From 2080d1f2b769916a247bb49e1c64ef75f1d9e30e Mon Sep 17 00:00:00 2001
From: EnderIce2 <enderice2@protonmail.com>
Date: Fri, 21 Mar 2025 01:58:14 +0000
Subject: [PATCH] feat(kernel/syscalls): add fcntl() syscall

Signed-off-by: EnderIce2 <enderice2@protonmail.com>
---
 Kernel/include/interface/syscalls.h | 22 ++++++++++++++++++++++
 Kernel/syscalls/native.cpp          |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/Kernel/include/interface/syscalls.h b/Kernel/include/interface/syscalls.h
index 3c0fbcc4..1d75bd71 100644
--- a/Kernel/include/interface/syscalls.h
+++ b/Kernel/include/interface/syscalls.h
@@ -830,6 +830,25 @@ typedef enum
 	 * - #EINVAL if the request is invalid
 	 */
 	SYS_IOCTL,
+	/**
+	 * @brief Function control
+	 *
+	 * @code
+	 * int fcntl(int fd, int cmd, void *arg);
+	 * @endcode
+	 *
+	 * @details Manipulates the underlying parameters of a device.
+	 *
+	 * @param fd File descriptor referring to the device
+	 * @param cmd Device-specific request code
+	 * @param arg Argument for the request
+	 *
+	 * @return
+	 * - #EOK on success
+	 * - #EBADF if `fd` is not valid
+	 * - #EINVAL if the request is invalid
+	 */
+	SYS_FCNTL,
 
 	/* File Status */
 
@@ -1678,6 +1697,9 @@ typedef enum
 /** @copydoc SYS_IOCTL */
 #define call_ioctl(fd, request, argp) syscall3(SYS_IOCTL, (scarg)fd, (scarg)request, (scarg)argp)
 
+/** @copydoc SYS_FCNTL */
+#define call_fcntl(fd, cmd, arg) syscall3(SYS_FCNTL, (scarg)fd, (scarg)cmd, (scarg)arg)
+
 /* File Status */
 
 /** @copydoc SYS_STAT */
diff --git a/Kernel/syscalls/native.cpp b/Kernel/syscalls/native.cpp
index b7ab94c7..9de911bd 100644
--- a/Kernel/syscalls/native.cpp
+++ b/Kernel/syscalls/native.cpp
@@ -135,6 +135,7 @@ static int sys_close(SysFrm *Frame, int fd)
 }
 
 static int sys_ioctl(SysFrm *Frame, int fd, unsigned long request, void *argp) { return -ENOSYS; }
+static int sys_fcntl(SysFrm *Frame, int fd, int cmd, void *arg) { return -ENOSYS; }
 static int sys_stat(SysFrm *Frame, const char *pathname, struct stat *statbuf) { return -ENOSYS; }
 static int sys_fstat(SysFrm *Frame, int fd, struct stat *statbuf) { return -ENOSYS; }
 static int sys_lstat(SysFrm *Frame, const char *pathname, struct stat *statbuf) { return -ENOSYS; }
@@ -275,6 +276,7 @@ __constructor void __init_native_syscalls(void)
 	scTbl[SYS_OPEN] = {"SYS_OPEN", (void *)sys_open};
 	scTbl[SYS_CLOSE] = {"SYS_CLOSE", (void *)sys_close};
 	scTbl[SYS_IOCTL] = {"SYS_IOCTL", (void *)sys_ioctl};
+	scTbl[SYS_FCNTL] = {"SYS_FCNTL", (void *)sys_fcntl};
 
 	/* File Status */
 	scTbl[SYS_STAT] = {"SYS_STAT", (void *)sys_stat};