Re: [PATCH] MdeModulePkg/UdfDxe: Remove negative comparison of unsigned number

[Paulo Alcantara <pcacjr@zytor.com>]

On September 13, 2017 2:08:54 AM GMT-03:00, "Zeng, Star" <star.zeng@intel.com> wrote:
>I do not understand the context of the code.
>The change is good to fix the build failure, but I want to ask a
>question before I gave Rb. :)
>
>Is it possible ReadFileInfo->FilePosition less than FilePosition?

Nope. When doing my tests, I briefly looked at code how it's used and also added an ASSERT() to make sure it is never lesser than FilePosition.

BTW, I *do* know that the code really needs refactoring, documentation, etc. --  I didnt do that before because I believed that it would never get upstream -- since its now -- I will look forward to that in my free time.

Its 2:46am here so I should get some sleep :-) Thanks!

Paulo

>
>
>Thanks,
>Star
>-----Original Message-----
>From: Paulo Alcantara [mailto:pcacjr@zytor.com] 
>Sent: Wednesday, September 13, 2017 12:45 PM
>To: edk2-devel@lists.01.org
>Cc: Paulo Alcantara <pcacjr@zytor.com>; Zeng, Star
><star.zeng@intel.com>; Dong, Eric <eric.dong@intel.com>; Ni, Ruiyu
><ruiyu.ni@intel.com>; Bi, Dandan <dandan.bi@intel.com>
>Subject: [PATCH] MdeModulePkg/UdfDxe: Remove negative comparison of
>unsigned number
>
>This patch gets rid of a negative comparison of an UINT64 type (Offset)
>as it'll never evaluate to true.
>
>Cc: Star Zeng <star.zeng@intel.com>
>Cc: Eric Dong <eric.dong@intel.com>
>Cc: Ruiyu Ni <ruiyu.ni@intel.com>
>Cc: Dandan Bi <dandan.bi@intel.com>
>Contributed-under: TianoCore Contribution Agreement 1.1
>Reported-by: Star Zeng <star.zeng@intel.com>
>Signed-off-by: Paulo Alcantara <pcacjr@zytor.com>
>---
> MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c | 3 ---
> 1 file changed, 3 deletions(-)
>
>diff --git a/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
>b/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
>index 7286265373..2039f80289 100644
>--- a/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
>+++ b/MdeModulePkg/Universal/Disk/UdfDxe/FileSystemOperations.c
>@@ -1082,9 +1082,6 @@ ReadFile (
> 
>        if (FilePosition + ExtentLength > ReadFileInfo->FilePosition) {
>           Offset = ReadFileInfo->FilePosition - FilePosition;
>-          if (Offset < 0) {
>-            Offset = -(Offset);
>-          }
>         } else {
>           Offset = 0;
>         }
>--
>2.11.0

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