liberror.h linking

gavinbeatty · 08-03-2005, 07:48 PM

Using the slackpack for liberror.h available on linuxpackages.net I get very verbose error output when trying to compile very simple use of the fundamentals of the library.

I've been doing

Code:

gcc err.c -o err -lerror

The file err.c is as follows:

Code:

#include <liberror.h>

int main (int argc, char **argv)
{
	err_init(&argc, &argv);
	err_add_stream (C_TAG_ALL, stdout, NULL);
	
	eprintf(C_TAG_BANNER, 0, "This is a test to see if I can compile");
}

I get HUGE output of:

/usr/lib/gcc-lib/i486-slackware-linux/3.3.4/../../../liberror.a(err_map_char_p_char_p.o)(.text+0x600e): In function `err_map_char_p_char_p_remove_internal(err_map_char_p_char_p_t*, char*, char**)':
src/err_map_char_p_char_p.cpp:4226: undefined reference to `operator delete(void*)'
/usr/lib/gcc-lib/i486-slackware-linux/3.3.4/../../../liberror.a(err_map_char_p_char_p.o)(.text+0x1d75): In function `err_map_char_p_char_p_free_sorted_iterator':
src/err_map_char_p_char_p.cpp:6128: undefined reference to `operator delete[](void*)'
/usr/lib/gcc-lib/i486-slackware-linux/3.3.4/../../../liberror.a(err_map_char_p_char_p.o)(.text+0x1d95): In function `err_map_char_p_char_p_free_sorted_iterator_ptr':
src/err_map_char_p_char_p.cpp:6134: undefined reference to `operator delete[](void*)'
/usr/lib/gcc-lib/i486-slackware-linux/3.3.4/../../../liberror.a(err_map_char_p_char_p.o)(.text+0x595a): In function `err_map_char_p_char_p_destroy_internal(err_map_char_p_char_p_t*)':
src/err_map_char_p_char_p.cpp:4549: undefined reference to `operator delete(void*)'
/usr/lib/gcc-lib/i486-slackware-linux/3.3.4/../../../liberror.a(err_map_char_p_char_p.o)(.text+0x5a81): In function `err_map_char_p_char_p_destroy_internal_flags(err_map_char_p_char_p_t*, unsigned char, unsigned char)':
src/err_map_char_p_char_p.cpp:4568: undefined reference to `operator delete(void*)'
/usr/lib/gcc-lib/i486-slackware-linux/3.3.4/../../../liberror.a(style-qt.o)(.eh_frame+0x11): undefined reference to `__gxx_personality_v0'
/usr/lib/gcc-lib/i486-slackware-linux/3.3.4/../../../liberror.a(style-qt3.o)(.eh_frame+0x12): undefined reference to `__gxx_personality_v0'
collect2: ld returned 1 exit status

and with much more than my terminal can scroll up aswell.

Is this an error in how liberror.h was compiled or have I got linking done incorrectly? It's my first time linking.

edit: I've tried compiling liberror on my own in Slack 10.1 and I get errors but the tgz is from a reputable packager and seems to work otherwise. ie the binaries it installs are fully functional

Tomasfuego · 08-03-2005, 09:50 PM

Does eprintf work? I just checked the site and it says that you can use that function from a shell.

Where did the library install to? Try
whereis liberror

Try also linking directly to that library with the -L/whereever/liberror.so option

To capture the output on the compile, you could do it inside an IDE like eclipse or in the shell you can do something like this:
gcc ... 2>1 &> log.txt

If i understand it right, all stderr (2) is directed back to stdout(1) and then stdout is put into log.txt

gavinbeatty · 08-04-2005, 11:39 AM

Yes, eprintf (in bash) works perfectly.

Also, I have no liberror.so or error.so. I only have a liberror.a and liberror.h in /usr/lib and /usr/include respectively.

I have only ever come across -lm for use of math.h. I have only previously used math.h, stdio.h, stdlib.h, string.h, time.h and only math.h (and seemingly randomly) requires a -l type option.

Thanks for your help so far. I've at least learned a bit about bash!

Tomasfuego · 08-04-2005, 07:43 PM

what does your gcc output look like?

also, with *.a libraries, I believe you include that directly and use the -l for shared libraries that liberror needs, so

gcc err.c -o err /path/to/liberror.a -lneeded_libraries_if_any

gavinbeatty · 08-05-2005, 10:12 AM

gcc output ising your bash method is identical to what I already posted.
I checked the man pages and it's 0, 1, 2 for stdin, stdout and stderr respectively so I don't think the wrong output is being directed to right place or vice-versa.

