I am trying to build an example program which uses WinPcap-functions. I’m working under Windows 7 64 Bit edition with MinGW. I am able to compile the C-code to an object file, but I can’t link against wpcap.lib.
My linker call looks like this:
gcc -L ../../lib/x64 send_packet.o -lwpcap -o WinPcapTest.exe
With this call I get the following errors:
undefined reference to pcap_open
undefined reference to pcap_sendpacket
undefined reference to pcap_geterr
Obviously I am not linking against wpcap.lib, but I don’t know why. The library is definitely found. If I change the lib include path for example, I get this error:
cannot find -lwpcap
Why does the linker find the lib but does not link against it? Thanks for your help.
Try listing you libraries after binary definition. As far as I remember, with provided gcc command, ld would be symbol matching for pcap symbols between send_packet.o and libwpcap.lib but not with WinPcapTest.exe. I would suggest moving -lwpcap at the end:
gcc -I ..\..\..\Downloads\WpdPack_4_1_2\WpdPack\Include ..\send_packet.c -L ..\..\..\Downloads\WpdPack_4_1_2\WpdPack\Lib\x64 -O0 -g3 -Wall -o WinPcapTest.exe -lwpcap
Related
probably this is a trivial newbie question, however, I can't figure out how to solve it.
I'm trying to build a test program using libtiff (test program copied from here). I've downloaded the static library libtiff.lib as well as the required header file tiffio.h. When I compile the main c function with no problem I have a main.o file. When I try to link main.o with libtiff using this command
gcc -g -Wall -o test.exe ./libtiff.lib ./test.o
I have this error:
undefined reference to `_imp__TIFFOpen'
I've looked into the lib file with nm -A libtiff.lib command and I can find this line
libtiff.lib:libtiff3.dll:00000000 I __imp__TIFFOpen
but it has 2 leading underscores instead of 1 as required by the linker. I'm using mingw on Windows 7 and all the required files are in the same directory.
No clue how to link with no errors.
Thanks in advance.
As suggested in the the comments, it was sufficient to invert the order of objects passed as arguments:
gcc -g -Wall -o test.exe ./test.o ./libtiff.lib
I am trying to compile a program within a docker container built from the Alpine 3.7 base image. The program uses argp.h, and includes it as #include <argp.h>. I have installed argp-standalone and verified that it is making it onto the image. The file argp.h is located in usr/include, however when I compile my program using the following commands:
gcc -W -Wall -Wextra -I/usr/include -c -o progname.o progname.c
gcc -largp -o progname progname.o
I get the following error:
progname.o: In function `parse_opt':
progname.c:(.text+0x4c9): undefined reference to `argp_failure'
progname.c:(.text+0x50f): undefined reference to `argp_failure'
progname.c:(.text+0x555): undefined reference to `argp_failure'
progname.c:(.text+0x59b): undefined reference to `argp_failure'
progname.c:(.text+0x5ce): undefined reference to `argp_error'
progname.c:(.text+0x5f4): undefined reference to `argp_error'
progname.o: In function `main':
progname.c:(.text+0x1397): undefined reference to `argp_parse'
collect2: error: ld returned 1 exit status
make: *** [Makefile:9: progname] Error 1
I have:
Ensured that the version of argp.h which is on the image does in fact include the argp_failure, argp_parse, and argp_error functions.
Tried moving argp.h into different locations on the machine (e.g. into the same directory where compilation is taking place, into /usr/lib)
Tried compiling with -l and -L.
The relevant packages also installed in the image are build-base, make, and gcc.
When compiling on an Ubuntu image these same commands work fine, even without the -largp and -I/usr/include flags. What could be happening differently within an Alpine image which would cause this not to work?
Edit
As per #Pablo's comment, I'm now compiling it as follows:
gcc -W -Wall -Wextra -I/usr/include -L/usr/lib -c -o progname.o progname.c
gcc -largp -o progname progname.o
After having verified that the static library, libargp.a, is located in /usr/lib. However, the same problem still persists.
Edit 2
Compiling as follows (and once again as per #Pablo's suggestion) has resolved the error I was having:
gcc -W -Wall -Wextra -I/usr/include -L/usr/lib -c -o progname.o progname.c
gcc -o progname progname.o /usr/lib/libargp.a
However, I am still curious why, using the exact same library and instructions, this would fail to compile in an Alpine image while compiling without issue in an Ubuntu image.
I am still curious why, using the exact same library and instructions, this would fail to compile in an Alpine image while compiling without issue in an Ubuntu image.
The reason for the linking error on Alpine may be kind of surprising, and is actually not specific to Alpine.
