ShellPkg: Create a homefilesystem environment variable

Create a homefilesystem environment variable whose value is the file
system on which the executing shell is located. For example: "FS14:".

This eliminates the need for people to have to try and find the "boot"
file system in their startup script.  After this change they can simply
execute %homefilesystem% to set the cwd to the root of the file system
where the shell is located.

A future enhancement could be to add "homefilesystem" to the list of
predefined, read-only variables listed in the EfiShellSetEnv function of
file ShellProtocol.c

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jim Dailey <jim_dailey@dell.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>

diff --git a/ShellPkg/Application/Shell/Shell.c b/ShellPkg/Application/Shell/Shell.c
index 3f3bcbb4b0ec6b9ae31c03df7b8387b137023794..6185b6ac80044e36a06977ed5f361bf9737add3b 100644 (file)
--- a/ShellPkg/Application/Shell/Shell.c
+++ b/ShellPkg/Application/Shell/Shell.c
@@ -1169,6 +1169,8 @@ LocateStartupScript (
       *TempSpot = CHAR_NULL;\r
     }\r
 \r
+    InternalEfiShellSetEnv(L"homefilesystem", StartupScriptPath, TRUE);\r
+\r
     StartupScriptPath = StrnCatGrow (&StartupScriptPath, &Size, ((FILEPATH_DEVICE_PATH *)FileDevicePath)->PathName, 0);\r
     PathRemoveLastItem (StartupScriptPath);\r
     StartupScriptPath = StrnCatGrow (&StartupScriptPath, &Size, mStartupScript, 0);\r