diff options
author | Nick Cooper <nmvc@google.com> | 2015-01-05 15:04:58 +1100 |
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committer | Nick Cooper <nmvc@google.com> | 2015-01-05 17:15:31 +1100 |
commit | 3eb064ebfe6b9b907715cf7eeda05c367c55f32d (patch) | |
tree | b4e1f9759ac31db8dc28da0d0f645e4580965153 | |
parent | 7006f7a1abbda37f3276216302f9eb7425e1dfa5 (diff) | |
download | net-3eb064ebfe6b9b907715cf7eeda05c367c55f32d.tar.gz |
webdav: add memFS, an initial implementation of an in-memory
filesystem.
See original mercurial CL: golang.org/cl/171700045
Change-Id: Ib18277df4f7f232afdf6331f4bca5aaa3b00b83b
-rw-r--r-- | webdav/file.go | 329 | ||||
-rw-r--r-- | webdav/file_test.go | 78 |
2 files changed, 406 insertions, 1 deletions
diff --git a/webdav/file.go b/webdav/file.go index 097fe6b..33ac017 100644 --- a/webdav/file.go +++ b/webdav/file.go @@ -11,6 +11,8 @@ import ( "path" "path/filepath" "strings" + "sync" + "time" ) // A FileSystem implements access to a collection of named files. The elements @@ -88,4 +90,329 @@ func (d Dir) Stat(name string) (os.FileInfo, error) { return os.Stat(name) } -// TODO: a MemFS implementation. +// NewMemFS returns a new in-memory FileSystem implementation. +func NewMemFS() FileSystem { + return &memFS{ + root: memFSNode{ + children: make(map[string]*memFSNode), + mode: 0660 | os.ModeDir, + modTime: time.Now(), + }, + } +} + +// A memFS implements FileSystem, storing all metadata and actual file data +// in-memory. No limits on filesystem size are used, so it is not recommended +// this be used where the clients are untrusted. +// +// Concurrent access is permitted. The tree structure is protected by a mutex, +// and each node's contents and metadata are protected by a per-node mutex. +// +// TODO: Enforce file permissions. +type memFS struct { + mu sync.Mutex + root memFSNode +} + +// walk walks the directory tree for the fullname, calling f at each step. If f +// returns an error, the walk will be aborted and return that same error. +// +// Each walk is atomic: fs's mutex is held for the entire operation, including +// all calls to f. +// +// dir is the directory at that step, frag is the name fragment, and final is +// whether it is the final step. For example, walking "/foo/bar/x" will result +// in 3 calls to f: +// - "/", "foo", false +// - "/foo/", "bar", false +// - "/foo/bar/", "x", true +func (fs *memFS) walk(op, fullname string, f func(dir *memFSNode, frag string, final bool) error) error { + fs.mu.Lock() + defer fs.mu.Unlock() + + original := fullname + fullname = path.Clean("/" + fullname) + + // Strip any leading "/"s to make fullname a relative path, as the walk + // starts at fs.root. + if fullname[0] == '/' { + fullname = fullname[1:] + } + dir := &fs.root + + for { + frag, remaining := fullname, "" + i := strings.IndexRune(fullname, '/') + final := i < 0 + if !final { + frag, remaining = fullname[:i], fullname[i+1:] + } + if err := f(dir, frag, final); err != nil { + return &os.PathError{ + Op: op, + Path: original, + Err: err, + } + } + if final { + break + } + child := dir.children[frag] + if child == nil { + return &os.PathError{ + Op: op, + Path: original, + Err: os.ErrNotExist, + } + } + if !child.IsDir() { + return &os.PathError{ + Op: op, + Path: original, + Err: os.ErrInvalid, + } + } + dir, fullname = child, remaining + } + return nil +} + +func (fs *memFS) Mkdir(name string, perm os.FileMode) error { + return fs.walk("mkdir", name, func(dir *memFSNode, frag string, final bool) error { + if !final { + return nil + } + if frag == "" { + return os.ErrInvalid + } + if _, ok := dir.children[frag]; ok { + return os.ErrExist + } + dir.children[frag] = &memFSNode{ + name: frag, + children: make(map[string]*memFSNode), + mode: perm.Perm() | os.ModeDir, + modTime: time.Now(), + } + return nil + }) +} + +func (fs *memFS) OpenFile(name string, flag int, perm os.FileMode) (File, error) { + var ret *memFile + err := fs.walk("open", name, func(dir *memFSNode, frag string, final bool) error { + if !final { + return nil + } + if frag == "" { + return os.ErrInvalid + } + if flag&(os.O_SYNC|os.O_APPEND) != 0 { + return os.ErrInvalid + } + n := dir.children[frag] + if flag&os.O_CREATE != 0 { + if flag&os.O_EXCL != 0 && n != nil { + return os.ErrExist + } + if n == nil { + n = &memFSNode{ + name: frag, + mode: perm.Perm(), + } + dir.children[frag] = n + } + } + if n == nil { + return os.ErrNotExist + } + if flag&(os.O_WRONLY|os.O_RDWR) != 0 && flag&os.O_TRUNC != 0 { + n.mu.Lock() + n.data = nil + n.mu.Unlock() + } + + children := make([]os.FileInfo, 0, len(n.children)) + for _, c := range n.children { + children = append(children, c) + } + ret = &memFile{ + n: n, + children: children, + } + return nil + }) + if err != nil { + return nil, err + } + return ret, nil +} + +func (fs *memFS) RemoveAll(name string) error { + return fs.walk("remove", name, func(dir *memFSNode, frag