While this fails to link:
gcc -largp -o progname progname.o
This works:
gcc -o progname progname.o -largp
The reason is the order of parameters passed to the linker, and it related to the linking algorithm. Typically, in the linking command line objects are specified first (and possibly user's static libraries in any), then libraries using -l. The standard linker algorithm is explained perfectly in Eli Bendersky's article, Library order in static linking:
Object files and libraries are provided in a certain order on the command-line, from left to right. This is the linking order. Here's what the linker does:
The linker maintains a symbol table. This symbol table does a bunch of things, but among them is keeping two lists:
A list of symbols exported by all the objects and libraries encountered so far.
A list of undefined symbols that the encountered objects and libraries requested to import and were not found yet.
When the linker encounters a new object file, it looks at:
The symbols it exports: these are added to the list of exported symbols mentioned above. If any symbol is in the undefined list, it's removed from there because it has now been found. If any symbol has already been in the exported list, we get a "multiple definition" error: two different objects export the same symbol and the linker is confused.
The symbols it imports: these are added to the list of undefined symbols, unless they can be found in the list of exported symbols.
When the linker encounters a new library, things are a bit more interesting. The linker goes over all the objects in the library. For each one, it first looks at the symbols it exports.
If any of the symbols it exports are on the undefined list, the object is added to the link and the next step is executed. Otherwise, the next step is skipped.
If the object has been added to the link, it's treated as described above - its undefined and exported symbols get added to the symbol table.
Finally, if any of the objects in the library has been included in the link, the library is rescanned again - it's possible that symbols imported by the included object can be found in other objects within the same library.
When -largp appears first, the linker does not include any of its objects in the linking procedure, since it doesn't have any undefined symbols yet. If the static library is provided by path, and not with -l, then all of its objects are added to the linking procedure.
The problem I have is the "undefined reference to '_imp__...' " error that comes up when I build my project. I am using Windows 7, MinGW, Eclipse and .lib and .dll file that I did not make, but I took directly from the company that sold me their product.
I link with the -l command the HRDL.lib file and i have the PicoHRDL.dll at the same directory. The lib file is found (I'm sure about this), but the error comes up. I have included the complete path with the -L command. I have included the header file with the declarations of the functions, I get the undefined reference to, but the error is still there.
I have contacted both Eclipse support and Picotech support (the said company) but they weren't able to locate the problem till now.
These are the commands:
gcc -O0 -g -Wall -c -fmessage-length=0 -o ACD_SOURCE.o "..\\ACD_SOURCE.c"
gcc "-LC:\\Users\\Falamana\\Desktop\\Eclipse\\ADC_project1\\Libraries" -shared -o libADC_24_DataLogger_App.exe ACD_SOURCE.o -lHRDL
These are the errors:
ACD_SOURCE.o: In function `main':
C:\Users\Falamana\Desktop\Eclipse\ADC_project1\Debug/../ACD_SOURCE.c:70:
undefined reference to `_imp__HRDLGetUnitInfo#16'
C:\Users\Falamana\Desktop\Eclipse\ADC_project1\Debug/../ACD_SOURCE.c:99:
undefined reference to `_imp__HRDLCloseUnit#4'
ACD_SOURCE.o: In function `SelectUnit':
C:\Users\Falamana\Desktop\Eclipse\ADC_project1\Debug/../ACD_SOURCE.c:115:
undefined reference to `_imp__HRDLGetUnitInfo#16'
C:\Users\Falamana\Desktop\Eclipse\ADC_project1\Debug/../ACD_SOURCE.c:167:
undefined reference to `_imp__HRDLGetUnitInfo#16'
In my case it helpt to add -mwindows flag to linker options.
Note that in your compiling information, the -L option symbol should be out of the quote. That's to say, the
gcc "-LC:\Users\Falamana\Desktop\Eclipse\ADC_project1\Libraries" -shared -o libADC_24_DataLogger_App.exe ACD_SOURCE.o -lHRDL
should be
gcc -L"C:\Users\Falamana\Desktop\Eclipse\ADC_project1\Libraries" -shared -o libADC_24_DataLogger_App.exe ACD_SOURCE.o -lHRDL
So please check your configuration of the lib directory in whatever IDE you are using, util the gcc line of compiling information looks normal( util -L stands right ahead of the quote character).
i have made a static library using the ar command after an object creation using gcc -o file.o -c file.c.
Now i'm trying to use the gcc to link this library in the compilation with a command similar to this
gcc -I /PathInclude -L /PathStaticLib -lm \
-std=c99 -o file file.o -lstatic_library_name
with static_library_name i mean that the file is named
libstatic_library_name.a
Since the files structure is quite complex (because basically in the compiling i also substitute some macro definition etc) i don't post all the code, do you have any thought on what is going on? if not what kind of info could i provide to you in order to help me?
