[libvirt] [PATCH v2 06/23] util: rewrite auto cleanup macros to use glib's equivalent

[Ján Tomko]

On Mon, Oct 07, 2019 at 06:14:08PM +0100, Daniel P. Berrangé wrote:
>To facilitate porting over to glib, this rewrites the auto cleanup
>macros to use glib's equivalent.
>
>As a result it is now possible to use g_autoptr/VIR_AUTOPTR, and
>g_auto/VIR_AUTOCLEAN, g_autofree/VIR_AUTOFREE interchangably, regardless
>of which macros were used to declare the cleanup types.
>
>Within the scope of any single method, code must remain consistent
>using either GLib or Libvirt macros, never mixing both. New code
>must preferentially use the GLib macros, and old code will be
>converted incrementally.
>
>Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
>---
> cfg.mk                  |  2 +-
> docs/hacking.html.in    | 18 ++++++++++++++++++
> src/util/viralloc.h     |  5 ++++-
> src/util/virautoclean.h | 38 ++++++++++++++++++++------------------
> 4 files changed, 43 insertions(+), 20 deletions(-)
>
>diff --git a/cfg.mk b/cfg.mk
>index 3eae469165..7319a14d19 100644
>--- a/cfg.mk
>+++ b/cfg.mk
>@@ -1061,7 +1061,7 @@ sc_prohibit_backslash_alignment:
> # Rule to ensure that variables declared using a cleanup macro are
> # always initialized.
> sc_require_attribute_cleanup_initialization:
>-	@prohibit='VIR_AUTO((FREE|PTR|UNREF|CLEAN)\(.+\)|CLOSE|STRINGLIST) *[^=]+;' \
>+	@prohibit='((g_auto(ptr|free)?)|(VIR_AUTO((FREE|PTR|UNREF|CLEAN)\(.+\)|CLOSE|STRINGLIST))) *[^=]+;' \
> 	in_vc_files='\.[chx]$$' \
> 	halt='variable declared with a cleanup macro must be initialized' \
> 	  $(_sc_search_regexp)
>diff --git a/docs/hacking.html.in b/docs/hacking.html.in
>index 5839464e99..40a3c60573 100644
>--- a/docs/hacking.html.in
>+++ b/docs/hacking.html.in
>@@ -1028,6 +1028,24 @@ BAD:
>       <dd>The GLib APIs g_strdup_printf / g_strdup_vprint can be used,
>         but beware that they don't abort on OOM, so the libvirt wrappers
>         may still be desirable to use. Don't use g_vasprintf or g_asprintf.</dd>
>+
>+      <dt>VIR_AUTOPTR, VIR_AUTOCLEAN, VIR_AUTOFREE</dt>
>+      <dd>The GLib macros g_autoptr, g_auto and g_autofree must be used
>+        instead in all new code. In existing code, the GLib macros must
>+        never be mixed with libvirt macros within a method, nor should
>+        they be mixed with VIR_FREE. If introducing GLib macros to an
>+        existing method, any use of libvirt macros must be converted
>+        in an independent commit.
>+      </dd>
>+
>+      <dt>VIR_DEFINE_AUTOPTR_FUNC, VIR_DEFINE_AUTOCLEAN_FUNC</dt>
>+      <dd>The Gib macros G_DEFINE_AUTOPTR_CLEANUP_FUNC and
>+        G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC must be used in all
>+        new code. Existing code should be converted to the
>+        new macros where relevant. It is permissible to use
>+        g_autoptr, g_auto on an object whose cleanup function
>+        is declared with the libvirt macros and vica-verca.

vice-versa

>+      </dd>
>     </dl>
>
>     <h2><a id="file_handling">File handling</a></h2>
>diff --git a/src/util/viralloc.h b/src/util/viralloc.h
>index 517f9aada6..f81ea42902 100644
>--- a/src/util/viralloc.h
>+++ b/src/util/viralloc.h
>@@ -494,8 +494,11 @@ void virDisposeString(char **strptr)
>  * VIR_AUTOFREE:
>  * @type: type of the variable to be freed automatically
>  *
>+ * DEPRECATED: use g_autofree for new code. See hacking

HACKING

>+ * for further guidance.
>+ *
>  * Macro to automatically free the memory allocated to
>  * the variable declared with it by calling virFree
>  * when the variable goes out of scope.
>  */
>-#define VIR_AUTOFREE(type) __attribute__((cleanup(virFree))) type
>+#define VIR_AUTOFREE(type) g_autofree type
>diff --git a/src/util/virautoclean.h b/src/util/virautoclean.h
>index 6da288e67d..d7c1c1ec8b 100644
>--- a/src/util/virautoclean.h
>+++ b/src/util/virautoclean.h
>@@ -20,7 +20,21 @@
>
> #pragma once
>
>-#define VIR_AUTOPTR_FUNC_NAME(type) type##AutoPtrFree
>+/**
>+ * DEPRECATION WARNING
>+ *
>+ * The macros in this file should not be used in newly written code.
>+ * Use the equivalent GLib macros instead.
>+ *
>+ * For existing code, use of the libvirt and GLib macros must NEVER
>+ * be mixed within a single method.
>+ *
>+ * The use of the libvirt VIR_FREE macros should also not be mixed
>+ * with GLib auto-free macros and vica-verca.

vice-versa

Reviewed-by: Ján Tomko <jtomko at redhat.com>

Jano
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