From 9893c90e74eb88ee532c013f2c04b871cf4255d2 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Fri, 17 Jan 2025 19:22:53 +0200
Subject: [PATCH] Kernel: Remove SYS_DUP and implement it using fcntl F_DUPFD

---
 kernel/include/kernel/OpenFileDescriptorSet.h |  1 -
 kernel/include/kernel/Process.h               |  1 -
 kernel/kernel/OpenFileDescriptorSet.cpp       | 37 +++++++++++--------
 kernel/kernel/Process.cpp                     |  6 ---
 .../libraries/LibC/include/sys/syscall.h      |  1 -
 userspace/libraries/LibC/unistd.cpp           |  2 +-
 6 files changed, 22 insertions(+), 26 deletions(-)

diff --git a/kernel/include/kernel/OpenFileDescriptorSet.h b/kernel/include/kernel/OpenFileDescriptorSet.h
index a36e4d80..b0882ac8 100644
--- a/kernel/include/kernel/OpenFileDescriptorSet.h
+++ b/kernel/include/kernel/OpenFileDescriptorSet.h
@@ -29,7 +29,6 @@ namespace Kernel
 
 		BAN::ErrorOr<void> pipe(int fds[2]);
 
-		BAN::ErrorOr<int> dup(int);
 		BAN::ErrorOr<int> dup2(int, int);
 
 		BAN::ErrorOr<int> fcntl(int fd, int cmd, int extra);
diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index 902f9669..0ba814cb 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -138,7 +138,6 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_pselect(sys_pselect_t* arguments);
 
 		BAN::ErrorOr<long> sys_pipe(int fildes[2]);
-		BAN::ErrorOr<long> sys_dup(int fildes);
 		BAN::ErrorOr<long> sys_dup2(int fildes, int fildes2);
 
 		BAN::ErrorOr<long> sys_fcntl(int fildes, int cmd, int extra);
diff --git a/kernel/kernel/OpenFileDescriptorSet.cpp b/kernel/kernel/OpenFileDescriptorSet.cpp
index 1f3907c0..b834b00a 100644
--- a/kernel/kernel/OpenFileDescriptorSet.cpp
+++ b/kernel/kernel/OpenFileDescriptorSet.cpp
@@ -159,22 +159,6 @@ namespace Kernel
 		return {};
 	}
 
-	BAN::ErrorOr<int> OpenFileDescriptorSet::dup(int fildes)
-	{
-		TRY(validate_fd(fildes));
-
-		int result = TRY(get_free_fd());
-		m_open_files[result] = m_open_files[fildes];
-
-		if (m_open_files[result]->path() == "<pipe wr>"_sv)
-		{
-			ASSERT(m_open_files[result]->inode()->is_pipe());
-			static_cast<Pipe*>(m_open_files[result]->inode().ptr())->clone_writing();
-		}
-
-		return result;
-	}
-
 	BAN::ErrorOr<int> OpenFileDescriptorSet::dup2(int fildes, int fildes2)
 	{
 		if (fildes2 < 0 || fildes2 >= (int)m_open_files.size())
@@ -204,6 +188,26 @@ namespace Kernel
 
 		switch (cmd)
 		{
+			case F_DUPFD:
+			case F_DUPFD_CLOEXEC:
+			{
+				const int new_fd = TRY(get_free_fd());
+
+				auto new_file = TRY(BAN::RefPtr<OpenFileDescription>::create(
+					TRY(m_open_files[fd]->file.clone()),
+					m_open_files[fd]->offset,
+					m_open_files[fd]->flags | (cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0)
+				));
+
+				if (new_file->path() == "<pipe wr>"_sv)
+				{
+					ASSERT(new_file->inode()->is_pipe());
+					static_cast<Pipe*>(new_file->inode().ptr())->clone_writing();
+				}
+
+				m_open_files[new_fd] = BAN::move(new_file);
+				return new_fd;
+			}
 			case F_GETFD:
 				return m_open_files[fd]->flags & FD_CLOEXEC;
 			case F_SETFD:
@@ -220,6 +224,7 @@ namespace Kernel
 				break;
 		}
 
+		dwarnln("TODO: fcntl command {}", cmd);
 		return BAN::Error::from_errno(ENOTSUP);
 	}
 
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index 763067db..a1c9d154 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -1462,12 +1462,6 @@ namespace Kernel
 		return 0;
 	}
 
-	BAN::ErrorOr<long> Process::sys_dup(int fildes)
-	{
-		LockGuard _(m_process_lock);
-		return TRY(m_open_file_descriptors.dup(fildes));
-	}
-
 	BAN::ErrorOr<long> Process::sys_dup2(int fildes, int fildes2)
 	{
 		LockGuard _(m_process_lock);
diff --git a/userspace/libraries/LibC/include/sys/syscall.h b/userspace/libraries/LibC/include/sys/syscall.h
index 365f926e..e8a2bb2e 100644
--- a/userspace/libraries/LibC/include/sys/syscall.h
+++ b/userspace/libraries/LibC/include/sys/syscall.h
@@ -36,7 +36,6 @@ __BEGIN_DECLS
 	O(SYS_SET_PWD,			setpwd)			\
 	O(SYS_CLOCK_GETTIME,	clock_gettime)	\
 	O(SYS_PIPE,				pipe)			\
-	O(SYS_DUP,				dup)			\
 	O(SYS_DUP2,				dup2)			\
 	O(SYS_KILL,				kill)			\
 	O(SYS_TCGETPGRP,		tcgetpgrp)		\
diff --git a/userspace/libraries/LibC/unistd.cpp b/userspace/libraries/LibC/unistd.cpp
index 3598421e..c90626e8 100644
--- a/userspace/libraries/LibC/unistd.cpp
+++ b/userspace/libraries/LibC/unistd.cpp
@@ -125,7 +125,7 @@ int fsync(int fildes)
 
 int dup(int fildes)
 {
-	return syscall(SYS_DUP, fildes);
+	return fcntl(fildes, F_DUPFD, 0);
 }
 
 int dup2(int fildes, int fildes2)