[PATCH] EmulatorPkg/Host/Unix: Drop dlopen() usage

["Marvin Häuser" <mhaeuser@posteo.de>]

To assist debugging, i.e. to have the OS load the image debug
symbols, EmulatorPkg/Unix used to load most UEFI executables with OS
APIs, namely dlopen() and dlclose(). After support was added for GDB
and LLDB debugging of images loaded by the EDK II code, this route
became orphaned. Namely, it does not work for a variety of reasons:

1) Support is explicitly disabled for Xcode builds.
2) The dlopen() route is only attempted if the PDB path name ends
with ".pdb", which has not been the case with recent GCC toolchains.
3) By default, the images are not 4K-aligned, which causes some OSes
to deny the image executioon.
4) With recent GCC toolchains, UEFI images are built as ELF
executables, which cannot be dynamically loaded via dlopen().

Drop support for the dlopen() path as realistically it has not been
used or functioning in a long time.

Cc: Andrew Fish <afish@apple.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Vitaly Cheptsov <vit9696@protonmail.com>
Signed-off-by: Marvin Häuser <mhaeuser@posteo.de>
---
 EmulatorPkg/Unix/Host/Host.c | 194 +-------------------
 1 file changed, 2 insertions(+), 192 deletions(-)

diff --git a/EmulatorPkg/Unix/Host/Host.c b/EmulatorPkg/Unix/Host/Host.c
index b4e5510613c8..e19e20ed2902 100644
--- a/EmulatorPkg/Unix/Host/Host.c
+++ b/EmulatorPkg/Unix/Host/Host.c
@@ -48,9 +48,6 @@ EMU_SYSTEM_MEMORY  *gSystemMemory;
 
 
 
-UINTN                        mImageContextModHandleArraySize = 0;
-IMAGE_CONTEXT_TO_MOD_HANDLE  *mImageContextModHandleArray = NULL;
-
 EFI_PEI_PPI_DESCRIPTOR  *gPpiList;
 
 
@@ -118,8 +115,7 @@ main (
   SecGdbConfigBreak ();
 
   //
-  // If dlopen doesn't work, then we build a gdb script to allow the
-  // symbols to be loaded.
+  // We build a gdb script to allow the symbols to be loaded.
   //
   Index = strlen (*Argv);
   gGdbWorkingFileName = AllocatePool (Index + strlen(".gdb") + 1);
@@ -762,7 +758,6 @@ SecPeCoffGetEntryPoint (
     ImageContext.EntryPoint = (UINTN)*EntryPoint;
   }
 
-  // On Unix a dlopen is done that will change the entry point
   SecPeCoffRelocateImageExtraAction (&ImageContext);
   *EntryPoint = (VOID *)(UINTN)ImageContext.EntryPoint;
 
