[PATCH 04 of 20] xenpaging: simplify file_op

[Olaf Hering <olaf@aepfle.de>]

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1321804899 -3600
# Node ID 0bc6eb35c8bf6d09dc13f1fedb70874c1962f95d
# Parent  b6c4a6f4f1f77b2471e4aa5fd23b375761691f79
xenpaging: simplify file_op

Catch lseek() errors.
Use -1 as return value and let caller read errno.
Remove const casts from buffer pointers, the page is writeable.
Use wrapper for write() which matches the read() prototype.
Remove unused stdarg.h inclusion.
Remove unused macro.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r b6c4a6f4f1f7 -r 0bc6eb35c8bf tools/xenpaging/file_ops.c
--- a/tools/xenpaging/file_ops.c
+++ b/tools/xenpaging/file_ops.c
@@ -21,55 +21,44 @@
 
 
 #include <unistd.h>
-#include <stdarg.h>
 #include <xc_private.h>
 
-
-#define page_offset(_pfn)     (((off_t)(_pfn)) << PAGE_SHIFT)
-
-
 static int file_op(int fd, void *page, int i,
-                   ssize_t (*fn)(int, const void *, size_t))
+                   ssize_t (*fn)(int, void *, size_t))
 {
     off_t seek_ret;
-    int total;
+    int total = 0;
     int bytes;
-    int ret;
 
     seek_ret = lseek(fd, i << PAGE_SHIFT, SEEK_SET);
+    if ( seek_ret == (off_t)-1 )
+        return -1;
 
-    total = 0;
     while ( total < PAGE_SIZE )
     {
         bytes = fn(fd, page + total, PAGE_SIZE - total);
         if ( bytes <= 0 )
-        {
-            ret = -errno;
-            goto err;
-        }
+            return -1;
 
         total += bytes;
     }
 
     return 0;
-
- err:
-    return ret;
 }
 
-static ssize_t my_read(int fd, const void *buf, size_t count)
+static ssize_t my_write(int fd, void *buf, size_t count)
 {
-    return read(fd, (void *)buf, count);
+    return write(fd, buf, count);
 }
 
 int read_page(int fd, void *page, int i)
 {
-    return file_op(fd, page, i, &my_read);
+    return file_op(fd, page, i, &read);
 }
 
 int write_page(int fd, void *page, int i)
 {
-    return file_op(fd, page, i, &write);
+    return file_op(fd, page, i, &my_write);
 }