cc68f8ee12
This adds a new top-level type FSConfig, which is configured via
`ModuleConfig.WithFSConfig(fcfg)`. This implements read-only and
read-write directory mounts, something not formally supported before. It
also implements `WithFS` which adapts a normal `fs.FS`. For convenience,
we retain the old `ModuleConfig.WithFS` signature so as to not affect
existing users much. A new configuration for our emerging raw
filesystem, `FSConfig.WithSysfs()` will happen later without breaking
this API.
Here's an example:
```
moduleConfig = wazero.NewModuleConfig().
// Make the current directory read-only accessible to the guest.
WithReadOnlyDirMount(".", "/")
// Make "/tmp/wasm" accessible to the guest as "/tmp".
WithDirMount("/tmp/wasm", "/tmp")
```
Signed-off-by: Adrian Cole <adrian@tetrate.io>
95 lines
2.2 KiB
Go
95 lines
2.2 KiB
Go
package sysfs
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import (
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"io/fs"
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"os"
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"syscall"
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)
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func NewDirFS(dir string) FS {
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return &dirFS{
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dir: dir,
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cleanedDir: ensureTrailingPathSeparator(dir),
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}
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}
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func ensureTrailingPathSeparator(dir string) string {
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if dir[len(dir)-1] != os.PathSeparator {
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return dir + string(os.PathSeparator)
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}
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return dir
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}
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type dirFS struct {
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UnimplementedFS
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dir string
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// cleanedDir is for easier OS-specific concatenation, as it always has
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// a trailing path separator.
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cleanedDir string
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}
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// String implements fmt.Stringer
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func (d *dirFS) String() string {
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return d.dir
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}
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// Open implements the same method as documented on fs.FS
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func (d *dirFS) Open(name string) (fs.File, error) {
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return fsOpen(d, name)
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}
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// OpenFile implements FS.OpenFile
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func (d *dirFS) OpenFile(name string, flag int, perm fs.FileMode) (fs.File, error) {
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f, err := os.OpenFile(d.join(name), flag, perm)
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if err != nil {
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return nil, unwrapPathError(err)
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}
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return maybeWrapFile(f), nil
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}
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// Mkdir implements FS.Mkdir
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func (d *dirFS) Mkdir(name string, perm fs.FileMode) error {
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err := os.Mkdir(d.join(name), perm)
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err = unwrapPathError(err)
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return adjustMkdirError(err)
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}
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// Rename implements FS.Rename
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func (d *dirFS) Rename(from, to string) error {
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if from == to {
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return nil
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}
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return rename(d.join(from), d.join(to))
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}
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// Rmdir implements FS.Rmdir
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func (d *dirFS) Rmdir(name string) error {
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err := syscall.Rmdir(d.join(name))
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return adjustRmdirError(err)
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}
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// Unlink implements FS.Unlink
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func (d *dirFS) Unlink(name string) error {
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err := syscall.Unlink(d.join(name))
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return adjustUnlinkError(err)
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}
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// Utimes implements FS.Utimes
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func (d *dirFS) Utimes(name string, atimeNsec, mtimeNsec int64) error {
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return syscall.UtimesNano(d.join(name), []syscall.Timespec{
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syscall.NsecToTimespec(atimeNsec),
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syscall.NsecToTimespec(mtimeNsec),
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})
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}
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func (d *dirFS) join(name string) string {
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switch name {
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case "", ".", "/":
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// cleanedDir includes an unnecessary delimiter for the root path.
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return d.cleanedDir[:len(d.cleanedDir)-1]
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}
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// TODO: Enforce similar to safefilepath.FromFS(name), but be careful as
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// relative path inputs are allowed. e.g. dir or name == ../
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return d.cleanedDir + name
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}
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