[PATCH 2/5] Save trace into CTF format

[Yao Qi]

On 03/02/2013 03:22 AM, Tom Tromey wrote:
> Yao> +  if (fwrite (buf, size, 1, fd) != 1)
> Yao> +    error (_("Unable to write file for saving trace data (%s)"),
> Yao> +	   safe_strerror (errno));
>
> We had this whole thread about using ui-out with patches and everything.
> Upthread you said that it was abandoned due to lack of error checking on
> write.  But I thought that was addressed in the previous thread?
>

I didn't follow up that discussion, but the the last mail on this topic 
was sent from Hui 
<http://sourceware.org/ml/gdb-patches/2012-12/msg00332.html>  and I 
don't see any discussions from then on.  Looks the problem of error 
checking on write was pointed out but don't have an idea to fix it.

> I suppose I don't really care enough to press it.
> I don't recall offhand why I thought it was important; maybe some code
> duplication, but I don't really see it any more.
>

OK.

>
> Yao> +  if (!data->tcs.datastream_fd)
>
> Use "!= NULL".
> I think there are some other cases I didn't point out.
>
> Yao> +  /* Tracepoint number.  */
> Yao> +  ctf_save_write (&data->tcs, (gdb_byte *) &tpnum, 2);
>
> Does endianness matter?
>

We set the "byte_order" to the host-endianness in metadata, and
write data to CTF datastream file in the host-endianness as well.  We 
don't have to worry about endianness here.

>
> Yao>    add_com ("tsave", class_trace, trace_save_command, _("\
> Yao>  Save the trace data to a file.\n\
> Yao>  Use the '-r' option to direct the target to save directly to the file,\n\
> Yao> +Use the '-ctf' option to save the data to CTF format,\n\
> Yao>  using its own filesystem."));
>
> This reads strangely after the change.
> Does -ctf direct the target to use its own filesystem?

Yes, it is a little bit confusing.

> Perhaps rewriting all this into a more "--help" style would be better;
> or otherwise at least repeating the final clause.

I rewrite it in the new patch.  The new patch addresses all the comments.

-- 
Yao (齐尧)
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