syscall: implement WaitStatus and Wait4() for windows

R=brainman, rsc, kardia, Joe Poirier
CC=golang-dev
https://golang.org/cl/1910041

src/pkg/syscall/exec_windows.go

@@ -117,7 +117,6 @@ func SetNonblock(fd int, nonblocking bool) (errno int) {
 
 // TODO(kardia): Add trace
 //The command and arguments are passed via the Command line parameter.
-//Thus, repeating the exec name in the first argument is unneeded.
 func forkExec(argv0 string, argv []string, envv []string, traceme bool, dir string, fd []int) (pid int, err int) {
 	if traceme == true {
 		return 0, EWINDOWS
@@ -150,23 +149,28 @@ func forkExec(argv0 string, argv []string, envv []string, traceme bool, dir stri
 		if ok, err := DuplicateHandle(currentProc, int32(fd[0]), currentProc, &startupInfo.StdInput, 0, true, DUPLICATE_SAME_ACCESS); !ok {
 			return 0, err
 		}
+		defer CloseHandle(int32(startupInfo.StdInput))
 	}
 	if len(fd) > 1 && fd[1] > 0 {
 		if ok, err := DuplicateHandle(currentProc, int32(fd[1]), currentProc, &startupInfo.StdOutput, 0, true, DUPLICATE_SAME_ACCESS); !ok {
 			return 0, err
 		}
+		defer CloseHandle(int32(startupInfo.StdOutput))
 	}
 	if len(fd) > 2 && fd[2] > 0 {
 		if ok, err := DuplicateHandle(currentProc, int32(fd[2]), currentProc, &startupInfo.StdErr, 0, true, DUPLICATE_SAME_ACCESS); !ok {
 			return 0, err
 		}
+		defer CloseHandle(int32(startupInfo.StdErr))
+	}
+	if len(argv) == 0 {
+		argv = []string{""}
 	}
-
 	// argv0 must not be longer then 256 chars
 	// but the entire cmd line can have up to 32k chars (msdn)
 	ok, err := CreateProcess(
 		nil,
-		StringToUTF16Ptr(escapeAddQuotes(argv0)+" "+stringJoin(argv, " ", escapeAddQuotes)),
+		StringToUTF16Ptr(escapeAddQuotes(argv0)+" "+stringJoin(argv[1:], " ", escapeAddQuotes)),
 		nil,  //ptr to struct lpProcessAttributes
 		nil,  //ptr to struct lpThreadAttributes
 		true, //bInheritHandles

src/pkg/syscall/syscall_windows.go

@@ -137,6 +137,8 @@ func getSysProcAddr(m uint32, pname string) uintptr {
 //sys	CryptAcquireContext(provhandle *uint32, container *uint16, provider *uint16, provtype uint32, flags uint32) (ok bool, errno int) = advapi32.CryptAcquireContextW
 //sys	CryptReleaseContext(provhandle uint32, flags uint32) (ok bool, errno int) = advapi32.CryptReleaseContext
 //sys	CryptGenRandom(provhandle uint32, buflen uint32, buf *byte) (ok bool, errno int) = advapi32.CryptGenRandom
+//sys OpenProcess(da uint32,b int, pid uint32) (handle uint32, errno int)
+//sys GetExitCodeProcess(h uint32, c *uint32) (ok bool, errno int)
 //sys	GetEnvironmentStrings() (envs *uint16, errno int) [failretval=nil] = kernel32.GetEnvironmentStringsW
 //sys	FreeEnvironmentStrings(envs *uint16) (ok bool, errno int) = kernel32.FreeEnvironmentStringsW
 //sys	GetEnvironmentVariable(name *uint16, buffer *uint16, size uint32) (n uint32, errno int) = kernel32.GetEnvironmentVariableW
@@ -691,15 +693,35 @@ type Rusage struct {
 	Nivcsw   int32
 }
 
-func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, errno int) {
-	return 0, EWINDOWS
+type WaitStatus struct {
+	Status   uint32
+	ExitCode uint32
 }
 
