Fix launching editor in Windows

Fixes the start command.
Saves the temporary file with .txt extension, so that Windows can correctly handle it.

utils/tempfile.go

@@ -0,0 +1,67 @@
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fileutils
+
+import (
+	"os"
+	"path/filepath"
+	"strconv"
+	"sync"
+	"time"
+)
+
+// Random number state.
+// We generate random temporary file names so that there's a good
+// chance the file doesn't exist yet - keeps the number of tries in
+// TempFile to a minimum.
+var rand uint32
+var randmu sync.Mutex
+
+func reseed() uint32 {
+	return uint32(time.Now().UnixNano() + int64(os.Getpid()))
+}
+
+func nextSuffix() string {
+	randmu.Lock()
+	r := rand
+	if r == 0 {
+		r = reseed()
+	}
+	r = r*1664525 + 1013904223 // constants from Numerical Recipes
+	rand = r
+	randmu.Unlock()
+	return strconv.Itoa(int(1e9 + r%1e9))[1:]
+}
+
+// TempFile creates a new temporary file in the directory dir
+// with a name beginning with prefix and ending with ext, opens the
+// file for reading and writing, and returns the resulting *os.File.
+// If dir is the empty string, TempFile uses the default directory
+// for temporary files (see os.TempDir).
+// Multiple programs calling TempFile simultaneously
+// will not choose the same file.  The caller can use f.Name()
+// to find the pathname of the file.  It is the caller's responsibility
+// to remove the file when no longer needed.
+func TempFile(dir, prefix, ext string) (f *os.File, err error) {
+	if dir == "" {
+		dir = os.TempDir()
+	}
+
+	nconflict := 0
+	for i := 0; i < 10000; i++ {
+		name := filepath.Join(dir, prefix+nextSuffix()+"."+ext)
+		f, err = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
+		if os.IsExist(err) {
+			if nconflict++; nconflict > 10 {
+				randmu.Lock()
+				rand = reseed()
+				randmu.Unlock()
+			}
+			continue
+		}
+		break
+	}
+	return
+}

writeas/posts.go

@@ -99,7 +99,7 @@ func getPosts() *[]Post {
 }
 
 func composeNewPost() *[]byte {
-	f, err := ioutil.TempFile(os.TempDir(), "WApost")
+	f, err := fileutils.TempFile(os.TempDir(), "WApost", "txt")
 	if err != nil {
 		if DEBUG {
 			panic(err)
@@ -109,6 +109,7 @@ func composeNewPost() *[]byte {
 		}
 	}
 	defer os.Remove(f.Name())
+	f.Close()
 
 	cmd := editPostCmd(f.Name())
 	if cmd == nil {

writeas/posts_win.go

@@ -17,5 +17,6 @@ func parentDataDir() string {
 }
 
 func editPostCmd(fname string) *exec.Cmd {
-	return exec.Command(fname)
+	// NOTE this won't work if fname contains spaces.
+	return exec.Command("cmd", "/C start /WAIT "+fname)
 }