new to emcc, who knows hot to solve the problems: error 'linux/if_link.h' file not found or warning:unresolved symbol: htons

[zhatian diao]

    Hello everyone , I m new to emcc.

   

    Today I followed the user guide to install emcc and run the hello world example successfully.

    However, things went wrong when I tried to compile another c file to js file.   

    At first, I got an error 

       testfiles/getip.c:10:17: fatal error: 'linux/if_link.h' file not found

       #include <linux/if_link.h>

                ^~~~~~~~~~~~~~~~~

      1 error generated.

      ERROR:root:compiler frontend failed to generate LLVM bitcode, halting

    The strange thing is that I compiled the c file early with gcc without error. It can be run successfully.

    So I changed my code and removed "<linux/if_link.h>". I got another compile warning:  warning:unresolved symbol: htons. 

    It s source c code can also be compiled with gcc.

    Is there anything I missed or unconfigured?

    Compile enviroment : ubuntu

    head include: 

       #include <arpa/inet.h>

       #include <sys/socket.h>

       #include <netdb.h>

       #include <ifaddrs.h>

       #include <stdio.h>

       #include <stdlib.h>

       #include <unistd.h>

       #include <string.h>

       #include <linux/if_link.h>

[Brion Vibber]

On Wed, May 9, 2018, 6:28 AM zhatian diao <x25836...@gmail.com> wrote:

    Hello everyone , I m new to emcc.

   

    Today I followed the user guide to install emcc and run the hello world example successfully.

Welcome! :)
 

    However, things went wrong when I tried to compile another c file to js file.   

    At first, I got an error 

       testfiles/getip.c:10:17: fatal error: 'linux/if_link.h' file not found

       #include <linux/if_link.h>

                ^~~~~~~~~~~~~~~~~

      1 error generated.

      ERROR:root:compiler frontend failed to generate LLVM bitcode, halting

    The strange thing is that I compiled the c file early with gcc without error. It can be run successfully.

emscripten is not Linux, and does not include Linux-specific kernel interfaces. Think of it as cross-compiling to another operating system... If your source code needs linux/if_link.h for Linux-specific code, it will need to be modified to build for emscripten.

Note that the networking support in emscripten is limited because the web runtime limited what is possible; you can't look up IP addresses or connect to arbitrary hosts or ports. Make sure your test program is something that would actually work.

 

    So I changed my code and removed "<linux/if_link.h>". I got another compile warning:  warning:unresolved symbol: htons. 

    It s source c code can also be compiled with gcc.

    Is there anything I missed or unconfigured?

    Compile enviroment : ubuntu

    head include: 

       #include <arpa/inet.h>

       #include <sys/socket.h>

       #include <netdb.h>

       #include <ifaddrs.h>

       #include <stdio.h>

       #include <stdlib.h>

       #include <unistd.h>

       #include <string.h>

       #include <linux/if_link.h>

htons is defined in arpa/inet.h which you're also including, so it should work. Can you provide a minimal test case? (Small complete .c file that can be compiled, and the command-line flags you're using to compile it)
 

-- brion

[zhatian diao]

thanks for your reply!

Here is the c source code:

---------------------------------------------

#include <arpa/inet.h>

#include <sys/socket.h>

#include <netdb.h>

#include <ifaddrs.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <string.h>

char * myFunction ();

int main(int argc, char *argv[])

{

        char *str = myFunction();

        printf("%s\n", str);

        return 0;

}

char * myFunction () {

         char *sub_str = malloc(1100 * sizeof(char));

        //char* sub_str = new char[100];

        char *split = ":";

        char *end = ";";

        struct ifaddrs *ifaddr, *ifa;

        int family, s;

        int x=0;

        char host[NI_MAXHOST];

        if (getifaddrs(&ifaddr) == -1)

        {

                perror("getifaddrs");

                exit(EXIT_FAILURE);

        }

        for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next)

        {

                if (ifa->ifa_addr == NULL)

                        continue;

                s=getnameinfo(ifa->ifa_addr,sizeof(struct sockaddr_in),host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST);

                if(ifa->ifa_addr->sa_family==AF_INET)

                {

                        if (s != 0)

                        {

                                printf("getnameinfo() failed: %s\n", gai_strerror(s));

                                exit(EXIT_FAILURE);

                        }

                        if(x==0){

                                strcpy(sub_str, ifa->ifa_name);

                                strcat(sub_str, split);

                                strcat(sub_str, host);

                                strcat(sub_str, end);

                        }else{

                                strcat(sub_str, ifa->ifa_name);

                                strcat(sub_str, split);

                                strcat(sub_str, host);

                                strcat(sub_str, end);

                        }

                        x++;

                }

        }

        int len = strlen(sub_str);

        sub_str[len - 1] = '\0';

        freeifaddrs(ifaddr);

        return sub_str;

}

---------------------------------------------------

and the command-line flags is  gcc -o getip getip.c

[zhatian diao]

By the way,  the emcc compile command  is emcc -g getip.c -o getip.js.   The emcc version is newest because I just installed it yesterday.