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syscall: implement Ftruncate using a single syscall on Windows

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Ftruncate can be implemented on Windows using a single syscall. This
makes the implementation more efficient and less prone to races when
used in combination with other Seek calls.

Change-Id: I5d9f780fba2710403fce89d3325e519f33ad9ae8
Reviewed-on: https://go-review.googlesource.com/c/go/+/618835
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
qmuntal 2024-10-09 10:12:57 +02:00 committed by Quim Muntal
parent 3352db152b
commit 0fd2d4d6c2
2 changed files with 16 additions and 13 deletions
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20
src/syscall/syscall_windows.go
View File

@ -323,6 +323,7 @@ func NewCallbackCDecl(fn any) uintptr {
//sys Process32First(snapshot Handle, procEntry *ProcessEntry32) (err error) = kernel32.Process32FirstW
//sys Process32Next(snapshot Handle, procEntry *ProcessEntry32) (err error) = kernel32.Process32NextW
//sys DeviceIoControl(handle Handle, ioControlCode uint32, inBuffer *byte, inBufferSize uint32, outBuffer *byte, outBufferSize uint32, bytesReturned *uint32, overlapped *Overlapped) (err error)
//sys setFileInformationByHandle(handle Handle, fileInformationClass uint32, buf unsafe.Pointer, bufsize uint32) (err error) = kernel32.SetFileInformationByHandle
// This function returns 1 byte BOOLEAN rather than the 4 byte BOOL.
//sys CreateSymbolicLink(symlinkfilename *uint16, targetfilename *uint16, flags uint32) (err error) [failretval&0xff==0] = CreateSymbolicLinkW
//sys CreateHardLink(filename *uint16, existingfilename *uint16, reserved uintptr) (err error) [failretval&0xff==0] = CreateHardLinkW
@ -610,20 +611,13 @@ func ComputerName() (name string, err error) {
}
func Ftruncate(fd Handle, length int64) (err error) {
curoffset, e := Seek(fd, 0, 1)
if e != nil {
return e
type _FILE_END_OF_FILE_INFO struct {
EndOfFile int64
}
defer Seek(fd, curoffset, 0)
_, e = Seek(fd, length, 0)
if e != nil {
return e
}
e = SetEndOfFile(fd)
if e != nil {
return e
}
return nil
const FileEndOfFileInfo = 6
var info _FILE_END_OF_FILE_INFO
info.EndOfFile = length
return setFileInformationByHandle(fd, FileEndOfFileInfo, unsafe.Pointer(&info), uint32(unsafe.Sizeof(info)))
}
func Gettimeofday(tv *Timeval) (err error) {

9
src/syscall/zsyscall_windows.go
View File

@ -150,6 +150,7 @@ var (
procSetEnvironmentVariableW = modkernel32.NewProc("SetEnvironmentVariableW")
procSetFileAttributesW = modkernel32.NewProc("SetFileAttributesW")
procSetFileCompletionNotificationModes = modkernel32.NewProc("SetFileCompletionNotificationModes")
procSetFileInformationByHandle = modkernel32.NewProc("SetFileInformationByHandle")
procSetFilePointer = modkernel32.NewProc("SetFilePointer")
procSetFileTime = modkernel32.NewProc("SetFileTime")
procSetHandleInformation = modkernel32.NewProc("SetHandleInformation")
@ -1071,6 +1072,14 @@ func SetFileCompletionNotificationModes(handle Handle, flags uint8) (err error)
return
}
func setFileInformationByHandle(handle Handle, fileInformationClass uint32, buf unsafe.Pointer, bufsize uint32) (err error) {
r1, _, e1 := Syscall6(procSetFileInformationByHandle.Addr(), 4, uintptr(handle), uintptr(fileInformationClass), uintptr(buf), uintptr(bufsize), 0, 0)
if r1 == 0 {
err = errnoErr(e1)
}
return
}
func SetFilePointer(handle Handle, lowoffset int32, highoffsetptr *int32, whence uint32) (newlowoffset uint32, err error) {
r0, _, e1 := Syscall6(procSetFilePointer.Addr(), 4, uintptr(handle), uintptr(lowoffset), uintptr(unsafe.Pointer(highoffsetptr)), uintptr(whence), 0, 0)
newlowoffset = uint32(r0)