Re: [Qemu-devel] [PATCH] let qemu-img info genereate json output

[Stefan Hajnoczi]

On Fri, Jul 27, 2012 at 06:20:48PM +0800, Wenchao Xia wrote:
>   This patch would add option -j in qemu-img info command, which
> would generate json output in stdout.
> 
> Signed-off-by: Wenchao Xia <address@hidden>
> ---
>  qemu-img.c |  306 +++++++++++++++++++++++++++++++++++++++++++++++++++--------
>  1 files changed, 264 insertions(+), 42 deletions(-)
> 
> diff --git a/qemu-img.c b/qemu-img.c
> index 80cfb9b..a514c17 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -33,6 +33,9 @@
>  #include <windows.h>
>  #endif
> 
> +#include "qint.h"
> +#include "qjson.h"
> +
>  typedef struct img_cmd_t {
>      const char *name;
>      int (*handler)(int argc, char **argv);
> @@ -84,6 +87,7 @@ static void help(void)
>             "  '-p' show progress of command (only certain commands)\n"
>             "  '-S' indicates the consecutive number of bytes that must 
> contain only zeros\n"
>             "       for qemu-img to create a sparse image during conversion\n"
> +           "  '-j' try get json output, which would be in stdout, only valid 
> in info command\n"

"try" makes it sound like this command can fail in some special way.  Instead, 
I suggest:

"  '--format=json' show output in machine-parsable JSON (only for info command)"


>             "\n"
>             "Parameters to check subcommand:\n"
>             "  '-r' tries to repair any inconsistencies that are found during 
> the check.\n"
> @@ -1102,21 +1106,210 @@ static void dump_snapshots(BlockDriverState *bs)
>      g_free(sn_tab);
>  }
> 
> +/* string must be allocated on heap */
> +struct img_infos {
> +    char *filename;
> +    char *fmt;
> +    uint64_t total_sectors;
> +    int64_t allocated_size;
> +    int32 enc_flag;
> +    BlockDriverInfo *bdi;
> +    char *backing_filename;
> +    char *backing_filename_full;
> +    QEMUSnapshotInfo *sn_tab;
> +    int nb_sns;
> +};
> +
> +static void img_infos_init(struct img_infos *pinfo)
> +{
> +    memset(pinfo, 0, sizeof(struct img_infos));
> +}
> +
> +#define TRY_FREE(p) { \
> +    if ((p) != NULL) { \
> +        g_free((p)); \
> +        (p) = NULL; \
> +    } \
> +}

This is not necessary because free(NULL) is a nop.

Stefan