Re: [Qemu-devel] [PATCH V3 4/4] block: dump snapshot and image info to specified output

[Luiz Capitulino <lcapitulino@redhat.com>]

On Sat, 25 May 2013 11:09:45 +0800
Wenchao Xia <xiawenc@linux.vnet.ibm.com> wrote:

> bdrv_snapshot_dump() and bdrv_image_info_dump() do not dump to a buffer now,
> some internal buffers are still used for format control, which have no
> chance to be truncated. As a result, these two functions have no more issue
> of truncation, and they can be used by both qemu and qemu-img with correct
> parameter specified.
> 
> Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>

I don't like the casting and the void pointers very much, but I can't
suggest anything better:

Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>

> ---
>  block/qapi.c         |   66 +++++++++++++++++++++++++++----------------------
>  include/block/qapi.h |    6 +++-
>  qemu-img.c           |    9 ++++---
>  savevm.c             |    7 +++--
>  4 files changed, 49 insertions(+), 39 deletions(-)
> 
> diff --git a/block/qapi.c b/block/qapi.c
> index 155e77e..794dbf8 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -259,7 +259,8 @@ static char *get_human_readable_size(char *buf, int buf_size, int64_t size)
>      return buf;
>  }
>  
> -char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn)
> +void bdrv_snapshot_dump(fprintf_function func_fprintf, void *f,
> +                        QEMUSnapshotInfo *sn)
>  {
>      char buf1[128], date_buf[128], clock_buf[128];
>      struct tm tm;
> @@ -267,9 +268,9 @@ char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn)
>      int64_t secs;
>  
>      if (!sn) {
> -        snprintf(buf, buf_size,
> -                 "%-10s%-20s%7s%20s%15s",
> -                 "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK");
> +        func_fprintf(f,
> +                     "%-10s%-20s%7s%20s%15s",
> +                     "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK");
>      } else {
>          ti = sn->date_sec;
>          localtime_r(&ti, &tm);
> @@ -282,17 +283,18 @@ char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn)
>                   (int)((secs / 60) % 60),
>                   (int)(secs % 60),
>                   (int)((sn->vm_clock_nsec / 1000000) % 1000));
> -        snprintf(buf, buf_size,
> -                 "%-10s%-20s%7s%20s%15s",
> -                 sn->id_str, sn->name,
> -                 get_human_readable_size(buf1, sizeof(buf1), sn->vm_state_size),
> -                 date_buf,
> -                 clock_buf);
> +        func_fprintf(f,
> +                     "%-10s%-20s%7s%20s%15s",
> +                     sn->id_str, sn->name,
> +                     get_human_readable_size(buf1, sizeof(buf1),
> +                                             sn->vm_state_size),
> +                     date_buf,
> +                     clock_buf);
>      }
> -    return buf;
>  }
>  
> -void bdrv_image_info_dump(ImageInfo *info)
> +void bdrv_image_info_dump(fprintf_function func_fprintf, void *f,
> +                          ImageInfo *info)
>  {
>      char size_buf[128], dsize_buf[128];
>      if (!info->has_actual_size) {
> @@ -302,43 +304,46 @@ void bdrv_image_info_dump(ImageInfo *info)
>                                  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);
> +    func_fprintf(f,
> +                 "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");
> +        func_fprintf(f, "encrypted: yes\n");
>      }
>  
>      if (info->has_cluster_size) {
> -        printf("cluster_size: %" PRId64 "\n", info->cluster_size);
> +        func_fprintf(f, "cluster_size: %" PRId64 "\n",
> +                       info->cluster_size);
>      }
>  
>      if (info->has_dirty_flag && info->dirty_flag) {
> -        printf("cleanly shut down: no\n");
> +        func_fprintf(f, "cleanly shut down: no\n");
>      }
>  
>      if (info->has_backing_filename) {
> -        printf("backing file: %s", info->backing_filename);
> +        func_fprintf(f, "backing file: %s", info->backing_filename);
>          if (info->has_full_backing_filename) {
> -            printf(" (actual path: %s)", info->full_backing_filename);
