syscall: exec_windows.go: arguments should not be escaped to work with msiexec

[josephspurrier]

Problem: When I try to run a command in Go on Windows using exec.Command() and then exec.Run(), the arguments are escaped using this logic: https://github.com/golang/go/blob/master/src/syscall/exec_windows.go#L26. That logic escapes the quotes around TARGETDIR="%v" which need to be there. I currently am assigning to Cmd.SysProcAttr manually to get around the escaping.

1. What version of Go are you using (go version)?
   Go 1.6.2
2. What operating system and processor architecture are you using (go env)?
   Windows 10 Pro x64
3. What did you do?
4. The code is available here, but needs to be run on Windows: https://play.golang.org/p/aU1PlbNTqM
5. Download any MSI. I used https://fastdl.mongodb.org/win32/mongodb-win32-x86_64-2008plus-ssl-3.2.6-signed.msi and renamed it to package.msi.
6. You can run Error() and NoError() to see the difference
7. What did you expect to see?
   I expect to see the MSI say: Completed the ... Setup Wizard.
8. What did you see instead?
   I see the Windows Installer help Windows and when I click it, I get: exit status 1639 which is:
   ERROR_INVALID_COMMAND_LINE 1639 Invalid command line argument. Consult the Windows Installer SDK for detailed command line help.

[alexbrainman]

args := fmt.Sprintf(/a "%v" TARGETDIR="%v", msiFile, targetDir)
cmd := exec.Command("msiexec", args)

How many arguments do you want msiexec to get? Because you are passing one argument - args (args is a single string). If you want to pass many arguments, than you should pass them one by one:

cmd := exec.Command("msiexec", "arg1", "arg2", "arg3")

and so on. I think waht you want is:

cmd := exec.Command("msiexec", "/a", "package.msi", `TARGETDIR=C:\test folder`)

Not tested. I don't even know how msiexec works.

Alex

[josephspurrier]

You are correct, I should have used that in the example. That is the way I originally tested and same error.

[josephspurrier]

Actually, let me clarify because it is a different error, but same reasoning.

When I run:

cmd := exec.Command("msiexec", "/a", "package.msi", `TARGETDIR="C:\testfolder"`)

I get this error: "Could not access network location "C:\testfolder". And then: exit status 1603

I need quotes around the TARGETDIR value because there could be a space in the path.

This is the command that ultimately I'm trying to run:

msiexec /a "package.msi" TARGETDIR="C:\test folder"

[alexbrainman]

I get this error: "Could not access network location "C:\testfolder". And then: exit status 1603

msiexec is, probably, confused about having " character in the file name. You confused it.

I need quotes around the TARGETDIR value because there could be a space in the path.

The exec.Command passes arguments to the program as is. It will deal with spaces, quotes, double quotes and everything else. That is what syscall.EscapeArg does. You job is to provide all parameters exactly as your child process expects them. Leave all the quoting to do for syscall.EscapeArg.

This is the command that ultimately I'm trying to run:

msiexec /a "package.msi" TARGETDIR="C:\test folder"

Like I suggested above, you want:

cmd := exec.Command("msiexec", "/a", "package.msi", `TARGETDIR=C:\test folder`)

syscall.EscapeArg will insert whatever escape characters to make sure that space in TARGETDIR=C:\test folder does make it across to msexec.

Alex

[mattn]

When run msiexec on cmd.exe, some of double-quotes will be removed.

dummy.c

#include <windows.h>
#include <stdio.h>

int
main(int argc, wchar_t* argv[]) {
  int i, narg = 0;
  LPWSTR* args = CommandLineToArgvW(GetCommandLineW(), &narg);
  for (i = 0; i < narg; i++) printf("%ws\n", args[i]);
  LocalFree(args);
  return 0;
}

C:\dev>dummy /a "package.msi" TARGETDIR="C:\testfolder"
dummy
/a
package.msi
TARGETDIR=C:\testfolder

But when run dummy.exe from go, those are not removed.

package main

import (
    "os"
    "os/exec"
)

func main() {
    cmd := exec.Command(`dummy`, "/a", "package.msi", `TARGETDIR="C:\testfolder"`)
    cmd.Stdout = os.Stdout
    cmd.Stderr = os.Stderr
    cmd.Run()
}

