From 1e7b32490dfdccddd04f46d4b0416b48d749d51b Mon Sep 17 00:00:00 2001
From: kim <89579420+NyaaaWhatsUpDoc@users.noreply.github.com>
Date: Mon, 27 May 2024 15:46:15 +0000
Subject: [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/).
---
 .../ncruces/go-sqlite3/internal/util/alloc_unix.go | 67 ++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 vendor/github.com/ncruces/go-sqlite3/internal/util/alloc_unix.go

(limited to 'vendor/github.com/ncruces/go-sqlite3/internal/util/alloc_unix.go')

diff --git a/vendor/github.com/ncruces/go-sqlite3/internal/util/alloc_unix.go b/vendor/github.com/ncruces/go-sqlite3/internal/util/alloc_unix.go
new file mode 100644
index 000000000..2b1d3916b
--- /dev/null
+++ b/vendor/github.com/ncruces/go-sqlite3/internal/util/alloc_unix.go
@@ -0,0 +1,67 @@
+//go:build unix && !sqlite3_nosys
+
+package util
+
+import (
+	"math"
+
+	"github.com/tetratelabs/wazero/experimental"
+	"golang.org/x/sys/unix"
+)
+
+func virtualAlloc(cap, max uint64) experimental.LinearMemory {
+	// Round up to the page size.
+	rnd := uint64(unix.Getpagesize() - 1)
+	max = (max + rnd) &^ rnd
+
+	if max > math.MaxInt {
+		// This ensures int(max) overflows to a negative value,
+		// and unix.Mmap returns EINVAL.
+		max = math.MaxUint64
+	}
+
+	// Reserve max bytes of address space, to ensure we won't need to move it.
+	// A protected, private, anonymous mapping should not commit memory.
+	b, err := unix.Mmap(-1, 0, int(max), unix.PROT_NONE, unix.MAP_PRIVATE|unix.MAP_ANON)
+	if err != nil {
+		panic(err)
+	}
+	return &mmappedMemory{buf: b[:0]}
+}
+
+// The slice covers the entire mmapped memory:
+//   - len(buf) is the already committed memory,
+//   - cap(buf) is the reserved address space.
+type mmappedMemory struct {
+	buf []byte
+}
+
+func (m *mmappedMemory) Reallocate(size uint64) []byte {
+	com := uint64(len(m.buf))
+	res := uint64(cap(m.buf))
+	if com < size && size < res {
+		// Round up to the page size.
+		rnd := uint64(unix.Getpagesize() - 1)
+		new := (size + rnd) &^ rnd
+
+		// Commit additional memory up to new bytes.
+		err := unix.Mprotect(m.buf[com:new], unix.PROT_READ|unix.PROT_WRITE)
+		if err != nil {
+			panic(err)
+		}
+
+		// Update committed memory.
+		m.buf = m.buf[:new]
+	}
+	// Limit returned capacity because bytes beyond
+	// len(m.buf) have not yet been committed.
+	return m.buf[:size:len(m.buf)]
+}
+
+func (m *mmappedMemory) Free() {
+	err := unix.Munmap(m.buf[:cap(m.buf)])
+	if err != nil {
+		panic(err)
+	}
+	m.buf = nil
+}
-- 
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