Kernel/LibC: Implement fchmod

kernel/include/kernel/Process.h

@@ -119,8 +119,9 @@ namespace Kernel
 
 		BAN::ErrorOr<long> sys_pread(int fd, void* buffer, size_t count, off_t offset);
 
-		BAN::ErrorOr<long> sys_chmod(const char*, mode_t);
+		BAN::ErrorOr<long> sys_chmod(const char* path, mode_t mode);
-		BAN::ErrorOr<long> sys_chown(const char*, uid_t, gid_t);
+		BAN::ErrorOr<long> sys_fchmod(int fildes, mode_t mode);
+		BAN::ErrorOr<long> sys_chown(const char* path, uid_t uid, gid_t gid);
 
 		BAN::ErrorOr<long> sys_socket(int domain, int type, int protocol);
 		BAN::ErrorOr<long> sys_getsockname(int socket, sockaddr* address, socklen_t* address_len);

kernel/kernel/Process.cpp

@@ -1103,6 +1103,18 @@ namespace Kernel
 		return 0;
 	}
 
+	BAN::ErrorOr<long> Process::sys_fchmod(int fildes, mode_t mode)
+	{
+		if (mode & S_IFMASK)
+			return BAN::Error::from_errno(EINVAL);
+
+		LockGuard _(m_process_lock);
+		auto inode = TRY(m_open_file_descriptors.inode_of(fildes));
+		TRY(inode->chmod(mode));
+
+		return 0;
+	}
+
 	BAN::ErrorOr<long> Process::sys_chown(const char* path, uid_t uid, gid_t gid)
 	{
 		LockGuard _(m_process_lock);

userspace/libraries/LibC/include/sys/syscall.h

@@ -55,6 +55,7 @@ __BEGIN_DECLS
 	O(SYS_TTY_CTRL,			tty_ctrl)		\
 	O(SYS_POWEROFF,			poweroff)		\
 	O(SYS_CHMOD,			chmod)			\
+	O(SYS_FCHMOD,			fchmod)			\
 	O(SYS_CREATE,			create)			\
 	O(SYS_CREATE_DIR,		create_dir)		\
 	O(SYS_UNLINK,			unlink) 		\

userspace/libraries/LibC/sys/stat.cpp

@@ -13,9 +13,9 @@ int chmod(const char* path, mode_t mode)
 	return syscall(SYS_CHMOD, path, mode);
 }
 
-int fchmod(int, mode_t)
+int fchmod(int fildes, mode_t mode)
 {
-	ASSERT_NOT_REACHED();
+	return syscall(SYS_FCHMOD, fildes, mode);
 }
 
 int fstat(int fildes, struct stat* buf)