Need help with my copy programme

The code is located here...

http://rafb.net/paste/results/QfwPRg55.html

Basically for an assignment at uni we have to create a small program that takes the following syntax.

copy source destination

SO far my program copies files correctly as far as I can tell but the thing is if i'm copying a executable file, when ever I try and run the copied file always says..

./ben permission denied. I do ls -l and it isnt set as executable in the permission list. How do I set the file to execuable or give permission for it to be executed. I haven't been using c or unix for very long so be kind.

TIA.

chmod

Everything has to be done from within the program.

Isn't chmod just a unix command??

Basically, you've copied the file, but you haven't copied the permissions.

> Isn't chmod just a unix command??
The chmod command is a wrapper around the chmod API call.

Do something like
man 2 chmod

Or how are you writing the file? If you're using open() you can specify the permissions right there as the 3rd parameter.

i don't feel like looking it up right now....

but the hackish way would be:
create a executable bash script from within your program
execute the script
make the script do chmod for you
erase the script
voila!

Can I have some more help using chmod please. I'm having trouble with mode_t. I have only been programming in c for a couple of months and I am stil having problems with it.

can someone please give me some sample code of how I would allow the destination file to be executed.

Thanks in advance.

Post what you tried.

- get value from stat
- pass value to chmod
would be my first guess without looking at the manuals.

Here's a copy program that I wrote at one point that I think worked:

Code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

int main(int argc, char **argv)
{
  int fdin, fdout;
  struct stat st;
  char buf[BUFSIZ];
  int n_read;

  if(argc != 3)
  {
    puts("Usage: mycp <source> <destination>");
    exit(1);
  }
  if((fdin = open(argv[1], O_RDONLY)) == -1)
  {
    printf("open(): %s\n", strerror(errno));
    exit(1);
  }
  if(fstat(fdin, &st) == -1)
  {
    printf("stat(): %s\n", strerror(errno));
    exit(1);
  }

  umask(0);
  if((fdout = open(argv[2], O_WRONLY|O_CREAT|O_TRUNC, st.st_mode)) == -1)
  {
    printf("open(): %s\n", strerror(errno));
    exit(1);
  }

  while((n_read = read(fdin, buf, sizeof(buf))) > 0)
  {
    if(write(fdout, buf, n_read) == -1)
    {
      printf("write(): %s\n", strerror(errno));
      exit(1);
    }
  }

  close(fdin);
  close(fdout);

  if(n_read == -1)
  {
    printf("read(): %s\n", strerror(errno));
    exit(1);
  }

  return 0;
}