[libvirt] [PATCH v2 1/4] util: string: Introduce macro for automatic string lists

[Erik Skultety]

On Tue, Feb 26, 2019 at 04:48:23PM +0100, Peter Krempa wrote:
> Similar to VIR_AUTOPTR, VIR_AUTOSTRINGLIST defines a list of strings
> which will be freed if the pointer is leaving scope.
>
> Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/util/virstring.c     | 10 ++++++++++
>  src/util/virstring.h     | 10 ++++++++++
>  3 files changed, 21 insertions(+)
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 038a744981..e68e3f3a3b 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -2958,6 +2958,7 @@ virStringHasControlChars;
>  virStringIsEmpty;
>  virStringIsPrintable;
>  virStringListAdd;
> +virStringListAutoFree;
>  virStringListFree;
>  virStringListFreeCount;
>  virStringListGetFirstWithPrefix;
> diff --git a/src/util/virstring.c b/src/util/virstring.c
> index e890dde546..8a791f96d4 100644
> --- a/src/util/virstring.c
> +++ b/src/util/virstring.c
> @@ -318,6 +318,16 @@ void virStringListFree(char **strings)
>  }
>
>
> +void virStringListAutoFree(char ***strings)
> +{
> +    if (!*strings)
> +        return;
> +
> +    virStringListFree(*strings);
> +    *strings = NULL;
> +}
> +
> +
>  /**
>   * virStringListFreeCount:
>   * @strings: array of strings to free
> diff --git a/src/util/virstring.h b/src/util/virstring.h
> index aef82471c2..d14b7f4f49 100644
> --- a/src/util/virstring.h
> +++ b/src/util/virstring.h
> @@ -53,6 +53,7 @@ int virStringListCopy(char ***dst,
>                        const char **src);
>
>  void virStringListFree(char **strings);
> +void virStringListAutoFree(char ***strings);
>  void virStringListFreeCount(char **strings,
>                              size_t count);
>
> @@ -307,6 +308,15 @@ int virStringParsePort(const char *str,
>                         unsigned int *port)
>      ATTRIBUTE_NONNULL(2) ATTRIBUTE_RETURN_CHECK;
>
> +/**
> + * VIR_AUTOSTRINGLIST:
> + *
> + * Declares a NULL-terminated list of strings which will be automatically freed
> + * when the pointer goes out of scope.
> + */
> +# define VIR_AUTOSTRINGLIST \
> +        __attribute__((cleanup(virStringListAutoFree))) char **
> +

IIRC at the beginning we said that all the VIR_AUTO macros should be consistent
in terms of how we use the macro, IOW:

VIR_AUTOFREE(type)
VIR_AUTOPTR(type)
VIR_AUTOCLEAN(type)

although I can't say I personally don't like your version, nevertheless, as I
said we should remain consistent and use 'char **' explicitly when using the
macro.

Reviewed-by: Erik Skultety <eskultet at redhat.com>

Unless someone has any objections to this approach but I find it way cleaner
than v1 :)