[experiment] add alternative wasm sqlite3 implementation available via build-tag (#2863)

This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).

1 files changed, 79 insertions, 0 deletions

diff --git a/vendor/github.com/tetratelabs/wazero/internal/wasm/binary/data.go b/vendor/github.com/tetratelabs/wazero/internal/wasm/binary/data.go
new file mode 100644
index 000000000..054ccb3c6
--- /dev/null
+++ b/vendor/github.com/tetratelabs/wazero/internal/wasm/binary/data.go
@@ -0,0 +1,79 @@
+package binary
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	"github.com/tetratelabs/wazero/api"
+	"github.com/tetratelabs/wazero/internal/leb128"
+	"github.com/tetratelabs/wazero/internal/wasm"
+)
+
+// dataSegmentPrefix represents three types of data segments.
+//
+// https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/binary/modules.html#data-section
+type dataSegmentPrefix = uint32
+
+const (
+	// dataSegmentPrefixActive is the prefix for the version 1.0 compatible data segment, which is classified as "active" in 2.0.
+	dataSegmentPrefixActive dataSegmentPrefix = 0x0
+	// dataSegmentPrefixPassive prefixes the "passive" data segment as in version 2.0 specification.
+	dataSegmentPrefixPassive dataSegmentPrefix = 0x1
+	// dataSegmentPrefixActiveWithMemoryIndex is the active prefix with memory index encoded which is defined for futur use as of 2.0.
+	dataSegmentPrefixActiveWithMemoryIndex dataSegmentPrefix = 0x2
+)
+
+func decodeDataSegment(r *bytes.Reader, enabledFeatures api.CoreFeatures, ret *wasm.DataSegment) (err error) {
+	dataSegmentPrefx, _, err := leb128.DecodeUint32(r)
+	if err != nil {
+		err = fmt.Errorf("read data segment prefix: %w", err)
+		return
+	}
+
+	if dataSegmentPrefx != dataSegmentPrefixActive {
+		if err = enabledFeatures.RequireEnabled(api.CoreFeatureBulkMemoryOperations); err != nil {
+			err = fmt.Errorf("non-zero prefix for data segment is invalid as %w", err)
+			return
+		}
+	}
+
+	switch dataSegmentPrefx {
+	case dataSegmentPrefixActive,
+		dataSegmentPrefixActiveWithMemoryIndex:
+		// Active data segment as in
+		// https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/binary/modules.html#data-section
+		if dataSegmentPrefx == 0x2 {
+			d, _, err := leb128.DecodeUint32(r)
+			if err != nil {
+				return fmt.Errorf("read memory index: %v", err)
+			} else if d != 0 {
+				return fmt.Errorf("memory index must be zero but was %d", d)
+			}
+		}
+
+		err = decodeConstantExpression(r, enabledFeatures, &ret.OffsetExpression)
+		if err != nil {
+			return fmt.Errorf("read offset expression: %v", err)
+		}
+	case dataSegmentPrefixPassive:
+		// Passive data segment doesn't need const expr nor memory index encoded.
+		// https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/binary/modules.html#data-section
+		ret.Passive = true
+	default:
+		err = fmt.Errorf("invalid data segment prefix: 0x%x", dataSegmentPrefx)
+		return
+	}
+
+	vs, _, err := leb128.DecodeUint32(r)
+	if err != nil {
+		err = fmt.Errorf("get the size of vector: %v", err)
+		return
+	}
+
+	ret.Init = make([]byte, vs)
+	if _, err = io.ReadFull(r, ret.Init); err != nil {
+		err = fmt.Errorf("read bytes for init: %v", err)
+	}
+	return
+}