#1288: ghci 6.6 foreign import stdcall broken, panic, panic!!!!
-----------------------------------+----------------------------------------
Reporter: [EMAIL PROTECTED] | Owner:
Type: bug | Status: new
Priority: high | Milestone:
Component: GHCi | Version: 6.6
Severity: critical | Keywords: ghci foreign ffi dll import
stdcall
Difficulty: Moderate (1 day) | Testcase:
Architecture: x86 | Os: Windows
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'''ghci 6.6 foreign import stdcall broken, panic, panic!!!!'''
I would like to report what I think is a problem with GHCI foreign
function imports
of c functions declared with stdcall calling convention (1) and also with
loading objects containing dll imports (2).
= WHAT IS THE PROBLEM ? =
== 1. ghci handling of mangling of stdcall function names broken ==
{{{
Prelude> :load htest3
[1 of 1] Compiling Main ( htest3.hs, interpreted )
During interactive linking, GHCi couldn't find the following symbol:
test
This may be due to you not asking GHCi to load extra object files,
archives or DLLs needed by your current session. Restart GHCi, specifying
the missing library using the -L/path/to/object/dir and -lmissinglibname
flags, or simply by naming the relevant files on the GHCi command line.
Alternatively, this link failure might indicate a bug in GHCi.
If you suspect the latter, please send a bug report to:
[email protected]
}}}
== 2. ghci loading of c object files dll imports name resolution broken ==
{{{
>ghci -fglasgow-exts test_proxy5a.o -ltest3b
test_proxy5a.o: unknown symbol `__imp__test'
final link ... : linking extra libraries/objects failed
}}}
detail follows ...
= CONCLUSSION REACHED =
== 1. Importing Stdcall Symbols ==
ghci dose not correctly look for symbols decorated in the stdcall manner
in the
object files ie. it looks for '''_test''' when it should (according to
stdcall convention) look for '''[EMAIL PROTECTED]'''.
stdcall symbols in object files are decorated with the number of bytes
that should
be popped from the stack before the function returns.
== 2. linking objects with dllimports ==
ghci cannot properly resolve dllimports in c object files i.e. if an
object loaded by ghci
(eg test_proxy, with c function test_proxy) calls functions from a dll (eg
'''test''') then
that function in the object file will be decorated as '''`__imp__test`'''
this in normal course linked agains a .lib or a .a file will be resolved
to '''_test'''
function in the dll but ghci does not do this.
Offcourse these problems go away when using ghc ... but well what's the
point of ghci then?
= SUMMARY OF TESTS and METHODOLOGY =
== 1. Reference Case ==
verify that ccall works ..
[[BR]]Create c file test1a.c and function test(int) in the file
[[BR]]create haskell file htest1.hs with function ctest calling test
[[BR]]check this works ok with
a. c object loaded (test1a.c, htest1.hs )-- OK, RIGHT [[BR]]
b. windows dll, c is function a dll export (test1b.c, htest1.hs ) --
OK, RIGHT
== 3. change calling convention to stdcall ==
a. check loading of function from object (test3a.c, htest3.hs) -- FAIL,
WRONG[[BR]]
b. check loading of stdcall function from dll -- FAIL, WRONG
== 4. try what shouldn't work ==
a. htest3 against object test1a
i.e. what hapens when you try loading a haskell module with foreign
import stdcall against c function declared with ccall convention.
ghci loaded -- OK!!, WRONG,
it should not have resolved the symbol and not loaded.[[BR]]
ghci called the function and crashed -- given that it resolved the
symbol and called the function, this is expected.
b. htest3 against dll htest1b.dll
same result as 4a -- expected,
behaviour consistent in both cases with resolving stdcall callouts
(symbol '''test''') in a manner consistent with ccalls.
i.e. resolving the call to c function '''test''' as a call to symbol
'''_test'''
rather than '''[EMAIL PROTECTED]''' as it should be according to the stdcall
convention.
yet the function is called as a stdcall c function, consequently ghci
crashes when
the ccall function returns and the stack has not been cleared of the
function arguments, as is required by the stdcall convention.
