Kernel: Make file description lookup return KResultOr

Instead of checking it at every call site (to generate EBADF), we make
file_description(fd) return a KResultOr<NonnullRefPtr<FileDescription>>.

This allows us to wrap all the calls in TRY(). :^)

The only place that got a little bit messier from this is sys$mount(),
and there's a whole bunch of things there in need of cleanup.

1 files changed, 3 insertions, 10 deletions

diff --git a/Kernel/Syscalls/sendfd.cpp b/Kernel/Syscalls/sendfd.cpp
index fd82027f4f..6c0fed3cac 100644
--- a/Kernel/Syscalls/sendfd.cpp
+++ b/Kernel/Syscalls/sendfd.cpp
@@ -14,9 +14,7 @@ KResultOr<FlatPtr> Process::sys$sendfd(int sockfd, int fd)
 {
     VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
     REQUIRE_PROMISE(sendfd);
-    auto socket_description = fds().file_description(sockfd);
-    if (!socket_description)
-        return EBADF;
+    auto socket_description = TRY(fds().file_description(sockfd));
     if (!socket_description->is_socket())
         return ENOTSOCK;
     auto& socket = *socket_description->socket();
@@ -25,10 +23,7 @@ KResultOr<FlatPtr> Process::sys$sendfd(int sockfd, int fd)
     if (!socket.is_connected())
         return ENOTCONN;
 
-    auto passing_descriptor = fds().file_description(fd);
-    if (!passing_descriptor)
-        return EBADF;
-
+    auto passing_descriptor = TRY(fds().file_description(fd));
     auto& local_socket = static_cast<LocalSocket&>(socket);
     return local_socket.sendfd(*socket_description, *passing_descriptor);
 }
@@ -37,9 +32,7 @@ KResultOr<FlatPtr> Process::sys$recvfd(int sockfd, int options)
 {
     VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
     REQUIRE_PROMISE(recvfd);
-    auto socket_description = fds().file_description(sockfd);
-    if (!socket_description)
-        return EBADF;
+    auto socket_description = TRY(fds().file_description(sockfd));
     if (!socket_description->is_socket())
         return ENOTSOCK;
     auto& socket = *socket_description->socket();