Fix store_read calls

store_read takes a look at the size to determine whether to fill the
provided buffer or not. Even if providing a null buffer we should set
the size to 0.

* defpager/defpager.c (pager_read_page): Initialize nread to 0.
* storeio/dev.c (buffered_rw): Initialize amount to 0.
* fatfs/fat.c (fat_read_sblock): Initialize read to the size of the boot
sector. Reuse it as such.

1 files changed, 3 insertions, 4 deletions

diff --git a/fatfs/fat.c b/fatfs/fat.c
index e191cfc4..f31ce115 100644
--- a/fatfs/fat.c
+++ b/fatfs/fat.c
@@ -69,11 +69,10 @@ void
 fat_read_sblock (void)
 {
   error_t err;
-  size_t read;
+  size_t read = sizeof(struct boot_sector);
 
-  sblock = malloc (sizeof (struct boot_sector));
-  err = store_read (store, 0, sizeof (struct boot_sector),
-		    (void **) &sblock, &read);
+  sblock = malloc (read);
+  err = store_read (store, 0, read, (void **) &sblock, &read);
   if (err)
     error (1, err, "Could not read superblock");