105cdcdef7
This rewrites compositeFS to syscallfs.FS following wasi-sdk preopen rules. Notably, this allows use of read-only mounts now. For example, ```bash $ GOOS=js GOARCH=wasm bin/go test -c -o template.wasm text/template $ wazero run -mount=src/text/template:/ -mount=/tmp:/tmp template.wasm -test.v === RUN TestExecute --- PASS: TestExecute (0.07s) --snip-- ``` This is the first step to native WASI handling of multiple pre-opens. After this change, it is still the case that there's only one pre-open FD visible to wasm. A later change will make it possible for WASI to see multiple pre-opens while `GOOS=js` which doesn't use preopens, remains on a rootFS. A future PR may need to add a CLI flag to disable escaping directories, (e.g. make ../.. EINVAL), similar to `fs.FS` in Go. The simplest way to allow this is to use a host-side RootFS even in WASI, and wrap that with a `syscallfs` filename filter. Signed-off-by: Adrian Cole <adrian@tetrate.io>
30 lines
887 B
Go
30 lines
887 B
Go
package testfs
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import "io/fs"
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// compile-time check to ensure File implements fs.File
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var _ fs.File = &File{}
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// compile-time check to ensure FS implements fs.FS
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var _ fs.FS = &FS{}
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// FS emulates fs.FS. Note: the path (map key) cannot begin with "/"!
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type FS map[string]*File
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// Open implements the same method as documented on fs.FS, except it doesn't
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// validate the path.
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func (f FS) Open(name string) (fs.File, error) {
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if file, ok := f[name]; !ok {
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return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
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} else {
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return file, nil
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}
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}
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type File struct{ CloseErr error }
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func (f *File) Close() error { return f.CloseErr }
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func (f *File) Stat() (fs.FileInfo, error) { return nil, nil }
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func (f *File) Read(_ []byte) (int, error) { return 0, nil }
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func (f *File) Seek(_ int64, _ int) (int64, error) { return 0, nil }
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