Re: [Qemu-devel] [PATCH V6 2/2] qemu-img: Add json output option to the info command.

[Kevin Wolf]

Am 27.08.2012 09:15, schrieb Benoît Canet:
> This option --output=[human|json] make qemu-img info output on
> human or JSON representation at the choice of the user.
> 
> example:
> {
>     "snapshots": [
>         {
>             "vm-clock-nsec": 637102488,
>             "name": "vm-20120821145509",
>             "date-sec": 1345553709,
>             "date-nsec": 220289000,
>             "vm-clock-sec": 20,
>             "id": "1",
>             "vm-state-size": 96522745
>         },
>         {
>             "vm-clock-nsec": 28210866,
>             "name": "vm-20120821154059",
>             "date-sec": 1345556459,
>             "date-nsec": 171392000,
>             "vm-clock-sec": 46,
>             "id": "2",
>             "vm-state-size": 101208714
>         }
>     ],
>     "virtual-size": 1073741824,
>     "filename": "snap.qcow2",
>     "cluster-size": 65536,
>     "format": "qcow2",
>     "actual-size": 985587712,
>     "dirty-flag": false
> }
> 
> Signed-off-by: Benoit Canet <address@hidden>
> ---
>  Makefile   |    3 +-
>  qemu-img.c |  259 
> ++++++++++++++++++++++++++++++++++++++++++++++++++----------
>  2 files changed, 218 insertions(+), 44 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index ab82ef3..9ba064b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -160,7 +160,8 @@ tools-obj-y = $(oslib-obj-y) $(trace-obj-y) qemu-tool.o 
> qemu-timer.o \
>       iohandler.o cutils.o iov.o async.o
>  tools-obj-$(CONFIG_POSIX) += compatfd.o
>  
> -qemu-img$(EXESUF): qemu-img.o $(tools-obj-y) $(block-obj-y)
> +qemu-img$(EXESUF): qemu-img.o $(tools-obj-y) $(block-obj-y) $(qapi-obj-y) \
> +                              qapi-visit.o qapi-types.o
>  qemu-nbd$(EXESUF): qemu-nbd.o $(tools-obj-y) $(block-obj-y)
>  qemu-io$(EXESUF): qemu-io.o cmd.o $(tools-obj-y) $(block-obj-y)
>  
> diff --git a/qemu-img.c b/qemu-img.c
> index 80cfb9b..fe4a4fc 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -21,12 +21,16 @@
>   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
>   * THE SOFTWARE.
>   */
> +#include "qapi-visit.h"
> +#include "qapi/qmp-output-visitor.h"
> +#include "qjson.h"
>  #include "qemu-common.h"
>  #include "qemu-option.h"
>  #include "qemu-error.h"
>  #include "osdep.h"
>  #include "sysemu.h"
>  #include "block_int.h"
> +#include <getopt.h>
>  #include <stdio.h>
>  
>  #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"
> +           "  '--output' takes the format in which the output must be done 
> (human or json)\n"
>             "\n"
>             "Parameters to check subcommand:\n"
>             "  '-r' tries to repair any inconsistencies that are found during 
> the check.\n"

qemu-img-cmds.hx and qemu-img.texi should be updated with documentation
of the new option as well.

> @@ -1102,21 +1107,196 @@ static void dump_snapshots(BlockDriverState *bs)
>      g_free(sn_tab);
>  }
>  
> -static int img_info(int argc, char **argv)
> +static void collect_snapshots(BlockDriverState *bs , ImageInfo *info)
> +{
> +    int i, sn_count;
> +    QEMUSnapshotInfo *sn_tab = NULL;
> +    SnapshotInfoList *info_list, *cur_item = NULL;
> +    sn_count = bdrv_snapshot_list(bs, &sn_tab);
> +
> +    for (i = 0; i < sn_count; i++) {
> +        info->has_snapshots = true;
> +        info_list = g_new0(SnapshotInfoList, 1);
> +
> +        info_list->value                = g_new0(SnapshotInfo, 1);
> +        info_list->value->id            = g_strdup(sn_tab[i].id_str);
> +        info_list->value->name          = g_strdup(sn_tab[i].name);
> +        info_list->value->vm_state_size = sn_tab[i].vm_state_size;
> +        info_list->value->date_sec      = sn_tab[i].date_sec;
> +        info_list->value->date_nsec     = sn_tab[i].date_nsec;
> +        info_list->value->vm_clock_sec  = sn_tab[i].vm_clock_nsec / 
> 1000000000;
> +        info_list->value->vm_clock_nsec = sn_tab[i].vm_clock_nsec % 
> 1000000000;
> +
> +        /* XXX: waiting for the qapi to support GSList */

No, GSList isn't typesafe and therefore to be avoided. If anything, the
support we want is for qemu-queue.h types.

