[binutils-gdb] Fix WOW64 process system DLL paths

[binutils-gdb] Fix WOW64 process system DLL paths

[Hannes Domani]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d503b685c6b7384b389767d5153235039e2b8fc4

commit d503b685c6b7384b389767d5153235039e2b8fc4
Author: Hannes Domani <ssbssa@yahoo.de>
Date:   Tue Mar 24 18:03:08 2020 +0100

    Fix WOW64 process system DLL paths
    
    GetModuleFileNameEx returns for some DLLs of WOW64 processes
    the path inside the 64bit system directory instead of the 32bit
    syswow64 directory.
    
    Problem happens e.g. with dbghelp.dll:
    
    (gdb) start
    Temporary breakpoint 1 at 0x415a00: file fiber.cpp, line 430.
    Starting program: C:\src\tests\fiber.exe
    warning: `C:\Windows\system32\dbghelp.dll': Shared library architecture i386:x86-64 is not compatible with target architecture i386.
    
    Temporary breakpoint 1, main () at fiber.cpp:430
    430     {
    (gdb) info sharedlibrary
    From        To          Syms Read   Shared Object Library
    0x77070000  0x771d4d20  Yes (*)     C:\Windows\SysWOW64\ntdll.dll
    0x74dc0000  0x74ebad9c  Yes (*)     C:\Windows\syswow64\kernel32.dll
    0x75341000  0x75386a18  Yes (*)     C:\Windows\syswow64\KernelBase.dll
    0x6f6a1000  0x6f7c48fc  Yes (*)     C:\Windows\system32\dbghelp.dll
    0x74d01000  0x74dab2c4  Yes (*)     C:\Windows\syswow64\msvcrt.dll
    (*): Shared library is missing debugging information.
    
    This detects this situation and converts the DLL path to the
    syswow64 equivalent.
    
    gdb/ChangeLog:
    
    2020-03-25  Hannes Domani  <ssbssa@yahoo.de>
    
            * windows-nat.c (windows_add_all_dlls): Fix system dll paths.

Diff:
---
 gdb/ChangeLog     |  4 ++++
 gdb/windows-nat.c | 44 +++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f5e54f6d654..5400a4e3484 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2020-03-25  Hannes Domani  <ssbssa@yahoo.de>
+
+	* windows-nat.c (windows_add_all_dlls): Fix system dll paths.
+
 2020-03-25  Tom de Vries  <tdevries@suse.de>
 
 	* symtab.h (is_main_symtab_of_compunit_symtab): New function.
diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 614b235edea..8547ec2f99b 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -2058,16 +2058,39 @@ windows_add_all_dlls (void)
 	return;
     }
 
+#ifdef __x86_64__
+  char system_dir[__PMAX];
+  char syswow_dir[__PMAX];
+  size_t system_dir_len = 0;
+  if (wow64_process)
+    {
+      UINT len = GetSystemDirectoryA (system_dir, sizeof (system_dir));
+      /* Error check.  */
+      gdb_assert (len != 0);
+      /* Check that we have passed a large enough buffer.  */
+      gdb_assert (len < sizeof (system_dir));
+
+      len = GetSystemWow64DirectoryA (syswow_dir, sizeof (syswow_dir));
+      /* Error check.  */
+      gdb_assert (len != 0);
+      /* Check that we have passed a large enough buffer.  */
+      gdb_assert (len < sizeof (syswow_dir));
+
+      strcat (system_dir, "\\");
+      strcat (syswow_dir, "\\");
+      system_dir_len = strlen (system_dir);
+    }
+#endif
   for (i = 1; i < (int) (cb_needed / sizeof (HMODULE)); i++)
     {
       MODULEINFO mi;
 #ifdef __USEWIDE
       wchar_t dll_name[__PMAX];
-      char name[__PMAX];
+      char dll_name_mb[__PMAX];
 #else
       char dll_name[__PMAX];
-      char *name;
 #endif
+      const char *name;
       if (GetModuleInformation (current_process_handle, hmodules[i],
 				&mi, sizeof (mi)) == 0)
 	continue;
@@ -2075,10 +2098,25 @@ windows_add_all_dlls (void)
 			       dll_name, sizeof (dll_name)) == 0)
 	continue;
 #ifdef __USEWIDE
-      wcstombs (name, dll_name, __PMAX);
+      wcstombs (dll_name_mb, dll_name, __PMAX);
+      name = dll_name_mb;
 #else
       name = dll_name;
 #endif
+#ifdef __x86_64__
+      /* Convert the DLL path of WOW64 processes returned by
+	 GetModuleFileNameEx from the 64bit system directory to the
+	 32bit syswow64 directory if necessary.  */
+      std::string syswow_dll_path;
+      if (wow64_process
+	  && strncasecmp (name, system_dir, system_dir_len) == 0
+	  && strchr (name + system_dir_len, '\\') == nullptr)
+	{
+	  syswow_dll_path = syswow_dir;
+	  syswow_dll_path += name + system_dir_len;
+	  name = syswow_dll_path.c_str();
+	}
+#endif
 
       solib_end->next = windows_make_so (name, mi.lpBaseOfDll);
       solib_end = solib_end->next;