I'm trying to use libusb for a project but i'm unable to get the library working properly. Here is some source code i'm trying to compile. It doesn't do anything special. It's just a dummy program that gets the USB driver list then frees it.
#include <stdio.h>
#include <usb.h>
#include <stdlib.h>
int main(int argc, char *argv[]){
struct libusb_device **devs;
struct libusb_context *context = NULL;
size_t list;
size_t i;
int ret;
ret = libusb_init(&context);
if(ret < 0)
{
perror("libusb_init");
exit(1);
}
list = libusb_get_device_list(context, &devs);
if(list < 0)
{
fprintf(stderr, "error in getting device list\n");
libusb_free_device_list(devs, 1);
libusb_exit(context);
exit(1);
}
libusb_free_device_list(devs, 1);
libusb_exit(context);
return 0;
}
I compile with
gcc -o test test.c -lusb
I get the error
/tmp/cc2hwzii.o: in function 'main:
test.c:(.text+0x24): undefined reference to 'libusb_init'
test.c:(.text+0x59): undefined reference to 'libusb_get_device_list'
test.c:(.text+0x8e): undefined reference to 'libusb_free_device_list'
test.c:(.text+0x9f): undefined reference to 'libusb_exit'
collect2: error: ld returned 1 exit status
I'm running ubuntu 14.04.3
I've installed libusb by sudo apt-get install libusb-dev
I've searched for my header file and it is called usb.h
I've looked to make sure I have the correct flag and it's -lusb
any ideas? I'd appreciate the help. If any more information is needed just ask.
those libusb_init are included in libusb-1.0.
you have to install libusb-1.0-0-dev
$ sudo apt-get install libusb-1.0-0-dev
$ gcc -o test test.c -lusb-1.0
/usr/lib/x86_64-linux-gnu/pkgconfig/libusb.pc which is included in libusb-dev says that the version is 0.1.12
and
/usr/lib/x86_64-linux-gnu/pkgconfig/libusb-1.0.pc which is included in libusb-1.0-0-dev says that the version is 1.0.17.
http://www.libusb.org/ says that 0.1 is legacy, and seems that API is different from 1.0.
You forgot to include the file that defines the functions, such as libusb_init. Have you tried including libusb.h?
Related
I am using the standard __wrap_function and __real_function to intercept function calls with -Wl,--wrap=function. This works successfully for most functions like malloc, fopen, etc. However, I am unable to wrap these two functions:
int connect(int, const struct sockaddr*, socklen_t)
int stat(const char*, struct stat*)
With these functions, the linker complains with undefined reference to __real_connect and __real_stat.
Is there any particular reason for this? (Note: I can also wrap socket functions for example)
It is likely you forgot to add -Wl,--wrap=connect and -Wl,--wrap=stat to your link line.
This works for me:
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <unistd.h>
int __wrap_connect (int s, const struct sockaddr *addr, socklen_t len)
{
puts(__func__);
return __real_connect(s, addr, len);
}
int __wrap_stat (const char *path, struct stat *buf)
{
puts(__func__);
return __real_stat(path, buf);
}
int main(void) {
connect(0, NULL, 0);
stat("/", 0);
return 0;
}
When compiled on my system.
$ uname -s -r
Linux 2.6.32-696.16.1.el6.x86_64
$ gcc --version | grep gcc
gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
$ gcc c.c -Wl,--wrap=connect -Wl,--wrap=stat
$
However, when leaving off -Wl,--wrap=stat, for example, I get:
$ gcc c.c -Wl,--wrap=connect
/tmp/cchVzvsE.o: In function `__wrap_stat':
c.c:(.text+0x65): undefined reference to `__real_stat'
collect2: ld returned 1 exit status
$
It seems like the error was caused due to cmake issues. Clearing the cmake cache and running cmake . followed by make all resolved it.
