Re: [Bug-apl] Cannot find libemacs on older mac

[Juergen Sauermann]

Hi Alexey,

GNU APL uses the C functions dlopen() to open the library and dlsym() to locate functions inside
the library.

From the printout we see that GNU APL finds the library file but the dlopen() of the existing file fails.

Although the dlopen() and dlsym() functions are quite standard among different platforms, the way
in which the dynamic library files are linked from the compiled object files differs considerably between
platforms.

In this particular case there could be 2 reasons for dlopen() to fail:

1. a bug in the platform as one of the posts below suggests. Somebody who had the same problem (although
with a different library) has reported that after an OS-X update his problem disappeared.

2. The library must be constructed in a specific way. On GNU/Linux this is often properly handled by libtool,
but I do not know if libtool even exists on OS-X and if it works properly. On GNU/Linux there is another
tool called libtoolize which prepares autoconf projects that do not use libtoolize into projects that do.
libtoolize does some magic to make shared library work and you may need to do something similar on
your box.

My proposal would be:

1. upgrade your OS-X as proposed in the post below.

2. If that does not fix the problem then learn from your platform documentation how shared libraries
for use with  dlopen() shall be built. And what namespaces are (they do not exist on GNU/Linux).

Good Luck!
/// Jürgen

On 12/12/2017 12:27 PM, Alexey Veretennikov wrote:

Hi,

Could you please hint me how to specify these flags so I can experiment myself?

Br,

/Alexey

2017-12-11 16:19 GMT+01:00 Juergen Sauermann <address@hidden>:

Hi Alexey,

I suppose that you need some platform specific linker flags when building libemacs.dylib.
Since I do not have access to a Mac OS-X machine, I can't tell you which ones.

Best Regards,
/// Jürgen

On 12/06/2017 08:18 PM, Alexey Veretennikov wrote:

It is really strange but reporting with otool shows two level:

otool -hV /Users/alexey/Applications/gnu-apl/lib/apl/libemacs.dylib
/Users/alexey/Applications/gnu-apl/lib/apl/libemacs.dylib:
Mach header
      magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
MH_MAGIC_64  X86_64        ALL  0x00       DYLIB    14       2272   NOUNDEFS DYLDLINK TWOLEVEL WEAK_DEFINES BINDS_TO_WEAK NO_REEXPORTED_DYLIBS

For flat libraries there should be no TWOLEVEL flag.

Br,

/Alexey

2017-12-04 17:33 GMT+01:00 Juergen Sauermann <address@hidden>:

Hi,

from the GNU APL printout it looks like the file was found, but something is wrong with the file:

    file /Users/alexey/Applications/gnu-apl/lib/apl/libemacs.dylib ( flat namespace
 in /Users/alexey/Applications/gnu-apl/lib/apl/libemacs.dylib )

So GNU APL was able to open the file (using dlopen()) but then gets the "flat namespace" error at some point.

The second link below says:

amandogra commented on Oct 2, 2016

It got solved by OS upgrade.
For someone who comes to this...
I was on Mac OSX El Capitan, but I upgraded to macOS Sierra.
Then, I executed the following command

brew unlink libevent && brew link libevent

This fixed my issue.

The posting was related to a different library but the (rest of the) error message looks very similar (considering
that GNU APL cuts off the start the error message text until the last : in it). The full error message was most likely:

Expected in: flat namespace

Maybe "nm -D" on the dylib file reveals some more information.

Best Regards,
/// Jürgen

On 12/04/2017 04:06 AM, Elias Mårtenson wrote:

Perhaps adding the path to the dylib file in DYLIB_LIBRARY_PATH will help? Don't forget to exprt the variable before starting apl.

Regards,

Elias

On 4 December 2017 at 01:56, Juergen Sauermann <address@hidden> wrote:

Hi,

I haven't changed anything in that area. One poster in one of the links below mentioned that an OS-X upgrade
had fixed a similar problem that the poster had, so my impression is that this is a problem than cannot be fixed
inside GNU APL.

Best Regards,
/// Jürgen

On 12/03/2017 12:02 PM, Elias Mårtenson wrote:

10.6.8 is indeed very old. I thought my Macbook was old and it's running 10.10.

I have to admit that I haven't tried the Emacs mode on OSX in a while since I don't use Macs anymore. That said, last time I did try, it worked fine.

Jürgen, could there be an issue with the way the libraries are built? Did anything change in the last couple of years?

Regards,

Elias

On 3 December 2017 at 18:58, Juergen Sauermann <address@hidden> wrote:

Hi Alexey,

I am not really familiar with emacs or OS X, so Elias is probably better informed than me.

Unfotunately shared libraries are rather platform dependent and so are the error messages that
they produce. From the output below it seems that the file libemacs.dylib exists and was found,
but could not be opened with dlopen(). It might be that your platform needs additional linker flags
for dynamic libraries to work, but I have no idea which ones.

See also:

https://github.com/tmux/tmux/issues/547 or

https://developer.apple.com/library/content/documentation/Porting/Conceptual/PortingUnix/compiling/compiling.html

Best Regards,
/// Jürgen

On 11/30/2017 08:39 PM, Alexey Veretennikov wrote:

Hi,

I've built GNU APL with the following parameters on my old  (OSX 10.6.8) macbook:

./configure --prefix=/Users/alexey/Applications/gnu-apl
make install

So nothing special(I did a small change though since strndup is not yet supported on this OS). I'm using gcc 7.2.0.

However when I try to run apl from emacs, I get the following error:

Could not find shared library 'libemacs'
The following directories and file names were tried:
    file /Users/alexey/Applications/gnu-apl/lib/apl/libemacs.so (No such file or directory)
    file /Users/alexey/Applications/gnu-apl/lib/apl/libemacs.dylib ( flat namespace
 in /Users/alexey/Applications/gnu-apl/lib/apl/libemacs.dylib )
    file /Users/alexey/Applications/gnu-apl/lib/apl/libemacs (No such file or directory)
    directory /usr/lib/apl
    directory /usr/local/lib/apl
    file ./libemacs.so                       (No such file or directory)
    file ./libemacs.dylib                    (No such file or directory)
    file ./libemacs                          (No such file or directory)
    directory ./native
    directory ./emacs_mode

The file /Users/alexey/Applications/gnu-apl/lib/apl/libemacs.dylib exists.

Br,

/Alexey