vboot_reference: fix CMOS writing for x86 platforms

VbCmosWrite should seek to correct offset before starting to write;
also fixed file handle leakage.

BUG=chromium-os:23000
TEST=crossystem recovery_request=1; echo $? # show: 0
     crossystem recovery_request # show: 1
     reboot # see recovery screen

Change-Id: Ie5cdc21acf11962dac9debd1ef26108a05181326
Reviewed-on: https://gerrit.chromium.org/gerrit/11756
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Gabe Black <gabeblack@chromium.org>
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/11828
Commit-Ready: Stefan Reinauer <reinauer@chromium.org>
Tested-by: Stefan Reinauer <reinauer@chromium.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

1 files changed, 9 insertions, 10 deletions

diff --git a/host/arch/x86/lib/crossystem_arch.c b/host/arch/x86/lib/crossystem_arch.c
index 92f0b9f5..1042c66e 100644
--- a/host/arch/x86/lib/crossystem_arch.c
+++ b/host/arch/x86/lib/crossystem_arch.c
@@ -112,12 +112,9 @@ static int VbCmosRead(int offs, size_t size, void *ptr) {
     VbFixCmosChecksum(f);
     res = fread(ptr, size, 1, f);
   }
-  if (1 != res) {
-    fclose(f);
-    return -1;
-  }
 
-  return 0;
+  fclose(f);
+  return (1 == res) ? 0 : -1;
 }
 
 
@@ -129,17 +126,19 @@ static int VbCmosWrite(int offs, size_t size, const void *ptr) {
   if (!f)
     return -1;
 
+  if (0 != fseek(f, offs, SEEK_SET)) {
+    fclose(f);
+    return -1;
+  }
+
   res = fwrite(ptr, size, 1, f);
   if (1 != res && errno == EIO && ferror(f)) {
     VbFixCmosChecksum(f);
     res = fwrite(ptr, size, 1, f);
   }
-  if (1 != res) {
-    fclose(f);
-    return -1;
-  }
 
-  return 0;
+  fclose(f);
+  return (1 == res) ? 0 : -1;
 }