== 5. Lets try a proxy function/object ==
Hmm, lets see what happens when we have a ccall c proxy function calling
stdcall c
function in dll etc?
a. test_proxy5a.o with test3b.dll
ccall function calling stdcall function in dll
{{{
unknown symbol __imp__test
}}}
FAILED, WRONG.
dllimports are decorated with '''`__imp__`''' so a stdcall dllimport
to a c function
'''test''' will appear as '''[EMAIL PROTECTED]'''
the dll will export symbol '''[EMAIL PROTECTED]''', usually it is the
function
of the import
library ( .a or .lib depending upon which linker mingw or msvc ) to
resolve
'''[EMAIL PROTECTED]''' to reference '''[EMAIL PROTECTED]''' in the dll
b. test_proxy5b.o with test3b.dll, htest5.hs
ccall function calling stdcall function (not declared as dllimport)
LOADS OK, RUNS OK
test_proxy5b imports symbol '''[EMAIL PROTECTED]''' the test3b.dll
exports
symbol
'''[EMAIL PROTECTED]'''. Arguably this is correct behaviour as
'''`__imp__`'''
decoration is an
MS innovation and case (a) should be handled together with case (b).
c. whell what about test_proxy5b.o with test1b.dll
i.e. c stdcall to a c function declared with ccall convention from
.o object
loaded by ghci should fail to resolve symbols, should crash program but
does niether ????
hey this has me stumped test_proxy5b.o imports symbol '''[EMAIL
PROTECTED]'''.
test1b.dll
exports symbol '''_test''' hmmm how is the symbol '''[EMAIL PROTECTED]'''
resolved ??? why
isn't the stack corrupted when '''test''' is called ??? MYSTERY ???
= DETAIL =
{{{
compiler: ghci version 6.6
platform: windows XP
}}}
''notes-''
* test1[a,b].c
* test3[a,b].c
difference in these files between a,b version is that the b version
declares
dllexport, required when building a dll with msvc (and not using def
file), not relevant with
mingw and using "dllwrap --export-all-symbols"
== TEST 1 ==
=== test1a.c ===
{{{
#include <stdio.h>
void test(int arg)
{
printf("The argument passed was %i\n", arg );
}
}}}
=== test1b.c ===
{{{
#include <stdio.h>
__declspec(dllexport) void test(int arg)
{
printf("The argument passed was %i\n", arg );
}
}}}
=== htest1.hs ===
{{{
import Foreign
import Foreign.C
foreign import ccall "test" ctest :: CInt -> IO ()
}}}
=== COMPILATION OF C DLL/OBJECTS ===
{{{
gcc -c test1a.c
gcc -c test1b.c
ar -rv test1b.a test1b.o
dllwrap --export-all-symbols --output-lib test1b.dll.a -o test1b.dll
test1b.a
}}}
=== TEST 1A results ===
{{{
ghci -fglasgow-exts test1a.o
Loading package base ... linking ... done.
Loading object (static) test1a.o ... done
final link ... done
Prelude> :load htest1
[1 of 1] Compiling Main ( htest1.hs, interpreted )
Ok, modules loaded: Main.
*Main> ctest 5
The argument passed was 5
*Main>
}}}
=== TEST 1B ===
{{{
ghci -fglasgow-exts -ltest1b
Loading package base ... linking ... done.
Loading object (dynamic) test1b ... done
final link ... done
Prelude> :load htest1
[1 of 1] Compiling Main ( htest1.hs, interpreted )
Ok, modules loaded: Main.
*Main> ctest 5
The argument passed was 5
*Main>
}}}
== TEST 3 ==
=== test3a.c ===
{{{
#include <stdio.h>
void _stdcall test(int arg)
{
printf("The argument passed was %i\n", arg );
}
}}}
=== test3b.c ===
{{{
#include <stdio.h>
__declspec(dllexport) void _stdcall test(int arg)
{
printf("The argument passed was %i\n", arg );
}
}}}
=== htest3.hs ===
{{{
import Foreign
import Foreign.C
foreign import stdcall "test" ctest :: CInt -> IO ()
}}}
=== COMPILATION OF C DLL/OBJECTS ===
{{{
compilation (mingw)
gcc -c test3a.c
gcc -c test3b.c
ar -rv test3b.a test3b.o
E:\vvv\WP03\S00\ffi>dllwrap --export-all-symbols --output-lib test3b.dll.a
-o
test3b.dll test3b.a
compilation msvc (same result with both mingw and msvc dll!!)
cl -c test3.c
link etc ...
