Re: [Qemu-devel] [PATCH v2 1/7] blkdebug: Use errp for read_config()

[Kevin Wolf <kwolf@redhat.com>]

Am 22.11.2013 um 17:10 hat Max Reitz geschrieben:
> Use an Error variable in the read_config() function.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/blkdebug.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index 16d2b91..9dfa712 100644
> --- a/block/blkdebug.c
> +++ b/block/blkdebug.c
> @@ -271,7 +271,7 @@ static void remove_rule(BlkdebugRule *rule)
>      g_free(rule);
>  }
>  
> -static int read_config(BDRVBlkdebugState *s, const char *filename)
> +static int read_config(BDRVBlkdebugState *s, const char *filename, Error **errp)

For a complete conversion, this should become a void function.

>  {
>      FILE *f;
>      int ret;
> @@ -279,11 +279,16 @@ static int read_config(BDRVBlkdebugState *s, const char *filename)
>  
>      f = fopen(filename, "r");
>      if (f == NULL) {
> +        error_setg_errno(errp, errno, "Could not read blkdebug config file "
> +                         "'%s'", filename);
>          return -errno;
>      }
>  
>      ret = qemu_config_parse(f, config_groups, filename);
>      if (ret < 0) {
> +        error_setg(errp, "Could not parse blkdebug config file '%s'",
> +                   filename);
> +        ret = -EINVAL;
>          goto fail;
>      }

Any reason for adding the file name here without mentioning it in the
commit message?

I'm not completely sure here, but the information is probably redundant;
the caller already knows what the config file was. On the command line,
this will lead to error messages such as:

qemu: -drive file=blkdebug:/path/to/blkdebug.cfg:foo.qcow2: Could not
read blkdebug config file '/path/to/blkdebug.cfg': No such file or
directory

> @@ -370,9 +375,8 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
>      /* Read rules from config file */
>      config = qemu_opt_get(opts, "config");
>      if (config) {
> -        ret = read_config(s, config);
> -        if (ret < 0) {
> -            error_setg_errno(errp, -ret, "Could not read blkdebug config file");
> +        ret = read_config(s, config, errp);
> +        if (ret) {
>              goto fail;
>          }
>      }

Hm, I see. You actually need to return -errno for bdrv_open(). Then
let's just check if we really want to add the file name in the message.

Kevin