I am working on an MP for my CS class. Our computer labs are working under Linux OS, but I tried compiling the code on my home computer (Mac OS X). I am getting the following error:
Undefined symbols for architecture x86_64:
"_tdestroy", referenced from:
_dictionary_destroy in libdictionary.o
_dictionary_destroy_free in libdictionary.o
ld: symbol(s) not found for architecture x86_64
I tried finding a solution online, but I was unsuccessful. We are using the following macros in the Makefile:
CC = gcc
INC = -I.
FLAGS = -g -W -Wall
LIBS = -lpthread
Any ideas?
From the GNU man page of tdestroy:
SVr4, POSIX.1-2001. The function tdestroy() is a GNU extension
This means that this function is not available on OS X
EDIT:
Put this after the includes:
#ifndef _GNU_SOURCE
void tdestroy(void *root, void (*free_node)(void *nodep)) { }
#endif
You can try to implement tdestroy by using twalk/tdelete/free - it should'n be very hard to do, but leaving it empty should work too (but it will create a memory leak on OSX).
EDIT 2: added link to the man page (10x to Cameron)
Related
I am self learning to code in C using Mac mini M1 and VS Code. I get the below error:
Undefined symbols for architecture arm64:
"_main", referenced from:
implicit entry/start for main executable
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Please note:
Installed the VS Code Insiders for ARM apple version!
Clang is installed!
Xcode command line tools installed!
C/C++ 1.4.0-insiders2 extension is installed in VS Code!
Code Runner 0.11.4 is installed in VS Code!
Code:
#include <stdio.h>
int main()
{
printf("test");
return 0;
}
Compiled using:
gcc -Wall -Wextra -Werror -o test test.c
Okay! It's because you forget to save your program before executing i.e you should compile and run. Instead of just running it! #Keeplearning!
I try this :
g++ -Wall affichage.c -o game -D_REENTRANT -I/usr/local/Cellar/sdl/1.2.15_1/SDL
but I have this error :
Undefined symbols for architecture x86_64:
"_SDL_EnableKeyRepeat", referenced from:
chargement_objets(img*, img*) in affichage-50cd48.o
"_SDL_Flip", referenced from:
affiche_menu(img, img) in affichage-50cd48.o
_SDL_main in affichage-50cd48.o
gcc Version :
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
Apple clang version 11.0.0 (clang-1100.0.33.8)
Target: x86_64-apple-darwin19.0.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
sdl installed in : /usr/local/Cellar/sdl/1.2.15_1
Mac OS Catalina
Undefined symbols errors happen at link time.
So just like specifying header lookup path as -I/usr/local/Cellar/sdl/1.2.15_1/SDL , which helps at compile time, specify the library search path as -L/usr/local/Cellar/sdl/1.2.15_1/SDL/lib or something like this pointing to the right path. You may also need to add something like -lSDL to specify the library in which the functions you used are. Note that -lSDL means link against libSDL.a
I thought of compiling Lua from source code and then create a C module.
I compiled Lua with success but I can't build my C module.
So, I compiled Lua like this:
gcc -o Lua *.c -Os -std=c99
Compiled my module like this:
gcc -Wall -shared -fPIC -o module.so -I. module.c
But there are a few errors here:
Undefined symbols for architecture x86_64:
"_lua_pushcclosure", referenced from:
_luaopen_module in module-fb0b1f.o
"_lua_pushnumber", referenced from:
_super in module-fb0b1f.o
"_lua_setglobal", referenced from:
_luaopen_module in module-fb0b1f.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
The C module itself:
#include "lua.h"
static int super(lua_State* L) {
lua_pushnumber(L, 5);
return 1;
}
int luaopen_module(lua_State* L) {
lua_register(L, "super", super);
return 0;
}
My Lua script:
require("module")
print(super())
I'm on Unix based system (Mac), but I want it to work on Linux as well.
Edit:
Problem to compile C module was fixed by entering -bundle -undefined dynamic_lookup instead of -shared (Thanks lhf).
But I can't import the module in Lua.
