Allow mfs files.write command to create parent directories

Adds support for a `-p/--parents` flag to the `files.write` command
similar to the one supported by the `files.mkdir` command. If this
is true and the directory for the file is not `"/"`, try to create
the containing directory before writing to the file.

License: MIT
Signed-off-by: Alex Potsides <alex@achingbrain.net>

core/commands/files.go

@@ -721,6 +721,7 @@ stat' on the file or any of its ancestors.
 	Options: []cmdkit.Option{
 		cmdkit.IntOption("offset", "o", "Byte offset to begin writing at."),
 		cmdkit.BoolOption("create", "e", "Create the file if it does not exist."),
+		cmdkit.BoolOption("parents", "p", "Make parent directories as needed."),
 		cmdkit.BoolOption("truncate", "t", "Truncate the file to size zero before writing."),
 		cmdkit.IntOption("count", "n", "Maximum number of bytes to read."),
 		cmdkit.BoolOption("raw-leaves", "Use raw blocks for newly created leaf nodes. (experimental)"),
@@ -735,6 +736,7 @@ stat' on the file or any of its ancestors.
 		}
 
 		create, _ := req.Options["create"].(bool)
+		mkParents, _ := req.Options["parents"].(bool)
 		trunc, _ := req.Options["truncate"].(bool)
 		flush, _ := req.Options["flush"].(bool)
 		rawLeaves, rawLeavesDef := req.Options["raw-leaves"].(bool)
@@ -757,6 +759,14 @@ stat' on the file or any of its ancestors.
 			return
 		}
 
+		if mkParents {
+			err := ensureContainingDirectoryExists(nd.FilesRoot, path, prefix)
+			if err != nil {
+				re.SetError(err, cmdkit.ErrNormal)
+				return
+			}
+		}
+
 		fi, err := getFileHandle(nd.FilesRoot, path, create, prefix)
 		if err != nil {
 			re.SetError(err, cmdkit.ErrNormal)
@@ -1146,6 +1156,19 @@ func getPrefix(req oldcmds.Request) (cid.Builder, error) {
 	return &prefix, nil
 }
 
+func ensureContainingDirectoryExists(r *mfs.Root, path string, builder cid.Builder) error {
+	dirtomake := gopath.Dir(path)
+
+	if dirtomake == "/" {
+		return nil
+	}
+
+	return mfs.Mkdir(r, dirtomake, mfs.MkdirOpts{
+		Mkparents:  true,
+		CidBuilder: builder,
+	})
+}
+
 func getFileHandle(r *mfs.Root, path string, create bool, builder cid.Builder) (*mfs.File, error) {
 	target, err := mfs.Lookup(r, path)
 	switch err {