1 files changed, 153 insertions, 0 deletions
diff --git a/vendor/github.com/blevesearch/mmap-go/mmap_windows.go b/vendor/github.com/blevesearch/mmap-go/mmap_windows.go
new file mode 100644
index 0000000000..631b3825f9
--- /dev/null
+++ b/vendor/github.com/blevesearch/mmap-go/mmap_windows.go
@@ -0,0 +1,153 @@
+// Copyright 2011 Evan Shaw. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mmap
+
+import (
+	"errors"
+	"os"
+	"sync"
+
+	"golang.org/x/sys/windows"
+)
+
+// mmap on Windows is a two-step process.
+// First, we call CreateFileMapping to get a handle.
+// Then, we call MapviewToFile to get an actual pointer into memory.
+// Because we want to emulate a POSIX-style mmap, we don't want to expose
+// the handle -- only the pointer. We also want to return only a byte slice,
+// not a struct, so it's convenient to manipulate.
+
+// We keep this map so that we can get back the original handle from the memory address.
+
+type addrinfo struct {
+	file     windows.Handle
+	mapview  windows.Handle
+	writable bool
+}
+
+var handleLock sync.Mutex
+var handleMap = map[uintptr]*addrinfo{}
+
+func mmap(len int, prot, flags, hfile uintptr, off int64) ([]byte, error) {
+	flProtect := uint32(windows.PAGE_READONLY)
+	dwDesiredAccess := uint32(windows.FILE_MAP_READ)
+	writable := false
+	switch {
+	case prot&COPY != 0:
+		flProtect = windows.PAGE_WRITECOPY
+		dwDesiredAccess = windows.FILE_MAP_COPY
+		writable = true
+	case prot&RDWR != 0:
+		flProtect = windows.PAGE_READWRITE
+		dwDesiredAccess = windows.FILE_MAP_WRITE
+		writable = true
+	}
+	if prot&EXEC != 0 {
+		flProtect <<= 4
+		dwDesiredAccess |= windows.FILE_MAP_EXECUTE
+	}
+
+	// The maximum size is the area of the file, starting from 0,
+	// that we wish to allow to be mappable. It is the sum of
+	// the length the user requested, plus the offset where that length
+	// is starting from. This does not map the data into memory.
+	maxSizeHigh := uint32((off + int64(len)) >> 32)
+	maxSizeLow := uint32((off + int64(len)) & 0xFFFFFFFF)
+	// TODO: Do we need to set some security attributes? It might help portability.
+	h, errno := windows.CreateFileMapping(windows.Handle(hfile), nil, flProtect, maxSizeHigh, maxSizeLow, nil)
+	if h == 0 {
+		return nil, os.NewSyscallError("CreateFileMapping", errno)
+	}
+
+	// Actually map a view of the data into memory. The view's size
+	// is the length the user requested.
+	fileOffsetHigh := uint32(off >> 32)
+	fileOffsetLow := uint32(off & 0xFFFFFFFF)
+	addr, errno := windows.MapViewOfFile(h, dwDesiredAccess, fileOffsetHigh, fileOffsetLow, uintptr(len))
+	if addr == 0 {
+		return nil, os.NewSyscallError("MapViewOfFile", errno)
+	}
+	handleLock.Lock()
+	handleMap[addr] = &addrinfo{
+		file:     windows.Handle(hfile),
+		mapview:  h,
+		writable: writable,
+	}
+	handleLock.Unlock()
+
+	m := MMap{}
+	dh := m.header()
+	dh.Data = addr
+	dh.Len = len
+	dh.Cap = dh.Len
+
+	return m, nil
+}
+
+func (m MMap) flush() error {
+	addr, len := m.addrLen()
+	errno := windows.FlushViewOfFile(addr, len)
+	if errno != nil {
+		return os.NewSyscallError("FlushViewOfFile", errno)
+	}
+
+	handleLock.Lock()
+	defer handleLock.Unlock()
+	handle, ok := handleMap[addr]
+	if !ok {
+		// should be impossible; we would've errored above
+		return errors.New("unknown base address")
+	}
+
+	if handle.writable {
+		if err := windows.FlushFileBuffers(handle.file); err != nil {
+			return os.NewSyscallError("FlushFileBuffers", err)
+		}
+	}
+
+	return nil
+}
+
+func (m MMap) lock() error {
+	addr, len := m.addrLen()
+	errno := windows.VirtualLock(addr, len)
+	return os.NewSyscallError("VirtualLock", errno)
+}
+
+func (m MMap) unlock() error {
+	addr, len := m.addrLen()
+	errno := windows.VirtualUnlock(addr, len)
+	return os.NewSyscallError("VirtualUnlock", errno)
+}
+
+func (m MMap) unmap() error {
+	err := m.flush()
+	if err != nil {
+		return err
+	}
+
+	addr := m.header().Data
+	// Lock the UnmapViewOfFile along with the handleMap deletion.
+	// As soon as we unmap the view, the OS is free to give the
+	// same addr to another new map. We don't want another goroutine
+	// to insert and remove the same addr into handleMap while
+	// we're trying to remove our old addr/handle pair.
+	handleLock.Lock()
+	defer handleLock.Unlock()
+	err = windows.UnmapViewOfFile(addr)
+	if err != nil {
+		return err
+	}
+
+	handle, ok := handleMap[addr]
+	if !ok {
+		// should be impossible; we would've errored above
+		return errors.New("unknown base address")
+	}
+	delete(handleMap, addr)
+
+	e := windows.CloseHandle(windows.Handle(handle.mapview))
+	return os.NewSyscallError("CloseHandle", e)
+}