From 7e2cb6950bb48e6cffc6d517153d9eb79aeb2f76 Mon Sep 17 00:00:00 2001
From: Thomas Bruyelle <thomasbruyelle@hey.com>
Date: Thu, 6 Apr 2023 15:31:25 +0200
Subject: [PATCH] chore: recoverable panic in native functions

Fix #663

Some panic invoked in native functions should be recoverable from gno
code. To do that, `panic` is replaced with `machine.Panic()` which
checks first beyond the call stack if there's a recover, before
panic-ing.
---
 gnovm/stdlibs/stdlibs.go    | 11 +++++++----
 gnovm/tests/files/std10.gno | 14 ++++++++++++++
 gnovm/tests/files/std11.gno | 14 ++++++++++++++
 gnovm/tests/files/std9.gno  | 14 ++++++++++++++
 gnovm/tests/imports.go      |  7 +++++--
 5 files changed, 54 insertions(+), 6 deletions(-)
 create mode 100644 gnovm/tests/files/std10.gno
 create mode 100644 gnovm/tests/files/std11.gno
 create mode 100644 gnovm/tests/files/std9.gno

diff --git a/gnovm/stdlibs/stdlibs.go b/gnovm/stdlibs/stdlibs.go
index 89329aeaf4b..95803558d06 100644
--- a/gnovm/stdlibs/stdlibs.go
+++ b/gnovm/stdlibs/stdlibs.go
@@ -152,7 +152,8 @@ func InjectPackage(store gno.Store, pn *gno.PackageNode) {
 			func(m *gno.Machine) {
 				isOrigin := len(m.Frames) == 2
 				if !isOrigin {
-					panic("invalid non-origin call")
+					m.Panic(typedString("invalid non-origin call"))
+					return
 				}
 			},
 		)
@@ -314,13 +315,15 @@ func InjectPackage(store gno.Store, pn *gno.PackageNode) {
 				arg0 := m.LastBlock().GetParams1().TV
 				n := arg0.GetInt()
 				if n <= 0 {
-					panic("GetCallerAt requires positive arg")
+					m.Panic(typedString("GetCallerAt requires positive arg"))
+					return
 				}
 				if n > m.NumFrames() {
 					// NOTE: the last frame's LastPackage
 					// is set to the original non-frame
 					// package, so need this check.
-					panic("frame not found")
+					m.Panic(typedString("frame not found"))
+					return
 				}
 				var pkgAddr string
 				if n == m.NumFrames() {
@@ -426,7 +429,7 @@ func InjectPackage(store gno.Store, pn *gno.PackageNode) {
 				}
 				b32, err := bech32.ConvertAndEncode(prefix, bz)
 				if err != nil {
-					panic(err)
+					panic(err) // should not happen
 				}
 				res0 := gno.Go2GnoValue(
 					m.Alloc,
diff --git a/gnovm/tests/files/std10.gno b/gnovm/tests/files/std10.gno
new file mode 100644
index 00000000000..7caf534c5ca
--- /dev/null
+++ b/gnovm/tests/files/std10.gno
@@ -0,0 +1,14 @@
+package main
+
+import "std"
+
+func main() {
+	defer func() {
+		// assert panic is recoverable
+		println(recover())
+	}()
+	std.GetCallerAt(0)
+}
+
+// Output:
+// GetCallerAt requires positive arg
diff --git a/gnovm/tests/files/std11.gno b/gnovm/tests/files/std11.gno
new file mode 100644
index 00000000000..ce02fa11ec3
--- /dev/null
+++ b/gnovm/tests/files/std11.gno
@@ -0,0 +1,14 @@
+package main
+
+import "std"
+
+func main() {
+	defer func() {
+		// assert panic is recoverable
+		println(recover())
+	}()
+	std.GetCallerAt(42)
+}
+
+// Output:
+// frame not found
diff --git a/gnovm/tests/files/std9.gno b/gnovm/tests/files/std9.gno
new file mode 100644
index 00000000000..95ccfb2c8a4
--- /dev/null
+++ b/gnovm/tests/files/std9.gno
@@ -0,0 +1,14 @@
+package main
+
+import "std"
+
+func main() {
+	defer func() {
+		// assert panic is recoverable
+		println(recover())
+	}()
+	std.AssertOriginCall()
+}
+
+// Output:
+// invalid non-origin call
diff --git a/gnovm/tests/imports.go b/gnovm/tests/imports.go
index 67ca1ba51e2..63ccd088f98 100644
--- a/gnovm/tests/imports.go
+++ b/gnovm/tests/imports.go
@@ -485,6 +485,7 @@ func testPackageInjector(store gno.Store, pn *gno.PackageNode) {
 			func(m *gno.Machine) {
 				if !isOriginCall(m) {
 					m.Panic(typedString("invalid non-origin call"))
+					return
 				}
 			},
 		)
@@ -515,13 +516,15 @@ func testPackageInjector(store gno.Store, pn *gno.PackageNode) {
 				arg0 := m.LastBlock().GetParams1().TV
 				n := arg0.GetInt()
 				if n <= 0 {
-					panic("GetCallerAt requires positive arg")
+					m.Panic(typedString("GetCallerAt requires positive arg"))
+					return
 				}
 				if n > m.NumFrames()-1 {
 					// NOTE: the last frame's LastPackage
 					// is set to the original non-frame
 					// package, so need this check.
-					panic("frame not found")
+					m.Panic(typedString("frame not found"))
+					return
 				}
 				var pkgAddr string
 				if n == m.NumFrames()-1 {