bug#24574: emacs-module is not GPL compatible (Windows)

[Mambo Levis]

Thank you for the pexports recommendation.

For somebody that just read this problem for the first time, a summary:

Emacs version: GNU Emacs 25.1.1

Emacs module repo: https://github.com/syohex/emacs-sqlite3

Build process: mingw64_shell.bat (Windows) 

Dependency: sqlite.lib

Makefile:

EMACS = D:\user\emacs-src\emacs-25-branch-src

INCLUDE = -I. -I$(EMACS)\src 

CC      = gcc

LD      = gcc

LDFLAGS =

# On MS-Windows, say "make SO=dll" to build the module

SO      = dll

# -fPIC is a no-op on Windows, but causes a compiler warning

ifeq ($(SO),dll)

CFLAGS  = -std=gnu99 -ggdb3 -Wall

else

CFLAGS  = -std=gnu99 -ggdb3 -Wall -fPIC

endif

all: sqlite3-core.$(SO)

%.$(SO): %.o

$(LD) -shared $(LDFLAGS) -o $@ $< sqlite3.lib

%.o: %.c

$(CC) $(CFLAGS) $(INCLUDE) -c $<

check:

$(EMACS)/src/emacs -batch -l ert -l test.el -f ert-run-tests-batch-and-exit

    

clean:

rm -rf *.o *.dll *.a *.d

--------------------------------------------------------------------------------------------------------------------------------

Now the result of my tests:

1. The symbols exported by the modules without considering any sqlite function are:

 LIBRARY sqlite3-core.dll

EXPORTS

emacs_module_init ; .text ; RVA 00001685

plugin_is_GPL_compatible DATA ; no section ; RVA 00007010

2. onsidering the following sqlite3 related function:

static void

el_sqlite3_free(void *arg)

{

sqlite3_close((sqlite3*)arg);

}

When I generate the sqlite3-core.dll using at least one sqlite3 DLL function, for example sqlite3_close , an error message appears:  (the module can't be found) 

..../modules/emacs-sqlite3/sqlite3-core.dll: Das angegebene Modul wurde nicht gefunden.

I check the sqlite3.dll using pexports tool, and the symbols sqlite3_close is exported.

LIBRARY sqlite3.dll

EXPORTS

.....

sqlite3_changes ; .text ; RVA 0009c648

sqlite3_clear_bindings ; .text ; RVA 000373dc

sqlite3_close ; .text ; RVA 0009c9e8

sqlite3_close_v2 ; .text ; RVA 0009ca08

sqlite3_collation_needed ; .text ; RVA 0009f4b3

sqlite3_collation_needed16 ; .text ; RVA 0009f51f

I check the module qlite3-core.dll again and the symbols are there.

; .text   : RVA: 00001000, File offset: 00000600

; .data   : RVA: 00003000, File offset: 00002400

; .rdata  : RVA: 00004000, File offset: 00002600

; .pdata  : RVA: 00005000, File offset: 00002e00

; .xdata  : RVA: 00006000, File offset: 00003200

; .bss    : RVA: 00007000, File offset: 00000000

; .edata  : RVA: 00008000, File offset: 00003400

; .idata  : RVA: 00009000, File offset: 00003600

; .CRT    : RVA: 0000a000, File offset: 00003e00

; .tls    : RVA: 0000b000, File offset: 00004000

; .reloc  : RVA: 0000c000, File offset: 00004200

; /4      : RVA: 0000d000, File offset: 00004400

; /19     : RVA: 0000e000, File offset: 00004800

; /31     : RVA: 00018000, File offset: 0000e200

; /45     : RVA: 0001a000, File offset: 0000fa00

; /57     : RVA: 0001c000, File offset: 00011200

; /70     : RVA: 0001d000, File offset: 00011e00

; /81     : RVA: 0001e000, File offset: 00012200

; /92     : RVA: 00021000, File offset: 00015200

; /105    : RVA: 0002b000, File offset: 0001f200

; Reading exports from section: .edata

; Export table: sqlite3-core.dll

; Ordinal base: 1

; Ordinal table RVA: 00008038

; Name table RVA: 0008030

; Export address table RVA: 00008028

LIBRARY sqlite3-core.dll

EXPORTS

emacs_module_init ; .text ; RVA 00001696

plugin_is_GPL_compatible DATA ; no section ; RVA 000078f0

Please, notice that this time the plugin_is_GPL_compatible. The problem is now that the module can't be found when a sqlite3.dll symbol is used.

Any Idea or suggestion?

Thanks

Levis

On Saturday, October 1, 2016 5:40 PM, Eli Zaretskii <eliz@gnu.org> wrote:

[Please don't cross post to help-gnu-emacs if you report bugs.]

> Date: Sat, 1 Oct 2016 12:31:26 +0000 (UTC)
> From: Mambo Levis <mambo.levis@gmail.com>
> Cc: 24574@debbugs.gnu.org, help-gnu-emacs@gnu.org
>
> 1. I commented all module's functions related with sqlite3 library and only leave uncommented one of function
> to verify if the module is working:
>
> /* emacs-sqlite-version*/
> static emacs_value
> Femacs_sqlite_version (emacs_env *env, ptrdiff_t nargs, emacs_value args[], void *data)
> {
> const char* msg_docstr = "emacs-sqlite module version 0.1";
> return env->make_string (env, msg_docstr, strlen(msg_docstr));
> }
>
> When I require (emacs-sqlite-version) it works as expected.
>
> 2. I tested only two function: the previous one Femacs_sqlite_version and other associated with sqlite. Once I
> consider a module function related to sqlite error message appears:
> is not GPL compatible
>
> I think the error is related with the linking process of the sqlite3.lib . One possible test is not linking sqlite3.lib
> and stead just using sqlite source code as a part of the module.
>
> Do you have any suggestion?

I'd start by using the pexports program (or something similar) to see
which symbols are exported by the sqlite DLL.