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package mount |
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|
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import ( |
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"context" |
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"os" |
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"path/filepath" |
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"strings" |
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"sync" |
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"syscall" |
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"time" |
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|
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"github.com/jacobsa/fuse" |
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"github.com/jacobsa/fuse/fuseops" |
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"github.com/jacobsa/fuse/fuseutil" |
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|
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"github.com/lain/larc/internal/core" |
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"github.com/lain/larc/internal/protocol" |
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) |
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|
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/* LarcFS implements a read-only FUSE filesystem for larc repositories. |
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* Files are lazily fetched from the server and cached locally. */ |
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|
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const ( |
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rootInodeID fuseops.InodeID = fuseops.RootInodeID |
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) |
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|
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type inodeInfo struct { |
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id fuseops.InodeID |
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name string |
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entry *core.TreeEntry // nil for synthetic directories |
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children map[string]fuseops.InodeID // name -> inode (only for dirs) |
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parent fuseops.InodeID |
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isDir bool |
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} |
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|
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// LarcFS is the FUSE filesystem implementation |
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type LarcFS struct { |
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fuseutil.NotImplementedFileSystem |
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|
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fetcher *BlobFetcher |
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repoName string |
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revision int64 |
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|
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inodes map[fuseops.InodeID]*inodeInfo |
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nextInode fuseops.InodeID |
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mu sync.RWMutex |
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|
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/* file handle tracking */ |
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handles map[fuseops.HandleID]fuseops.InodeID |
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nextHandle fuseops.HandleID |
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handleMu sync.Mutex |
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} |
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|
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// NewLarcFS creates a new filesystem from a tree |
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func NewLarcFS(client *protocol.Client, repoName string, revision int64, tree *core.Tree, cache *BlobCache) *LarcFS { |
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fs := &LarcFS{ |
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fetcher: NewBlobFetcher(client, repoName, cache), |
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repoName: repoName, |
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revision: revision, |
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inodes: make(map[fuseops.InodeID]*inodeInfo), |
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nextInode: rootInodeID + 1, |
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handles: make(map[fuseops.HandleID]fuseops.InodeID), |
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nextHandle: 1, |
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} |
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|
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fs.buildInodeTree(tree) |
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return fs |
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} |
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|
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func (fs *LarcFS) buildInodeTree(tree *core.Tree) { |
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/* create root inode */ |
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root := &inodeInfo{ |
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id: rootInodeID, |
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name: "", |
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isDir: true, |
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children: make(map[string]fuseops.InodeID), |
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parent: rootInodeID, |
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} |
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fs.inodes[rootInodeID] = root |
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|
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/* process all entries and build directory structure */ |
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for i := range tree.Entries { |
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entry := &tree.Entries[i] |
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fs.addEntry(entry) |
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} |
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} |
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|
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func (fs *LarcFS) addEntry(entry *core.TreeEntry) { |
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parts := strings.Split(entry.Path, string(filepath.Separator)) |
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if len(parts) == 0 { |
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return |
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} |
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|
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/* ensure all parent directories exist */ |
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currentInode := rootInodeID |
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for i, part := range parts[:len(parts)-1] { |
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current := fs.inodes[currentInode] |
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if childID, ok := current.children[part]; ok { |
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currentInode = childID |
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} else { |
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/* create synthetic directory */ |
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newID := fs.nextInode |
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fs.nextInode++ |
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|
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dirPath := strings.Join(parts[:i+1], string(filepath.Separator)) |
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newDir := &inodeInfo{ |
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id: newID, |
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name: part, |
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isDir: true, |
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children: make(map[string]fuseops.InodeID), |
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parent: currentInode, |
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entry: &core.TreeEntry{ |
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Path: dirPath, |
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Kind: core.EntryKindDir, |
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Mode: 0755, |
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}, |
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} |
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fs.inodes[newID] = newDir |
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current.children[part] = newID |
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currentInode = newID |
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} |
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} |
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|
