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/pipe.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 linux/fs/pipe.c

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

diff --git a/linux/fs/pipe.c b/linux/fs/pipe.c
new file mode 100644
index 0000000..7e03e13
--- /dev/null
+++ b/linux/fs/pipe.c
@@ -0,0 +1,92 @@
+#include <signal.h>
+
+#include <linux/sched.h>
+#include <linux/mm.h>	/* for get_free_page */
+#include <asm/segment.h>
+
+int read_pipe(struct m_inode * inode, char * buf, int count)
+{
+	char * b=buf;
+
+	while (PIPE_EMPTY(*inode)) {
+		wake_up(&inode->i_wait);
+		if (inode->i_count != 2) /* are there any writers left? */
+			return 0;
+		sleep_on(&inode->i_wait);
+	}
+	while (count>0 && !(PIPE_EMPTY(*inode))) {
+		count --;
+		put_fs_byte(((char *)inode->i_size)[PIPE_TAIL(*inode)],b++);
+		INC_PIPE( PIPE_TAIL(*inode) );
+	}
+	wake_up(&inode->i_wait);
+	return b-buf;
+}
+	
+int write_pipe(struct m_inode * inode, char * buf, int count)
+{
+	char * b=buf;
+
+	wake_up(&inode->i_wait);
+	if (inode->i_count != 2) { /* no readers */
+		current->signal |= (1<<(SIGPIPE-1));
+		return -1;
+	}
+	while (count-->0) {
+		while (PIPE_FULL(*inode)) {
+			wake_up(&inode->i_wait);
+			if (inode->i_count != 2) {
+				current->signal |= (1<<(SIGPIPE-1));
+				return b-buf;
+			}
+			sleep_on(&inode->i_wait);
+		}
+		((char *)inode->i_size)[PIPE_HEAD(*inode)] = get_fs_byte(b++);
+		INC_PIPE( PIPE_HEAD(*inode) );
+		wake_up(&inode->i_wait);
+	}
+	wake_up(&inode->i_wait);
+	return b-buf;
+}
+
+int sys_pipe(unsigned long * fildes)
+{
+	struct m_inode * inode;
+	struct file * f[2];
+	int fd[2];
+	int i,j;
+
+	j=0;
+	for(i=0;j<2 && i<NR_FILE;i++)
+		if (!file_table[i].f_count)
+			(f[j++]=i+file_table)->f_count++;
+	if (j==1)
+		f[0]->f_count=0;
+	if (j<2)
+		return -1;
+	j=0;
+	for(i=0;j<2 && i<NR_OPEN;i++)
+		if (!current->filp[i]) {
+			current->filp[ fd[j]=i ] = f[j];
+			j++;
+		}
+	if (j==1)
+		current->filp[fd[0]]=NULL;
+	if (j<2) {
+		f[0]->f_count=f[1]->f_count=0;
+		return -1;
+	}
+	if (!(inode=get_pipe_inode())) {
+		current->filp[fd[0]] =
+			current->filp[fd[1]] = NULL;
+		f[0]->f_count = f[1]->f_count = 0;
+		return -1;
+	}
+	f[0]->f_inode = f[1]->f_inode = inode;
+	f[0]->f_pos = f[1]->f_pos = 0;
+	f[0]->f_mode = 1;		/* read */
+	f[1]->f_mode = 2;		/* write */
+	put_fs_long(fd[0],0+fildes);
+	put_fs_long(fd[1],1+fildes);
+	return 0;
+}
-- 
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