I am trying to compile a minimal test shared library in FreeBSD using:
FreeBSD clang version 6.0.1 (tags/RELEASE_601/final 335540) (based on LLVM 6.0.1)
Target: x86_64-unknown-freebsd12.0
Thread model: posix
InstalledDir: /usr/bin
test.c
#include "test.h"
int SampleFunction(int a, int b)
{
return a * b;
}
test.h
#ifndef TESTLIB_H
#define TESTLIB_H
extern int SampleFunction(int a, int b);
#endif
Makefile
# Makefile TESTLIB
TEST_OBJS = test.o
TEST_HEADERS = test.h
TEST_LIB = test.so
CC = cc
testlib: $(TEST_OBJS)
$(CC) -fpic -o $(TEST_LIB) $(TEST_OBJS)
# Rebuilt if this Makefile or header changes
$(TEST_OBJS): Makefile $(TEST_HEADERS)
Output:
$ make testlib
cc -O2 -pipe -c test.c -o test.o
cc -fpic -o test.so test.o
/usr/bin/ld: error: undefined symbol: main
>>> referenced by crt1.c:76 (/usr/src/lib/csu/amd64/crt1.c:76)
>>> /usr/lib/crt1.o:(_start)
cc: error: linker command failed with exit code 1 (use -v to see invocation)
*** Error code 1
Stop.
make: stopped in /usr/home/user/testlib
As well as adding -shared to the linker stage (as mentioned by Oo.oO), you probably also want to compile with the -fPIC flag as well. So if you are using the makefile implicit rules for the compiling (looks like you are) then you will probably want to add that flag to CFLAGS. I don't think you need it for the linking stage:
# Makefile TESTLIB
TEST_OBJS = test.o
TEST_HEADERS = test.h
TEST_LIB = test.so
CFLAGS += -fPIC
CC = cc
testlib: $(TEST_OBJS)
$(CC) -shared -o $(TEST_LIB) $(TEST_OBJS)
# Rebuilt if this Makefile or header changes
$(TEST_OBJS): Makefile $(TEST_HEADERS)
I prefer using the OS-provided bsd.lib.mk for such building libraries. The following should do the right thing -- whatever it may be:
SHLIB_NAME= testlib
SRCS= test.c
.include <bsd.lib.mk>
(For building executables there is bsd.prog.mk, BTW.)
Related
I am trying to compile two c files into one executable. In the directory I have only three files; Makefile, main.c and myfunction.c.
Makefile:
CC = gcc
CFLAGS = -Wall -g -O0
LIBS = -lm
SRCS = $(wildcard *.c)
OBJS = $(SRCS:.c=.o)
MAIN = main
all: $(MAIN)
#echo Program has been compiled
$(MAIN): $(OBJS)
$(CC) $(CFLAGS) $(INCLUDES) -o $(MAIN) $(OBJS) $(LIBS)
clean:
$(RM) *.o *~ $(MAIN)
main.c:
#include <stdio.h>
void myfunc();
int main (int argc, char *argv[]) {
myfunc();
return 0;
}
myfunction.c:
#include <stdio.h>
void myfunc() { printf("hello world"); }
output after make:
gcc -Wall -g -O0 -c -o main.o main.c
gcc -Wall -g -O0 -c -o myfunction.o myfunction.c
gcc -Wall -g -O0 -o main main.o myfunction.o -lm
Undefined symbols for architecture x86_64:
"_myfunc", referenced from:
_main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [main] Error 1
I had something nearly identical working in the past. I have since clean installed MacOS and updated to Big Sur. Is this the issue or have I overlooked something?
I fixed the issue. I’m not sure what part fixed it, but installed Homebrew and used it to install gcc-10. I also deleted the project and started over.
myfunc would define like file header
myfunc.h
void myfunc()
Declare in another file
myfunc.c
void myfunc() { printf("hello world"); }
Follow the following tutorial
https://developer.gnome.org/anjuta-build-tutorial/stable/build-make.html.en
I am trying to reorganize someone's code and I seem to have hit a wall.
I have a function int fnc() in fnc.c that is called by either main1.c or main2.c. An executable is compiled from either main1.c or main2.c using a makefile:
main1: main1.o fnc.o
gcc main1.o fnc.o -o main1.x
main2: main2.o fnc.o
gcc main2.o fnc.o -o main2.x
main1.o: main1.c
gcc -c main1.c
main2.o: main2.c
gcc -c main2.c
fnc.o:
gcc -c fnc.c
The only problem is, there are two header files header1.h and header2.h to be included in the preamble of fnc.c depending on whether main1.x or main2.x is compiled:
#include "header1.h"
int fnc(){
// do stuff
}
Is it possible to select which header to be loaded depending on whether one types make main1 or make main2?
