From: djberg96@... (Daniel Berger)
Date: 2002-04-17T05:04:06+09:00
Subject: Help wanted for statvfs extension

Hi all,

A few people (including myself) have asked about a ruby interface to
the unix 'df' command.  Since there doesn't seem to be one (at least,
not one that isn't calling 'system' or 'syscall' at some point), I
thought I'd give it a shot.

First, I should mention that I wrote this with Ruby 1.6.6 on Solaris
8.  This is my first attempt at a C extension (no laughing please!). 
I have no idea how portable it is.  Mostly what I'm looking for are
opinions on how I've set things up, if there are any potential memory
leaks, and whether or not I should make this a subclass of File::Stat.
 I realize that there are plenty of missing methods.  Once everything
else is established, the methods will come easy (since they'll just be
struct attribute values).

Anyway, here's the code (below the build instructions).  The module is
called 'statvfs'.  The constructor is 'Statvfs.new'.  The one and only
method at the moment is 'favail'.  Any and all help/opinions are
appreciated.  Thanks!

Regards,

Daniel Berger

# Instructions

To build, create a file called 'extconf.rb' and add these two lines:

require 'mkmf'
create_makefile("statvfs")

Then do:

ruby extconf.rb
make
make install

Then, in a separate script do:

require 'statvfs'
df = Statvfs.new
favail = df.favail('/tmp') # or whatever
puts favail

# SOURCE CODE - statvfs.c
/*****************************
 Statvfs.c

 $Author: djberg96 $
 $Date: 2002/04/15 12:00:00 $

******************************/

#include "ruby.h"
#include <sys/statvfs.h>

VALUE info;

VALUE statvfs_new(VALUE class)
{
   statvfs_t *p;
   p = ALLOC(statvfs_t);
   info = Data_Wrap_Struct(class,0,free,p);
   return info;
}

VALUE statvfs_favail(VALUE self, VALUE dir)
{
   statvfs_t *p;
   int favail;

   Data_Get_Struct(self,statvfs_t,p);
   statvfs(STR2CSTR(dir),p);
   favail = p->f_favail;
   return rb_int_new(favail);
}

static VALUE mStatvfs;
VALUE cStatvfs;

void Init_statvfs()
{
   mStatvfs = rb_define_module("statvfs");
   cStatvfs = rb_define_class("Statvfs",rb_cObject); 

   rb_define_singleton_method(cStatvfs,"new",statvfs_new,0);
   rb_define_method(cStatvfs,"favail",statvfs_favail,1);
}