I am trying to compile an application that uses freetype2, I downloaded and compiled the latest version of freetype2 from an official site.
I compile the program using this command:
gcc ttf2sfn.c -I/home/emilia/os/freetype-2.10.1/include -L/home/emilia/os/freetype-2.10.1/objs -lfreetype
However, the linker cannot find the `FT_Error_String' character.
It prints this error message:
/tmp/cc6FGxyc.o: In function `main':
ttf2sfn.c:(.text+0x25aa): undefined reference to `FT_Error_String'
ttf2sfn.c:(.text+0x352c): undefined reference to `FT_Error_String'
collect2: error: ld returned 1 exit status
Why is this happening?
Thanks.
It doesn't seem to actually exist. I use my own function, called ftstrerror, to do something equivalent:
static const char *ftstrerror(FT_Error error)
{
#undef FTERRORS_H_
#define FT_ERRORDEF(error_code, value, string) case error_code: return string;
#define FT_ERROR_START_LIST switch(error) {
#define FT_ERROR_END_LIST default: return "Unknown error"; }
#include FT_ERRORS_H
}
[Tested with FreeType 2.10.3.] You must have done something wrong. FT_Error_String is always defined. However, only if the library has been configured (at build time) with macro FT_CONFIG_OPTION_ERROR_STRINGS set, it returns non-NULL values. Since the default is off, you have to explicitly enable this feature in file include/freetype/config/ftoption.h.
Related
[Edit: The question is flawed, the file I described as "main.c" was actually "main.cpp" and that it why I was having an issue, calling a C function from a C++ file. The question is thus incorrect and doesn't have an answer, but if you have this undefined symbol issue, also think about checking you're not mixing C & C++.]
I'm using uVision 5 to develop a firmware, however I can't get the linker to find one of my functions.
main.c :
#include "Test.h"
int main()
{
return three();
}
Test.h :
#ifndef TEST_H
#define TEST_H
int three();
#endif
Test.c
#include "Test.h"
int three()
{
return 3;
}
All those files are at the root of my project, I know they get compiled as if I introduce a syntax error in them, compiler reports an error.
Also looking at the map file produced, I see that three() was removed:
Removing test.o(i.three), (4 bytes).
For testing purposes, I had --no_remove to linker command line, map file now contains:
0x0002ba76 0x00000004 Code RO 1 i.three test.o
So obviously, the linker is well aware of my function, and will or won't remove it depending on flags.
Regardless, it reports:
.\build\uvision5\test.axf: Error: L6218E: Undefined symbol three() (referred from main.o).
Not enough information to list image symbols.
Flawed question, it was actually a case of mixing C/C++, in which case you'll get a symbol missing if you call a C function from C++ without declaring it extern C.
I wrote a small c file to test DRMAA but it keeps telling me that the DRMAA functions I used are not defined. I included the drmaa.h file in the C code. When I use -idrmaa I get this error:
[mkatouzi#argo-1 ~]$ cc -o drmtest -I$SGE_ROOT/include/ -ldrmaa -ldl drmtest.c
/usr/bin/ld: cannot find -ldrmaa
the DRMAA header file is in this path: $SGE_ROOT/include/
If I compile the file without -ldrmaa I get this error:
[mkatouzi#argo-1 ~]$ cc -o drmtest -I$SGE_ROOT/include/ drmtest.c
/tmp/cclsPr9O.o: In function `main':
drmtest.c:(.text+0x3c): undefined reference to `drmaa_init'
drmtest.c:(.text+0x83): undefined reference to `drmaa_exit'
collect2: ld returned 1 exit status
I am using my school's UNIX system and I am very new to it. Can anyone help me with this?
This is my drmtest.c file:
#include <stdio.h>
#include "drmaa.h"
int main (int argc, char **argv) {
char error[DRMAA_ERROR_STRING_BUFFER];
int errnum = 0;
errnum = drmaa_init (argv[0], error, DRMAA_ERROR_STRING_BUFFER);
if (errnum != DRMAA_ERRNO_SUCCESS) {
fprintf (stderr, "Couldn't init DRMAA library: %s\n", error);
return 1; }
/* Do Stuff */
errnum = drmaa_exit (error, DRMAA_ERROR_STRING_BUFFER);
if (errnum != DRMAA_ERRNO_SUCCESS) {
fprintf (stderr, "Couldn't exit DRMAA library: %s\n", error);
return 1; }
return 0;
}
In the first case, the linker is you telling it does not know where to find the drmaa library. In the second case, since you have not included the drmaa library, the linker is telling you it does not know how to resolve the drmaa functions you are using.
