On 07/29/14 20:18, lowell_den...@dell.com wrote:
> Every copy of EFI Shell V2.0 that I have found seems to have a file
> processing bug.
>
>
>
> It looks like appending to a file does not work as expected. The
> following shell snippet does not work:
>
>
>
> del test.dat
>
> echo 1234 >> test.dat # This works
>
> echo 5678 >> test.dat # This give
> “Error. Unable to redirect file”
>
>
>
> If I modify that shell snippet as follows it works:
>
>
>
> del test.dat
>
> echo 1234 > test.dat
>
> echo 5678 >> test.dat
>
>
>
> Additionally appending as ASCII also works:
>
>
>
> del test.dat
>
> echo 1234 >>a test.dat
>
> echo 5678 >>a test.dat
>
>
>
> This error carries over to programming interfaces. If I try to open an
> existing file for append in Python I get an error”
>
>
>
> f = open(‘ExistingFile’, ‘a’)
>
> # ERROR
>
>
>
> However, if I open the file in mode ‘r+’ there is no error:
>
>
>
> f = open(‘ExistingFile’, ‘r+’)
>
> f.seek(0,2)
>
>
>
> What is going on here?
This is intended behavior. (I'm not saying it is correct, but it is intended.)
Refer to UpdateStdInStdOutStdErr() in
"ShellPkg/Application/Shell/ShellParametersProtocol.c". Specifically, this
check:
//
// Check that filetypes (Unicode/Ascii) do not change during an append
//
...
||(StdOutFileName != NULL && OutUnicode && OutAppend &&
(!EFI_ERROR(ShellFileExists(StdOutFileName)) &&
EFI_ERROR(IsUnicodeFile(StdOutFileName))))
...
Status = EFI_INVALID_PARAMETER;
With >> you are requesting stdout redirection (StdOutFileName != NULL), unicode
(OutUnicode), append mode (OutAppend). The file you're redirecting to already
exists (!EFI_ERROR(ShellFileExists(StdOutFileName)), and it does *not* have a
BOM (byte order mark) at the beginning, because previously you created the file
with contents "1234", which does not contain a BOM.
Therefore the IsUnicodeFile() function
[ShellPkg/Application/Shell/ShellParametersProtocol.c], which checks for the
BOM ("gUnicodeFileTag", EFI_UNICODE_BYTE_ORDER_MARK) fails, and you get
EFI_INVALID_PARAMETER.
Hence the bug is not in the "append check" for the second >> redirection. The
bug is in the first >> redirection, because it doesn't place the BOM at the
beginning of the new file. (According to your testing, the first > redirection
*does* create the BOM.) I'm posting a patchset soon, please test it.
Thanks,
Laszlo
------------------------------------------------------------------------------
Infragistics Professional
Build stunning WinForms apps today!
Reboot your WinForms applications with our WinForms controls.
Build a bridge from your legacy apps to the future.
http://pubads.g.doubleclick.net/gampad/clk?id=153845071&iu=/4140/ostg.clktrk
_______________________________________________
edk2-devel mailing list
edk2-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/edk2-devel
