Kernel: Add KResult and KResultOr<T> classes.

The idea here is to combine a potential syscall error code with an arbitrary
type in the case of success. I feel like this will end up much less error
prone than returning some arbitrary type that kinda sorta has bool semantics
(but sometimes not really) and passing the error through an out-param.

This patch only converts a few syscalls to using it. More to come.

1 files changed, 6 insertions, 3 deletions

diff --git a/Kernel/ProcFS.cpp b/Kernel/ProcFS.cpp
index 680c46b187..0b26b30102 100644
--- a/Kernel/ProcFS.cpp
+++ b/Kernel/ProcFS.cpp
@@ -1049,12 +1049,16 @@ ssize_t ProcFSInode::write_bytes(off_t offset, size_t size, const byte* buffer,
 
 bool ProcFSInode::add_child(InodeIdentifier child_id, const String& name, byte file_type, int& error)
 {
+    (void)child_id;
+    (void)name;
+    (void)file_type;
     error = -EPERM;
     return false;
 }
 
 bool ProcFSInode::remove_child(const String& name, int& error)
 {
+    (void)name;
     error = -EPERM;
     return false;
 }
@@ -1074,10 +1078,9 @@ size_t ProcFSInode::directory_entry_count() const
     return count;
 }
 
-bool ProcFSInode::chmod(mode_t, int& error)
+KResult ProcFSInode::chmod(mode_t)
 {
-    error = -EPERM;
-    return false;
+    return KResult(-EPERM);
 }
 
 ProcFS::ProcFS()