You can use the -D compiler flag to define a symbol that will be visible to preprocessor. And then to check it with the preprocessor #ifdef directive. Such as:
Makefile:
main1: main1.o fnc1.o
gcc main1.o fnc1.o -o main1.x
main2: main2.o fnc2.o
gcc main2.o fnc2.o -o main2.x
main1.o: main1.c
gcc -c main1.c
main2.o: main2.c
gcc -c main2.c
fnc1.o:
gcc -o fnc1.o -c fnc.c -DCONFIG1
fnc2.o:
gcc -o fnc2.o -c fnc.c -DCONFIG2
And your source:
#ifdef CONFIG1
#include "header1.h"
#elif defined(CONFIG2)
#include "header2.h"
#else
#error "blah"
#endif
int fnc(){
// do stuff
}
Note - this is neither tested nor an optimal solution. Just giving the idea
I have a file main.c, a header rippledp.h and a library rippledp.a. The problem is: when I execute the "make" command, I get this output:
g++ -O2 -DNDEBUG -static -o rippledp main.o rippledp.a -lm -pthread
main.o: In function `main':
main.c:(.text+0x24): undefined reference to `rippledp_read'
main.c:(.text+0x39): undefined reference to `rippledp'
main.c:(.text+0x43): undefined reference to `rippledp_write'
collect2: ld returned 1 exit status
make: ** [rippledp] Erro 1
Here is the Makefile:
#--------------------------------------------------#
# Ripple-DP (ISPD2015 contest version) #
# Copyright (c) 2015 #
# Department of Computer Science and Engineering #
# The Chinese Univeristy of Hong Kong #
# #
# Contact: #
# Wing-Kai Chow <wkchow#cse.cuhk.edu.hk> #
# Evangeline F.Y. Young <fyyoung#cse.cuhk.edu.hk> #
#--------------------------------------------------#
OPT= -O2 -DNDEBUG
#OPT= -O0 -ggdb
TYPE= -static
#WFLAG= -Wall -Winline
CC= g++ $(OPT) $(TYPE) $(WFLAG) $(DEBUG)
LIBS= -lm -pthread
SRCS = ${OBJS:%.o=%.c}
BFILE = rippledp
all: $(BFILE)
#$(BFILE): main.o rippledp.a libdef.a liblef.a
# $(CC) -o $(BFILE) main.o rippledp.a libdef.a liblef.a $(LIBS)
$(BFILE): main.o rippledp.a
$(CC) -o $(BFILE) main.o rippledp.a $(LIBS)
%.o : %.c %.h
$(CC) -c $*.c
clean:
rm -f *.o $(BFILE) core
Here is main.c:
#include "rippledp.h"
int main(int argc, char **argv){
/* read benchmark files: tech.lef, cells.lef, floorplan.def */
/* read global placement solution: placed.def */
rippledp_read((char*) "tech.lef", (char*) "cells.lef", (char*) "floorplan.def", (char*) "placed.def");
/* detailed placement with target utility and maximum displacement constraint */
rippledp(0.8, 200000);
/* write the detailed placement solution to output file */
rippledp_write((char*)"dplaced.def");
return 0;
}
And here is rippledp.h:
/*--------------------------------------------------*/
/* Ripple-DP (ISPD2014 contest version) */
/* Copyright (c) 2014 */
/* Department of Computer Science and Engineering */
/* The Chinese Univeristy of Hong Kong */
/* */
/* Contact: */
/* Wing-Kai Chow <wkchow#cse.cuhk.edu.hk> */
/* Evangeline F.Y. Young <fyyoung#cse.cuhk.edu.hk> */
/*--------------------------------------------------*/
#ifndef _RIPPLEDP_H_
#define _RIPPLEDP_H_
/*read benchmarks and placed global placement solution*/
void rippledp_read(char *tech_file, char *cell_file, char *floorplan_file, char *placed_file);
/*Perform displacement-constrained legalization and detailed placement*/
/* target_util = target utility */
/* max_disp = maximum displacement constraint */
void rippledp(double target_util, double max_disp);
/*write placement result in DEF format*/
void rippledp_write(char *output_file);
#endif
I also tried to compile and link manually. I first compiled using:
gcc -c main.c
Then, I tried all these alternatives for linking (I renamed rippledp.a to librippledp.a):
gcc -o out -L. -lrippledp main.o
gcc -o out -L. main.o -lrippledp
gcc -o out main.o -L. -lrippledp
gcc main.o -o out -L. -lrippledp
gcc -o out -lrippledp -L. main.o
gcc -lrippledp -o out -L. main.o
and the output was the same.
