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dlopen is located in libdl.a but when I link my application against libdl.a , gcc linker throw this error : unknow reference to __dlopen called in dlopen
Should I import another .a?
412
dlopen() The function dlopen() loads the dynamic library file named by the null-terminated string filename and returns an opaque "handle" for the dynamic library. If filename is NULL, then the returned handle is for the main program.
To fix this error, correct the spelling of the main() function.
An “Undefined Reference” error occurs when we have a reference to object name (class, function, variable, etc.) in our program and the linker cannot find its definition when it tries to search for it in all the linked object files and libraries.
DESCRIPTION. The dlsym() function shall obtain the address of a symbol defined within an object made accessible through a dlopen() call. The handle argument is the value returned from a call to dlopen() (and which has not since been released via a call to dlclose()), and name is the symbol's name as a character string.
When I try to compile statically a dlopen mockup program, gcc (Archlinux/gcc version 4.6.1 20110819 (prerelease)) tells me:
$ gcc test.c -ldl -static
/tmp/ccsWe4RN.o: In function `main': test.c:(.text+0x13):
warning: Using 'dlopen' in statically linked applications requires
at runtime the shared libraries from the glibc version used for linking
and indeed, when I ran this script in /usr/lib/
for i in *.a;
do
echo $i;
readelf -a $i | grep __dlopen;
done
I saw:
libc.a
16: 0000000000000080 69 FUNC GLOBAL DEFAULT 1 __dlopen
000000000000 002300000001 R_X86_64_64 0000000000000000 __dlopen + 0
35: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND __dlopen
so as per the first line, libc.a does define your missing symbole.
In my system, gcc test.c -ldl -static is enough to make the application run, but
gcc <file> -static -ldl -lc
should fix the problem in your system.
92
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