From b31d51e0b16f6233f2285adbab674ecfa2ace4ff Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@sbcglobal.net>
Date: Sat, 5 Sep 2015 13:59:36 -0600
Subject: inotify: Avoid most of the race conditions, get rid of Cint

There's still a condition that could be a race with fd-reuse, if one
goroutine is calling inotify.{AddWatch,RmWatch,Read}(); another
goroutine is calling inotify.Close(), and several things happen between
loadFd() running and the add_watch/rm_watch/read syscall launching:
 - syscall.Close() returns
 - syscall.Open() reuses the filedescriptor

           A                                  B
    syscall(loadFd())         inotify.Close(); syscall.Open()
    ----------------------------------------------------------
           loadFd()
                                     syscall.Close()
                                     syscall.Open()
           syscall()

Given that Read() can't be allowed to block Close() from running, I'm not
sure there's a way to fix this.
---
 inotify/syscall.go | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

(limited to 'inotify/syscall.go')

diff --git a/inotify/syscall.go b/inotify/syscall.go
index 1b5c426..721a10a 100644
--- a/inotify/syscall.go
+++ b/inotify/syscall.go
@@ -1,14 +1,11 @@
 package inotify
 
 import (
-	"C"
 	"os"
 	"syscall"
 )
 
-type Cint C.int
-
-func pathError(op string, path string, err error) error {
+func newPathError(op string, path string, err error) error {
 	if err == nil {
 		return nil
 	}
@@ -16,26 +13,26 @@ func pathError(op string, path string, err error) error {
 }
 
 /* Create and initialize inotify instance.  */
-func inotify_init() (Cint, error) {
+func inotify_init() (Fd, error) {
 	fd, errno := syscall.InotifyInit()
-	return Cint(fd), os.NewSyscallError("inotify_init", errno)
+	return Fd(fd), os.NewSyscallError("inotify_init", errno)
 }
 
 /* Create and initialize inotify instance.  */
-func inotify_init1(flags Cint) (Cint, error) {
-	fd, errno := syscall.InotifyInit1(int(flags))
-	return Cint(fd), os.NewSyscallError("inotify_init1", errno)
+func inotify_init1(flags int) (Fd, error) {
+	fd, errno := syscall.InotifyInit1(flags)
+	return Fd(fd), os.NewSyscallError("inotify_init1", errno)
 }
 
 /* Add watch of object NAME to inotify instance FD.  Notify about
    events specified by MASK.  */
-func inotify_add_watch(fd Cint, name string, mask uint32) (Cint, error) {
-	wd, errno := syscall.InotifyAddWatch(int(fd), name, mask)
-	return Cint(wd), pathError("inotify_add_watch", name, errno)
+func inotify_add_watch(fd Fd, name string, mask Mask) (Wd, error) {
+	wd, errno := syscall.InotifyAddWatch(int(fd), name, uint32(mask))
+	return Wd(wd), newPathError("inotify_add_watch", name, errno)
 }
 
 /* Remove the watch specified by WD from the inotify instance FD.  */
-func inotify_rm_watch(fd Cint, wd Cint) error {
+func inotify_rm_watch(fd Fd, wd Wd) error {
 	success, errno := syscall.InotifyRmWatch(int(fd), uint32(wd))
 	switch success {
 	case -1:
@@ -52,11 +49,11 @@ func inotify_rm_watch(fd Cint, wd Cint) error {
 	panic("should never happen")
 }
 
-func sysclose(fd Cint) error {
+func sysclose(fd Fd) error {
 	return os.NewSyscallError("close", syscall.Close(int(fd)))
 }
 
-func sysread(fd Cint, p []byte) (Cint, error) {
+func sysread(fd Fd, p []byte) (int, error) {
 	n, err := syscall.Read(int(fd), p)
-	return Cint(n), os.NewSyscallError("read", err)
+	return n, os.NewSyscallError("read", err)
 }
-- 
cgit v1.2.3