wasm: introduce new package for host->guest buffer passing

Signed-off-by: Xe Iaso <me@xeiaso.net>

4 files changed, 65 insertions, 4 deletions

diff --git a/go.mod b/go.mod
index bb60ab9..2a1e06e 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module within.website/x
 
-go 1.24
+go 1.23
 
 require (
 	al.essio.dev/pkg/shellescape v1.5.1
@@ -63,7 +63,7 @@ require (
 	github.com/sebest/xff v0.0.0-20210106013422-671bd2870b3a
 	github.com/speps/go-hashids v2.0.0+incompatible
 	github.com/stoewer/go-strcase v1.3.0
-	github.com/tetratelabs/wazero v1.8.2
+	github.com/tetratelabs/wazero v1.9.0
 	github.com/thoj/go-ircevent v0.0.0-20210723090443-73e444401d64
 	github.com/tmc/scp v0.0.0-20170824174625-f7b48647feef
 	github.com/twitchtv/twirp v8.1.3+incompatible
@@ -267,5 +267,3 @@ require (
 	golang.org/x/tools v0.30.0
 	google.golang.org/protobuf v1.36.4
 )
-
-tool golang.org/x/tools/cmd/stringer
diff --git a/go.sum b/go.sum
index e6a0eb1..2f03dd2 100644
--- a/go.sum
+++ b/go.sum
@@ -843,6 +843,10 @@ github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOf
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/tetratelabs/wazero v1.8.2 h1:yIgLR/b2bN31bjxwXHD8a3d+BogigR952csSDdLYEv4=
 github.com/tetratelabs/wazero v1.8.2/go.mod h1:yAI0XTsMBhREkM/YDAK/zNou3GoiAce1P6+rp/wQhjs=
+github.com/tetratelabs/wazero v1.8.3-0.20250217185257-70a9688a9f40 h1:+8cbydI2qMGurXlnljiiqpDSIXdVxtWfB+uZPM/BAxs=
+github.com/tetratelabs/wazero v1.8.3-0.20250217185257-70a9688a9f40/go.mod h1:yAI0XTsMBhREkM/YDAK/zNou3GoiAce1P6+rp/wQhjs=
+github.com/tetratelabs/wazero v1.9.0 h1:IcZ56OuxrtaEz8UYNRHBrUa9bYeX9oVY93KspZZBf/I=
+github.com/tetratelabs/wazero v1.9.0/go.mod h1:TSbcXCfFP0L2FGkRPxHphadXPjo1T6W+CseNNY7EkjM=
 github.com/thlib/go-timezone-local v0.0.0-20210907160436-ef149e42d28e/go.mod h1:/Tnicc6m/lsJE0irFMA0LfIwTBo4QP7A8IfyIv4zZKI=
 github.com/thoj/go-ircevent v0.0.0-20210723090443-73e444401d64 h1:l/T7dYuJEQZOwVOpjIXr1180aM9PZL/d1MnMVIxefX4=
 github.com/thoj/go-ircevent v0.0.0-20210723090443-73e444401d64/go.mod h1:Q1NAJOuRdQCqN/VIWdnaaEhV8LpeO2rtlBP7/iDJNII=
diff --git a/wasm/malloc_wasip1.go b/wasm/malloc_wasip1.go
new file mode 100644
index 0000000..d7bb0a6
--- /dev/null
+++ b/wasm/malloc_wasip1.go
@@ -0,0 +1,6 @@
+package wasm
+
+//go:wasmexport malloc
+func Malloc(size uint32) Buffer {
+	return FromSlice(make([]byte, size))
+}
diff --git a/wasm/wasm.go b/wasm/wasm.go
new file mode 100644
index 0000000..5981c06
--- /dev/null
+++ b/wasm/wasm.go
@@ -0,0 +1,53 @@
+package wasm
+
+import (
+	"unsafe"
+
+	"github.com/tetratelabs/wazero/api"
+)
+
+type String uint64
+
+func (value String) Load(module api.Module) string {
+	return string(value.LoadBytes(module))
+}
+
+func (value String) LoadBytes(module api.Module) []byte {
+	data, ok := module.Memory().Read(uint32(value>>32), uint32(value))
+	if !ok {
+		panic("memory read out of bounds")
+	}
+	return data
+}
+
+func FromString(value string) String {
+	position := uint32(uintptr(unsafe.Pointer(unsafe.StringData(value))))
+	bytes := uint32(len(value))
+	return String(uint64(position)<<32 | uint64(bytes))
+}
+
+type Buffer uint64
+
+func (buffer Buffer) Address() uint32 {
+	return uint32(buffer >> 32)
+}
+
+func (buffer Buffer) Length() uint32 {
+	return uint32((buffer << 32) >> 32)
+}
+
+func FromSlice(value []byte) Buffer {
+	if len(value) == 0 {
+		return 0
+	}
+	ptr := uint64(uintptr(unsafe.Pointer(&value[0])))
+	return Buffer(ptr<<32 | uint64(len(value)))
+}
+
+func (buffer Buffer) Slice() []byte {
+	return unsafe.Slice((*byte)(unsafe.Pointer(uintptr(buffer.Address()))), buffer.Length())
+}
+
+func (buffer Buffer) String() string {
+	return unsafe.String((*byte)(unsafe.Pointer(uintptr(buffer.Address()))), buffer.Length())
+}