Re: [PATCH v1 6/7] MdeModulePkg/UdfDxe: Remove dead codes in FileName.c

[Leif Lindholm <leif.lindholm@linaro.org>]

On Mon, Oct 15, 2018 at 12:55:21PM +0800, Hao Wu wrote:
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1249
> 
> We found potential dead codes within File.c during the code coverage test.
> 
> After manual review, we think the below ones are positive reports:
> 
> A. In function MangleFileName():
> 
>   FileName = TrimString (FileName);
>   // Begin of dead codes
>   if (*FileName == L'\0') {
>     goto Exit;
>   }
>   // End of dead codes
> 
> When the code reaches the TrimString() call, the string in 'FileName' is
> guaranteed to have a '\' character due to the call patterns of

What in the call pattern guarantees this? Please be precise.

> MangleFileName(). So after trimming the lead-off/tailing white spaces,
> string in 'FileName' will not be an empty string.
> 
> B. In function MangleFileName():
> 
>   if (FileName[0] == L'.') {
>     if (FileName[1] == L'.') {
>       if (FileName[2] == L'\0') {
>         goto Exit;
>       } else {
>         FileName += 2;
>       }
>     } else if (FileName[1] == L'\0') {
>       goto Exit;
>     }
>   }
> 
> When the code hits the above checks, string in 'FileName' will always have
> a leading '\' character (denoting an absolute path) due to the call
> patterns of MangleFileName(). So no leading '.' can be there in string
> 'FileName'.

What in the call pattern guarantees this? Please be precise.

Regards,

Leif