[edk2-devel] [edk2-libc Patch 1/1] edk2-libc/StdLib: Fix console jump to 0, 0 issue in lseek()

["Jayaprakash, N" <n.jayaprakash@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4531

Python code opens console file descriptor and uses lseek()
with position == 0 and SEEK_CUR as
'do nothing, check console is alive' operation.

Current implementation of daConsole ignores whence argument,
this is wrong in case lseek(0, SEEK_CUR) will send cursor to (0,0).
This fix is not generic, but solves the particular situation.

Cc: Rebecca Cran <rebecca@bsdio.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Jayaprakash N <n.jayaprakash@intel.com>
Signed-off-by: Kloper Dimitry <dimitry.kloper@intel.com>
---
 StdLib/LibC/Uefi/Devices/Console/daConsole.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/StdLib/LibC/Uefi/Devices/Console/daConsole.c b/StdLib/LibC/Uefi/Devices/Console/daConsole.c
index 56571af..ba031d6 100644
--- a/StdLib/LibC/Uefi/Devices/Console/daConsole.c
+++ b/StdLib/LibC/Uefi/Devices/Console/daConsole.c
@@ -141,8 +141,16 @@ da_ConSeek(
     EFIerrno = RETURN_UNSUPPORTED;
     return -1;
   }
-  // Everything is OK to do the final verification and "seek".
+
   Proto = (EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL *)Stream->Dev;
+
+  if(Position == 0 && whence == SEEK_CUR) {
+    CursorPos.XYpos.Column  = (UINT32)Proto->Mode->CursorColumn;
+    CursorPos.XYpos.Row     = (UINT32)Proto->Mode->CursorRow;
+    return CursorPos.Offset;
+  }
+
+  // Everything is OK to do the final verification and "seek".
   CursorPos.Offset = Position;
 
   EFIerrno = Proto->SetCursorPosition(Proto,
-- 
2.40.0.windows.1



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