From 833db5481f1f86745979d3ceda580c2d8fdd24a8 Mon Sep 17 00:00:00 2001
From: Corinna Vinschen <corinna@vinschen.de>
Date: Tue, 16 Aug 2011 20:08:34 +0000
Subject: [PATCH] 	* dlfcn.cc (dlopen): Reimplement RTLD_NODELETE for
 Windows 2000 using 	internal datastructures.  Explain the code. 	*
 ntdll.h (struct _LDR_DATA_TABLE_ENTRY): Define. 	(struct
 _PEB_LDR_DATA): Define. 	(struct _PEB): Change PVOID LoaderData to
 PPEB_LDR_DATA Ldr.

	* fhandler_process.cc (format_process_maps): Call NtQueryVirtualMemory
	with valid return length pointer.  Explain why.
---
 winsup/cygwin/ChangeLog           | 11 +++++++++++
 winsup/cygwin/dlfcn.cc            | 27 +++++++++++++++++++++------
 winsup/cygwin/fhandler_process.cc |  8 ++++++--
 winsup/cygwin/ntdll.h             | 30 +++++++++++++++++++++++++++++-
 4 files changed, 67 insertions(+), 9 deletions(-)

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index 452d17c4d..315972e58 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,14 @@
+2011-08-16  Corinna Vinschen  <corinna@vinschen.de>
+
+	* dlfcn.cc (dlopen): Reimplement RTLD_NODELETE for Windows 2000 using
+	internal datastructures.  Explain the code.
+	* ntdll.h (struct _LDR_DATA_TABLE_ENTRY): Define.
+	(struct _PEB_LDR_DATA): Define.
+	(struct _PEB): Change PVOID LoaderData to PPEB_LDR_DATA Ldr.
+
+	* fhandler_process.cc (format_process_maps): Call NtQueryVirtualMemory
+	with valid return length pointer.  Explain why.
+
 2011-08-16  Corinna Vinschen  <corinna@vinschen.de>
 
 	* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Bump.
diff --git a/winsup/cygwin/dlfcn.cc b/winsup/cygwin/dlfcn.cc
index 91ffc9a6c..fbcdfedfb 100644
--- a/winsup/cygwin/dlfcn.cc
+++ b/winsup/cygwin/dlfcn.cc
@@ -120,12 +120,27 @@ dlopen (const char *name, int flags)
 					  (HMODULE *) &ret))
 		{
 		  /* Windows 2000 is missing the GetModuleHandleEx call, so we
-		     just use a trick.  Call LoadLibrary 10 times more if the
-		     RTLD_NODELETE flag has been specified.  That makes it
-		     unlikely (but not impossible) that dlclose will actually
-		     free the library. */
-		  for (int i = 0; i < 10; ++i)
-		    LoadLibraryW (path);
+		     use a non-documented way to set the DLL to "don't free".
+		     This is how it works:  Fetch the Windows Loader data from
+		     the PEB.  Iterate backwards through the list of loaded
+		     DLLs and compare the DllBase address with the address
+		     returned by LoadLibrary.  If they are equal we found the
+		     right entry.  Now set the LoadCount to -1, which is the
+		     marker for a DLL which should never be free'd. */
+		  PPEB_LDR_DATA ldr = NtCurrentTeb ()->Peb->Ldr;
+
+		  for (PLDR_DATA_TABLE_ENTRY entry = (PLDR_DATA_TABLE_ENTRY)
+					     ldr->InLoadOrderModuleList.Blink;
+		       entry && entry->DllBase;
+		       entry = (PLDR_DATA_TABLE_ENTRY)
+			       entry->InLoadOrderLinks.Blink)
+		    {
+		      if (entry->DllBase == ret)
+			{
+			  entry->LoadCount = (WORD) -1;
+			  break;
+			}
+		    }
 		}
 	    }
 
diff --git a/winsup/cygwin/fhandler_process.cc b/winsup/cygwin/fhandler_process.cc
index eb36d9d56..36270d1ba 100644
--- a/winsup/cygwin/fhandler_process.cc
+++ b/winsup/cygwin/fhandler_process.cc
@@ -960,12 +960,16 @@ format_process_maps (void *data, char *&destbuf)
 	  // if a new allocation, figure out what kind it is
 	  if (newbase && !last_pass && mb.State != MEM_FREE)
 	    {
+	      /* If the return length pointer is missing, NtQueryVirtualMemory
+		 returns with STATUS_ACCESS_VIOLATION on Windows 2000. */
+	      ULONG ret_len = 0;
+
 	      st.st_dev = 0;
 	      st.st_ino = 0;
 	      if ((mb.Type & (MEM_MAPPED | MEM_IMAGE))
-		  && NT_SUCCESS (NtQueryVirtualMemory (proc, cur.abase,
+		  && NT_SUCCESS (status = NtQueryVirtualMemory (proc, cur.abase,
 						       MemorySectionName,
-						       msi, 65536, NULL)))
+						       msi, 65536, &ret_len)))
 		{
 		  PWCHAR dosname =
 		      drive_maps.fixup_if_match (msi->SectionFileName.Buffer);
diff --git a/winsup/cygwin/ntdll.h b/winsup/cygwin/ntdll.h
index c5b3597a7..ce1a87a34 100644
--- a/winsup/cygwin/ntdll.h
+++ b/winsup/cygwin/ntdll.h
@@ -579,6 +579,34 @@ typedef struct _KERNEL_USER_TIMES
   LARGE_INTEGER UserTime;
 } KERNEL_USER_TIMES, *PKERNEL_USER_TIMES;
 
+typedef struct _LDR_DATA_TABLE_ENTRY
+{
+  LIST_ENTRY InLoadOrderLinks;
+  LIST_ENTRY InMemoryOrderLinks;
+  LIST_ENTRY InInitializationOrderLinks;
+  PVOID DllBase;
+  PVOID EntryPoint;
+  ULONG SizeOfImage;
+  UNICODE_STRING FullDllName;
+  UNICODE_STRING BaseDllName;
+  ULONG Flags;
+  WORD LoadCount;
+  /* More follows.  Left out since it's just not used.  The aforementioned
+     part of the structure is stable from at least NT4 up to Windows 7,
+     including WOW64. */
+} LDR_DATA_TABLE_ENTRY, *PLDR_DATA_TABLE_ENTRY;
+
+typedef struct _PEB_LDR_DATA
+{
+  ULONG Length;
+  UCHAR Initialized;
+  PVOID SsHandle;
+  LIST_ENTRY InLoadOrderModuleList;
+  LIST_ENTRY InMemoryOrderModuleList;
+  LIST_ENTRY InInitializationOrderModuleList;
+  PVOID EntryInProgress;
+} PEB_LDR_DATA, *PPEB_LDR_DATA;
+
 typedef struct _RTL_USER_PROCESS_PARAMETERS
 {
   ULONG AllocationSize;
@@ -616,7 +644,7 @@ typedef struct _PEB
   BYTE Reserved1[2];
   BYTE BeingDebugged;
   BYTE Reserved2[9];
-  PVOID LoaderData;
+  PPEB_LDR_DATA Ldr;
   PRTL_USER_PROCESS_PARAMETERS ProcessParameters;
   BYTE Reserved3[4];
   PVOID ProcessHeap;