I'm trying to compile this code which call func from "libcfmapi.so" to decrypt "cfg" file
#include <stdlib.h>
#include <stdio.h>
int restorebackup(const char *tmp_cfg_name,const char *xml_cfg_name);
int ATP_CFM_ExtCustomImportEncryptedUserCfgFile(const char *tmp_cfg_name);
int main(int argc, char **argv)
{
int ret;
if(argc < 3)
{
printf("specify temp config file name.\n");
exit(1);
}
ret=restorebackup(argv[1],argv[2]);
return ret;
}
int restorebackup(const char *tmp_cfg_name,const char *xml_cfg_name)
{
int ret=0;
//ret = ATP_CFM_ExtDigVerifyFile(tmp_cfg_name,tmp_cfg_name);
if(ret != 0)
{
printf("Verify File failed.\n");
return ret;
}
ret = ATP_CFM_ExtCustomImportEncryptedUserCfgFile(tmp_cfg_name);
return ret;
}
but got error regarding func type declare
root#kali:~/debian-qemu# gcc h.c -o demo
/tmp/ccVbt5NT.o: In function `restorebackup':
h.c:(.text+0x8c): undefined reference to `ATP_CFM_ExtCustomImportEncryptedUserCfgFile'
collect2: error: ld returned 1 exit status
any help appreciated
The reason you're getting this error is because you're not linking against the required library, libcfmapi.so.
This is not a library you would expect to find in your Debian system as it is unique to the BT device you're trying to hack.
In short - get the lib from your device, cross compile to the device architecture against the lib you extracted from the device and you should be fine.
More information based on Ishay Peled answer:
readelf -s <pulled library> | grep ATP_CFM_ExtCustomImportEncryptedUserCfgFile
I suspect the problem isn't that function you call doesn't exist but rather there are no functions being displayed it is most likely empty just like nm result:
nm: libcfmapi.so: no symbols
do the command without piping to grep, my bet is your output is:
readelf -s libcfmapi.so
Dynamic symbol information is not available for displaying symbols.
If someone knows the way of getting the headers from the file, i believe then you can find your function you require then link and run (i too am trying to use libcfmapi.so, but lack the programming/reversing knowledge required).
when using a library, then must:
include that library in the link statement via
-l cfmapi
include the header file for that library in the source code:
#include <cfmapi.h>
I'm trying to go through this tutorial:
http://www.tcpdump.org/pcap.html
Now I have install pcap (code hints and all that is working) using :
sudo apt-get install libpcap-dev
and so far I have the following code (file name is example_pcap.c):
#include <stdio.h>
#include <pcap.h>
int main(int argc, char *argv[]) {
char *dev, errbuf[PCAP_ERRBUF_SIZE];
dev = pcap_lookupdev(errbuf);
return 0;
}
According to many questions I have seen already they said to compile it using this:
gcc -lpcap example_pcap.c -o example_pcap
However I still get the following error:
example_pcap.c:(.text+0x32): undefined reference to `pcap_lookupdev'
Move -lpcap to the end of the command line
See Why does the order in which libraries are linked sometimes cause errors in GCC?
Here is some code from Ben Straub's (link blog) that I am basing this on:
static int do_clone(const char *url, const char *path)
{
git_repository *repo = NULL;
int ret = git_clone(&repo, url, path, NULL);
git_repository_free(repo);
return ret;
}
And here is my code:
#include <git2.h>
int main(void) {
git_repository *out = NULL;
git_clone(&out, "https://github.com/lehitoskin/racketball", "/home/maxwell", NULL);
return 0;
}
I am very inexperienced with C, so I apologize for having such elementary problems. Anyway, here is the error my compiler gives me:
maxwell#max-pc ~ $ gcc -I libgit2/include gitfun.c
/tmp/ccB64nPh.o: In function `main':
gitfun.c:(.text+0x31): undefined reference to `git_clone'
collect2: error: ld returned 1 exit status
Why can't I call git_clone this way?
It looks like you didn't link to the library. Add -lgit2 if libgit2 is the lib name.
gcc -I libgit2/include gitfun.c -L<path to lib> -l<libname minus the "lib" part>
IOW, you compile fine but when the linker goes looking for git_clone it can't find it because you haven't specified the library that it is in.
I need to create an application to extract one file from zip archive, after which I want to compile it for Android.
I'm using Ubuntu, with libzip-0.10.1 pre-installed.
I created C project in Eclipse, added include path and found simple script for extracting file. Unfortunately I cannot get the following to build and I could use some advice.