> +            func_fprintf(f, " (actual path: %s)", info->full_backing_filename);
>          }
> -        putchar('\n');
> +        func_fprintf(f, "\n");
>          if (info->has_backing_filename_format) {
> -            printf("backing file format: %s\n", info->backing_filename_format);
> +            func_fprintf(f, "backing file format: %s\n",
> +                         info->backing_filename_format);
>          }
>      }
>  
>      if (info->has_snapshots) {
>          SnapshotInfoList *elem;
> -        char buf[256];
>  
> -        printf("Snapshot list:\n");
> -        printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
> +        func_fprintf(f, "Snapshot list:\n");
> +        bdrv_snapshot_dump(func_fprintf, f, NULL);
> +        func_fprintf(f, "\n");
>  
>          /* Ideally bdrv_snapshot_dump() would operate on SnapshotInfoList but
>           * we convert to the block layer's native QEMUSnapshotInfo for now.
> @@ -354,7 +359,8 @@ void bdrv_image_info_dump(ImageInfo *info)
>  
>              pstrcpy(sn.id_str, sizeof(sn.id_str), elem->value->id);
>              pstrcpy(sn.name, sizeof(sn.name), elem->value->name);
> -            printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), &sn));
> +            bdrv_snapshot_dump(func_fprintf, f, &sn);
> +            func_fprintf(f, "\n");
>          }
>      }
>  }
> diff --git a/include/block/qapi.h b/include/block/qapi.h
> index 55d1848..e6e568d 100644
> --- a/include/block/qapi.h
> +++ b/include/block/qapi.h
> @@ -36,6 +36,8 @@ void bdrv_collect_image_info(BlockDriverState *bs,
>  BlockInfo *bdrv_query_info(BlockDriverState *s);
>  BlockStats *bdrv_query_stats(const BlockDriverState *bs);
>  
> -char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn);
> -void bdrv_image_info_dump(ImageInfo *info);
> +void bdrv_snapshot_dump(fprintf_function func_fprintf, void *f,
> +                        QEMUSnapshotInfo *sn);
> +void bdrv_image_info_dump(fprintf_function func_fprintf, void *f,
> +                          ImageInfo *info);
>  #endif
> diff --git a/qemu-img.c b/qemu-img.c
> index 5d1e480..82c7977 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1554,16 +1554,17 @@ static void dump_snapshots(BlockDriverState *bs)
>  {
>      QEMUSnapshotInfo *sn_tab, *sn;
>      int nb_sns, i;
> -    char buf[256];
>  
>      nb_sns = bdrv_snapshot_list(bs, &sn_tab);
>      if (nb_sns <= 0)
>          return;
>      printf("Snapshot list:\n");
> -    printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
> +    bdrv_snapshot_dump(fprintf, stdout, NULL);
> +    printf("\n");
>      for(i = 0; i < nb_sns; i++) {
>          sn = &sn_tab[i];
> -        printf("%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn));
> +        bdrv_snapshot_dump(fprintf, stdout, sn);
> +        printf("\n");
>      }
>      g_free(sn_tab);
>  }
> @@ -1613,7 +1614,7 @@ static void dump_human_image_info_list(ImageInfoList *list)
>          }
>          delim = true;
>  
> -        bdrv_image_info_dump(elem->value);
> +        bdrv_image_info_dump(fprintf, stdout, elem->value);
>      }
>  }
>  
> diff --git a/savevm.c b/savevm.c
> index f988e89..9b9d037 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -2540,7 +2540,6 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
>      int nb_sns, i, ret, available;
>      int total;
>      int *available_snapshots;
> -    char buf[256];
>  
>      bs = find_vmstate_bs();
>      if (!bs) {
> @@ -2583,10 +2582,12 @@ void do_info_snapshots(Monitor *mon, const QDict *qdict)
>      }
>  
>      if (total > 0) {
> -        monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), NULL));
> +        bdrv_snapshot_dump((fprintf_function)monitor_printf, mon, NULL);
> +        monitor_printf(mon, "\n");
>          for (i = 0; i < total; i++) {
>              sn = &sn_tab[available_snapshots[i]];
> -            monitor_printf(mon, "%s\n", bdrv_snapshot_dump(buf, sizeof(buf), sn));
> +            bdrv_snapshot_dump((fprintf_function)monitor_printf, mon, sn);
> +            monitor_printf(mon, "\n");
>          }
>      } else {
>          monitor_printf(mon, "There is no suitable snapshot available\n");