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/).
---
 .../wazero/internal/platform/mmap_unix.go          | 49 ++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 vendor/github.com/tetratelabs/wazero/internal/platform/mmap_unix.go

(limited to 'vendor/github.com/tetratelabs/wazero/internal/platform/mmap_unix.go')

diff --git a/vendor/github.com/tetratelabs/wazero/internal/platform/mmap_unix.go b/vendor/github.com/tetratelabs/wazero/internal/platform/mmap_unix.go
new file mode 100644
index 000000000..a61996d58
--- /dev/null
+++ b/vendor/github.com/tetratelabs/wazero/internal/platform/mmap_unix.go
@@ -0,0 +1,49 @@
+//go:build (darwin || linux || freebsd) && !tinygo
+
+package platform
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+const (
+	mmapProtAMD64 = syscall.PROT_READ | syscall.PROT_WRITE | syscall.PROT_EXEC
+	mmapProtARM64 = syscall.PROT_READ | syscall.PROT_WRITE
+)
+
+const MmapSupported = true
+
+func munmapCodeSegment(code []byte) error {
+	return syscall.Munmap(code)
+}
+
+// mmapCodeSegmentAMD64 gives all read-write-exec permission to the mmap region
+// to enter the function. Otherwise, segmentation fault exception is raised.
+func mmapCodeSegmentAMD64(size int) ([]byte, error) {
+	// The region must be RWX: RW for writing native codes, X for executing the region.
+	return mmapCodeSegment(size, mmapProtAMD64)
+}
+
+// mmapCodeSegmentARM64 cannot give all read-write-exec permission to the mmap region.
+// Otherwise, the mmap systemcall would raise an error. Here we give read-write
+// to the region so that we can write contents at call-sites. Callers are responsible to
+// execute MprotectRX on the returned buffer.
+func mmapCodeSegmentARM64(size int) ([]byte, error) {
+	// The region must be RW: RW for writing native codes.
+	return mmapCodeSegment(size, mmapProtARM64)
+}
+
+// MprotectRX is like syscall.Mprotect with RX permission, defined locally so that freebsd compiles.
+func MprotectRX(b []byte) (err error) {
+	var _p0 unsafe.Pointer
+	if len(b) > 0 {
+		_p0 = unsafe.Pointer(&b[0])
+	}
+	const prot = syscall.PROT_READ | syscall.PROT_EXEC
+	_, _, e1 := syscall.Syscall(syscall.SYS_MPROTECT, uintptr(_p0), uintptr(len(b)), uintptr(prot))
+	if e1 != 0 {
+		err = syscall.Errno(e1)
+	}
+	return
+}
-- 
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