> require("module")
error loading module 'module' from file './module.so':
dynamic libraries not enabled; check your Lua installation
Another thing:
This seems to be a quick fix only; -bundle -undefined dynamic_lookup. This does not work on Linux. How can I do this on linux? I wanted a solution for Unix based systems.
Download Lua from lua.org and build Lua with make macosx. See Getting started.
Use -bundle -undefined dynamic_lookup instead of -shared to build module.so.
Use require"module" to load it into Lua.
Call super.
Make sure you're running the lua program that you have built above, not some other version that is installed.
I am trying to create a dynamic library which is meant to be linked and loaded into a host environment at runtime (e.g. similar to how class loading works in Java). As such, I want the dynamic library to be left with a few "dangling" references, which I expect it to pick up from its host environment when it is loaded into that environment.
My problem is that I cannot figure out how to create the dynamic library without explicitly linking it to existing symbols. I am hoping to produce a dynamic library that does not depend on a specific host executable (or host library), rather one that is able to be loaded (e.g. by dlopen) in any host as long as the host makes a couple symbols available for use.
Right now, any linking command I've tried results in a complaint of missing symbols. I'd like it to allow symbols to be missing (ideally, just particularly specified symbols).
For example, here's a transcript with the error on OS X:
$ cat frotz.c
void blort(void);
void run(void) {
blort();
}
$ cc -c -o frotz.o frotz.c
$ cc -dynamiclib -o libfrotz.dylib frotz.o
Undefined symbols for architecture x86_64:
"_blort", referenced from:
_run in frotz.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
If I do the same thing using a GNU toolchain (on Linux), it helpfully tells me:
$ gcc -shared -o libfrotz.so frotz.o
/usr/bin/ld: frotz.o: relocation R_X86_64_PC32 against undefined symbol `blort'
can not be used when making a shared object; recompile with -fPIC
and indeed, adding -fPIC to the C compile command seems to fix the problem in that environment. However, it doesn't seem to have any effect in OS X.
All the other dynamic-linking questions I could find on SO seem to be about the more usual arrangement of libraries, where a library is being built to be linked into an executable before that executable runs, rather than the other way around. The closest related question I found was this:
Can an executable be linked to a dynamic library after its built?
which unfortunately has very little info, none of it relevant to the question I'm asking here.
UPDATE: I distilled the info from the answer along with everything else I'd figured
out, and put together this example:
https://github.com/danfuzz/dl-example
As far as my knowledge goes, you want to use weak linkage:
// mark function as weakly-linked
extern void foo() __attribute__((weak));
// inform the linker about that too
clang -dynamiclib -o bar.dylib bar.o -flat_namespace -undefined dynamic_lookup
If a weak function can be resolved at runtime, it will then be resolved. If it can't, it will be NULL, instead of generating a runtime (or, obviously, link-time) error.
Ok, what we have:
Program written on C which compiling and running without problems in Linux and MacOSX (leopard).
I embedded lua code today. Linux: compiled lua 5.1 from source. Everything works and compiles without any problems. Macos: compiled the same lua 5.1 package.
Linked with --llua.
Started compile and got an error:
CC=gcc-4.0 make
ld: warning: in /usr/local/lib/liblua.a, file is not of required architecture
Also tried reinstall, complete remove and installing from macports. The same.
So is there any fix for that?
The error "file is not of required architecture" hints to the fact that you're trying to mix architectures.
Check the architecture of the /usr/local/lib/liblua.a and make sure it matches the architecture or the object you're trying to build.
E.g.
We have a i386 object:
==== cat fun.c ====
#include <stdio.h>
void fun()
{
printf("%s", "foobar\n");
}
gcc -arch i386 -c fun.c -o fun.o
if we try to use it when compiling a x86_64 object (default architecture in Mac OS X):
===== cat test.c ==
extern void fun();
int main()
{
fun();
}
we get:
$ gcc test.c fun.o
ld: warning: ignoring file fun.o, file was built for i386 which is not the architecture being linked (x86_64)
Undefined symbols for architecture x86_64:
"_fun", referenced from:
_main in ccXVCQhG.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status