os: Getwd doesn't return canonical case of current directory on macOS

[glinton]

What version of Go are you using (go version)?

go version go1.8.3 linux/amd64

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/opt/src/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build179514568=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

This may very well be an issue for mac regarding the case sensitivity of their nfs server, but here goes. We have a utility that adds an entry to /etc/exports by grabbing the current directory: os.Getwd(). Window's case insensitivity is handled because os.Getwd() returns syscall.Getwd() on a mac, however, we get whatever the user typed on their cd.

On a darwin machine:

mkdir /tmp/TestDir

cd /tmp/testdir
# fails, as 'PWD' is '/tmp/testdir'
# run playground code here

cd /tmp/TestDir
# works, as 'PWD' is '/tmp/TestDir'
# run playground code here

Build and run this code: https://play.golang.org/p/Yqk90j5ud5 https://play.golang.org/p/QmTFAiLcL4

For the next two expect/result sections, this:

package main

import "os"

func main() {
	cwd, _ := os.Getwd()
	os.Stdout.WriteString(cwd + "\n")
}

What did you expect to see?

Output of printing os.Getwd()

/tmp/TestDir

What did you see instead?

Output of printing os.Getwd()

/tmp/testdir

[bradfitz]

I cannot reproduce.

ward5k:foobar bradfitz$ mkdir /tmp/FooBar
ward5k:foobar bradfitz$ cd /tmp/FooBar/
ward5k:foobar bradfitz$ curl --silent https://play.golang.org/p/Yqk90j5ud5.go > getwd.go
ward5k:FooBar bradfitz$ go run getwd.go 
/private/tmp/FooBar
/tmp/FooBar
ward5k:FooBar bradfitz$ cd /tmp/foobar
ward5k:foobar bradfitz$ go run getwd.go 
/private/tmp/FooBar
/tmp/foobar
ward5k:foobar bradfitz$ sw_vers 
ProductName:	Mac OS X
ProductVersion:	10.12.5
BuildVersion:	16F73

It's not clear from your bug report which output you expect from which directory.

[glinton]

I've updated the original comment with a more straightforward example - https://play.golang.org/p/QmTFAiLcL4.

I expect it to return the same actual filepath regardless of the way it is cdd to

edit - I imagine there's a reason for it, but moving this block below the syscall one below it, should resolve this. For now, a workaround is to use syscall.Getwd() where appropriate.

[davecheney]

Both answers are equally correct, osx's hfs+ is by default case preserving case insensitive.

…

On Sat, 8 Jul 2017, 05:01 Brad Fitzpatrick ***@***.***> wrote: I cannot reproduce. ward5k:foobar bradfitz$ mkdir /tmp/FooBar ward5k:foobar bradfitz$ cd /tmp/FooBar/ ward5k:foobar bradfitz$ curl --silent https://play.golang.org/p/Yqk90j5ud5.go > getwd.go ward5k:FooBar bradfitz$ go run getwd.go /private/tmp/FooBar /tmp/FooBar ward5k:FooBar bradfitz$ cd /tmp/foobar ward5k:foobar bradfitz$ go run getwd.go /private/tmp/FooBar /tmp/foobar ward5k:foobar bradfitz$ sw_vers ProductName: Mac OS X ProductVersion: 10.12.5 BuildVersion: 16F73 It's not clear from your bug report which output you expect from which directory. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#20947 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAcA_dJFGgIfXeUFnOK7KDuG2xF2S-Hks5sLoCegaJpZM4ORTdj> .

[henvic]

@glinton have you ran into a, possibly, edge case where this is an issue?

[glinton]

@henvic (from the 'What did you do?' section of the original issue)

This may very well be an issue for mac regarding the case sensitivity of their nfs server, but here goes. We have a utility that adds an entry to /etc/exports by grabbing the current directory: os.Getwd(). Window's case insensitivity is handled because os.Getwd() returns syscall.Getwd(). On a mac, however, we get whatever the user typed on their cd.

So we end up getting permission denied when trying to mount, because the directory is /tmp/ExportedDir but /etc/exports (and the client) only has /tmp/exporteddir. Our current workaround is to use syscall.Getwd() to populate the exports file and provide the client with a target.

[ifarobi]

I have the same issue. I use Go version 1.9.
But my in my case, os.Getwd() not returning the working directory as the projects folder, but it return the temporary build folder, such as var/folders/7d/b5gjzcc15cg04vtgz1xd6fth0000gn/T/go-build340557118/.../.../.

[ianlancetaylor]

I think this is enough of a special case that we aren't going to try to address it. Using $PWD is often the right thing to do. In this case, it apparently isn't, but there is a workaround.