"net/http"
"os"
"path"
+ "path/filepath"
"strings"
"sync"
"time"
}
func (n *treenode) FileInfo() os.FileInfo {
- n.Lock()
- defer n.Unlock()
- n.fileinfo.size = int64(len(n.inodes))
- return n.fileinfo
+ n.RLock()
+ defer n.RUnlock()
+ fi := n.fileinfo
+ fi.size = int64(len(n.inodes))
+ return fi
}
func (n *treenode) Readdir() (fi []os.FileInfo, err error) {
+ // We need RLock to safely read n.inodes, but we must release
+ // it before calling FileInfo() on the child nodes. Otherwise,
+ // we risk deadlock when filter groups A and B match each
+ // other, concurrent Readdir() calls try to RLock them in
+ // opposite orders, and one cannot be RLocked a second time
+ // because a third caller is waiting for a write lock.
n.RLock()
- defer n.RUnlock()
- fi = make([]os.FileInfo, 0, len(n.inodes))
+ inodes := make([]inode, 0, len(n.inodes))
for _, inode := range n.inodes {
+ inodes = append(inodes, inode)
+ }
+ n.RUnlock()
+ fi = make([]os.FileInfo, 0, len(inodes))
+ for _, inode := range inodes {
fi = append(fi, inode.FileInfo())
}
return
return nil, ErrSyncNotSupported
}
dirname, name := path.Split(name)
- parent, err := rlookup(fs.root, dirname)
+ ancestors := map[inode]bool{}
+ parent, err := rlookup(fs.root, dirname, ancestors)
if err != nil {
return nil, err
}
return nil, err
}
}
+ // If n and one of its parents/ancestors are [hardlinks to]
+ // the same node (e.g., a filter group that matches itself),
+ // open an "empty directory" node instead, so the inner
+ // hardlink appears empty. This is needed to ensure
+ // Open("a/b/c/x/x").Readdir() appears empty, matching the
+ // behavior of rlookup("a/b/c/x/x/z") => ErrNotExist.
+ if hl, ok := n.(*hardlink); (ok && ancestors[hl.inode]) || ancestors[n] {
+ n = &treenode{
+ fs: n.FS(),
+ parent: parent,
+ inodes: nil,
+ fileinfo: fileinfo{
+ name: name,
+ modTime: time.Now(),
+ mode: 0555 | os.ModeDir,
+ },
+ }
+ }
return &filehandle{
inode: n,
append: flag&os.O_APPEND != 0,
func (fs *fileSystem) Mkdir(name string, perm os.FileMode) error {
dirname, name := path.Split(name)
- n, err := rlookup(fs.root, dirname)
+ n, err := rlookup(fs.root, dirname, nil)
if err != nil {
return err
}
}
func (fs *fileSystem) Stat(name string) (os.FileInfo, error) {
- node, err := rlookup(fs.root, name)
+ node, err := rlookup(fs.root, name, nil)
if err != nil {
return nil, err
}
if name == "" || name == "." || name == ".." {
return ErrInvalidArgument
}
- dir, err := rlookup(fs.root, dirname)
+ dir, err := rlookup(fs.root, dirname, nil)
if err != nil {
return err
}
// rlookup (recursive lookup) returns the inode for the file/directory
// with the given name (which may contain "/" separators). If no such
// file/directory exists, the returned node is nil.
-func rlookup(start inode, path string) (node inode, err error) {
+//
+// The visited map should be either nil or empty. If non-nil, all
+// nodes and hardlink targets visited by the given path will be added
+// to it.
+//
+// If a cycle is detected, the second occurrence of the offending node
+// will be replaced by an empty directory. For example, if "x" is a
+// filter group that matches itself, then rlookup("a/b/c/x") will
+// return the filter group, and rlookup("a/b/c/x/x") will return an
+// empty directory.
+func rlookup(start inode, path string, visited map[inode]bool) (node inode, err error) {
+ if visited == nil {
+ visited = map[inode]bool{}
+ }
node = start
+ // Clean up ./ and ../ and double-slashes, but (unlike
+ // filepath.Clean) retain a trailing slash, because looking up
+ // ".../regularfile/" should fail.
+ trailingSlash := strings.HasSuffix(path, "/")
+ path = filepath.Clean(path)
+ if trailingSlash && path != "/" {
+ path += "/"
+ }
for _, name := range strings.Split(path, "/") {
+ visited[node] = true
if node.IsDir() {
if name == "." || name == "" {
continue
if node == nil || err != nil {
break
}
+ checknode := node
+ if hardlinked, ok := checknode.(*hardlink); ok {
+ checknode = hardlinked.inode
+ }
+ if visited[checknode] {
+ node = &treenode{
+ fs: node.FS(),
+ parent: node.Parent(),
+ inodes: nil,
+ fileinfo: fileinfo{
+ name: name,
+ modTime: time.Now(),
+ mode: 0555 | os.ModeDir,
+ },
+ }
+ } else {
+ visited[checknode] = true
+ }
}
if node == nil && err == nil {
err = os.ErrNotExist
projects / arvados.git / blobdiff