ShellPkg/ShellCommandLib: add ShellSortFileList()

Introduce the ShellSortFileList() function, for sorting an
EFI_SHELL_FILE_INFO list, by FileName or by FullName.

Duplicates can be kept in the same list, or separated out to a new list.
In either case, the relative order between duplicates does not change (the
sorting is stable).

For the sorting, use OrderedCollectionLib rather than SortLib:

- The PerformQuickSort() function from the latter has quadratic worst-case
  time complexity, plus it is implemented recursively (see
  "MdeModulePkg/Library/UefiSortLib/UefiSortLib.c"). It can also not
  return an error on memory allocation failure.

- In comparison, the Red-Black Tree instance of OrderedCollectionLib sorts
  in O(n*log(n)) worst-case time, contains no recursion with the default
  PcdValidateOrderedCollection=FALSE setting, and the OrderedCollectionLib
  class APIs return errors appropriately.

The OrderedCollectionLib APIs do not permit duplicates natively, but by
using lists as collection entries, stable sorting of duplicates can be
achieved.

Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Zhichao Gao <zhichao.gao@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3151
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>
Message-Id: <20210113085453.10168-7-lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

ShellPkg/Library/UefiShellCommandLib/UefiShellCommandLib.h

@@ -39,6 +39,7 @@
 #include <Library/HiiLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/UefiLib.h>
+#include <Library/OrderedCollectionLib.h>
 
 typedef struct{
   LIST_ENTRY                  Link;
@@ -60,6 +61,24 @@ typedef struct {
   CHAR16            *Path;
 } SHELL_COMMAND_FILE_HANDLE;
 
+//
+// Collects multiple EFI_SHELL_FILE_INFO objects that share the same name.
+//
+typedef struct {
+  //
+  // A string that compares equal to either the FileName or the FullName fields
+  // of all EFI_SHELL_FILE_INFO objects on SameNameList, according to
+  // gUnicodeCollation->StriColl(). The string is not dynamically allocated;
+  // instead, it *aliases* the FileName or FullName field of the
+  // EFI_SHELL_FILE_INFO object that was first encountered with this name.
+  //
+  CONST CHAR16 *Alias;
+  //
+  // A list of EFI_SHELL_FILE_INFO objects whose FileName or FullName fields
+  // compare equal to Alias, according to gUnicodeCollation->StriColl().
+  //
+  LIST_ENTRY SameNameList;
+} SHELL_SORT_UNIQUE_NAME;
 
 #endif //_UEFI_COMMAND_LIB_INTERNAL_HEADER_