Kernel: Implement unveil() as a prefix-tree

Fixes #4530.

1 files changed, 19 insertions, 14 deletions

diff --git a/Kernel/Syscalls/unveil.cpp b/Kernel/Syscalls/unveil.cpp
index 57807cd8e9..74f75252c5 100644
--- a/Kernel/Syscalls/unveil.cpp
+++ b/Kernel/Syscalls/unveil.cpp
@@ -68,19 +68,19 @@ int Process::sys$unveil(Userspace<const Syscall::SC_unveil_params*> user_params)
     for (const char permission : permissions) {
         switch (permission) {
         case 'r':
-            new_permissions |= UnveiledPath::Access::Read;
+            new_permissions |= UnveilAccess::Read;
             break;
         case 'w':
-            new_permissions |= UnveiledPath::Access::Write;
+            new_permissions |= UnveilAccess::Write;
             break;
         case 'x':
-            new_permissions |= UnveiledPath::Access::Execute;
+            new_permissions |= UnveilAccess::Execute;
             break;
         case 'c':
-            new_permissions |= UnveiledPath::Access::CreateOrRemove;
+            new_permissions |= UnveilAccess::CreateOrRemove;
             break;
         case 'b':
-            new_permissions |= UnveiledPath::Access::Browse;
+            new_permissions |= UnveilAccess::Browse;
             break;
         default:
             return -EINVAL;
@@ -97,7 +97,7 @@ int Process::sys$unveil(Userspace<const Syscall::SC_unveil_params*> user_params)
     auto custody_or_error = VFS::the().resolve_path_without_veil(path.value(), root_directory(), &parent_custody);
     if (!custody_or_error.is_error()) {
         new_unveiled_path = custody_or_error.value()->absolute_path();
-    } else if (custody_or_error.error() == -ENOENT && parent_custody && (new_permissions & UnveiledPath::Access::CreateOrRemove)) {
+    } else if (custody_or_error.error() == -ENOENT && parent_custody && (new_permissions & UnveilAccess::CreateOrRemove)) {
         String basename = LexicalPath(path.value()).basename();
         new_unveiled_path = String::formatted("{}/{}", parent_custody->absolute_path(), basename);
     } else {
@@ -105,16 +105,21 @@ int Process::sys$unveil(Userspace<const Syscall::SC_unveil_params*> user_params)
         return custody_or_error.error();
     }
 
-    for (auto& unveiled_path : m_unveiled_paths) {
-        if (unveiled_path.path == new_unveiled_path) {
-            if (new_permissions & ~unveiled_path.permissions)
-                return -EPERM;
-            unveiled_path.permissions = new_permissions;
-            return 0;
-        }
+    LexicalPath lexical_path(new_unveiled_path);
+    auto it = lexical_path.parts().begin();
+    auto& matching_node = m_unveiled_paths.traverse_until_last_accessible_node(it, lexical_path.parts().end());
+    if (it.is_end()) {
+        if (new_permissions & ~matching_node.permissions())
+            return -EPERM;
+        matching_node.set_metadata({ matching_node.path(), (UnveilAccess)new_permissions, true });
+        return 0;
     }
 
-    m_unveiled_paths.append({ new_unveiled_path, new_permissions });
+    matching_node.insert(
+        it,
+        lexical_path.parts().end(),
+        { new_unveiled_path, (UnveilAccess)new_permissions, true },
+        [](auto& parent, auto& it) -> Optional<UnveilMetadata> { return UnveilMetadata { String::formatted("{}/{}", parent.path(), *it), parent.permissions(), false }; });
     ASSERT(m_veil_state != VeilState::Locked);
     m_veil_state = VeilState::Dropped;
     return 0;