> +        if (!cur_item) {
> +            info->snapshots = cur_item = info_list;
> +        } else {
> +            cur_item->next = info_list;
> +            cur_item = info_list;
> +        }
> +
> +    }
> +
> +    g_free(sn_tab);
> +}
> +
> +static void dump_json_image_info(ImageInfo *info)
> +{
> +    Error *errp = NULL;
> +    QString *str;
> +    QmpOutputVisitor *ov = qmp_output_visitor_new();
> +    QObject *obj;
> +    visit_type_ImageInfo(qmp_output_get_visitor(ov),
> +                         &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);
> +}
> +
> +static void collect_backing_file_format(ImageInfo *info, char *filename)
> +{
> +    BlockDriverState *bs = NULL;
> +    bs = bdrv_new_open(filename, NULL,
> +                       BDRV_O_FLAGS | BDRV_O_NO_BACKING);
> +    if (!bs) {
> +        return;
> +    }
> +    info->backing_filename_format =
> +                    g_strdup(bdrv_get_format_name(bs));
> +    bdrv_delete(bs);
> +    info->has_backing_filename_format = true;
> +}

This is new functionality and should be added in a separate patch.

It is also wrong because it uses NULL instead of the explicitly
specified format to open the image.

> +
> +static void collect_image_info(BlockDriverState *bs,
> +                   ImageInfo *info,
> +                   const char *filename,
> +                   const char *fmt)
>  {
> -    int c;
> -    const char *filename, *fmt;
> -    BlockDriverState *bs;
> -    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;
> +    struct stat st;
> +
> +    bdrv_get_geometry(bs, &total_sectors);
> +
> +    info->filename        = g_strdup(filename);
> +    info->format          = g_strdup(bdrv_get_format_name(bs));
> +    info->virtual_size    = total_sectors * 512;
> +    info->actual_size     = bdrv_get_allocated_file_size(bs);
> +    info->has_actual_size = info->actual_size >= 0;
> +    if (bdrv_is_encrypted(bs)) {
> +        info->encrypted = true;
> +        info->has_encrypted = true;
> +    }
> +    if (bdrv_get_info(bs, &bdi) >= 0) {
> +        if (bdi.cluster_size != 0) {
> +            info->cluster_size = bdi.cluster_size;
> +            info->has_cluster_size = true;
> +        }
> +        if (bdi.is_dirty) {
> +            info->dirty_flag = true;
> +        } else {
> +            info->dirty_flag = false;
> +        }

Shorter written as:

info->dirty_flag = bdi.is_dirty;

> +        info->has_dirty_flag = true;
> +    }
> +    bdrv_get_backing_filename(bs, backing_filename, 
> sizeof(backing_filename));
> +    if (backing_filename[0] != '\0') {
> +        info->backing_filename = g_strdup(backing_filename);
> +        info->has_backing_filename = true;
> +        bdrv_get_full_backing_filename(bs, backing_filename2,
> +                                       sizeof(backing_filename2));
> +
> +        if (strcmp(backing_filename, backing_filename2) != 0) {
> +            info->full_backing_filename =
> +                        g_strdup(backing_filename2);
> +             info->has_full_backing_filename = true;
> +        }
> +
> +        if (access(backing_filename2, R_OK) == 0 &&
> +            !stat(backing_filename2, &st) &&
> +            S_ISREG(st.st_mode)) {

What are you doing here? This is most certainly wrong because it doesn't
consider protocols supported by qemu.

Also, I believe what you really want to expose is the backing file
format as specified in the image file (if any), i.e. bs->backing_format.
Opening the backing isn't even necessary then.

> +                collect_backing_file_format(info, backing_filename2);
> +
> +        }
> +    }
> +}
> +
> +static void dump_human_image_info(ImageInfo *info)
> +{
> +    char size_buf[128], dsize_buf[128];
> +    if (!info->has_actual_size) {
> +        snprintf(dsize_buf, sizeof(dsize_buf), "unavailable");
> +    } else {
> +        get_human_readable_size(dsize_buf, sizeof(dsize_buf),
> +                                info->actual_size);
> +    }
> +    get_human_readable_size(size_buf, sizeof(size_buf), info->virtual_size);
> +    printf("image: %s\n"
> +           "file format: %s\n"
> +           "virtual size: %s (%" PRId64 " bytes)\n"
> +           "disk size: %s\n",
> +           info->filename, info->format, size_buf,
> +           info->virtual_size,
> +           dsize_buf);
> +
> +    if (info->has_encrypted && info->encrypted) {
> +        printf("encrypted: yes\n");
> +    }
> +
> +    if (info->has_cluster_size) {
> +        printf("cluster_size: %" PRId64 "\n", info->cluster_size);
> +    }
> +
> +    if (info->has_dirty_flag && info->dirty_flag) {
> +        printf("cleanly shut down: no\n");
> +    }
> +