@@ -891,115 +886,6 @@ Returns:
 }
 
 
-/*++
-
-Routine Description:
-  Store the ModHandle in an array indexed by the Pdb File name.
-  The ModHandle is needed to unload the image.
-
-Arguments:
-  ImageContext - Input data returned from PE Loader Library. Used to find the
-                 .PDB file name of the PE Image.
-  ModHandle    - Returned from LoadLibraryEx() and stored for call to
-                 FreeLibrary().
-
-Returns:
-  EFI_SUCCESS - ModHandle was stored.
-
-**/
-EFI_STATUS
-AddHandle (
-  IN  PE_COFF_LOADER_IMAGE_CONTEXT         *ImageContext,
-  IN  VOID                                 *ModHandle
-  )
-{
-  UINTN                       Index;
-  IMAGE_CONTEXT_TO_MOD_HANDLE *Array;
-  UINTN                       PreviousSize;
-
-
-  Array = mImageContextModHandleArray;
-  for (Index = 0; Index < mImageContextModHandleArraySize; Index++, Array++) {
-    if (Array->ImageContext == NULL) {
-      //
-      // Make a copy of the string and store the ModHandle
-      //
-      Array->ImageContext = ImageContext;
-      Array->ModHandle    = ModHandle;
-      return EFI_SUCCESS;
-    }
-  }
-
-  //
-  // No free space in mImageContextModHandleArray so grow it by
-  // IMAGE_CONTEXT_TO_MOD_HANDLE entires. realloc will
-  // copy the old values to the new location. But it does
-  // not zero the new memory area.
-  //
-  PreviousSize = mImageContextModHandleArraySize * sizeof (IMAGE_CONTEXT_TO_MOD_HANDLE);
-  mImageContextModHandleArraySize += MAX_IMAGE_CONTEXT_TO_MOD_HANDLE_ARRAY_SIZE;
-
-  mImageContextModHandleArray = ReallocatePool (
-                                  (mImageContextModHandleArraySize - 1) * sizeof (IMAGE_CONTEXT_TO_MOD_HANDLE),
-                                  mImageContextModHandleArraySize * sizeof (IMAGE_CONTEXT_TO_MOD_HANDLE),
-                                  mImageContextModHandleArray
-                                  );
-  if (mImageContextModHandleArray == NULL) {
-    ASSERT (FALSE);
-    return EFI_OUT_OF_RESOURCES;
-  }
-
-  memset (mImageContextModHandleArray + PreviousSize, 0, MAX_IMAGE_CONTEXT_TO_MOD_HANDLE_ARRAY_SIZE * sizeof (IMAGE_CONTEXT_TO_MOD_HANDLE));
-
-  return AddHandle (ImageContext, ModHandle);
-}
-
-
-/*++
-
-Routine Description:
-  Return the ModHandle and delete the entry in the array.
-
-Arguments:
-  ImageContext - Input data returned from PE Loader Library. Used to find the
-                 .PDB file name of the PE Image.
-
-Returns:
-  ModHandle - ModHandle associated with ImageContext is returned
-  NULL      - No ModHandle associated with ImageContext
-
-**/
-VOID *
-RemoveHandle (
-  IN  PE_COFF_LOADER_IMAGE_CONTEXT         *ImageContext
-  )
-{
-  UINTN                        Index;
-  IMAGE_CONTEXT_TO_MOD_HANDLE  *Array;
-
-  if (ImageContext->PdbPointer == NULL) {
-    //
-    // If no PDB pointer there is no ModHandle so return NULL
-    //
-    return NULL;
-  }
-
-  Array = mImageContextModHandleArray;
-  for (Index = 0; Index < mImageContextModHandleArraySize; Index++, Array++) {
-    if (Array->ImageContext == ImageContext) {
-      //
-      // If you find a match return it and delete the entry
-      //
-      Array->ImageContext = NULL;
-      return Array->ModHandle;
-    }
-  }
-
-  return NULL;
-}
-
-
-
 BOOLEAN
 IsPdbFile (
   IN  CHAR8   *PdbFileName
@@ -1052,67 +938,6 @@ PrintLoadAddress (
 }
 
 
-/**
-  Loads the image using dlopen so symbols will be automatically
-  loaded by gdb.
-
-  @param  ImageContext  The PE/COFF image context
-
-  @retval TRUE - The image was successfully loaded
-  @retval FALSE - The image was successfully loaded
-
-**/
-BOOLEAN
-DlLoadImage (
-  IN OUT PE_COFF_LOADER_IMAGE_CONTEXT         *ImageContext
-  )
-{
-
-#ifdef __APPLE__
-
-  return FALSE;
-
-#else
-
-  void        *Handle = NULL;
-  void        *Entry = NULL;
-
-  if (ImageContext->PdbPointer == NULL) {
-    return FALSE;
-  }
-
-  if (!IsPdbFile (ImageContext->PdbPointer)) {
-    return FALSE;
-  }
-
-  fprintf (
-     stderr,
-     "Loading %s 0x%08lx - entry point 0x%08lx\n",
-     ImageContext->PdbPointer,
-     (unsigned long)ImageContext->ImageAddress,
-     (unsigned long)ImageContext->EntryPoint
-     );
-
-  Handle = dlopen (ImageContext->PdbPointer, RTLD_NOW);
-  if (Handle != NULL) {
-    Entry = dlsym (Handle, "_ModuleEntryPoint");
-    AddHandle (ImageContext, Handle);
-  } else {
-    printf("%s\n", dlerror());
-  }
-
-  if (Entry != NULL) {
-    ImageContext->EntryPoint = (UINTN)Entry;
-    printf ("Change %s Entrypoint to :0x%08lx\n", ImageContext->PdbPointer, (unsigned long)Entry);
-    return TRUE;
-  } else {
-    return FALSE;
-  }
-
-#endif
-}
-
-
 #ifdef __APPLE__
 __attribute__((noinline))
 #endif
@@ -1195,9 +1020,7 @@ SecPeCoffRelocateImageExtraAction (
   IN OUT PE_COFF_LOADER_IMAGE_CONTEXT         *ImageContext
   )
 {
-  if (!DlLoadImage (ImageContext)) {
-    GdbScriptAddImage (ImageContext);
-  }
+  GdbScriptAddImage (ImageContext);
 }
 
 
@@ -1264,19 +1087,6 @@ SecPeCoffUnloadImageExtraAction (
   IN PE_COFF_LOADER_IMAGE_CONTEXT         *ImageContext
   )
 {
-  VOID *Handle;
-
-  //
-  // Check to see if the image symbols were loaded with gdb script, or dlopen
-  //
-  Handle = RemoveHandle (ImageContext);
-  if (Handle != NULL) {
-#ifndef __APPLE__
-    dlclose (Handle);
-#endif
-    return;
-  }
-
   GdbScriptRemoveImage (ImageContext);
 }
 
-- 
2.31.1