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/* add the file/final entry */ |
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name := parts[len(parts)-1] |
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parent := fs.inodes[currentInode] |
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|
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newID := fs.nextInode |
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fs.nextInode++ |
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|
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isDir := entry.Kind == core.EntryKindDir |
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info := &inodeInfo{ |
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id: newID, |
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name: name, |
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entry: entry, |
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parent: currentInode, |
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isDir: isDir, |
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} |
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if isDir { |
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info.children = make(map[string]fuseops.InodeID) |
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} |
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|
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fs.inodes[newID] = info |
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parent.children[name] = newID |
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} |
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|
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func (fs *LarcFS) allocHandle(inode fuseops.InodeID) fuseops.HandleID { |
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fs.handleMu.Lock() |
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defer fs.handleMu.Unlock() |
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|
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h := fs.nextHandle |
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fs.nextHandle++ |
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fs.handles[h] = inode |
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return h |
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} |
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|
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func (fs *LarcFS) freeHandle(h fuseops.HandleID) { |
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fs.handleMu.Lock() |
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defer fs.handleMu.Unlock() |
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delete(fs.handles, h) |
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} |
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|
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/* FUSE operations */ |
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|
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func (fs *LarcFS) StatFS(ctx context.Context, op *fuseops.StatFSOp) error { |
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op.BlockSize = 4096 |
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op.Blocks = 1000000 |
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op.BlocksFree = 0 |
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op.BlocksAvailable = 0 |
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op.IoSize = 65536 |
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op.Inodes = uint64(len(fs.inodes)) |
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op.InodesFree = 0 |
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return nil |
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} |
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|
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func (fs *LarcFS) LookUpInode(ctx context.Context, op *fuseops.LookUpInodeOp) error { |
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fs.mu.RLock() |
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defer fs.mu.RUnlock() |
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|
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parent, ok := fs.inodes[op.Parent] |
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if !ok { |
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return fuse.ENOENT |
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} |
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|
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childID, ok := parent.children[op.Name] |
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if !ok { |
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return fuse.ENOENT |
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} |
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|
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child := fs.inodes[childID] |
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op.Entry.Child = childID |
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op.Entry.Attributes = fs.getAttrs(child) |
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op.Entry.AttributesExpiration = time.Now().Add(time.Hour) |
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op.Entry.EntryExpiration = time.Now().Add(time.Hour) |
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|
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return nil |
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} |
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|
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func (fs *LarcFS) GetInodeAttributes(ctx context.Context, op *fuseops.GetInodeAttributesOp) error { |
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fs.mu.RLock() |
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defer fs.mu.RUnlock() |
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|
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info, ok := fs.inodes[op.Inode] |
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if !ok { |
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return fuse.ENOENT |
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} |
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|
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op.Attributes = fs.getAttrs(info) |
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op.AttributesExpiration = time.Now().Add(time.Hour) |
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return nil |
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} |
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|
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func (fs *LarcFS) getAttrs(info *inodeInfo) fuseops.InodeAttributes { |
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attrs := fuseops.InodeAttributes{ |
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Nlink: 1, |
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Uid: uint32(os.Getuid()), |
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Gid: uint32(os.Getgid()), |
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} |
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|
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if info.isDir { |
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attrs.Mode = os.ModeDir | 0755 |
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attrs.Size = 4096 |
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} else if info.entry != nil { |
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attrs.Mode = os.FileMode(info.entry.Mode) & 0777 |
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attrs.Size = uint64(info.entry.Size) |
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} else { |
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attrs.Mode = 0644 |
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} |
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|
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return attrs |
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} |
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|
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func (fs *LarcFS) OpenDir(ctx context.Context, op *fuseops.OpenDirOp) error { |
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fs.mu.RLock() |
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defer fs.mu.RUnlock() |
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|
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info, ok := fs.inodes[op.Inode] |
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if !ok { |
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return fuse.ENOENT |
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} |
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if !info.isDir { |
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return syscall.ENOTDIR |
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} |
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|
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op.Handle = fs.allocHandle(op.Inode) |
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return nil |
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} |
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|
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func (fs *LarcFS) ReadDir(ctx context.Context, op *fuseops.ReadDirOp) error { |
