Exposes writeable filesystem as experimentalsys.FS (#1605)

Signed-off-by: Adrian Cole <[email protected]>

cmd/wazero/wazero.go

@@ -21,6 +21,7 @@ import (
 	"github.com/tetratelabs/wazero/experimental/gojs"
 	"github.com/tetratelabs/wazero/experimental/logging"
 	"github.com/tetratelabs/wazero/experimental/sock"
+	"github.com/tetratelabs/wazero/experimental/sysfs"
 	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
 	"github.com/tetratelabs/wazero/internal/platform"
 	internalsys "github.com/tetratelabs/wazero/internal/sys"
@@ -394,7 +395,7 @@ func validateMounts(mounts sliceFlag, stdErr logging.Writer) (rc int, rootPath s
 			readOnly = true
 		}
 
-		// TODO(anuraaga): Support wasm paths with colon in them.
+		// TODO: Support wasm paths with colon in them.
 		var dir, guestPath string
 		if clnIdx := strings.LastIndexByte(mount, ':'); clnIdx != -1 {
 			dir, guestPath = mount[:clnIdx], mount[clnIdx+1:]
@@ -418,12 +419,13 @@ func validateMounts(mounts sliceFlag, stdErr logging.Writer) (rc int, rootPath s
 			fmt.Fprintf(stdErr, "invalid mount: path %q is not a directory\n", dir)
 		}
 
+		root := sysfs.NewDirFS(dir)
 		if readOnly {
-			config = config.WithReadOnlyDirMount(dir, guestPath)
-		} else {
-			config = config.WithDirMount(dir, guestPath)
+			root = sysfs.NewReadFS(root)
 		}
 
+		config = config.(sysfs.FSConfig).WithSysFSMount(root, guestPath)
+
 		if internalsys.StripPrefixesAndTrailingSlash(guestPath) == "" {
 			rootPath = dir
 		}

config.go

@@ -11,10 +11,10 @@ import (
 	"time"
 
 	"github.com/tetratelabs/wazero/api"
+	experimentalsys "github.com/tetratelabs/wazero/experimental/sys"
 	"github.com/tetratelabs/wazero/internal/engine/compiler"
 	"github.com/tetratelabs/wazero/internal/engine/interpreter"
 	"github.com/tetratelabs/wazero/internal/filecache"
-	"github.com/tetratelabs/wazero/internal/fsapi"
 	"github.com/tetratelabs/wazero/internal/internalapi"
 	"github.com/tetratelabs/wazero/internal/platform"
 	internalsock "github.com/tetratelabs/wazero/internal/sock"
@@ -846,7 +846,7 @@ func (c *moduleConfig) toSysContext() (sysCtx *internalsys.Context, err error) {
 		environ = append(environ, result)
 	}
 
-	var fs []fsapi.FS
+	var fs []experimentalsys.FS
 	var guestPaths []string
 	if f, ok := c.fsConfig.(*fsConfig); ok {
 		fs, guestPaths = f.preopens()

internal/fsapi/dir.go → experimental/sys/dir.go

@@ -1,10 +1,9 @@
-package fsapi
+package sys
 
 import (
 	"fmt"
 	"io/fs"
 
-	experimentalsys "github.com/tetratelabs/wazero/experimental/sys"
 	"github.com/tetratelabs/wazero/sys"
 )
 
@@ -21,7 +20,7 @@ type FileType = fs.FileMode
 //   - This extends `dirent` defined in POSIX with some fields defined by
 //     Linux. See https://man7.org/linux/man-pages/man3/readdir.3.html and
 //     https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/dirent.h.html
-//   - This has a subset of fields defined in Stat_t. Notably, there is no
+//   - This has a subset of fields defined in sys.Stat_t. Notably, there is no
 //     field corresponding to Stat_t.Dev because that value will be constant
 //     for all files in a directory. To get the Dev value, call File.Stat on
 //     the directory File.Readdir was called on.
@@ -58,8 +57,8 @@ func (DirFile) IsAppend() bool {
 }
 
 // SetAppend implements File.SetAppend
-func (DirFile) SetAppend(bool) experimentalsys.Errno {
-	return experimentalsys.EISDIR
+func (DirFile) SetAppend(bool) Errno {
+	return EISDIR
 }
 
 // IsNonblock implements File.IsNonblock
@@ -68,41 +67,41 @@ func (DirFile) IsNonblock() bool {
 }
 
 // SetNonblock implements File.SetNonblock
-func (DirFile) SetNonblock(bool) experimentalsys.Errno {
-	return experimentalsys.EISDIR
+func (DirFile) SetNonblock(bool) Errno {
+	return EISDIR
 }
 
 // IsDir implements File.IsDir
-func (DirFile) IsDir() (bool, experimentalsys.Errno) {
+func (DirFile) IsDir() (bool, Errno) {
 	return true, 0
 }
 
 // Read implements File.Read
-func (DirFile) Read([]byte) (int, experimentalsys.Errno) {
-	return 0, experimentalsys.EISDIR
+func (DirFile) Read([]byte) (int, Errno) {
+	return 0, EISDIR
 }
 
 // Pread implements File.Pread
-func (DirFile) Pread([]byte, int64) (int, experimentalsys.Errno) {
-	return 0, experimentalsys.EISDIR
+func (DirFile) Pread([]byte, int64) (int, Errno) {
+	return 0, EISDIR
 }
 
 // Poll implements File.Poll
-func (DirFile) Poll(Pflag, int32) (ready bool, errno experimentalsys.Errno) {
-	return false, experimentalsys.ENOSYS
+func (DirFile) Poll(Pflag, int32) (ready bool, errno Errno) {
+	return false, ENOSYS
 }
 
 // Write implements File.Write
-func (DirFile) Write([]byte) (int, experimentalsys.Errno) {
-	return 0, experimentalsys.EISDIR
+func (DirFile) Write([]byte) (int, Errno) {
+	return 0, EISDIR
 }
 
 // Pwrite implements File.Pwrite
-func (DirFile) Pwrite([]byte, int64) (int, experimentalsys.Errno) {
-	return 0, experimentalsys.EISDIR
+func (DirFile) Pwrite([]byte, int64) (int, Errno) {
+	return 0, EISDIR
 }
 
 // Truncate implements File.Truncate
-func (DirFile) Truncate(int64) experimentalsys.Errno {
-	return experimentalsys.EISDIR
+func (DirFile) Truncate(int64) Errno {
+	return EISDIR
 }