I tried

Code:

gcc err.c -o err /usr/lib/liberror.a -lerror

and

Code:

gcc err.c -o err /usr/lib/liberror.a -lliberror

and the same tow with -L in front of /usr/lib/liberror.a, but I get the exact same output from gcc (and no executable as usual) as without -L/usr/lib/liberror.a

Also, the gcc man page says -lerror should find /usr/lib/liberror.a as it automatically scans relevant dirs and adds lib and .a to start and end respectively. It says I should use -L/usr/lb/liberror.a OR -lerror.

Problem is, neither seem to work.

I hope people have more suggestions because I'm pretty stumped. I'll try look into my installation of the library and header but I think I have some small compiling problem

gavinbeatty · 08-05-2005, 11:36 AM

Well I removed the tgz and compiled successfully from source with --prefix=/usr and tried

Code:

gcc err.c -I/usr/include -L /usr/lib/liberror.a -lerror -lm -o err

and a few other variants with the exact same problems.

Any ideas? I'm quite stuck.

Think I'm gonna try make a custom SLAX live-cd and see what happens.

Still, the matter is by no means closed

Thanks for your help so far Tomasfuego

deiussum · 08-05-2005, 12:09 PM

try:

gcc err.c -o err -lerror -lm -static

The static flag usually tells gcc to use .a files instead of .so. The -L parameter is usually just used when you need to include additional library search paths. For instance if your liberror librar was in /usr/local/error/lib you would add -L/usr/local/error/lib so that that path would be searched as well for the libraries.

deiussum · 08-05-2005, 12:19 PM

I downloaded that package to try and compile your test code there and found that I had to use g++ instead of gcc. It appears that the liberror package uses stuff from the standard C++ library, so if you use gcc w/o including the standard C++ libraries, it complains about undefined references to things like operator delete[]...

Anyway, your test code compiled nicely with the following:

g++ err.c -o err -lerror -static

Edit: I just tried it w/o the -static flag and it compiles cleanly that way too, so long as you use g++. That was probably your problem all along.

Edit 2: The reason it compiles cleanly with g++ and not with gcc might not even be because it is trying to link to stuff in the standard C++ library. More likely, the stuff in the .a file itself has C++ style name mangling, which is much different from the C-style name decorations.

gavinbeatty · 08-06-2005, 03:08 PM

Thanks deiussum, problem solved.

gavinbeatty · 08-06-2005, 04:22 PM

Sorry, this is kind of off-topic now but using g++ throws up a compile error when trying to use liberror.h for what I originally intended.

I have a program that has all sorts of functions to do with SuDoku tables and was using argp.h for passing arguments from the command line.

Now, in parse_opt (NOTE: prototype: static error_t parse_opt (int key, char *arg, struct argp_state *state)) doing

Code:

struct arguments *arguments = state->input;

gives me an error where the compiler says

su_argp.c: In function `error_t parse_opt(int, char*, argp_state*)':
su_argp.c:45: error: invalid conversion from `void*' to `arguments*'

Why does this appear when using C++? I had hoped I could simply try use my C knowledge (limited) and know that C++ is simply a superset of C so everything should be fine.

If argp.h isn't really for C++ at all, can you recommend a similar system?

deiussum · 08-06-2005, 05:29 PM

You likely need to use casting somewhere. The C++ compilers are generally a bit stricter on matching types than C compilers. I'm assuming that your state->input value is declared as a void*. Try changing that line to:

struct arguments *arguments = (arguments*)state->input;

Note that this is the C-style casting and C++ has other preferred methods of casting, but should work for your current problem. If you want to learn more about the new C++ style casting look into static_cast, dynamic_cast, reinterpret_cast, and const_cast...

gavinbeatty · 08-07-2005, 07:12 AM

Thanks for your help again! Forgot all about casting - only ever read about it in a tutorial on the web and didn't really remember it obviously.

What you gave me didn't actually compile but

Code:

struct arguments *arguments = (struct arguments*)state->input;

did.

But that's really something you almost always miss until you actually compile the damn thing.

Thanks again. I actually learned a few things from all this.