From 8baac760500980d4b83e8de2e90265bfaa19df13 Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Tue, 4 Jun 2019 05:57:47 -0400
Subject: support read() and write() bigger than one page

---
 file.c | 36 ++++--------------------------------
 1 file changed, 4 insertions(+), 32 deletions(-)

(limited to 'file.c')

diff --git a/file.c b/file.c
index 44dd538..2a903b0 100644
--- a/file.c
+++ b/file.c
@@ -113,33 +113,17 @@ fileread(struct file *f, uint64 addr, int n)
   if(f->readable == 0)
     return -1;
 
-  // XXX break into page-size pieces.
-  if(n > PGSIZE)
-    panic("fileread PGSIZE");
-
-  buf = kalloc();
-  if(buf == 0)
-    panic("fileread kalloc");
-
   if(f->type == FD_PIPE){
-    r = piperead(f->pipe, buf, n);
+    r = piperead(f->pipe, addr, n);
   } else if(f->type == FD_INODE){
     ilock(f->ip);
-    if((r = readi(f->ip, buf, f->off, n)) > 0)
+    if((r = readi(f->ip, 1, addr, f->off, n)) > 0)
       f->off += r;
     iunlock(f->ip);
   } else {
     panic("fileread");
   }
 
-  if(r > 0){
-    if(copyout(p->pagetable, addr, buf, n) < 0){
-      r = -1;
-    }
-  }
-
-  kfree(buf);
-
   return r;
 }
 
@@ -156,18 +140,8 @@ filewrite(struct file *f, uint64 addr, int n)
   if(f->writable == 0)
     return -1;
 
-  // XXX break into pieces
-  if(n > PGSIZE)
-    panic("filewrite PGSIZE");
-
-  buf = kalloc();
-  if(copyin(p->pagetable, buf, addr, n) < 0){
-    kfree(buf);
-    return -1;
-  }
-
   if(f->type == FD_PIPE){
-    ret = pipewrite(f->pipe, buf, n);
+    ret = pipewrite(f->pipe, addr, n);
   } else if(f->type == FD_INODE){
     // write a few blocks at a time to avoid exceeding
     // the maximum log transaction size, including
@@ -184,7 +158,7 @@ filewrite(struct file *f, uint64 addr, int n)
 
       begin_op();
       ilock(f->ip);
-      if ((r = writei(f->ip, buf + i, f->off, n1)) > 0)
+      if ((r = writei(f->ip, 1, addr + i, f->off, n1)) > 0)
         f->off += r;
       iunlock(f->ip);
       end_op();
@@ -200,8 +174,6 @@ filewrite(struct file *f, uint64 addr, int n)
     panic("filewrite");
   }
 
-  kfree(buf);
-  
   return ret;
 }
 
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