PS. there aren't a lot o files, but the internal structure is a bit complicated to explain in few words, so... let me know what do you need.
I can give you the make file content if you need, is not complicated.
PS. The command is...
gcc -I../CModels -L../CModels/ -std=c99 -o ref_approx_bs3_log2_4_4_1ulp_arch1
ref_approx_bs3_log2_4_4_1ulp_arch1.o -lm -lmy_float
The error is
ref_approx_bs3_log2_4_4_1ulp_arch1.o: In function `cogen_fp_bs3_log2_4_4_1ulp_arch1':
ref_approx_log2.c:(.text+0x2229): undefined reference to `cast'
ref_approx_log2.c:(.text+0x22d0): undefined reference to `cast'
ref_approx_log2.c:(.text+0x22f7): undefined reference to `cast'
ref_approx_log2.c:(.text+0x232e): undefined reference to `sumFP'
ref_approx_log2.c:(.text+0x2350): undefined reference to `diffFP'
ref_approx_log2.c:(.text+0x2375): undefined reference to `mulFP'
ref_approx_log2.c:(.text+0x239c): undefined reference to `sumFP'
collect2: ld returned 1 exit status
Using
nm my_float.a
the output is
my_float.o:
0000000000000ca8 T _Z11castToFixedyPyyyy
0000000000000a0c T _Z12splitIntFracyPyS_yy
0000000000000324 T _Z28rightShift_and_round2NearestyyPyyy
000000000000005c T _Z3ldzy
0000000000000132 T _Z3mulyyy
000000000000048a T _Z4castyPyyyyy
0000000000000000 T _Z4maxuyy
000000000000002e T _Z4minuyy
00000000000014dc T _Z5mulFPyyPyyy
0000000000000cc2 T _Z5sumFPyyPyyy
000000000000147a T _Z6diffFPyyPyyy
0000000000000300 T _Z9ldzFormatyy
U __gxx_personality_v0
So i guess the library .a is ok...
As per the gcc manual, AFAIR, there should be no space in between -L or -I and the path. Change your command to
.. -I/PathInclude -L/PathStaticLib ...
Error says that the references to cast, sumFP, diffFP , mulFP are not defined. Need to make sure that they are defined in the library.
My program uses the GNU Multiple Precision Arithmetic Library to deal with numbers of an arbitrary size. I successfully compile it using GCC with:
gcc main.c -o diff -g -lgmp
However, when I try to use the MinGW crosscompiler compiler, I get the following error:
i686-w64-mingw32-gcc main.c -o diff.exe -g -lgmp
main.c:3:46: fatal error: gmp.h: No such file or directory
#include <gmp.h>//For files of arbitrary size
I then tried to tell it exactly where the header file was:
i686-w64-mingw32-gcc main.c -o diff.exe -I/usr/include -g -lgmp
/usr/lib/gcc/i686-w64-mingw32/4.9.2/../../../../i686-w64-mingw32/bin/ld: cannot find -lgmp
collect2: error: ld returned 1 exit status
Ok, so I figure now it successfully found the header, but cant find the library. So I tried again:
i686-w64-mingw32-gcc main.c -o diff.exe -I/usr/include -g -L/usr/lib -lgmp
/usr/lib/gcc/i686-w64-mingw32/4.9.2/../../../../i686-w64-mingw32/bin/ld: cannot find -lgmp
collect2: error: ld returned 1 exit status
I guess I need to specify the exact files to use, so I tried this:
i686-w64-mingw32-gcc main.c -o diff.exe -I/usr/include -g /usr/lib/libgmp.so
/usr/lib/libgmp.so: file not recognized: File format not recognized
collect2: error: ld returned 1 exit status
So, I honestly don't know what to do and I'd really really appreciate your help.
First, a disclaimer: the cross-compiler you are using is neither distributed by, nor supported by MinGW.org, whom I represent; if you are looking for a pre-compiled solution, you should seek it from the distributor of the specific cross-compiler itself.
That said, I can offer the following insight, (which will apply, in general, to any cross-compiler): the headers you find in /usr/include, or in /usr/local/include, and the libgmp.so which you find in /usr/lib, or in /usr/local/lib, are intended for use with your native platform compiler. They are not suitable for, and cannot be used with your MinGW cross-compiler; attempting to do so will surely never work. Thus, you have two options:
Ask your cross-compiler distributor to provide a pre-compiled copy of gmp.dll, (or at the very least, a compatible import library, although you may need the gmp.dll to distribute with your own application anyway), and any associated header files, and/or equivalent statically linkable library, for use with your cross-compiler.
Use your cross-compiler to build gmp.dll yourself, then install it, its associated headers, and perhaps also its associated import library and/or equivalent statically linkable library, into the same prefix-path as the cross-compiler itself.