I dont have access to the library content.
Your library is compiled with C++ and thus contains C++ mangled names. But you compiled main.c as C, so it looked for unmangled names and thus couldn't find them. Rename main.c to main.cpp and compile it with g++ to fix this issue.
I am trying to use matlab libmat.dll in a C application. To compile my C application I use MinGW, for now I use matlab exemple "matcreate.c" and try to compile it, so the projects consist of only one file : main.c .
Here is the makefile I use :
MATINCLUDE = "C:\Program Files\MATLAB\R2010a\extern\include"
MATLIBRARY = "C:\Program Files\MATLAB\R2010a\bin\win64"
#
CC = gcc
LD = gcc
CFLAGS = -O3 -Wall
LFLAGS = -Wall -O3
LIBS = -I$(MATINCLUDE) -L$(MATLIBRARY)
#
PROG = matTest
LISTEOBJ = \
main.o
.c.o :
$(CC) -c $(CFLAGS) $(LIBS) -o $# $<
all : $(PROG)
$(PROG) : $(LISTEOBJ)
$(LD) -o $(PROG) $(LFLAGS) $(LISTEOBJ) $(LIBS)
clean :
rm -f *.obj
Here is what I get in the console
E:\Users\Desk\Dropbox\matTest>make
gcc -c -O3 -Wall -I"C:\Program Files\MATLAB\R2010a\extern\include" -L"C:\Pr
ogram Files\MATLAB\R2010a\bin\win64" -o main.o main.c
gcc -o Hello_world -Wall -O3 main.o -I"C:\Program Files\MATLAB\R2010a\extern\i
nclude" -L"C:\Program Files\MATLAB\R2010a\bin\win64"
main.o:main.c:(.text.startup+0x48): undefined reference to `matOpen'
main.o:main.c:(.text.startup+0x6e): undefined reference to `mxCreateDoubleMatrix
_730'
e:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: main.o: ba
d reloc address 0x6e in section `.text.startup'
e:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: final link
failed: Invalid operation
collect2.exe: error: ld returned 1 exit status
make: *** [Hello_world] Error 1
Why do I have "undefined reference to matOpen'" and "undefined reference to mxCreateDoubleMatrix" ?? those function are declared in mat.h. and I added #include "mat.h" to the begining of main.c
thank you
Looks like you have included the path to the matlab library, but not the library itself. You need to add a -l<libraryname> to your link line.
Here is my console output:
Tylers-MacBook-Pro:laser_finder_c tylerjw$ make
gcc -g -Wall -c -o dots_img.o dots_img.c
gcc -g -Wall -c -o no_dots_img.o no_dots_img.c
gcc -g -Wall -c -o point.o point.c
gcc -g -Wall -c -o images.o images.c
gcc -g -Wall -c -o laser_finder_c.o laser_finder_c.c
gcc dots_img.o no_dots_img.o point.o images.o laser_finder_c.o -g -Wall -o laser_finder_c
Undefined symbols for architecture x86_64:
"_main", referenced from:
implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [laser_finder_c] Error 1
This doesn't seem to make any sense as the main function is defined in laser_finder_c.c. Below is my makefile. I'm real confused as to why this is happening.
TARGET = laser_finder_c
OBJECTS = dots_img.o no_dots_img.o point.o images.o laser_finder_c.o
#######################################################################################
CFLAGS = -g -Wall
ASFLAGS = -Wall
LDFLAGS = -g -Wall
CC = gcc
AS = gcc
########################################################################################
$(TARGET): $(OBJECTS)
$(CC) $(OBJECTS) $(LDFLAGS) -o $(TARGET)
point.o: point.h
images.o: images.h
laser_finder_c.o: images.h point.h
dots_img.o: images.h
no_dots_img.o: images.h
clean:
rm -f $(OBJECTS) $(TARGET)
Here is the definition of main in laser_finder_c.c
// laser_finder.c - finds the location of laser points comparing two images
#include "point.h"
#include <stdio.h>
#include <stdlib.h>
// #defines ... removed
int main()
{
// ... code removed
return 0;
}
For context the output of gcc -v is:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 5.1 (clang-503.0.38) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.1.0
Thread model: posix