Re: [Qemu-devel] [PATCH V3 2/2] qemu-img: Add json output option to the info command.

[Kevin Wolf <kwolf@redhat.com>]

Am 15.08.2012 20:48, schrieb Benoît Canet:
> This additionnal --machine=json option make qemu-img info output on
> stdout a JSON formated representation of the image informations.
> 
> --machine=json was choosen instead of --format=json because the
> info command already have a -f parameter.

Which is not a problem. A machine doesn't care about shortcut options,
always specifying the long option is fine.

However, I wouldn't call that option --format (which would intuitively
relate to the image format) nor --machine (--machine=human looks really
weird), but --output=(json|human)

>  #ifdef _WIN32
> @@ -84,6 +88,7 @@ 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"
> +           "  '-m' or '--machine' takes the format in which the output must be done (json)\n"

You should mention both options, not only the non-default one.

>             "\n"
>             "Parameters to check subcommand:\n"
>             "  '-r' tries to repair any inconsistencies that are found during the check.\n"
> @@ -1102,21 +1107,86 @@ static void dump_snapshots(BlockDriverState *bs)
>      g_free(sn_tab);
>  }
>  
> +static void collect_snapshots(BlockDriverState *bs , ImageInfo *image_info)
> +{
> +    int i, sn_count;
> +    QEMUSnapshotInfo *sn_tab = NULL;
> +    SnapshotInfoList *sn_info_list, *cur_item = NULL;
> +    sn_count = bdrv_snapshot_list(bs, &sn_tab);
> +
> +    for (i = 0; i < sn_count; i++) {
> +        image_info->has_snapshots = true;
> +        sn_info_list = g_new0(SnapshotInfoList, 1);
> +
> +        sn_info_list->value = g_new0(SnapshotInfo, 1);
> +        sn_info_list->value->id = g_strdup(sn_tab[i].id_str);
> +        sn_info_list->value->name = g_strdup(sn_tab[i].name);
> +        sn_info_list->value->vm_state_size = sn_tab[i].vm_state_size;
> +        sn_info_list->value->date_sec = sn_tab[i].date_sec;
> +        sn_info_list->value->date_nsec = sn_tab[i].date_nsec;
> +        sn_info_list->value->vm_clock_nsec = sn_tab[i].vm_clock_nsec;

Aligning the = to the same column wouldn't hurt.

> +
> +        /* XXX: waiting for the qapi to support GSList */

Is this even planned? I would agree with qemu-queue.h structures
available from QAPI, but not GSList. Please change or remove the comment.

> +        if (!cur_item) {
> +            image_info->snapshots = cur_item = sn_info_list;
> +        } else {
> +            cur_item->next = sn_info_list;
> +            cur_item = sn_info_list;
> +        }
> +
> +    }
> +
> +    g_free(sn_tab);
> +}
> +
> +static void dump_json_image_info(ImageInfo *image_info)
> +{
> +    Error *errp = NULL;
> +    QString *str;
> +    QmpOutputVisitor *ov = qmp_output_visitor_new();
> +    QObject *obj;
> +    visit_type_ImageInfo(qmp_output_get_visitor(ov),
> +                         &image_info, NULL, &errp);
> +    obj = qmp_output_get_qobject(ov);
> +    str = qobject_to_json_pretty(obj);
> +    assert(str != NULL);
> +    printf("%s\n", qstring_get_str(str));
> +    qobject_decref(obj);
> +    qmp_output_visitor_cleanup(ov);
> +    QDECREF(str);
> +}
> +
> +#define PRINTH(human, args...) do { \
> +    if (human) {                    \
> +        printf(args);               \
> +    } } while (0);

Extra semicolon,

The existence of this macro doesn't look quite right at the first sight,
but let me check how it's used.

