Re: [tlug] Compile/load problem with graphics library

[Brian Chandler <brian@example.com>]

Many thanks for responses.

I may not have mentioned: this program has been compiled several times, 
and was running for more than 3 years. So it seems unlikely that I made 
a fundamental mistake. I got the response about object order on the 
magick forum too; I have tried putting the configure script which 
generates the library references after the .o files, but it makes no 
difference.

One big problem is that I simply cannot understand the mass of subtly 
different library names involved. The configure script generates the 
following for the libraries to be searched:

-L/usr/local/lib -lMagick++-6.Q16 -lMagickWand-6.Q16 -lMagickCore-6.Q16

The -L parameter adds /usr/local/lib to the directories to be searched; 
I do not understand the relation to the three libraries. Should there be 
files with this name in /usr/local/lib? There are not; the following are 
the files including "Magic" in their names...

------------------------------------------------------------------
libGraphicsMagick++.a           libGraphicsMagickWand.so.2.7.3
libGraphicsMagick++.so          libGraphicsMagickWand.so.2.7.4
libGraphicsMagick++.so.12       libGraphicsMagickWand.so.2.8.0
libGraphicsMagick++.so.12.1.0   libGraphicsMagickWand.so.2.8.1
libGraphicsMagick++.so.12.1.1   libGraphicsMagickWand.so.2.8.2
libGraphicsMagick++.so.12.2.0   libGraphicsMagickWand.so.2.9.0
libGraphicsMagick++.so.12.3.0   libMagick++-6.Q16.a
libGraphicsMagick++.so.12.3.1   libMagick++-6.Q16.la
libGraphicsMagick++.so.12.3.2   libMagick++-6.Q16.so
libGraphicsMagick.a             libMagick++-6.Q16.so.6
libGraphicsMagick.so            libMagick++-6.Q16.so.6.0.0
libGraphicsMagick.so.3          libMagickCore-6.Q16.a
libGraphicsMagick.so.3.15.0     libMagickCore-6.Q16.la
libGraphicsMagick.so.3.15.1     libMagickCore-6.Q16.so
libGraphicsMagick.so.3.16.0     libMagickCore-6.Q16.so.2
libGraphicsMagick.so.3.17.0     libMagickCore-6.Q16.so.2.0.0
libGraphicsMagick.so.3.17.2     libMagickWand-6.Q16.a
libGraphicsMagick.so.3.18.0     libMagickWand-6.Q16.la
libGraphicsMagickWand.a         libMagickWand-6.Q16.so
libGraphicsMagickWand.so        libMagickWand-6.Q16.so.2
libGraphicsMagickWand.so.2      libMagickWand-6.Q16.so.2.0.0

GraphicsMagick:
config

ImageMagick-6.9.1:
config-Q16

ImageMagick-6.9.4:
config-Q16
------------------------------------------------------------------

---- Latest error: with the library files after the .o files ----
horigome@kulle% make imagetrim
g++ imagetrim.o boundingbox.o `Magick++-config --ldflags --libs` -o 
imagetrim
imagetrim.o: In function `main':
imagetrim.cpp:(.text+0x3c1): undefined reference to 
`Magick::Image::read(std::__cxx11::basic_string<char, 
std::char_traits<char>, std::allocator<char> > const&)'
imagetrim.cpp:(.text+0x783): undefined reference to 
`Magick::Image::write(std::__cxx11::basic_string<char, 
std::char_traits<char>, std::allocator<char> > const&)'
imagetrim.cpp:(.text+0xd55): undefined reference to 
`Magick::Image::write(std::__cxx11::basic_string<char, 
std::char_traits<char>, std::allocator<char> > const&)'
collect2: error: ld returned 1 exit status
*** Error code 1

Stop.
make: stopped in /usr/home/horigome/c

.... so far no progress. I have to get this sorted out. Where would I 
find an ld expert (paid or otherwise)? Grateful for any suggestions.

Brian Chandler

On 2018-08-05 09:49, Joe Foran wrote:
> Hi Brian,
>
> The linker is giving this error because it cannot find the functions in
> question.
> The order in which the object files are provided to the linker is very
> important.
> They should be specified in order of most specific (application object
> files)
> to most general (library object files).
> In the makefile you provide on the forum thread, you have lines like|
> $(CC) $(LDFLAGS) test.o cutoutbg.o boundingbox.o -o $@|
> ||||
>
> |The LDFLAGS variable contains the necessary information about the
> ImageMagick library files and should come after the application object
> files. i.e. ||$(CC) test.o cutoutbg.o boundingbox.o |||$(LDFLAGS) -o $@||
> ||
>
> You will need to do this everywhere LDFLAGS is referenced.
> Does this help?
>
> Joe
>
>
> On 2018/08/05 3:55, Brian Chandler wrote:
> > Hello! I'm looking for help with a software problem. I have a small C++
> > program to do some basic image manipulation (basic, but very specific),
> > using the Imagemagick++ library; it ran on my webserver (at pair.com
> > hosting) for years, but stopped because of an "upgrade". I cannot now
> > recompile, cannot really understand the problem, and can't seem to get
> > any help either from pair.com or the Imagemagick forum. Here's my
> > question in full:
> >
> > https://www.imagemagick.org/discourse-server/viewtopic.php?f=23&t=34332&sid=364f3a5fa340bcbb3d0057542983ff5f
> >
> >
> > It looks as though the loader has some problem. Unfortunately the forum
> > responses I've received don't suggest to me that the helpers know any
> > more than I do. Obviously the best answer is a change to the makefile,
> > or similar, that makes the library work again. But failing that, I would
> > try to install the library in my own server space, giving up on the one
> > provided by Pair.com. The worst option I suppose is to rewrite the
> > program to use something else, but I hope it doesn't come to that.
> >
> > Can anyone suggest where to start? If I need to provide other
> > information, then sorry, but just say. Thanks!
> >
> > Brian Chandler