code review 5272042: syscall: dll function load and calling changes

syscall: dll function load and calling changes

New DLL and Proc types to manage and call dll functions. These were
used to simplify syscall tests in runtime package. They were also
used to implement LazyDLL and LazyProc.

LazyProc, like Proc, now have Call function, that just a wrapper for
SyscallN. It is not as efficient as Syscall, but easier to use.

NewLazyDLL now supports non-ascii filenames.

LazyDLL and LazyProc now have Load and Find methods. These can be used
during runtime to discover if some dll functions are not present.

All dll functions now return errors that fit os.Error interface. They
also contain Windows error number.

Some of these changes are suggested by jp.

[brainman, 2011-10-13 12:25:16]

Hello golang-dev@googlegroups.com (cc: jp@webmaster.ms),

I'd like you to review this change to
https://go.googlecode.com/hg/

[jp, 2011-10-13 13:08:31]

http://codereview.appspot.com/5272042/diff/5001/src/pkg/runtime/windows/sysca...
File src/pkg/runtime/windows/syscall.goc (right):

http://codereview.appspot.com/5272042/diff/5001/src/pkg/runtime/windows/sysca...
src/pkg/runtime/windows/syscall.goc:10: func loadlibrary(filename uintptr)
(handle uintptr, err uintptr) {
Maybe func loadlibrary(filename *uint16) ?
It will remove 2 extra castings at the call point.

And returns (handle syscall.Handle, err syscall.Errno)
Not sure if it possible in cgo to specify such a type.

http://codereview.appspot.com/5272042/diff/5001/src/pkg/runtime/windows/sysca...
src/pkg/runtime/windows/syscall.goc:24: func getprocaddress(handle uintptr,
procname uintptr) (proc uintptr, err uintptr) {
same: procname *uint8

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.go
File src/pkg/syscall/dll_windows.go (right):

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:18: type Errno uint64
uint32.
Even on Win64.

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:48: if e != 0 {
h, e := loadlibrary(StringToUTF16Ptr(name)) /* if loadlibrary would accept
*uint16 */

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:52: Msg:     "Failed to load " + name + ": " +
Errstr(int(e)),
Errno:   e,
ObjName: name,
Msg:     "Failed to load " + name + ": " + e.String()
/* if loadlibrary would return syscall.Errno */

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:74: a, e := getprocaddress(uintptr(d.Handle),
uintptr(unsafe.Pointer(StringBytePtr(name))))
a, e := getprocaddress(uintptr(d.Handle), StringBytePtr(name)) /* if
getprocaddress would accept *uint8 */

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:79: Msg:     "Failed to find " + name + "
procedure in " + d.Name + ": " + Errstr(int(e)),
Errno:   e,
ObjName: name,
Msg:     "Failed to find " + name + " procedure in " + d.Name + ": " +
e.String(),
/* if getprocaddrress would return syscall.Errno */

[rsc, 2011-10-13 16:52:18]

LGTM

The sentences that say "Returns error..." should be "It returns an error...".

[brainman, 2011-10-15 06:30:05]

*** Submitted as http://code.google.com/p/go/source/detail?r=9e73a59f386c ***

syscall: dll function load and calling changes

New DLL and Proc types to manage and call dll functions. These were
used to simplify syscall tests in runtime package. They were also
used to implement LazyDLL and LazyProc.

LazyProc, like Proc, now have Call function, that just a wrapper for
SyscallN. It is not as efficient as Syscall, but easier to use.

NewLazyDLL now supports non-ascii filenames.

LazyDLL and LazyProc now have Load and Find methods. These can be used
during runtime to discover if some dll functions are not present.

All dll functions now return errors that fit os.Error interface. They
also contain Windows error number.

Some of these changes are suggested by jp.

R=golang-dev, jp, rsc
CC=golang-dev
http://codereview.appspot.com/5272042

http://codereview.appspot.com/5272042/diff/5001/src/pkg/runtime/windows/sysca...
File src/pkg/runtime/windows/syscall.goc (right):

http://codereview.appspot.com/5272042/diff/5001/src/pkg/runtime/windows/sysca...
src/pkg/runtime/windows/syscall.goc:10: func loadlibrary(filename uintptr)
(handle uintptr, err uintptr) {
On 2011/10/13 13:08:31, jp wrote:
> Maybe func loadlibrary(filename *uint16) ?
> It will remove 2 extra castings at the call point.

Done.

> 
> And returns (handle syscall.Handle, err syscall.Errno)
> Not sure if it possible in cgo to specify such a type.

I don't think it is possible too.

http://codereview.appspot.com/5272042/diff/5001/src/pkg/runtime/windows/sysca...
src/pkg/runtime/windows/syscall.goc:24: func getprocaddress(handle uintptr,
procname uintptr) (proc uintptr, err uintptr) {
On 2011/10/13 13:08:31, jp wrote:
> same: procname *uint8

Done.

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.go
File src/pkg/syscall/dll_windows.go (right):

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:18: type Errno uint64
On 2011/10/13 13:08:31, jp wrote:
> uint32.
> Even on Win64.

I copied this from os package. I expect this to be temporary. We will change it
once os.Errno will move to syscall package. Then we could decide what the value
of it should be.

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:48: if e != 0 {
On 2011/10/13 13:08:31, jp wrote:
> h, e := loadlibrary(StringToUTF16Ptr(name)) /* if loadlibrary would accept
> *uint16 */

Done.

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:52: Msg:     "Failed to load " + name + ": " +
Errstr(int(e)),
On 2011/10/13 13:08:31, jp wrote:
> /* if loadlibrary would return syscall.Errno */

It would not.

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:74: a, e := getprocaddress(uintptr(d.Handle),
uintptr(unsafe.Pointer(StringBytePtr(name))))
On 2011/10/13 13:08:31, jp wrote:
> a, e := getprocaddress(uintptr(d.Handle), StringBytePtr(name)) /* if
> getprocaddress would accept *uint8 */

Done.

http://codereview.appspot.com/5272042/diff/5001/src/pkg/syscall/dll_windows.g...
src/pkg/syscall/dll_windows.go:79: Msg:     "Failed to find " + name + "
procedure in " + d.Name + ": " + Errstr(int(e)),
On 2011/10/13 13:08:31, jp wrote:
> /* if getprocaddrress would return syscall.Errno */

It would not.