Simple C Program for compression?

[Lakshmipathi]

I need to compress file(s) ..i want it to be tar.bz2 format.
How to do this in a C program?
any idea on this?

I'm think about something like this,
tar -cf - filenames.txt | bzip2 >archivefile.tar.bz2
Try and implement above command by combining fork() and exec() and pipe() system call.

Is there any simple way to achieve this?

[wje_lf]

Will this work for you? Warning: I haven't actually tested this code.

#include <stdlib.h>

int return_status;

return_status=system("tar -cf - filenames.txt | bzip2 >archivefile.tar.bz2");

if(return_status==-1)
{
  fprintf(stderr,"the system() call failed completely");

  exit(1);
}

if(WIFEXITED(return_status))
{
  if(WEXITSTATUS(return_status))
  {
    fprintf(stderr,"the system() call returned with bad status %d\n",WEXITSTATUS(return_status));

    exit(1);
  }
}

if(WIFSIGNALED(return_status))
{
  fprintf(stderr,"the system() call caught signal %d\n",WTERMSIG(return_status));

  exit(1);
}

#ifdef WCOREDUMP
if(WCOREDUMP(return_status))
{
  fprintf(stderr,"a core dump was produced\n");
}
else
{
  fprintf(stderr,"a core dump was not produced\n");
}
#endif

if(WIFSTOPPED(return_status))
{
  fprintf(stderr,"the system() call was interrupted with signal %d\n",WSTOPSIG(return_status));

  exit(2);
}

if(WIFCONTINUED(return_status))
{
  fprintf(stderr,"the system() call was resumed. you should never see this.\n");

  exit(3);
}

You can get more information from these commands at the shell prompt:

man 3 system
man 2 wait

[Lakshmipathi]

thanks wje_lf it works !!
I got another query , is it possible to use tar api in c program rather than using tar as command.

something like this :

tar_compress(char *filename);

Have you come across such stuff?

[wje_lf]

Have you come across such stuff?

tar, no. bz2, yes.

[Cabhan]

I tried Googling for "libtar", and I found a library that appears to be rather old, but it might work.

Another option is to use popen(). It's not using a tar API, but because tar can read and write from/to stdin/stdout, you can actually just open a pipe right to it and write your data directly into the pipe:

char *data;

...

FILE *tar = popen("tar czf tarball.tar -", "w");
fputs(data, tar);

[Lakshmipathi]

Thanks wje_lf I'll check it out the bz2 link...

Thanks Cabhan,I think pipe() will be enough for me ....I'll try both bz2 and pipe with tar and get back here with results...