> +    if (info->has_backing_filename) {
> +        printf("backing file: %s", info->backing_filename);
> +    }
> +
> +    if (info->has_full_backing_filename) {
> +        printf(" (actual path: %s)", info->full_backing_filename);
> +    }
> +
> +    if (info->has_backing_filename) {
> +        putchar('\n');
> +    }

The full filename is only present if the "normal" name is present
(otherwise the output would come out wrong anyway). So:

if (info->has_backing_filename) {
    printf("backing file: %s", info->backing_filename);
    if (info->has_full_backing_filename) {
       printf(" (actual path: %s)", info->full_backing_filename);
    }
    putchar('\n');
}

> +}
> +
> +enum {OPTION_OUTPUT = 256};
> +
> +typedef enum Format {
> +    FORMAT_JSON,
> +    FORMAT_HUMAN,
> +} Format;

Hm, calling this Format is asking for naming conflicts. Maybe OutputFormat?

> +
> +static int img_info(int argc, char **argv)
> +{
> +    int c;
> +    Format output_format;

Format output_format = FORMAT_HUMAN;

> +    const char *filename, *fmt, *output;
> +    BlockDriverState *bs;
> +    ImageInfo *info;
>  
>      fmt = NULL;
> +    output = NULL;
>      for(;;) {
> -        c = getopt(argc, argv, "f:h");
> +        int option_index = 0;
> +        static const struct option long_options[] = {
> +            {"help", no_argument, 0, 'h'},
> +            {"format", required_argument, 0, 'f'},
> +            {"output", required_argument, 0, OPTION_OUTPUT},
> +            {0, 0, 0, 0}
> +        };
> +        c = getopt_long(argc, argv, "f:h",
> +                        long_options, &option_index);
>          if (c == -1) {
>              break;
>          }
> @@ -1128,6 +1308,9 @@ static int img_info(int argc, char **argv)
>          case 'f':
>              fmt = optarg;
>              break;
> +        case OPTION_OUTPUT:
> +            output = optarg;
> +            break;
>          }
>      }
>      if (optind >= argc) {
> @@ -1135,48 +1318,38 @@ static int img_info(int argc, char **argv)
>      }
>      filename = argv[optind++];
>  
> -    bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING);
> -    if (!bs) {
> +    if (output && !strcmp(output, "json")) {
> +        output_format = FORMAT_JSON;
> +    } else if (output && !strcmp(output, "human")) {
> +        output_format = FORMAT_HUMAN;
> +    } else if (output) {
> +        fprintf(stderr,
> +            "Error: --output must be used with human or json as 
> argument.\n");

error_report()?

>          return 1;
> -    }
> -    bdrv_get_geometry(bs, &total_sectors);
> -    get_human_readable_size(size_buf, sizeof(size_buf), total_sectors * 512);
> -    allocated_size = bdrv_get_allocated_file_size(bs);
> -    if (allocated_size < 0) {
> -        snprintf(dsize_buf, sizeof(dsize_buf), "unavailable");
>      } else {
> -        get_human_readable_size(dsize_buf, sizeof(dsize_buf),
> -                                allocated_size);
> +        output_format = FORMAT_HUMAN;
>      }

When you add the default above, you don't need the else branch here.

> -    printf("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);
> -    if (bdrv_is_encrypted(bs)) {
> -        printf("encrypted: yes\n");
> +
> +    info = g_new0(ImageInfo, 1);
> +    bs = bdrv_new_open(filename, fmt, BDRV_O_FLAGS | BDRV_O_NO_BACKING);
> +    if (!bs) {
> +        g_free(info);
> +        return 1;
>      }
> -    if (bdrv_get_info(bs, &bdi) >= 0) {
> -        if (bdi.cluster_size != 0) {
> -            printf("cluster_size: %d\n", bdi.cluster_size);
> -        }
> -        if (bdi.is_dirty) {
> -            printf("cleanly shut down: no\n");
> -        }
> +
> +    collect_image_info(bs, info, filename, fmt);
> +
> +    if (output_format == FORMAT_HUMAN) {
> +        dump_human_image_info(info);
> +        dump_snapshots(bs);
>      }
> -    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);
> -        if (strcmp(backing_filename, backing_filename2) != 0) {
> -            printf(" (actual path: %s)", backing_filename2);
> -        }
> -        putchar('\n');
> +
> +    if (output_format == FORMAT_JSON) {
> +        collect_snapshots(bs, info);
> +        dump_json_image_info(info);
>      }

Use a switch instead of two independent ifs?

> -    dump_snapshots(bs);
> +
> +    qapi_free_ImageInfo(info);
>      bdrv_delete(bs);
>      return 0;
>  }
> 

Kevin