exec.Command can't get exit code from batch files on windows.

[mattn]

What steps will reproduce the problem?
1.put test.go and test.bat in same directory.
2.compile test.go & run.

What is the expected output?

false
true
false
true


What do you see instead?

true
true
false
true

Which compiler are you using (5g, 6g, 8g, gccgo)?

8g

Which operating system are you using?

WindowsXP SP3

Which revision are you using?  (hg identify)

5323e969c66a+ tip

Please provide any additional information below.

https://groups.google.com/d/topic/golang-dev/ujtLlrp8e_c/discussion

This cause:
1. Batch files don't pass exit code to parent process.
   You can only get %ERRORLEVEL%.
2. Batch file is kicked with new console in cmd.exe.
3. If use 'call' command, cmd.exe can get the exit code.

See LINE3 and LINE4 in test.go.
They can get exit code from batch files.

And 'call' command is used for 'exe' files.

Thus, go have to better to provide new Command object.
For example,

  out, err := exec.ShellCommand(command).ConbineOutput()

This object runs command with "cmd.exe /c call".

For unix, it works with "sh -c "

Attachments:

1. test.bat (23 bytes)
2. test.go (351 bytes)

[mattn]

Comment 1:

If you accept my design "exec.ShellCommand", I'll start to implement.

[rsc]

Comment 2:

This should not require new API.
This is just a Windows bug we need to fix.
Let's make syscall.StartCommand work.

[alexbrainman]

Comment 3:

Are we saying exec.Command("hello.bat") should be automatically rewritten into
syscall.CreateProcess("cmd", "/c", "hello.bat")?
Alex

Owner changed to @alexbrainman.

Status changed to WaitingForReply.

[mattn]

Comment 4:

Yes

[alexbrainman]

Comment 5:

Can we try and understand the problem you are having first. The example you have
provided so far is not very good. If you change your batch file to:
@echo off
exit %1
then your program will print
true
false
false
true
as is expected by your explanation. Would this be enough to solve your problem?
Alex

[gopherbot]

Comment 6 by hcwfrichter:

For what it's worth, I see the same results as Alex (no problem seen), and without
changing the batch file at all (though it works with Alex's change as well).  
Vista32, 8g, tip(b9195358cc18)
Perhaps the problem is limited to XP SP3?
Also, the initial problem description says
   What is the expected output?
   false
   true
   false
   true
but based on the the ordering of tests in test.go, I think that's a typo.

[alexbrainman]

Comment 7:

I assumed "expected output" have a typo.
Alex

[mattn]

Comment 8:

As far as I said in few days ago, "exit 1" is not "HOW TO QUIT BATCH FILE WITH CODE 1".
This is "HOW TO QUIT CMD.EXE WITH CODE 1".
Then, If you call the batch file in your command prompt, cmd.exe will be destroyed.
For example, if hg.bat include "exit 1":
-------------------
C:\go>vim go/src/pkg/syscall/syscall_windwos.go
C:\go>echo "ok, i'll edit next file. before editing, I'll update repo."
ok, i'll edit next file. before editing, I'll update repo.
C:\go>hg pull
-------------------
You will lost your command prompt.
This is not problem "how batch file should be changed".

[alexbrainman]

Comment 9:

I tried running your batch file from command line. It does appear to return 0 all the
time regardless:
C:\>test.bat 0 && echo "Zero result"
"Zero result"
C:\>test.bat 1 && echo "Zero result"
"Zero result"
C:\>test.bat 0 || echo "Non-zero result"
C:\>test.bat 1 || echo "Non-zero result"
C:\>
It looks to me that cmd.exe always see 0 exit code. That is what current os.StartProcess
does. Isn't it?
I think there are too many "tricky" things to make it work simple and clear. I think
people should avoid using batch files when they can. If you can't avoid batch file, then
you still have an option to use os.StartProcess with appropriate parameters, but then at
least you supposed to know what you are doing.
Alex

[mattn]

Comment 10:

You can get exit code of test.bat with following
C:\>cmd /c test.bat 0
C:\>echo %ERRORLEVEL%
0
C:\>cmd /c test.bat 1
C:\>echo %ERRORLEVEL%
1
Then, we should call:
  CreateProcess("c:/windows/system32/cmd.exe", "c:/windows/system32/cmd.exe /c call test.bat 1", ...)
Or
  CreateProcess("c:/windows/system32/cmd.exe", "c:/windows/system32/cmd.exe /v:on /c call test.bat 1 & exit !ERRORLEVEL!", ...)

[mattn]

Comment 11:

Or new option for os.StartProcess(), or cmd := &exec.ShellCommand{...}.

[alexbrainman]

Comment 12:

If you think, you should change your program, then do. I am not convinced there is
anything needs to be change in standard library.
Alex

[rsc]

Comment 13:

What does mingw do if you try to exec one of these
batch files in a C program?  Does it let you get at
the batch file status code?
Russ

[mattn]

Comment 14:

> What does mingw do if you try to exec one of these
> batch files in a C program?  Does it let you get at
> the batch file status code?
No (if doing without workaround)

[rsc]

Comment 15:

If mingw gets it wrong, then I think it is not so bad
for Go to get it wrong.  It sounds like the root problem
is a Windows design flaw and a mistake by the hg developers
to rely on a batch file.
I will fix hgpatch to work around this bug.
Russ