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fs.mu.RLock() |
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defer fs.mu.RUnlock() |
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|
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info, ok := fs.inodes[op.Inode] |
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if !ok { |
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return fuse.ENOENT |
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} |
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|
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/* collect children in stable order */ |
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type dirEntry struct { |
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name string |
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inode fuseops.InodeID |
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} |
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var entries []dirEntry |
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for name, id := range info.children { |
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entries = append(entries, dirEntry{name: name, inode: id}) |
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} |
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|
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/* write entries starting from offset */ |
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var bytesWritten int |
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for i := int(op.Offset); i < len(entries); i++ { |
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e := entries[i] |
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child := fs.inodes[e.inode] |
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|
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var dtype fuseutil.DirentType |
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if child.isDir { |
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dtype = fuseutil.DT_Directory |
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} else { |
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dtype = fuseutil.DT_File |
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} |
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|
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dirent := fuseutil.Dirent{ |
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Offset: fuseops.DirOffset(i + 1), |
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Inode: e.inode, |
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Name: e.name, |
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Type: dtype, |
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} |
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|
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n := fuseutil.WriteDirent(op.Dst[bytesWritten:], dirent) |
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if n == 0 { |
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break |
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} |
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bytesWritten += n |
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} |
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|
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op.BytesRead = bytesWritten |
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return nil |
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} |
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|
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func (fs *LarcFS) ReleaseDirHandle(ctx context.Context, op *fuseops.ReleaseDirHandleOp) error { |
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fs.freeHandle(op.Handle) |
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return nil |
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} |
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|
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func (fs *LarcFS) OpenFile(ctx context.Context, op *fuseops.OpenFileOp) error { |
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fs.mu.RLock() |
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defer fs.mu.RUnlock() |
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|
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info, ok := fs.inodes[op.Inode] |
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if !ok { |
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return fuse.ENOENT |
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} |
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if info.isDir { |
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return syscall.EISDIR |
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} |
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|
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op.Handle = fs.allocHandle(op.Inode) |
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op.KeepPageCache = true |
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return nil |
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} |
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|
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func (fs *LarcFS) ReadFile(ctx context.Context, op *fuseops.ReadFileOp) error { |
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fs.mu.RLock() |
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info, ok := fs.inodes[op.Inode] |
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fs.mu.RUnlock() |
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|
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if !ok { |
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return fuse.ENOENT |
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} |
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if info.entry == nil || info.entry.BlobHash == "" { |
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return fuse.EIO |
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} |
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|
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/* fetch blob (from cache or server) */ |
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data, err := fs.fetcher.Fetch(info.entry.BlobHash) |
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if err != nil { |
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return fuse.EIO |
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} |
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|
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/* handle offset and size */ |
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start := int(op.Offset) |
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if start >= len(data) { |
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op.BytesRead = 0 |
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return nil |
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} |
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|
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end := start + len(op.Dst) |
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if end > len(data) { |
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end = len(data) |
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} |
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|
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op.BytesRead = copy(op.Dst, data[start:end]) |
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return nil |
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} |
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|
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func (fs *LarcFS) ReleaseFileHandle(ctx context.Context, op *fuseops.ReleaseFileHandleOp) error { |
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fs.freeHandle(op.Handle) |
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return nil |
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} |
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|
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// Mount mounts the filesystem at the given path |
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func Mount(mountPoint string, fs *LarcFS) (*fuse.MountedFileSystem, error) { |
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server := fuseutil.NewFileSystemServer(fs) |
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|
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cfg := &fuse.MountConfig{ |
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FSName: "larc:" + fs.repoName, |
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ReadOnly: true, |
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} |
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|
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return fuse.Mount(mountPoint, server, cfg) |
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} |
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|
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// Unmount unmounts the filesystem at the given path |
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func Unmount(mountPoint string) error { |
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return fuse.Unmount(mountPoint) |
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} |
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|