flag: Parse incorrectly interprets quoted path with a trailing slash as having escaped quotes.

[swernli]

Please answer these questions before submitting your issue. Thanks!

1. What version of Go are you using (go version)?
   go version go1.6.2 windows/amd64
2. What operating system and processor architecture are you using (go env)?
   set GOARCH=amd64
   set GOBIN=
   set GOEXE=.exe
   set GOHOSTARCH=amd64
   set GOHOSTOS=windows
   set GOOS=windows
   set GOPATH=s:\docker
   set GORACE=
   set GOROOT=C:\Go
   set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64
   set GO15VENDOREXPERIMENT=1
   set CC=gcc
   set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0
   set CXX=g++
   set CGO_ENABLED=1
3. What did you do?
   using import "flag" and Windows cmd, compile this program into an executable:
   import (
   "flag"
   "fmt"
   )
   func main() {
   flag.Parse()
   fmt.Println(flag.Arg(0))
   }

and then run it using the following argument:
test.exe "c:\test\"

1. What did you expect to see?
   Either the argument as passed at the cmdline, "c:\test\", or the argument with the quotes stripped, c:\test\.
2. What did you see instead?
   The program displays c:\test\" because somehow flag.Parse() incorrectly interprets the seconds quote as being escaped.

[swernli]

@jterry75 FYI

[adg]

Is there a document somewhere that explains how Windows treats quotes on the command line? I'd like to understand it once and for all.

[alexbrainman]

Is there a document somewhere that explains how Windows treats quotes on the command line? I'd like to understand it once and for all.

Most Windows programs call CommandLineToArgvW WinAPI (or similar) to parse input parameters. Go does too. Go also has syscall.EscapeArg to do the opposite - convert []string into command line string. The syscall.EscapeArg doc also has some references.

Some Windows programs use different rules for encoding []string into command line. Most notably cmd.exe and msiexec.exe (see #15566 for details).

Alex

[alexbrainman]

This is working as expected.

Go does not have its own command line into parameter list converter (not yet). It uses Windows CommandLineToArgvW for that job. And CommandLineToArgvW converts

`test.exe "c:\test\"`

into

 []string{`test.exe`, `c:\test"`}.

See https://msdn.microsoft.com/en-us/library/ms880421 for CommandLineToArgvW rules.

Luckily we also have new CL https://go-review.googlesource.com/#/c/22932 pending, that replaces call into Windows CommandLineToArgvW with a Go code. I just tried adding your command line to the test there https://go-review.googlesource.com/#/c/22932/2/src/os/exec_windows_test.go@32, and the test still pass. I also printed out from the test:

C:\Users\Alex>u:\test -test.v -test.run=Command
=== RUN   TestCommandLineToArgv
--- PASS: TestCommandLineToArgv (0.01s)
        exec_windows_test.go:44: out=["test"]
        exec_windows_test.go:44: out=["test" "a" "b" "c"]
        exec_windows_test.go:44: out=["test" ""]
        exec_windows_test.go:44: out=["test" ""]
        exec_windows_test.go:44: out=["test" "\""]
        exec_windows_test.go:44: out=["test" "" "a"]
        exec_windows_test.go:44: out=["test" "123"]
        exec_windows_test.go:44: out=["test" "\"123\""]
        exec_windows_test.go:44: out=["test" "\"123" "456\""]
        exec_windows_test.go:44: out=["test" "\\"]
        exec_windows_test.go:44: out=["test" "\\\""]
        exec_windows_test.go:44: out=["test" "\\\\\""]
        exec_windows_test.go:44: out=["test" "\\\"x"]
        exec_windows_test.go:44: out=["test" "\"\"\\\""]
        exec_windows_test.go:44: out=["cmd line" "abc"]
        exec_windows_test.go:44: out=["test" "\\\\\"x\"y z"]
        exec_windows_test.go:44: out=["test" "b" "x\ty"]
        exec_windows_test.go:44: out=["test.exe" "c:\\test\""]
PASS

C:\Users\Alex>

As you can see, the last line looks just like output of your program.

Alex