You need to figure out where the drmaa library files are, i.e. in which directory.
Once you know that, you can specify -L/path/to/drmaa/directory when compiling/linking to resolve the problem.
As per Brian Cain's answer, the library (drmaa.a or drmaa.so) is probably under $SGE_ROOT/lib.
Finally, since the directory where the library is stored is not in the system's standard library search path, you have to tell the dynamic linker where to find the library when running the executable. There are two ways to achieve this:
Set (and export) the LD_LIBRARY_PATH environment variable to the library's directory (e.g. $SGE_ROOT/lib)
Or add the -R/path/to/drmaa/directory option when compiling/linking.
You likely need to specify the library path at which libdrmaa.so is found.
e.g.
cc -o drmtest -I$SGE_ROOT/include/ -L$SGE_ROOT/lib/ -ldrmaa -ldl drmtest.c
If you encounter a run-time problem linking against the library, you should check your system configuration.
The LD_LIBRARY_PATH environment variable can be used in a pinch, but on many modern systems you can/should use ld.so.conf.
e.g.
echo <<EOF > /etc/ld.so.conf.d/sge.conf
/usr/sge/lib
EOF
I want write simple C program to set ACL to one particular file on Linux. My starting code is trying to use function from "acl.h". I'm using Ubuntu 13.10, I've installed "Access control list utilities" - "acl 2.2.52-1". Here is my code:
#include <sys/acl.h>
#include <stdio.h>
int main () {
acl_t aclvar;
int count = 1;
aclvar = acl_init(count);
return 0;
}
The problem is, that I get error while compiling with "gcc myAcl.c" or "gcc -lacl myAcl.c":
/tmp/cc5sVzSR.o: In function `main':
myAcl.c:(.text+0x15): undefined reference to `acl_init'
collect2: error: ld returned 1 exit status
How can I resolve this error?
The libraries you link to needs to come last
gcc myAcl.c -lacl
So there's plenty of information about calling C APIs from within D, but how about the reverse? What do you need to do to write a library in D that works like a normal C shared library? Here's an easy case:
main.c
extern int foo(int x);
void main() {
printf("foo(5)=%d\n",foo(5));
}
foo.d
extern(C)
{
int foo(int x)
{
return x*x;
}
}
Naively trying to build and link these with gcc and dmd just results in linker errors.
Linking with gcc main.o foo.o:
doFoo.o: In function `no symbol':
doFoo.d:(.text+0x7): undefined reference to `_Dmodule_ref'
collect2: ld returned 1 exit status
Linking with dmd main.o foo.o:
/usr/lib64/libphobos2.a(deh2_2eb_525.o): In function `_D2rt4deh213__eh_finddataFPvZPS2rt4deh213DHandlerTable':
src/rt/deh2.d:(.text._D2rt4deh213__eh_finddataFPvZPS2rt4deh213DHandlerTable+0xa): undefined reference to `_deh_beg'
src/rt/deh2.d:(.text._D2rt4deh213__eh_finddataFPvZPS2rt4deh213DHandlerTable+0x14): undefined reference to `_deh_beg'
src/rt/deh2.d:(.text._D2rt4deh213__eh_finddataFPvZPS2rt4deh213DHandlerTable+0x1e): undefined reference to `_deh_end'
src/rt/deh2.d:(.text._D2rt4deh213__eh_finddataFPvZPS2rt4deh213DHandlerTable+0x46): undefined reference to `_deh_end'
/usr/lib64/libphobos2.a(lifetime.o): In function `_D2rt8lifetime18_sharedStaticCtor9FZv':
src/rt/lifetime.d:(.text._D2rt8lifetime18_sharedStaticCtor9FZv+0x15): undefined reference to `_tlsend'
src/rt/lifetime.d:(.text._D2rt8lifetime18_sharedStaticCtor9FZv+0x29): undefined reference to `_tlsstart'
/usr/lib64/libphobos2.a(thread_a3_258.o): In function `_D4core6thread6Thread6__ctorMFPFZvmZC4core6thread6Thread':
src/core/thread.d:(.text._D4core6thread6Thread6__ctorMFPFZvmZC4core6thread6Thread+0x2b): undefined reference to `_tlsend'
src/core/thread.d:(.text._D4core6thread6Thread6__ctorMFPFZvmZC4core6thread6Thread+0x36): undefined reference to `_tlsstart'
/usr/lib64/libphobos2.a(thread_a3_258.o): In function `_D4core6thread6Thread6__ctorMFDFZvmZC4core6thread6Thread':
src/core/thread.d:(.text._D4core6thread6Thread6__ctorMFDFZvmZC4core6thread6Thread+0x28): undefined reference to `_tlsend'