string, final bool) error { + if !final { + return nil + } + if frag == "" { + return os.ErrInvalid + } + if _, ok := dir.children[frag]; !ok { + return os.ErrNotExist + } + delete(dir.children, frag) + return nil + }) +} + +func (fs *memFS) Stat(name string) (os.FileInfo, error) { + var n *memFSNode + err := fs.walk("stat", name, func(dir *memFSNode, frag string, final bool) error { + if !final { + return nil + } + if frag == "" { + return os.ErrInvalid + } + n = dir.children[frag] + if n == nil { + return os.ErrNotExist + } + return nil + }) + if err != nil { + return nil, err + } + return n, nil +} + +// A memFSNode represents a single entry in the in-memory filesystem and also +// implements os.FileInfo. +type memFSNode struct { + name string + + mu sync.Mutex + modTime time.Time + mode os.FileMode + children map[string]*memFSNode + data []byte +} + +func (n *memFSNode) Name() string { + return n.name +} + +func (n *memFSNode) Size() int64 { + n.mu.Lock() + defer n.mu.Unlock() + return int64(len(n.data)) +} + +func (n *memFSNode) Mode() os.FileMode { + n.mu.Lock() + defer n.mu.Unlock() + return n.mode +} + +func (n *memFSNode) ModTime() time.Time { + n.mu.Lock() + defer n.mu.Unlock() + return n.modTime +} + +func (n *memFSNode) IsDir() bool { + return n.Mode().IsDir() +} + +func (n *memFSNode) Sys() interface{} { + return nil +} + +// A memFile is a File implementation for a memFSNode. It is a per-file (not +// per-node) read/write position, and if the node is a directory, a snapshot of +// that node's children. +type memFile struct { + n *memFSNode + children []os.FileInfo + // Changes to pos are guarded by n.mu. + pos int +} + +func (f *memFile) Close() error { + return nil +} + +func (f *memFile) Read(p []byte) (int, error) { + if f.n.IsDir() { + return 0, os.ErrInvalid + } + f.n.mu.Lock() + defer f.n.mu.Unlock() + if f.pos >= len(f.n.data) { + return 0, io.EOF + } + n := copy(p, f.n.data[f.pos:]) + f.pos += n + return n, nil +} + +func (f *memFile) Readdir(count int) ([]os.FileInfo, error) { + if !f.n.IsDir() { + return nil, os.ErrInvalid + } + f.n.mu.Lock() + defer f.n.mu.Unlock() + old := f.pos + if old >= len(f.children) { + return nil, io.EOF + } + if count > 0 { + f.pos += count + if f.pos > len(f.children) { + f.pos = len(f.children) + } + } else { + f.pos = len(f.children) + old = 0 + } + return f.children[old:f.pos], nil +} + +func (f *memFile) Seek(offset int64, whence int) (int64, error) { + f.n.mu.Lock() + defer f.n.mu.Unlock() + npos := f.pos + // TODO: How to handle offsets greater than the size of system int? + switch whence { + case os.SEEK_SET: + npos = int(offset) + case os.SEEK_CUR: + npos += int(offset) + case os.SEEK_END: + npos = len(f.n.data) + int(offset) + default: + npos = -1 + } + if npos < 0 { + return 0, os.ErrInvalid + } + f.pos = npos + return int64(f.pos), nil +} + +func (f *memFile) Stat() (os.FileInfo, error) { + return f.n, nil +} + +func (f *memFile) Write(p []byte) (int, error) { + f.n.mu.Lock() + defer f.n.mu.Unlock() + epos := len(p) + f.pos + if epos > len(f.n.data) { + d := make([]byte, epos) + copy(d, f.n.data) + f.n.data = d + } + copy(f.n.data[f.pos:], p) + f.n.modTime = time.Now() + return len(p), nil +} diff --git a/webdav/file_test.go b/webdav/file_test.go index 502b236..a25e080 100644 --- a/webdav/file_test.go +++ b/webdav/file_test.go @@ -5,7 +5,9 @@ package webdav import ( + "fmt" "path/filepath" + "strings" "testing" ) @@ -115,3 +117,79 @@ func TestDir(t *testing.T) { } } } + +func TestWalk(t *testing.T) { + type walkStep struct { + name, frag string + final bool + } + + testCases := []struct { + dir string + want []walkStep + }{ + {"", []walkStep{ + {"", "", true}, + }}, + {"/", []walkStep{ + {"", "", true}, + }}, + {"/a", []walkStep{ + {"", "a", true}, + }}, + {"/a/", []walkStep{ + {"", "a", true}, + }}, + {"/a/b", []walkStep{ + {"", "a", false}, + {"a", "b", true}, + }}, + {"/a/b/", []walkStep{ + {"", "a", false}, + {"a", "b", true}, + }}, + {"/a/b/c", []walkStep{ + {"", "a", false}, + {"a", "b", false}, + {"b", "c", true}, + }}, + // The following test case is the one mentioned explicitly + // in the method description. + {"/foo/bar/x", []walkStep{ + {"", "foo", false}, + {"foo", "bar", false}, + {"bar", "x", true}, + }}, + } + + for _, tc := range testCases { + fs := NewMemFS().(*memFS) + + parts := strings.Split(tc.dir, "/") + for p := 2; p < len(parts); p++ { + d := strings.Join(parts[:p], "/") + if err := fs.Mkdir(d, 0666); err != nil { + t.Errorf("tc.dir=%q: mkdir: %q: %v", tc.dir, d, err) + } + } + + i := 0 + err := fs.walk("test", tc.dir, func(dir *memFSNode, frag string, final bool) error { + got := walkStep{ + name: dir.name, + frag: frag, + final: final, + } + want := tc.want[i] + + if got != want { + return fmt.Errorf("got %+v, want %+v", got, want) + } + i++ + return nil + }) + if err != nil { + t.Errorf("tc.dir=%q: %v", tc.dir, err) + } + } +} |