-type WaitStatus uint32
+func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, errno int) {
+	handle, errno := OpenProcess(PROCESS_ALL_ACCESS, 0, uint32(pid))
+	if errno != 0 {
+		return 0, errno
+	}
+	defer CloseHandle(int32(handle))
+	e, errno := WaitForSingleObject(int32(handle), INFINITE)
+	var c uint32
+	if ok, errno := GetExitCodeProcess(handle, &c); !ok {
+		return 0, errno
+	}
+	*wstatus = WaitStatus{e, c}
+	return pid, 0
+}
 
-func (WaitStatus) Exited() bool { return false }
 
-func (WaitStatus) ExitStatus() int { return -1 }
+func (w WaitStatus) Exited() bool { return w.Status == WAIT_OBJECT_0 }
+
+func (w WaitStatus) ExitStatus() int {
+	if w.Status == WAIT_OBJECT_0 {
+		return int(w.ExitCode)
+	}
+	return -1
+}
 
 func (WaitStatus) Signal() int { return -1 }
 
@@ -711,6 +733,6 @@ func (WaitStatus) Continued() bool { return false }
 
 func (WaitStatus) StopSignal() int { return -1 }
 
-func (WaitStatus) Signaled() bool { return false }
+func (w WaitStatus) Signaled() bool { return w.Status == WAIT_OBJECT_0 }
 
 func (WaitStatus) TrapCause() int { return -1 }

src/pkg/syscall/zsyscall_windows_386.go

@@ -53,6 +53,8 @@ var (
 	procCryptAcquireContextW       = getSysProcAddr(modadvapi32, "CryptAcquireContextW")
 	procCryptReleaseContext        = getSysProcAddr(modadvapi32, "CryptReleaseContext")
 	procCryptGenRandom             = getSysProcAddr(modadvapi32, "CryptGenRandom")
+	procOpenProcess                = getSysProcAddr(modkernel32, "OpenProcess")
+	procGetExitCodeProcess         = getSysProcAddr(modkernel32, "GetExitCodeProcess")
 	procGetEnvironmentStringsW     = getSysProcAddr(modkernel32, "GetEnvironmentStringsW")
 	procFreeEnvironmentStringsW    = getSysProcAddr(modkernel32, "FreeEnvironmentStringsW")
 	procGetEnvironmentVariableW    = getSysProcAddr(modkernel32, "GetEnvironmentVariableW")
@@ -679,6 +681,36 @@ func CryptGenRandom(provhandle uint32, buflen uint32, buf *byte) (ok bool, errno
 	return
 }
 
+func OpenProcess(da uint32, b int, pid uint32) (handle uint32, errno int) {
+	r0, _, e1 := Syscall(procOpenProcess, uintptr(da), uintptr(b), uintptr(pid))
+	handle = (uint32)(r0)
+	if handle == 0 {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
+func GetExitCodeProcess(h uint32, c *uint32) (ok bool, errno int) {
+	r0, _, e1 := Syscall(procGetExitCodeProcess, uintptr(h), uintptr(unsafe.Pointer(c)), 0)
+	ok = (bool)(r0 != 0)
+	if !ok {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
 func GetEnvironmentStrings() (envs *uint16, errno int) {
 	r0, _, e1 := Syscall(procGetEnvironmentStringsW, 0, 0, 0)
 	envs = (*uint16)(unsafe.Pointer(r0))

src/pkg/syscall/ztypes_windows_386.go

@@ -105,6 +105,9 @@ const (
 	INFINITE              = 0xffffffff
 
 	WAIT_TIMEOUT   = 258
+	WAIT_ABANDONED = 0x00000080
+	WAIT_OBJECT_0  = 0x00000000
+	WAIT_FAILED    = 0xFFFFFFFF
 
 	CREATE_UNICODE_ENVIRONMENT = 0x00000400
 )
@@ -473,3 +476,10 @@ type DNSRecord struct {
 	Reserved uint32
 	Data     [40]byte
 }
+
+const (
+	HANDLE_FLAG_INHERIT            = 0x00000001
+	HANDLE_FLAG_PROTECT_FROM_CLOSE = 0x00000002
+
+	PROCESS_ALL_ACCESS = 0x001fffff
+)