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Old 11-12-2007, 09:13 PM   #1
pbhat
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how to call shared library from within a C program


Hello List,

I need to call a C program from web(cgi-bin).This program depends upon an SDK in the form of binary shared library.But on the target machine which is hosted web-site,the hosting provoder is not willing to place them there.Neither is he willing to include the library path in ld.so.conf.

This is a quick question.I want to know if it is possible for a C program to call it's shared library by itslef into memory?

OR Can a shared library be compiled into a binary?

As I have not done this before,I am asking the question.Any help will be great.

Thanks in advance.
 
Old 11-12-2007, 09:53 PM   #2
matthewg42
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If you link with the -static option when you build your program, everything which is used will be copied from shared libraries into your executable. Of course the executable will be larger than if it is shared, but it should run regardless of the available shared libraries on the target system.
 
Old 11-14-2007, 04:19 AM   #3
pbhat
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Hello matthewg42,

I tried your suggestion.gcc complains it cannot find the library when I use the option '-static'.The files are *so files.I tried by giving full name of the files.If I omit it without changing any other option,it compiles fine. So, my syntax is right.Am I missing something here?

Thank You.
 
Old 11-18-2007, 11:58 AM   #4
matthewg42
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What is the exact command you are using to build with?
 
Old 11-18-2007, 09:30 PM   #5
pbhat
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Hi,

My command is,

gcc -o 'somename.cgi' -L'dir_of_shared_lib' \
-l'NImage_where_lib_is_libNImage.so' -l'simialr' -l'simialr'\
-static file.c

That results in error 'file not found'.

But if I omit '-static' option that compiles.

I do not have source to shared lib files which comec from a proprietary SDK.

thanks

P.Bhat
 
Old 11-18-2007, 10:20 PM   #6
matthewg42
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You should not include the .so when using the -l option, e.g. to use libbananas.a / libbananas.so, you would use the -l option like this:
Code:
gcc -lbananas ...
 
Old 11-18-2007, 11:16 PM   #7
pbhat
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Exactly.I am calling that way only.I was trying to show the involved library name.That's all.

PBhat
 
Old 11-19-2007, 12:23 AM   #8
matthewg42
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Please paste the actual command you are using, not some representation of it...
 
Old 11-19-2007, 02:38 AM   #9
pbhat
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Command with -static option

pbhat@pb:/media/disk/test/Code$ gcc-2.95 -o verify.cgi -L/media/disk/test/libs -lNCore -lNImages -lVLExtractor -lVLMatcher -lVLook verify.c verifying.c -I/media/disk/test/includes/ -static
/usr/bin/ld: cannot find -lNCore
collect2: ld returned 1 exit status

Command without -static option

pbhat@pb:/media/disk/test/Code$ gcc-2.95 -o verify1.cgi -L/media/disk/test/libs -lNCore -lNImages -lVLExtractor -lVLMatcher -lVLook verify.c verifying.c -I/media/disk/test/includes/
pbhat@pb:/media/disk/test/Code$


P.Bhat
 
Old 11-19-2007, 03:44 AM   #10
matthewg42
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Find libNCore.a and add that as an object file. e.g. if the libNCore.a file is found in /usr/lib, do it like this:
Code:
gcc-2.95 -o verify.cgi -L/media/disk/test/libs -lNImages -lVLExtractor -lVLMatcher -lVLook verify.c verifying.c -I/media/disk/test/includes/ -static /usr/lib/libNCore.a
 
Old 11-19-2007, 04:25 AM   #11
pbhat
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Hi,

I do not have *.a library files which is not provided by the SDK.And I have no privilege to place these *.so files in standard library path on the target system which is at the root of my difficulty.

But this is solved by -wl,-R/path option to the gcc

P Bhat
 
Old 11-19-2007, 09:49 AM   #12
matthewg42
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Please can you post the solution command?
 
Old 11-19-2007, 11:09 AM   #13
pbhat
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Here is the code.My previous example lowercased 'w' in '-Wl,-R/path'.Uppercase is right.

[HTML]gcc-2.95 -o verify1.cgi -L/media/disk/test/libs/ -lNCore -lNImages -lVLExtractor -lVLMatcher -lVLook verify.c verifying.c -I/media/disk/test/includes/ -Wl,-R/hshere/local/home/user/*.co.in/faceidentity/lib/[/HTML]

P Bhat

Last edited by pbhat; 11-19-2007 at 11:12 AM.
 
  


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