From 723428bebe3105ad3c3406e416402d1831b482c4 Mon Sep 17 00:00:00 2001
From: Andrew Lee <alee14498@protonmail.com>
Date: Sun, 15 Aug 2021 00:16:45 -0400
Subject: Inital commit

---
 linux/fs/fcntl.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 linux/fs/fcntl.c

(limited to 'linux/fs/fcntl.c')

diff --git a/linux/fs/fcntl.c b/linux/fs/fcntl.c
new file mode 100644
index 0000000..169f376
--- /dev/null
+++ b/linux/fs/fcntl.c
@@ -0,0 +1,69 @@
+#include <string.h>
+#include <errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <asm/segment.h>
+
+#include <fcntl.h>
+#include <sys/stat.h>
+
+extern int sys_close(int fd);
+
+static int dupfd(unsigned int fd, unsigned int arg)
+{
+	if (fd >= NR_OPEN || !current->filp[fd])
+		return -EBADF;
+	if (arg >= NR_OPEN)
+		return -EINVAL;
+	while (arg < NR_OPEN)
+		if (current->filp[arg])
+			arg++;
+		else
+			break;
+	if (arg >= NR_OPEN)
+		return -EMFILE;
+	current->close_on_exec &= ~(1<<arg);
+	(current->filp[arg] = current->filp[fd])->f_count++;
+	return arg;
+}
+
+int sys_dup2(unsigned int oldfd, unsigned int newfd)
+{
+	sys_close(newfd);
+	return dupfd(oldfd,newfd);
+}
+
+int sys_dup(unsigned int fildes)
+{
+	return dupfd(fildes,0);
+}
+
+int sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg)
+{	
+	struct file * filp;
+
+	if (fd >= NR_OPEN || !(filp = current->filp[fd]))
+		return -EBADF;
+	switch (cmd) {
+		case F_DUPFD:
+			return dupfd(fd,arg);
+		case F_GETFD:
+			return (current->close_on_exec>>fd)&1;
+		case F_SETFD:
+			if (arg&1)
+				current->close_on_exec |= (1<<fd);
+			else
+				current->close_on_exec &= ~(1<<fd);
+			return 0;
+		case F_GETFL:
+			return filp->f_flags;
+		case F_SETFL:
+			filp->f_flags &= ~(O_APPEND | O_NONBLOCK);
+			filp->f_flags |= arg & (O_APPEND | O_NONBLOCK);
+			return 0;
+		case F_GETLK:	case F_SETLK:	case F_SETLKW:
+			return -1;
+		default:
+			return -1;
+	}
+}
-- 
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