C:\dev>go run d.go
dummy
/a
package.msi
TARGETDIR="C:\testfolder"

[josephspurrier]

When I run this command, it works properly:

cmd := exec.Command("msiexec", "/a", "package.msi", `TARGETDIR=C:\testfolder`)

When I run this command, I get the MSIEXEC WIndows Installer Help and then exit status 1639:

cmd := exec.Command("msiexec", "/a", "package.msi", `TARGETDIR=C:\test folder`)

[alexbrainman]

When I run this command, I get the MSIEXEC WIndows Installer Help and then exit status 1639:

I actually tried running your program, and I agree that exec.Command escaping rules don't work with msiexec. It is second program (that I know of) that behaves this way - first one is cmd.exe (https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/).

The Go exec.Command escaping will work if child program reads its arguments with CommandLineToArgv. And most programs doo. But cmd.exe and msiexec.exe do not. So you have to use Cmd.SysProcAttr.CmdLine to build command line by hand. And you do that already. I don't see what else you could do.

Alex

[alexbrainman]

But when run dummy.exe from go, those are not removed.

This is to be expected. Arguments are passed as is - quotes and all. If you don't want quotes, don't pass them inside parameters.

Alex

[mattn]

@alexbrainman This is my expected. Just explaining go's behavior. :)

[josephspurrier]

Ah very interesting! I didn't know cmd and msiexec behaved differently. It looks like other languages have this problem as well. Luckily, we can specify the arguments in a raw format directly using Cmd.SysProcAttr.CmdLine. Do you think a comment added to exec.Command would be sufficient enough?

Just for reference, it looks like arguments will be parsed differently depending on the compiler of the program you are passing to: http://daviddeley.com/autohotkey/parameters/parameters.htm#WIN.

[alexbrainman]

Do you think a comment added to exec.Command would be sufficient enough?

Do you propose to say that it is a mess? :-)

Also #15588 might be of interest to you.

Alex

[josephspurrier]

Haha yeah, that should do it! Or something like: The Cmd's Args are escaped and may not work properly with some programs. You can skip escaping them by manually assigning the Args to Cmd.SysProcAttr.CmdLine after prefixing with a space.

And I checked out 15588 - CommandLineToArgv() looks like a good way to test commands to ensure they will be split correctly when read by a C/C++ programs - thanks.

And for more reference, I ran tests with different syntax in command prompt and the results are below. It's a shame you can't put quotes around the entire property like this because this wouldn't be an issue, but it's a msiexec problem, not a Go problem: "TARGETDIR=C:\testfolder"

# MSI Success
msiexec /a package.msi TARGETDIR=C:\testfolder

# MSI Success
msiexec /a package.msi TARGETDIR="C:\test folder"

# MSI Error
msiexec /a package.msi "TARGETDIR=C:\test folder"

# MSI Error
msiexec /a package.msi TARGETDIR=\"C:\test folder\"

# MSI Error
msiexec /a package.msi TARGETDIR=""C:\test folder""

# MSI Error
msiexec /a package.msi TARGETDIR=^\"C:\test folder^\"

# MSI Error
msiexec /a package.msi TARGETDIR='C:\test folder'

[alexbrainman]

The Cmd's Args are escaped and may not work properly with some programs. You can skip escaping them by manually assigning the Args to Cmd.SysProcAttr.CmdLine after prefixing with a space.

I am bit concerned about adding a lot of confusing mambo jambo because of two programs (cmd.exe and msiexec.exe). For most users we don't even need to say word "escape", and everything works perfectly.

Maybe we should specifically mention cmd.exe and msexec.exe as being different. And say that for some argument strings Cmd.Args will not work, and they should build command line by hand and pass it via Cmd.SysProcAttr.CmdLine. What do you think?

Another alternative would be to create new function similar to syscall.EscapeArg, but specifically for cmd.exe. And ignore msexec.exe altogether.

Alex

[josephspurrier]

I agree on preventing it from becoming confusing. Can we do both options? Since manually setting Cmd.SysProcAttr.CmdLine is an option, adding a comment about it would be helpful.

And for a more official way, I like the idea of adding an alternative syscall.EscapeArg for cmd. We could then run (hopefully) msiexec and other applications by passing them to cmd like this:

cmd /k "msiexec /a C:\package.msi TARGETDIR=^"C:\test folder^""