1 files changed, 90 insertions, 0 deletions

diff --git a/src/fs/file_dev.c b/src/fs/file_dev.c
new file mode 100644
index 0000000..4661b6f
--- /dev/null
+++ b/src/fs/file_dev.c
@@ -0,0 +1,90 @@
+/*
+ *  linux/fs/file_dev.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <asm/segment.h>
+
+#define MIN(a,b) (((a)<(b))?(a):(b))
+#define MAX(a,b) (((a)>(b))?(a):(b))
+
+int file_read(struct m_inode * inode, struct file * filp, char * buf, int count)
+{
+        int left,chars,nr;
+        struct buffer_head * bh;
+
+        if ((left=count)<=0)
+                return 0;
+        while (left) {
+                if ((nr = bmap(inode,(filp->f_pos)/BLOCK_SIZE))) {
+                        if (!(bh=bread(inode->i_dev,nr)))
+                                break;
+                } else
+                        bh = NULL;
+                nr = filp->f_pos % BLOCK_SIZE;
+                chars = MIN( BLOCK_SIZE-nr , left );
+                filp->f_pos += chars;
+                left -= chars;
+                if (bh) {
+                        char * p = nr + bh->b_data;
+                        while (chars-->0)
+                                put_fs_byte(*(p++),buf++);
+                        brelse(bh);
+                } else {
+                        while (chars-->0)
+                                put_fs_byte(0,buf++);
+                }
+        }
+        inode->i_atime = CURRENT_TIME;
+        return (count-left)?(count-left):-ERROR;
+}
+
+int file_write(struct m_inode * inode, struct file * filp, char * buf, int count)
+{
+        off_t pos;
+        int block,c;
+        struct buffer_head * bh;
+        char * p;
+        int i=0;
+
+/*
+ * ok, append may not work when many processes are writing at the same time
+ * but so what. That way leads to madness anyway.
+ */
+        if (filp->f_flags & O_APPEND)
+                pos = inode->i_size;
+        else
+                pos = filp->f_pos;
+        while (i<count) {
+                if (!(block = create_block(inode,pos/BLOCK_SIZE)))
+                        break;
+                if (!(bh=bread(inode->i_dev,block)))
+                        break;
+                c = pos % BLOCK_SIZE;
+                p = c + bh->b_data;
+                bh->b_dirt = 1;
+                c = BLOCK_SIZE-c;
+                if (c > count-i) c = count-i;
+                pos += c;
+                if (pos > inode->i_size) {
+                        inode->i_size = pos;
+                        inode->i_dirt = 1;
+                }
+                i += c;
+                while (c-->0)
+                        *(p++) = get_fs_byte(buf++);
+                brelse(bh);
+        }
+        inode->i_mtime = CURRENT_TIME;
+        if (!(filp->f_flags & O_APPEND)) {
+                filp->f_pos = pos;
+                inode->i_ctime = CURRENT_TIME;
+        }
+        return (i?i:-1);
+}