Re: [Libguestfs] [PATCH V3] virt-diff: add new virt-diff tool
On Tue, Aug 21, 2012 at 04:04:54PM +0800, Wanlong Gao wrote:
[...]
>> + spid = fork ();
>> + if (spid == -1) {
>> + perror ("fork");
>> + exit (EXIT_FAILURE);
>> + }
>> + if (spid == 0) {
>> + if (guestfs_mount_local_run (sg) == -1)
>> + exit (EXIT_FAILURE);
>> + _exit (EXIT_SUCCESS);
>> + }
>> +
>> + dpid = fork();
>> + if (dpid == -1) {
>> + perror ("fork");
>> + exit (EXIT_FAILURE);
>> + }
>> + if (dpid == 0) {
>> + if (guestfs_mount_local_run (dg) == -1)
>> + exit (EXIT_FAILURE);
>> + _exit (EXIT_SUCCESS);
>> + }
>> +
>> + const char *dir = argv[optind];
>> + char system_arg[BUFSIZ];
>> + sprintf (system_arg, "diff -urN %s%s %s%s", stempdir, dir,
>> + dtempdir, dir);
>> + sleep (5);
>
> ?
I think I'm waiting for guest launching?
No, that's the wrong thing to do.
The API is in two parts: First guestfs_mount_local prepares the mount
point. Second guestfs_mount_local_run causes requests to be
processed.
You can access the mount point after guestfs_mount_local has returned.
Your process will block until guestfs_mount_local_run is called, but
that doesn't matter in this case (in fact, it's what you want).
Another thing: Don't use sprintf, ever. With the wrong $TMPDIR that
code above is a security hole. Since you need to quote 'dir' (since
it comes from user input) you're going to have to rewrite the whole
call to system(3) so that it uses fork + exec instead.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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