}}}
=== TEST 3A ===
{{{
ghci -fglasgow-exts test3a.o
Loading package base ... linking ... done.
Loading object (static) test3a.o ... done
final link ... done
Prelude> :load htest3.hs
[1 of 1] Compiling Main ( htest3.hs, interpreted )
During interactive linking, GHCi couldn't find the following symbol:
test
}}}
=== TEST 3B ===
{{{
ghci -fglasgow-exts -ltest3b
Loading package base ... linking ... done.
Loading object (dynamic) test3b ... done
final link ... done
Prelude> :load htest3.hs
[1 of 1] Compiling Main ( htest3.hs, interpreted )
During interactive linking, GHCi couldn't find the following symbol:
test
}}}
the actual symbol in the object file is '''[EMAIL PROTECTED]'''
=== TEST 4A ===
{{{
ghci -fglasgow-exts test1a.o
Prelude> :load htest3
[1 of 1] Compiling Main ( htest3.hs, interpreted )
Ok, modules loaded: Main.
*Main> ctest 5
The argument passed was 5
}}}
... ghci then crashes .... as expected ...
after all ccall function was called using the stdcall calling convention !
but the module should not have loaded as ghci should have been looking for
a
'''[EMAIL PROTECTED]''' symbol
== TEST 5 ==
=== test_proxy5a.c ===
{{{
#include <stdio.h>
__declspec(dllimport) void _stdcall test(int arg);
void test_proxy(int arg)
{
test(arg);
}
}}}
=== test_proxy5a.c ===
{{{
#include <stdio.h>
void _stdcall test(int arg);
void test_proxy(int arg)
{
test(arg);
}
}}}
=== htest5.hs ===
{{{
module Main where
import Foreign
import Foreign.C
foreign import ccall "test_proxy" ctest :: CInt -> IO ()
}}}
=== COMPILATION OF C OBJECTS ===
{{{
gcc -c test_proxy5a.c
gcc -c test_proxy5b.c
}}}
=== TEST 5A ===
{{{
E:\vvv\WP03\S00\ffi>ghci -fglasgow-exts test_proxy5a.o -ltest3b
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.6, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\____/\/ /_/\____/|_| Type :? for help.
Loading package base ... linking ... done.
Loading object (static) test_proxy5a.o ... done
Loading object (dynamic) test3b ... done
:
test_proxy5a.o: unknown symbol `__imp__test'
final link ... : linking extra libraries/objects failed
}}}
=== TEST 5B ===
{{{
E:\vvv\WP03\S00\ffi>ghci -fglasgow-exts test_proxy5b.o -ltest3b
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.6, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\____/\/ /_/\____/|_| Type :? for help.
Loading package base ... linking ... done.
Loading object (static) test_proxy5b.o ... done
Loading object (dynamic) test3b ... done
final link ... done
Prelude> :load htest5
[1 of 1] Compiling Main ( htest5.hs, interpreted )
Ok, modules loaded: Main.
*Main> ctest 5
The argument passed was 5
*Main>
}}}
=== TEST 5C ===
{{{
E:\vvv\WP03\S00\ffi>ghci -fglasgow-exts test_proxy5b.o -ltest1b
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.6, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\____/\/ /_/\____/|_| Type :? for help.
Loading package base ... linking ... done.
Loading object (static) test_proxy5b.o ... done
Loading object (dynamic) test1b ... done
final link ... done
Prelude> :load htest5
[1 of 1] Compiling Main ( htest5.hs, interpreted )
Ok, modules loaded: Main.
*Main> ctest 5
The argument passed was 5
*Main> ctest 5
The argument passed was 5
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1288>
GHC <http://www.haskell.org/ghc/>
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