Bug #6790: mingw-w64: rb_libruby_handle and libruby changes when extensions are loaded

• Status: Closed
• Assignee: nobu (Nobuyoshi Nakada)
• Target version: 2.0.0
• ruby -v: ruby 2.0.0dev (2012-07-25 trunk 36527) [x64-mingw32]

[luislavena (Luis Lavena)]

=begin
Hello,

I started to look into this failure when running dl/handle tests:

test_initialize_noargs(DL::TestHandle):
DL::DLError: unknown symbol "rb_str_new"
C:/Users/Worker/Jenkins/workspace/git-ruby-trunk/test/dl/test_handle.rb:110:in []' C:/Users/Worker/Jenkins/workspace/git-ruby-trunk/test/dl/test_handle.rb:110:in test_initialize_noargs'

Above error only happens with compiled 64bits ruby.

After looking a bit more closer, it seems DllMain from libruby gets called several times when (({x64-msvcrt-ruby200.dll})) is loaded but also when extensions are loaded.

Adding some debug strings into DllMain like the following:

diff --git a/ruby.c b/ruby.c
index ab4b674..6d1a715 100644
--- a/ruby.c
+++ b/ruby.c
@@ -315,8 +315,22 @@ static HMODULE libruby;
BOOL WINAPI
DllMain(HINSTANCE dll, DWORD reason, LPVOID reserved)
{

• HMODULE self;
• char filename[MAX_PATH];
• if (reason == DLL_PROCESS_ATTACH)

•   libruby = dll;
  

• {

•    printf("DLL_PROCESS_ATTACH\n");
  

•    self = GetModuleHandle(NULL);
  

•    GetModuleFileName(self, filename, MAX_PATH);
  

•    printf("self: %#x (%s)\n", self, filename);
  

•    GetModuleFileName(dll, filename, MAX_PATH);
  

•    printf("dll: %#x (%s)\n", dll, filename);
  

•    libruby = dll;
  

• }
  return TRUE;
  }

Produces the following:

32bits compilation:

C:\Users\Luis\Code\ruby\ruby\x86-installed>ruby -v -rdl -e "puts :ok"
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x86-installed\bin\ruby.exe)
dll: 0x66780000 (C:\Users\Luis\Code\ruby\ruby\x86-installed\bin\msvcrt-ruby200.dll)
ruby 2.0.0dev (2012-07-25 trunk 36527) [i386-mingw32]
ok

64bits (mingw-w64):

C:\Users\Luis\Code\ruby\ruby\x64-installed>ruby -v -rdl -e "puts :ok"
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x6f100000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\x64-msvcrt-ruby200.dll)
ruby 2.0.0dev (2012-07-25 trunk 36527) [x64-mingw32]
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x1ee0000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\lib\ruby\2.0.0\x64-mingw32\enc\encdb.so)
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x6aa00000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\lib\ruby\2.0.0\x64-mingw32\enc\iso_8859_1.so)
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x68080000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\lib\ruby\2.0.0\x64-mingw32\enc\trans\transdb.so)
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x623c0000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\lib\ruby\2.0.0\x64-mingw32\dl.so)
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x63d80000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\lib\ruby\2.0.0\x64-mingw32\fiddle.so)
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x6e6c0000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\lib\ruby\2.0.0\x64-mingw32\enc\utf_16le.so)
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x6a340000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\lib\ruby\2.0.0\x64-mingw32\enc\trans\single_byte.so)
DLL_PROCESS_ATTACH
self: 0x400000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\bin\ruby.exe)
dll: 0x1f10000 (C:\Users\Luis\Code\ruby\ruby\x64-installed\lib\ruby\2.0.0\x64-mingw32\enc\trans\utf_16_32.so)
ok

I just tested a simple project which loads multiple DLLs and DllMain of each DLL do not get invoked several times.

Since each extension depends on (({x86-msvcrt-ruby200.dll})), perhaps that is the reason why (({DllMain})) is invoked multiple times.

Maybe there is something I'm missing? Perhaps a workaround will be set (({libruby})) only once?
=end

[nobu (Nobuyoshi Nakada)]

Seems it occurs only in x64-mingw; and does not occur when loading the DLL by x64-mswin ruby.exe.
Needs more investigation.

[luislavena (Luis Lavena)]

nobu (Nobuyoshi Nakada) wrote:

Seems it occurs only in x64-mingw; and does not occur when loading the DLL by x64-mswin ruby.exe.
Needs more investigation.

Do you think this simplification is good enough?

https://github.com/luislavena/experiments/tree/master/dll-handles

DllMain is only invoked once on this example, which might indicate something going on on Ruby.

After a GDB session, seems that dln.c line 1271 (LoadLibrary) is causing x64-msvcrt-ruby200.dll be loaded again.

Will keep investigating on this.

[phasis68 (Heesob Park)]

After some investigating, I found this bug is due to exporting "DllMain" symbol of x64-msvcrt-ruby200.dll.

You can see the following line in the x64-msvcrt-ruby200.def.

VERSION 2.0
EXPORTS
DllMain
FD_CLR=rb_w32_fdclr
FD_ISSET=rb_w32_fdisset
...

I think that DllMain should not be exported.

Here is a simple workaround for win32/mkexports.rb

diff --git a/mkexports.rb b/mkexports.rb.new
index 3a1a91a..9dc8a19 100644
--- a/mkexports.rb
+++ b/mkexports.rb.new
@@ -38,6 +38,7 @@ class Exports
winapis = {}
syms["ruby_sysinit_real"] = "ruby_sysinit"
each_export(objs) do |internal, export|

•  next if internal == 'DllMain'
   syms[internal] = export
   winapis[$1] = internal if /^_?(rb_w32_\w+)(?:@\d+)?$/ =~ internal
  

  end

With the patched and rebuilt version, I confirmed this bug is solved.

[usa (Usaku NAKAMURA)]

=begin
Hmm, I see.

Is this patch OK?

Index: win32/mkexports.rb

--- win32/mkexports.rb (revision 36541)
+++ win32/mkexports.rb (working copy)
@@ -116,7 +116,7 @@ class Exports::Mswin < Exports
is_data = !$1
if noprefix or /^[@_]/ =~ l
next if /(?!^)@.*@/ =~ l || /@[[:xdigit:]]{8,16}$/ =~ l ||

•          /^_(?:Init_|.*_threadptr_|DllMain@)/ =~ l
  

•          /^_?(?:Init_|.*_threadptr_|DllMain\b)/ =~ l
  

l.sub!(/^[@_]/, '') if /@\d+$/ !~ l
elsif !l.sub!(/^(\S+) ([^@?]`'*)$/, '\1')
next
@@ -150,7 +150,7 @@ class Exports::Cygwin < Exports
def each_export(objs)
symprefix = RbConfig::CONFIG["SYMBOL_PREFIX"]
symprefix.strip! if symprefix

• re = /\s(?:(T)|[[:upper:]])\s#{symprefix}((?!Init_|.threadptr|DllMain@).)$/

• re = /\s(?:(T)|[[:upper:]])\s#{symprefix}((?!Init_|.threadptr|DllMain\b).)$/
  objdump(objs) do |l|
  next if /@.*@/ =~ l
  yield $2, !$1 if re =~ l

=end

[usa (Usaku NAKAMURA)]

• Status changed from Assigned to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r36544.
Luis, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• win32/mkexports.rb: should not export DllMain().
  reported by luis at [ruby-core:46743] [Bug #6790], solved by
  Heesob Park, and confirmed by nobu.

[luislavena (Luis Lavena)]

Thank you Heesob Park, Usaku Nakamura and Nobu for fixing this!