ADD file via upload

fs/pipe.c

@@ -0,0 +1,111 @@
+/*
+ *  linux/fs/pipe.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#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)
+{
+	int chars, size, read = 0;
+
+	while (count>0) {
+		while (!(size=PIPE_SIZE(*inode))) {
+			wake_up(&inode->i_wait);
+			if (inode->i_count != 2) /* are there any writers? */
+				return read;
+			sleep_on(&inode->i_wait);
+		}
+		chars = PAGE_SIZE-PIPE_TAIL(*inode);
+		if (chars > count)
+			chars = count;
+		if (chars > size)
+			chars = size;
+		count -= chars;
+		read += chars;
+		size = PIPE_TAIL(*inode);
+		PIPE_TAIL(*inode) += chars;
+		PIPE_TAIL(*inode) &= (PAGE_SIZE-1);
+		while (chars-->0)
+			put_fs_byte(((char *)inode->i_size)[size++],buf++);
+	}
+	wake_up(&inode->i_wait);
+	return read;
+}
+	
+int write_pipe(struct m_inode * inode, char * buf, int count)
+{
+	int chars, size, written = 0;
+
+	while (count>0) {
+		while (!(size=(PAGE_SIZE-1)-PIPE_SIZE(*inode))) {
+			wake_up(&inode->i_wait);
+			if (inode->i_count != 2) { /* no readers */
+				current->signal |= (1<<(SIGPIPE-1));
+				return written?written:-1;
+			}
+			sleep_on(&inode->i_wait);
+		}
+		chars = PAGE_SIZE-PIPE_HEAD(*inode);
+		if (chars > count)
+			chars = count;
+		if (chars > size)
+			chars = size;
+		count -= chars;
+		written += chars;
+		size = PIPE_HEAD(*inode);
+		PIPE_HEAD(*inode) += chars;
+		PIPE_HEAD(*inode) &= (PAGE_SIZE-1);
+		while (chars-->0)
+			((char *)inode->i_size)[size++]=get_fs_byte(buf++);
+	}
+	wake_up(&inode->i_wait);
+	return written;
+}
+
+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;
+}