> +
>  static int img_info(int argc, char **argv)
>  {
>      int c;
> -    const char *filename, *fmt;
> -    BlockDriverState *bs;
> +    bool human = true;
> +    const char *filename, *fmt, *machine;
> +    BlockDriverState *bs, *backing_bs = NULL;
>      char size_buf[128], dsize_buf[128];
>      uint64_t total_sectors;
>      int64_t allocated_size;
>      char backing_filename[1024];
>      char backing_filename2[1024];
>      BlockDriverInfo bdi;
> +    ImageInfo *image_info;
>  
>      fmt = NULL;
> +    machine = NULL;
>      for(;;) {
> -        c = getopt(argc, argv, "f:h");
> +        int option_index = 0;
> +        static struct option long_options[] = {
> +            {"help", no_argument, 0, 'h'},
> +            {"format", required_argument, 0, 'f'},
> +            {"machine", required_argument, 0, 'm'},
> +            {0, 0, 0, 0}
> +        };
> +        c = getopt_long(argc, argv, "f:h",
> +                        long_options, &option_index);
>          if (c == -1) {
>              break;
>          }
> @@ -1128,6 +1198,9 @@ static int img_info(int argc, char **argv)
>          case 'f':
>              fmt = optarg;
>              break;
> +        case 'm':
> +            machine = optarg;
> +            break;
>          }
>      }
>      if (optind >= argc) {
> @@ -1135,8 +1208,14 @@ static int img_info(int argc, char **argv)
>      }
>      filename = argv[optind++];
>  
> +    image_info = g_new0(ImageInfo, 1);
> +    if (machine && !strncmp(machine, "json", strlen("json"))) {
> +        human = false;
> +    }

Check against the valid values and exit with an error if it's neither
"json" nor "human" (or "text" or whatever you want to call it).

> +
>      bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING);
>      if (!bs) {
> +        g_free(image_info);
>          return 1;
>      }
>      bdrv_get_geometry(bs, &total_sectors);
> @@ -1148,39 +1227,71 @@ static int img_info(int argc, char **argv)
>          get_human_readable_size(dsize_buf, sizeof(dsize_buf),
>                                  allocated_size);
>      }
> -    printf("image: %s\n"
> +    PRINTH(human, "image: %s\n"
>             "file format: %s\n"
>             "virtual size: %s (%" PRId64 " bytes)\n"
>             "disk size: %s\n",
>             filename, bdrv_get_format_name(bs), size_buf,
>             (total_sectors * 512),
>             dsize_buf);
> +    image_info->filename = g_strdup(filename);
> +    image_info->format = g_strdup(bdrv_get_format_name(bs));
> +    image_info->virtual_size = total_sectors * 512;
> +    image_info->actual_size = allocated_size >= 0 ? allocated_size : 0;
>      if (bdrv_is_encrypted(bs)) {
> -        printf("encrypted: yes\n");
> +        PRINTH(human, "encrypted: yes\n");
> +        image_info->encrypted = true;
> +        image_info->has_encrypted = true;
>      }
>      if (bdrv_get_info(bs, &bdi) >= 0) {
> +        image_info->has_cluster_size = true;
> +        image_info->has_dirty_flag = true;
>          if (bdi.cluster_size != 0) {
> -            printf("cluster_size: %d\n", bdi.cluster_size);
> +            PRINTH(human, "cluster_size: %d\n", bdi.cluster_size);
> +            image_info->cluster_size = bdi.cluster_size;
>          }
>          if (bdi.is_dirty) {
> -            printf("cleanly shut down: no\n");
> +            PRINTH(human, "cleanly shut down: no\n");
> +            image_info->dirty_flag = true;
> +        } else {
> +            image_info->dirty_flag = false;
>          }
>      }
>      bdrv_get_backing_filename(bs, backing_filename, sizeof(backing_filename));
>      if (backing_filename[0] != '\0') {
>          bdrv_get_full_backing_filename(bs, backing_filename2,
>                                         sizeof(backing_filename2));
> -        printf("backing file: %s", backing_filename);
> +        backing_bs = bdrv_new_open(backing_filename2, fmt,
> +                                   BDRV_O_FLAGS | BDRV_O_NO_BACKING);
> +        image_info->backing_filename = g_strdup(backing_filename);
> +        image_info->backing_filename_format =
> +                    g_strdup(bdrv_get_format_name(backing_bs));
> +        bdrv_delete(backing_bs);
> +        PRINTH(human, "backing file: %s", backing_filename);
>          if (strcmp(backing_filename, backing_filename2) != 0) {
> -            printf(" (actual path: %s)", backing_filename2);
> +            PRINTH(human, " (actual path: %s)", backing_filename2);
> +        }
> +        if (human) {
> +            putchar('\n');
>          }
> -        putchar('\n');
> +        image_info->has_backing_filename = true;
> +        image_info->has_backing_filename_format = true;
>      }
> -    dump_snapshots(bs);
> +
> +    if (human) {
> +        dump_snapshots(bs);
> +    } else {
> +        collect_snapshots(bs, image_info);
> +        dump_json_image_info(image_info);
> +    }
> +
> +    qapi_free_ImageInfo(image_info);
>      bdrv_delete(bs);
>      return 0;
>  }

I'm not sure if mixing both modes this way is a great idea. Maybe it's
better to have separate functions for either filling the ImageInfo
struct or human output, that are called only in the appropriate mode.

Kevin