close all file descriptors using fork

[scienzia]

Hi,

I have an application that uses a fork and and the execv function to start an application.

The problem is that I don't want the child process to inherit the open files of the parent.
I found out that the child is able to access the files opened by the parent before the fork.

Is there a way to close all the files opened in the child process before launching the execv?

Is there another way to solve this problem?

Thanks in advance.

 

[hectorDUQUE]

you have to start your child process by closing all the file descriptors. I think there is not option, because the fork function duplicates the program context, which includes the file descriptors.

   ...
   FILE *fd;
   fd=fopen(filename, "r");
   ...
   if (Fork() == 0) {  //child process
      Close(fd); /* child closes its file descriptor*/

      ...
      // process to be done by the child

      exit(0);         /* child exits */

    } else{ //parent process

     ...
      // process to be done by the parent

    }

if not, you can use threads ...

 

[scienzia]

Hi,

thanks for the response.

I found the solution:

fcntl(fd_gpio, F_SETFD, FD_CLOEXEC);

This makes the file close as soon as you make an exec function.

Thankyou anyway.