Re: [Qemu-devel] [PATCH 1/2] config: qemu_config_parse() return number of config groups

[Markus Armbruster]

Uh, I totally forgot about this series.  My apologies...

Eduardo Habkost <address@hidden> writes:

> Change qemu_config_parse() to return the number of config groups
> in success and -EINVAL on error. This will allow callers of
> qemu_config_parse() to check if something was really loaded from
> the config file.
>
> All existing callers of qemu_config_parse() and
> qemu_read_config_file() only check if the return value was
> negative, so the change shouldn't affect them.

Two of them:

* read_config() maps negative value to -EINVAL.  Callers:

  - blkdebug_open() passes it on.  As a .bdrv_file_open() method, it's
    supposed to return -errno on failure.  Good.

* qemu_read_config_file() maps non-zero value to -EINVAL.  Callers:

  - qemu_read_default_config_file() maps -EINVAL to zero.  WTF?

  - main() passes sterror(EINVAL) to error_report().  Good.

Also: qemu_config_parse() reports errors with error_report().  Let's
have another look at its callers:

* read_config() has an Error ** parameter.  Bad.  Care to convert the
  sucker to Error?

* qemu_read_config_file() doesn't report errors.  Callers:

  - qemu_read_default_config_file() doesn't report errors.  Its called
    by main(), and ...

  - main() reports with error_report().  Good.

>
> Signed-off-by: Eduardo Habkost <address@hidden>
> ---
>  util/qemu-config.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/util/qemu-config.c b/util/qemu-config.c
> index 5527100a01..560c201bd3 100644
> --- a/util/qemu-config.c
> +++ b/util/qemu-config.c
> @@ -379,6 +379,7 @@ void qemu_config_write(FILE *fp)
>      }
>  }
>  
> +/* Returns number of config groups on success, -errno on error */
>  int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname)
>  {
>      char line[1024], group[64], id[64], arg[64], value[1024];
> @@ -386,7 +387,8 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, 
> const char *fname)
>      QemuOptsList *list = NULL;
>      Error *local_err = NULL;
>      QemuOpts *opts = NULL;
> -    int res = -1, lno = 0;
> +    int res = -EINVAL, lno = 0;
> +    int count = 0;
>  
>      loc_push_none(&loc);
>      while (fgets(line, sizeof(line), fp) != NULL) {
> @@ -407,6 +409,7 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, 
> const char *fname)
>                  goto out;
>              }
>              opts = qemu_opts_create(list, id, 1, NULL);
> +            count++;
>              continue;
>          }
>          if (sscanf(line, "[%63[^]]]", group) == 1) {
> @@ -417,6 +420,7 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, 
> const char *fname)
>                  goto out;
>              }
>              opts = qemu_opts_create(list, NULL, 0, &error_abort);
> +            count++;
>              continue;
>          }
>          value[0] = '\0';
> @@ -441,7 +445,7 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, 
> const char *fname)
>          error_report("error reading file");
>          goto out;
>      }
> -    res = 0;
> +    res = count;
>  out:
>      loc_pop(&loc);
>      return res;
> @@ -458,12 +462,7 @@ int qemu_read_config_file(const char *filename)
>  
>      ret = qemu_config_parse(f, vm_config_groups, filename);
>      fclose(f);
> -
> -    if (ret == 0) {
> -        return 0;
> -    } else {
> -        return -EINVAL;
> -    }
> +    return ret;
>  }
>  
>  static void config_parse_qdict_section(QDict *options, QemuOptsList *opts,

I think this mapping to -EINVAL is also superfluous now:

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 6117ce5..fbefa9e 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -252,7 +252,6 @@ static int read_config(BDRVBlkdebugState *s, const char 
*filename,
         ret = qemu_config_parse(f, config_groups, filename);
         if (ret < 0) {
             error_setg(errp, "Could not parse blkdebug config file");
-            ret = -EINVAL;
             goto fail;
         }
     }