// zip.c file
#include <stdio.h>
#include <stdlib.h>
#include <zip.h>
int main(int argc, char **argv) {
struct zip *zip_file;
struct zip_file *file_in_zip;
int err;
int files_total;
int file_number;
int r;
char buffer[10000];
if (argc < 3) {
fprintf(stderr,"usage: %s <zipfile> <fileindex>\n",argv[0]);
return -1;
};
zip_file = zip_open(argv[1], 0, &err);
if (!zip_file) {
fprintf(stderr,"Error: can't open file %s\n",argv[1]);
return -1;
};
file_number = atoi(argv[2]);
files_total = zip_get_num_files(zip_file);
if (file_number > files_total) {
printf("Error: we have only %d files in ZIP\n",files_total);
return -1;
};
file_in_zip = zip_fopen_index(zip_file, file_number, 0);
if (file_in_zip) {
while ( (r = zip_fread(file_in_zip, buffer, sizeof(buffer))) > 0) {
printf("%s",buffer);
};
zip_fclose(file_in_zip);
} else {
fprintf(stderr,"Error: can't open file %d in zip\n",file_number);
};
zip_close(zip_file);
return 0;
};
Also I added few .h files to include directory in my project and few .c files to directory with zip.c file. After that all dependences was good, but I have an error:
‘struct zip’ has no member named ‘default_password’ in file zip_fopen_index.c
The file zip_fopen_index.c is:
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include "zipint.h"
ZIP_EXTERN struct zip_file *
zip_fopen_index(struct zip *za, zip_uint64_t fileno, int flags)
{
return zip_fopen_index_encrypted(za, fileno, flags, za->default_password); // error here
}
First of all allow me some comments:
Your program is not compiled and linked by Eclipse.
Compiling is done by the compiler (gcc using option -c):
make all
Building file: ../zip.c
Invoking: GCC C Compiler
gcc -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"zip.d" -MT"zip.d" -o "zip.o" "../zip.c"
Finished building: ../zip.c
Linking is done by the linker (via the compiler using option -o):
Invoking: GCC C Linker
gcc -o "unzipper" ./zip.o
./main.o: In function `zip':
/home/alk/workspace/unzipper/Debug/../zip.c:20: undefined reference to `zip_open'
/home/alk/workspace/unzipper/Debug/../zip.c:27: undefined reference to `zip_get_num_files'
/home/alk/workspace/unzipper/Debug/../zip.c:33: undefined reference to `zip_fopen_index'
/home/alk/workspace/unzipper/Debug/../zip.c:35: undefined reference to `zip_fread'
/home/alk/workspace/unzipper/Debug/../zip.c:38: undefined reference to `zip_fclose'
/home/alk/workspace/unzipper/Debug/../zip.c:43: undefined reference to `zip_close'
collect2: ld returned 1 exit status
Eclipse provides a framework helping you in managing all sources and their references as also spawing compiler and linker tasks and setting their options.
When the linker told you there where undefined references to the zip_*function during the build of your program, the cause for this was, you were missing to tell the linker (via the compiler, via Eclipse) where those zip_* functions could be found.
Those zip_* functions are located in a library, namely libzip.
So what you as the programmer need to tell the linker (via the compiler, via Eclipse) is to link those functions against what the compiler compiled from your sources.
As the result the linker is able to create a runnable program from your compiled sources together with all libraries needed. Certain libraries are know to Eclipse (and therfore to the linker) by default, for example the one containing the C standard functions, namely libc.
To get things going:
1 Remove the source files you pulled from the libzip librarie's sources from your project. Those sources had been compiled into the library libzip, which you will use in your project.
2 Tell the linker (via Eclipse) to use libzip for your project.
Do so by following the steps below:
open the project's properties
click 'C/C++ General'
click 'Path and Symbols', on the left select the 'Libraries' tab, there click 'Add' and enter zip
finally click 'OK'
3 Then try to build your program:
Building target: unzipper
Invoking: GCC C Linker
gcc -o "unzipper" ./zip.o -lzip
Finished building target: unzipper
(Please note additional option -lzip!)
If the developement version of 'libzip' had been installed properly before, you should be fine.
PS: unzipper was the name I used for the Eclispe project to produce the examples.
PSS: I used Eclipse Juno SR1