archive/zip: AddFS omits trailing slash in directory names

[jba]

Go version

go version go1.24-20241213-RC00 cl/706019355 +e39e965e0e X:fieldtrack,boringcrypto linux/amd64

Output of go env in your module/workspace:

AR='ar'
CC='clang'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='clang++'
GCCGO='gccgo'
GO111MODULE='on'
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/usr/local/google/home/jba/.cache/go-build'
GODEBUG=''
GOENV='/usr/local/google/home/jba/.config/go/env'
GOEXE=''
GOEXPERIMENT='fieldtrack,boringcrypto'
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2446417499=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/usr/local/google/home/jba/repos/go/src/go.mod'
GOMODCACHE='/usr/local/google/home/jba/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/usr/local/google/home/jba/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org'
GOROOT='/usr/lib/google-golang'
GOSUMDB='sum.golang.org'
GOTELEMETRY='on'
GOTELEMETRYDIR='/usr/local/google/home/jba/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/lib/google-golang/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.24-20241213-RC00 cl/706019355 +e39e965e0e X:fieldtrack,boringcrypto'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

The doc for zip.FileHeader.Name says "A trailing slash indicates that this file is a directory."
When change https://go.dev/cl/578415 added directories, it did not include the trailing slashes.

repro: https://go.dev/play/p/9C5y2uZ1A2U?v=gotip

What did you see happen?

dir
dir/file

What did you expect to see?

dir/
dir/file

[gabyhelp]

Related Issues

• archive/zip: fs.WalkDir fails if archive contains a directory without a trailing slash #50390 (closed)
• archive/{zip,tar}: (*Writer).AddFS omits empty directories #66831 (closed)
• archive/zip: duplicate entries in FS interface #45345 (closed)
• archive/zip: produces incorrect zip archives #30627 (closed)
• archive/zip: Reader.Open lies about directory fs.FileMode #48106
• archive/zip: FileHeader struct lacks Unicode Path Extra Field (0x7075) #36760
• os: `Lstat` on `darwin` sometimes fails to expand symlinks in paths with trailing slashes #59586
• io/fs,os: fs.ReadDir with an os.DirFS can produce invalid paths #44166 (closed)

Related Code Changes

• archive/tar: improve handling of directory paths
• archive/zip: improve Writer.Create documentation on how to add directories

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[dmitshur]

CC @songgao, @ianlancetaylor.

[gopherbot]

Change https://go.dev/cl/642375 mentions this issue: archive/zip: dir add slash