x/net/webdav: microsoft miniredirector fails setting properties of directories

[klarose]

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

$ go version
go version go1.15 linux/amd64

Does this issue reproduce with the latest release?

Yes

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/kyle/.cache/go-build"
GOENV="/home/kyle/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/kyle/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/kyle/"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build009155035=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Ran a simple wrapper around x/net/webdav. Pointed the windows mini redirector (from windows 10) at it, then tried to clone golang/net: git clone https://github.com/golang/net.git

What did you expect to see?

The git clone succeed.

What did you see instead?

Z:\>git clone https://github.com/golang/net.git
Cloning into 'net'...
//files.kyle-shares.agilicus.cloud@SSL/DavWWWRoot/agent/net/.git: Input/output error

Digging in, it's clear that the issue is due to windows trying to set properties directories such as ./.git.

I added some logging to the proppatch handler and found it doing these operations:

2021/01/26 12:16:21 Patching /net {urn:schemas-microsoft-com: Win32CreationTime}
2021/01/26 12:16:21 Patching /net {urn:schemas-microsoft-com: Win32LastAccessTime}
2021/01/26 12:16:21 Patching /net {urn:schemas-microsoft-com: Win32LastModifiedTime}
2021/01/26 12:16:21 Patching /net {urn:schemas-microsoft-com: Win32FileAttributes}
2021/01/26 12:16:21 Fail on patch: open /home/kyle/shared/net: is a directory

[klarose]

I was able to address this in testing by first checking if the file was a directory, then returning forbidden for every patch. That seemed to let it move forward at least. We may want to look at a more abstract way of handling this, but I'll submit a patch for now, since we need this to be fixed for our usecase.

[gopherbot]

Change https://golang.org/cl/286992 mentions this issue: webdav: return forbidden on failed proppatch

[ncw]

This has come up with rclone serve webdav very recently - see https://forum.rclone.org/t/writeable-readonly-directories/21919/

Rclone already returns EPERM when you try to open a directory Read/Write and Windows seems to accept that as OK as it doesn't report an error. However it makes a nasty ERROR in the log.

Your patch looks like it will solve our problem too.

Did you try your webdav implementation with the Windows explorer?

[klarose]

@ncw awesome, I'm glad to hear it'll fix the problem for you!

I tested using both linux davfs2 and Windows Explorer (via map network drive). The issue was only present when using Windows Explorer. With my patch in place, the issue did not occur at all.