Re: [PATCH 2/3] migration: Make save_snapshot() return bool, not 0/-1

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 10/8/20 7:48 PM, Philippe Mathieu-Daudé wrote:
> Just for consistency, following the example documented since
> commit e3fe3988d7 ("error: Document Error API usage rules").

I meant to use this description:

   Just for consistency, following the example documented since
   commit e3fe3988d7 ("error: Document Error API usage rules"),
   return a boolean value indicating an error is set or not.

> Document the function.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>   include/migration/snapshot.h |  9 ++++++++-
>   migration/savevm.c           | 16 ++++++++--------
>   replay/replay-debugging.c    |  2 +-
>   replay/replay-snapshot.c     |  2 +-
>   4 files changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
> index c85b6ec75b..a40c34307b 100644
> --- a/include/migration/snapshot.h
> +++ b/include/migration/snapshot.h
> @@ -15,7 +15,14 @@
>   #ifndef QEMU_MIGRATION_SNAPSHOT_H
>   #define QEMU_MIGRATION_SNAPSHOT_H
>   
> -int save_snapshot(const char *name, Error **errp);
> +/**
> + * save_snapshot: Save a snapshot.
> + * @name: path to snapshot
> + * @errp: pointer to error object
> + * On success, return %true.
> + * On failure, store an error through @errp and return %false.
> + */
> +bool save_snapshot(const char *name, Error **errp);
>   int load_snapshot(const char *name, Error **errp);
>   
>   #endif
> diff --git a/migration/savevm.c b/migration/savevm.c
> index a52da440f4..fd2e5e8b66 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2658,7 +2658,7 @@ int qemu_load_device_state(QEMUFile *f)
>       return 0;
>   }
>   
> -int save_snapshot(const char *name, Error **errp)
> +bool save_snapshot(const char *name, Error **errp)
>   {
>       BlockDriverState *bs;
>       QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
> @@ -2671,29 +2671,29 @@ int save_snapshot(const char *name, Error **errp)
>       AioContext *aio_context;
>   
>       if (migration_is_blocked(errp)) {
> -        return ret;
> +        return false;
>       }
>   
>       if (!replay_can_snapshot()) {
>           error_setg(errp, "Record/replay does not allow making snapshot "
>                      "right now. Try once more later.");
> -        return ret;
> +        return false;
>       }
>   
>       if (!bdrv_all_can_snapshot(errp)) {
> -        return ret;
> +        return false;
>       }
>   
>       /* Delete old snapshots of the same name */
>       if (name) {
>           if (bdrv_all_delete_snapshot(name, errp) < 0) {
> -            return ret;
> +            return false;
>           }
>       }
>   
>       bs = bdrv_all_find_vmstate_bs(errp);
>       if (bs == NULL) {
> -        return ret;
> +        return false;
>       }
>       aio_context = bdrv_get_aio_context(bs);
>   
> @@ -2702,7 +2702,7 @@ int save_snapshot(const char *name, Error **errp)
>       ret = global_state_store();
>       if (ret) {
>           error_setg(errp, "Error saving global state");
> -        return ret;
> +        return false;
>       }
>       vm_stop(RUN_STATE_SAVE_VM);
>   
> @@ -2779,7 +2779,7 @@ int save_snapshot(const char *name, Error **errp)
>       if (saved_vm_running) {
>           vm_start();
>       }
> -    return ret;
> +    return ret == 0;
>   }
>   
>   void qmp_xen_save_devices_state(const char *filename, bool has_live, bool live,
> diff --git a/replay/replay-debugging.c b/replay/replay-debugging.c
> index 8785489c02..5458a73fce 100644
> --- a/replay/replay-debugging.c
> +++ b/replay/replay-debugging.c
> @@ -327,7 +327,7 @@ void replay_gdb_attached(void)
>        */
>       if (replay_mode == REPLAY_MODE_PLAY
>           && !replay_snapshot) {
> -        if (save_snapshot("start_debugging", NULL) != 0) {
> +        if (!save_snapshot("start_debugging", NULL)) {
>               /* Can't create the snapshot. Continue conventional debugging. */
>           }
>       }
> diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
> index e26fa4c892..4f2560d156 100644
> --- a/replay/replay-snapshot.c
> +++ b/replay/replay-snapshot.c
> @@ -77,7 +77,7 @@ void replay_vmstate_init(void)
>   
>       if (replay_snapshot) {
>           if (replay_mode == REPLAY_MODE_RECORD) {
> -            if (save_snapshot(replay_snapshot, &err) != 0) {
> +            if (!save_snapshot(replay_snapshot, &err)) {
>                   error_report_err(err);
>                   error_report("Could not create snapshot for icount record");
>                   exit(1);
>