " + C.GoString(msg))
+}
diff --git a/crypto/secp256k1/secp256.go b/crypto/secp256k1/secp256.go
index 634e1c0b8..4269b6a8c 100644
--- a/crypto/secp256k1/secp256.go
+++ b/crypto/secp256k1/secp256.go
@@ -35,6 +35,10 @@ package secp256k1
 #define NDEBUG
 #include "./libsecp256k1/src/secp256k1.c"
 #include "./libsecp256k1/src/modules/recovery/main_impl.h"
+
+typedef void (*callbackFunc) (const char* msg, void* data);
+extern void secp256k1GoPanicIllegal(const char* msg, void* data);
+extern void secp256k1GoPanicError(const char* msg, void* data);
 */
 import "C"
 
@@ -61,6 +65,8 @@ var context *C.secp256k1_context
 func init() {
 	// around 20 ms on a modern CPU.
 	context = C.secp256k1_context_create(3) // SECP256K1_START_SIGN | SECP256K1_START_VERIFY
+	C.secp256k1_context_set_illegal_callback(context, C.callbackFunc(C.secp256k1GoPanicIllegal), nil)
+	C.secp256k1_context_set_error_callback(context, C.callbackFunc(C.secp256k1GoPanicError), nil)
 }
 
 var (