Re: [Qemu-devel] [PATCH] qemu-img: sort block formats in help message

[Stefan Hajnoczi <stefanha@redhat.com>]

On Fri, May 02, 2014 at 09:11:15AM -0400, Mike Day wrote:
> The help message for qemu-img lists the supported block formats, of
> which there are 27 as of version 2.0.50. The formats are printed in
> the order of their driver's position in a linked list, which appears
> random. This patch prints the formats in sorted order, making it
> easier to read and to find a specific format in the list.

Looks useful, thanks!

> Signed-off-by: Mike Day <ncmike@ncultra.org>
> ---

This patch is whitespace-damaged so git-am(1) refuses to apply it.
Please use git-send-email(1) to send patches so that the right format is
used.

$ git am
Applying: qemu-img: sort block formats in help message
fatal: unrecognized input

>  qemu-img.c | 33 ++++++++++++++++++++++++++++++++-
>  1 file changed, 32 insertions(+), 1 deletion(-)
> 
>  diff --git a/qemu-img.c b/qemu-img.c
>  index 96f4463..d8b7ef4 100644
>  --- a/qemu-img.c
>  +++ b/qemu-img.c
>  @@ -32,6 +32,7 @@
>  #include "block/block_int.h"
>  #include "block/qapi.h"
>  #include <getopt.h>
>  +#include <glib.h>
>  
>  #define QEMU_IMG_VERSION "qemu-img version " QEMU_VERSION \
>  ", Copyright (c) 2004-2008 Fabrice Bellard\n"
>  @@ -60,6 +61,32 @@ static void format_print(void *opaque, const char *name)
>  printf(" %s", name);
>  }
>  
>  +static gint compare_data(gconstpointer a, gconstpointer b, gpointer user)
>  +{
>  +    return g_strcmp0((const char *)a, (const char *)b);
>  +}
>  +
>  +static void GFunc_print_format(gpointer data, gpointer user)

QEMU coding style is lowercase function and variable names.  The
scripts/checkpatch.pl script should identify coding style violations,
please run it.

>  +{
>  +    format_print(user, data);
>  +}

format_print() isn't called anywhere else, please inline it here since
we no longer need it as its own function.

>  +
>  +static GSequence *init_sequence(void)
>  +{
>  +    return g_sequence_new(NULL);
>  +}

Any reason to hide g_sequence_new(NULL) in it's own helper function?

>  +
>  +static void add_format_to_seq(void *opaque, const char *fmt_name)
>  +{
>  +    GSequence *seq = (GSequence *)opaque;
>  +
>  +    if (!g_sequence_lookup(seq, (gpointer)fmt_name,
>  +                          compare_data, NULL)) {
>  +        g_sequence_insert_sorted(seq, (gpointer)fmt_name,
>  +                                 compare_data, NULL);
>  +    }

The type casts in this patch aren't necessary.  In C void* casts to and
from any type without an explicit cast.  Only C++ demands explicit
casts of void*.