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pkg/pidfile: windows: replace magic consts for golang.org/x/sys consts 

These consts were defined locally, but are now defined in golang.org/x/sys, so
we can use those.

Also added some documentation about how this function works, taking the description
from the GetExitCodeProcess function (processthreadsapi.h) API reference:
https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-getexitcodeprocess

> The GetExitCodeProcess function returns a valid error code defined by the
> application only after the thread terminates. Therefore, an application should
> not use `STILL_ACTIVE` (259) as an error code (`STILL_ACTIVE` is a macro for
> `STATUS_PENDING` (minwinbase.h)). If a thread returns `STILL_ACTIVE` (259) as
> an error code, then applications that test for that value could interpret it
> to mean that the thread is still running, and continue to test for the
> completion of the thread after the thread has terminated, which could put
> the application into an infinite loop.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This commit is contained in:
Sebastiaan van Stijn 2022-10-09 12:48:35 +02:00
parent 9582dd10e1
commit 89de943401
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GPG Key ID: 76698F39D527CE8C
1 changed files with 13 additions and 8 deletions
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21
pkg/pidfile/pidfile_windows.go
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@ -4,14 +4,8 @@ import (
"golang.org/x/sys/windows"
)
const (
processQueryLimitedInformation = 0x1000
stillActive = 259
)
func processExists(pid int) bool {
h, err := windows.OpenProcess(processQueryLimitedInformation, false, uint32(pid))
h, err := windows.OpenProcess(windows.PROCESS_QUERY_LIMITED_INFORMATION, false, uint32(pid))
if err != nil {
return false
}
@ -19,7 +13,18 @@ func processExists(pid int) bool {
err = windows.GetExitCodeProcess(h, &c)
windows.Close(h)
if err != nil {
return c == stillActive
// From the GetExitCodeProcess function (processthreadsapi.h) API docs:
// https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-getexitcodeprocess
//
// The GetExitCodeProcess function returns a valid error code defined by the
// application only after the thread terminates. Therefore, an application should
// not use STILL_ACTIVE (259) as an error code (STILL_ACTIVE is a macro for
// STATUS_PENDING (minwinbase.h)). If a thread returns STILL_ACTIVE (259) as
// an error code, then applications that test for that value could interpret it
// to mean that the thread is still running, and continue to test for the
// completion of the thread after the thread has terminated, which could put
// the application into an infinite loop.
return c == uint32(windows.STATUS_PENDING)
}
return true
}