For some reasons, I want to build a static shared library: a self sustain
library that without any external dependent library.
My build environment is alpine linux.
(I believe that gcc is /usr/bin/aarch64-alpine-linux-musl-gcc)
I build my shared library as follows:
gcc -fpic -c jpg_to_bmp.c -o jpg_to_bmp.o
ld -fpic -shared -static -lc -lstdc++ jpg_to_bmp.o FreeImage/Dist/libfreeimage.a -o libmy_img_static.so
gcc -I ./ -L ./ main.c -o main.o
However
LD_LIBRARY_PATH=`pwd` ./main test.jpg test.bmp
dies with Segmentation fault
if I link the shared library without -static -lc -lstdc++
ld -fpic -shared -static -lc -lstdc++ jpg_to_bmp.o FreeImage/Dist/libfreeimage.a -o libmy_img_static.so
Everything works fine.
How do I build a static shared library(self-sustain) using musl ?
Did I miss any step or flag ?
Related
To link gcc statically into a shared library, based on the answer in this question, the remaining problem is how to let the linker use the PIC version of libc.a instead of the non-PIC version. The problem is the same as that answer:
g++ -fPIC -Wall -O0 -fexceptions -g -c main.cpp -o main.o
ld -shared -static -o test.so main.o -lc
ld: //usr/lib/x86_64-linux-gnu/libc.a(malloc.o): relocation R_X86_64_TPOFF32 against `tcache' can not be used when making a shared object; recompile with -fPIC
This is what I'v tried:
sudo apt-get install libc-pic //then libc6-pic get installed successfully
ld -shared -static -o test.so main.o -lc //same as above, same error
ld -shared -static -o test.so main.o -lc-pic //not working: cannot find -lc-pic
ld -shared -static -o test.so main.o -lc6-pic //not working: cannot find -lc6-pic
Looking at the list of files in the package there is a libc_pic.a so the correct option seems to be -lc_pic.
I'm working on a Linux project in C consisting of two different open source applications. "Project A" (libduo) creates an archive used for linking a couple test programs and creates the library like this:
/usr/bin/ar rv libduo.a duo.o http_parser.o https.o match.o parson.o urlenc.o
/usr/bin/ar: creating libduo.a
a - duo.o
a - http_parser.o
a - https.o
a - match.o
a - parson.o
a - urlenc.o
ranlib libduo.a
One of the libduo test programs is built like this:
gcc -g -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -I. -I. -DDUODIR=\"/usr/local/duo/libduo/etc\" -DHAVE_CONFIG_H -c test-duologin.c
gcc -o test-duologin test-duologin.o -L. -lduo -lssl -lcrypto
"Project B" is an OpenLDAP module which I've built with -lduo and a few options to tell it where to find things:
(cd .libs && rm -f pw-apr1.la && ln -s ../pw-apr1.la pw-apr1.la)
../../../libtool --mode=compile gcc -g -O2 -Wall -I../../../include -I../../../include -I../../../servers/slapd -I../../../contrib/slapd-modules/passwd/libduo -c pw-duo.c
gcc -g -O2 -Wall -I../../../include -I../../../include -I../../../servers/slapd -I../../../contrib/slapd-modules/passwd/libduo -c pw-duo.c -fPIC -DPIC -o .libs/pw-duo.o
gcc -g -O2 -Wall -I../../../include -I../../../include -I../../../servers/slapd -I../../../contrib/slapd-modules/passwd/libduo -c pw-duo.c -o pw-duo.o >/dev/null 2>&1
../../../libtool --mode=link gcc -g -O2 -Wall -version-info 0:0:0 \
-rpath /usr/local/libexec/openldap -module -o pw-duo.la pw-duo.lo libduo.a -lduo
*** Warning: Linking the shared library pw-duo.la against the
*** static library libduo.a is not portable!
cc -shared .libs/pw-duo.o libduo.a -lduo -Wl,-soname -Wl,pw-duo.so.0 -o .libs/pw-duo.so.0.0.0
/usr/bin/ld: libduo.a(duo.o): relocation R_X86_64_32 against `.rodata.str1.1' can not be used when making a shared object; recompile with -fPIC
libduo.a: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
Makefile:51: recipe for target 'pw-duo.la' failed
make: *** [pw-duo.la] Error 1
The Makefile I'm using is the same one distributed with the OpenLDAP project. I've just added a section in the Makefile to build my module, using the same options for the other modules already there but adding -lduo to my section along with the paths to the libduo includes and libduo.a.
As make suggests above, I've recompiled by adding -fPIC after the -Wall option but it the same error was repeated. As a last resort, I tried adding -static to the module build but make was having none of that either:
*** Warning: Linking the shared library pw-duo.la against the
*** static library libduo.a is not portable!
This is the first time I've tried to build a C application against a lib not in the standard Linux locations so not exactly sure what's going on. I suspect libduo is built intended to be statically linked into everything, but the OpenLDAP modules are designed to use shared libraries. Can anyone elucidate?
