Kernel: Make Inode::lookup() return a RefPtr<Inode>

Previously this API would return an InodeIdentifier, which meant that
there was a race in path resolution where an inode could be unlinked
in between finding the InodeIdentifier for a path component, and
actually resolving that to an Inode object.

Attaching a test that would quickly trip an assertion before.

Test: Kernel/path-resolution-race.cpp

1 files changed, 3 insertions, 3 deletions

diff --git a/Kernel/FileSystem/DevPtsFS.cpp b/Kernel/FileSystem/DevPtsFS.cpp
index bec4c302d9..d7d618d77e 100644
--- a/Kernel/FileSystem/DevPtsFS.cpp
+++ b/Kernel/FileSystem/DevPtsFS.cpp
@@ -169,17 +169,17 @@ size_t DevPtsFSInode::directory_entry_count() const
     return 2 + ptys->size();
 }
 
-InodeIdentifier DevPtsFSInode::lookup(StringView name)
+RefPtr<Inode> DevPtsFSInode::lookup(StringView name)
 {
     ASSERT(identifier().index() == 1);
 
     if (name == "." || name == "..")
-        return identifier();
+        return fs().get_inode(identifier());
 
     bool ok;
     unsigned pty_index = name.to_uint(ok);
     if (ok && ptys->contains(pty_index)) {
-        return { fsid(), pty_index_to_inode_index(pty_index) };
+        return fs().get_inode({ fsid(), pty_index_to_inode_index(pty_index) });
     }
 
     return {};