src/core/thread.d:(.text._D4core6thread6Thread6__ctorMFDFZvmZC4core6thread6Thread+0x33): undefined reference to `_tlsstart'
/usr/lib64/libphobos2.a(thread_a3_258.o): In function `_D4core6thread6Thread6__ctorMFZC4core6thread6Thread':
src/core/thread.d:(.text._D4core6thread6Thread6__ctorMFZC4core6thread6Thread+0x26): undefined reference to `_tlsend'
src/core/thread.d:(.text._D4core6thread6Thread6__ctorMFZC4core6thread6Thread+0x31): undefined reference to `_tlsstart'
/usr/lib64/libphobos2.a(thread_a0_713.o): In function `thread_entryPoint':
src/core/thread.d:(.text.thread_entryPoint+0x36): undefined reference to `_tlsend'
src/core/thread.d:(.text.thread_entryPoint+0x41): undefined reference to `_tlsstart'
collect2: ld returned 1 exit status
--- errorlevel 1
My answer is about using D static libraries from C.
Yes, this is a bit off topic, but shared libraries for Windows are described in D's documentation (http://www.d-programming-language.org/dll.html) and for Linux are still under construction (http://www.digitalmars.com/d/2.0/changelog.html). Working examples for both systems are attached.
Win32: dmd+dmc works great. Example: test_d_from_c_win32.zip
Linux32: dmd adds some required stuff once it has found D main function, so D's main is needed (tested for dmd2+gcc on Linux32).
It's linkage name is "_Dmain" and it will not be mixed with C's one (real "main").
So one can just add the file dfakemain.d with text void main(){}.
dmd -c dfakemain.d will create dfakemain.o with missing symbols. Link it with your object files and you will be happy. Example: test_d_from_c_linux32.tar.gz
According to a quick glance at the compiler source code, _Dmodule_ref is the linked list of module constructors. To fix the issue, add this to your main.c:
void* _Dmodule_ref;
The program now links and runs fine.
(At least, that's how I think it works.)
If gcc is compiling as C++, the default linkage used for the extern will be C++, not C. Try this instead:
extern "C" int foo(int x);
There does not seem to be anything wrong with your D syntax. There is a paragraph confirming your approach here: http://www.digitalmars.com/d/2.0/interfaceToC.html
I am working from a book: TCP/IP Sockets in C and its website code.
I am trying to build a client and server based on those files. My make gives lots of
error related to not being able to find functions from DieWithMessage.c
Here it is:
#include <stdio.h>
#include <stdlib.h>
#include "Practical.h"
void DieWithUserMessage(const char *msg, const char *detail) {
fputs(msg, stderr);
fputs(": ", stderr);
fputs(detail, stderr);
fputc('\n', stderr);
exit(1);
}
void DieWithSystemMessage(const char *msg) {
perror(msg);
exit(1);
}
When I do gcc DieWithMessage.c, I get the following error:
/usr/lib/i386-linux-gnu/gcc/i686-linux-gnu/4.5.2/../../../crt1.o: In function _start':
(.text+0x18): undefined reference tomain'
collect2: ld returned 1 exit status
How do I compile this by itself so that the errors will stop happening when using the makefile?
Thanks for any help.
Your C code needs a main function if you're going to try an link/run it. This is a requirement for hosted C applications under the standard.
That error message indicates what's wrong. The C runtime/startup code (CRT) has an entry point of start which sets up the environment then calls your main. Since you haven't provided a main, it complains.
If you only want to generate an object file for later linking with a main (see here for one description of the process), use something like:
gcc -c -o DieWithMessage.o DieWithMessage.c
(-c is the "compile but don't link" flag). You can then link it later with your main program with something like (although there are other options):
gcc -o myProg myProg.c DieWithMessage.o
If you want a placeholder main to update later with a real one, you can add the following to your code:
int main (void) { return 0; }