Description
What version of Go are you using (go version)?
$ go version go version go1.16.2 linux/amd64
Does this issue reproduce with the latest release?
Yes.
What operating system and processor architecture are you using (go env)?
amd64, linux
go env Output
$ go env GO111MODULE="" GOARCH="amd64" GOBIN="" GOCACHE="redacted/.cache/go-build" GOENV="redacted/go/env" GOEXE="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="redacted/go/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="linux" GOPATH="redacted/go" GOPRIVATE="" GOPROXY="https://proxy.golang.org,direct" GOROOT="redacted/go1.16.2.linux.amd64" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="redacted/go1.16.2.linux.amd64/pkg/tool/linux_amd64" GOVCS="" GOVERSION="go1.16.2" GCCGO="gccgo" AR="ar" CC="gcc" CXX="g++" CGO_ENABLED="1" GOMOD="redacted/embedtest/go.mod" 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-build424344437=/tmp/go-build -gno-record-gcc-switches"
What did you do?
- Create a new Go module.
- Create the directories
./filesand./files/subdir - Create the files:
./files/file,./files/-file - Add the following source to
./main.go
package main
import (
"embed"
"fmt"
"io/fs"
)
//go:embed files
var files embed.FS
func main() {
err := fs.WalkDir(files, "files", walk)
if err != nil {
panic(err)
}
}
func walk(path string, d fs.DirEntry, _ error) error {
fmt.Println(path)
return nil
}- Run with
go run .
What did you expect to see?
files
files/-file
files/file
files/subdir/-file
What did you see instead?
files
files/file
Analysis
This behavior was introduced with commit 930c2c9 where isBadEmbedName has been extended with if err := module.CheckFilePath(name); err != nil {.
The thing with module.CheckFilePath is, that it expects a full path as argument. For such a path, the first segment is not allowed to start with a - (dash) according to https://github.com/golang/mod/blob/d6ab96f2441f9631f81862375ef66782fc4a9c12/module/module.go#L374.
In the case of isBadEmbedName, the function module.CheckFilePath is called with the filename only (without the rest of the path), which prevents any file, starting with - to be embedded.
This behavior is nowhere documented. The current documentation only mentions, that files starting with . and _ are ignored.
Additionally, nor the documentation of module.CheckFilePath neither of module.CheckImportPath do mention, that paths starting with - are not allowed.
Related: #45197, #43854, #44486
Update: add #44486 as related issue