Update: with help of comments below and this link I created a shared library from the .o files and distributed/built against that.
I have problem link libgcc into a static linked .so
it only happens when linking 64bit module with -m64
Ubuntu 64bit 12.10 gcc 4.7
also failed on Ubuntu 64bit 12.04 gcc 4.6
32bit no problem
$gcc -fPIC -c -o hello.o hello.c -m32
$gcc -shared -m32 hello.o -o libhello.so -static-libgcc -Wl,-Bstatic -lc
$ ldd libhello.so
statically linked
64bit failed
$ make
gcc -fPIC -c -o hello.o hello.c
gcc -shared -m64 hello.o -o libhello.so -static-libgcc -Wl,-Bstatic -lc
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../x86_64-linux-gnu/libc.a(iofclose.o): relocation R_X86_64_32 against `__gcc_personality_v0' can not be used when making a shared object; recompile with -fPIC
/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../x86_64-linux-gnu/libc.a: could not read symbols: Bad value
collect2: error: ld returned 1 exit status
make: *** [libhello.so] Error 1
hello.c
#include <stdio.h>
int f(){
FILE *out = fopen("/tmp/x.log", "wb");
fclose(out);
return 1;
}
Makefile
all: libhello.so
libhello.so: hello.o
gcc -shared -m64 hello.o -o libhello.so -static-libgcc -Wl,-Bstatic -lc
hello.o: hello.c
gcc -fPIC -c -o hello.o hello.c
clean:
rm -f hello.o libhello.so
The answer is basically "you can't do that." You're trying to link non-PIC code into a shared library, which is simply impossible on the x86_64 (amd64) architecture. You would need a static but PIC version of libgcc, and I suspect that would be only the start of your problems.
One of the reasons why libgcc is normally shared is that a given running executable has to have one and only one copy of some of the key data structures that libgcc maintains. Static linking makes sense for a final executable, since that one and only one copy will be the one statically linked into the executable, but the whole point of a dynamic object is to be loaded into another executable (which in turn will have its own copy of libgcc, either shared or static).
I'm trying to build a simple c application using gcc on aix
gcc -I. -c hello.c -o hello.o
gcc -o helloWorld hello.o -L helloHelper.so -ldl
I get the following errors
ld 0711-317 ERROR: Undefined symbol: .PrintHello
PrintHello is a method in the library helloHelper.
I can build the application in windows.
The option -L is for indicating directories where to search for libraries. To link a dynamic library directly, just put it in the linker command:
gcc -o helloWorld hello.o helloHelper.so -ldl
Other option would be to use -lhelloHelper but then the library should be called libhelloHelper.so.
Try this:
gcc -o helloworld hello.o -L. -lhelloHelper -ldl
Am facing a problem that may be slightly complicated to explain and understand as giving the entire picture would be too big and difficult.
Please excuse me for it.
Consider the following Makefile:
all: clients.so simulator backup
LD_PRELOAD=/home/Juggler/client/clients.so ./simulator
backup: backup.c libclient.a
gcc backup.c -o backup -L /home/Juggler/client -L. -lclient -ldl
simulator: simulator.c libclient.a
gcc -g simulator.c -o simulator -L /home/Juggler/client -L. -lclient -ldl -pthread
libclient.a: libclient.o client.o
ar rcs libclient.a libclient.o client.o
libclient.o:libclient.c
gcc -c libclient.c -o libclient.o -pthread
clients.so: client.o client_invoke.o
ld -shared -o clients.so client_invoke.o client.o -ldl
client_invoke.o: client_invoke.c
gcc -Wall -fPIC -DPIC -c -g client_invoke.c
client.o: client.c
gcc -Wall -fPIC -DPIC -c -g client.c -ldl -pthread
We call function written in client.c from libclient.c and these functions in client.c make call to pthread_key_create(), pthread_setspecific..etc.
Threads are created by simulator.c and theses threads access functions written in he other files.
On doing make...Errors like the following appear.
/home/Juggler/client/libclient.a(client.o):In function 'setup_connection':
/home/Juggler/client/client.c:35: undefined reference to 'pthread_setspecific'
pthread.h has been included in both client.c and libclient.c
Would be grateful for anypointers . I understand information is very less...
Thanks
On linux, pthread functions live in the libpthread library. So you have to link to that.
The proper way, when using pthreads, is to compile and link using the -pthread , which, among other things, will link in the pthread library. You have the -pthread flag for some of your executables, but not for others, and not for your clients.so library, so add the flag where required.
Also, remember, when you are creating a shared library, you should compile the source files with the -fPIC flag.
(And, seems you are calling ld directly to produce the client.so library, you really should use gcc to do the linking.)