Re: [PATCH] contrib/plugins/execlog: Fix compiler warning

[Peter Maydell]

On Wed, 20 Mar 2024 at 02:05, Yao Xingtao via <qemu-devel@nongnu.org> wrote:
>
> 1. The g_pattern_match_string() is deprecated when glib2 version >= 2.70.
>    Use g_pattern_spec_match_string() instead to avoid this problem.
>
> 2. The type of second parameter in g_ptr_array_add() is
>    'gpointer' {aka 'void *'}, but the type of reg->name is 'const char*'.
>    Cast the type of reg->name to 'gpointer' to avoid this problem.
>
> compiler warning message:
> /root/qemu/contrib/plugins/execlog.c:330:17: warning: ‘g_pattern_match_string’
> is deprecated: Use 'g_pattern_spec_match_string'
> instead [-Wdeprecated-declarations]
>   330 |                 if (g_pattern_match_string(pat, rd->name) ||
>       |                 ^~
> In file included from /usr/include/glib-2.0/glib.h:67,
>                  from /root/qemu/contrib/plugins/execlog.c:9:
> /usr/include/glib-2.0/glib/gpattern.h:57:15: note: declared here
>    57 | gboolean      g_pattern_match_string   (GPatternSpec *pspec,
>       |               ^~~~~~~~~~~~~~~~~~~~~~
> /root/qemu/contrib/plugins/execlog.c:331:21: warning: ‘g_pattern_match_string’
> is deprecated: Use 'g_pattern_spec_match_string'
> instead [-Wdeprecated-declarations]
>   331 |                     g_pattern_match_string(pat, rd_lower)) {
>       |                     ^~~~~~~~~~~~~~~~~~~~~~
> /usr/include/glib-2.0/glib/gpattern.h:57:15: note: declared here
>    57 | gboolean      g_pattern_match_string   (GPatternSpec *pspec,
>       |               ^~~~~~~~~~~~~~~~~~~~~~
> /root/qemu/contrib/plugins/execlog.c:339:63: warning: passing argument 2 of
> ‘g_ptr_array_add’ discards ‘const’ qualifier from pointer target type
> [-Wdiscarded-qualifiers]
>   339 |                             g_ptr_array_add(all_reg_names, reg->name);
>       |                                                            ~~~^~~~~~
> In file included from /usr/include/glib-2.0/glib.h:33:
> /usr/include/glib-2.0/glib/garray.h:198:62: note: expected
> ‘gpointer’ {aka ‘void *’} but argument is of type ‘const char *’
>   198 |                                            gpointer          data);
>       |                                            ~~~~~~~~~~~~~~~~~~^~~~
>

Hi; thanks for this patch.

This fixes a bug reported in the bug tracker so we should put

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2210

in the commit message just above your signed-off-by tag.


> Signed-off-by: Yao Xingtao <yaoxt.fnst@fujitsu.com>
> ---
>  contrib/plugins/execlog.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/contrib/plugins/execlog.c b/contrib/plugins/execlog.c
> index a1dfd59ab7..41f6774116 100644
> --- a/contrib/plugins/execlog.c
> +++ b/contrib/plugins/execlog.c
> @@ -327,8 +327,13 @@ static GPtrArray *registers_init(int vcpu_index)
>              for (int p = 0; p < rmatches->len; p++) {
>                  g_autoptr(GPatternSpec) pat = 
> g_pattern_spec_new(rmatches->pdata[p]);
>                  g_autofree gchar *rd_lower = g_utf8_strdown(rd->name, -1);
> +#if GLIB_VERSION_MAX_ALLOWED < G_ENCODE_VERSION(2, 70)

Elsewhere we do glib version checks with

#if GLIB_CHECK_VERSION(2, 70, 0)
    code for 2.70.0 and up;
#else
    code for older versions
#endif

so I think we should probably do that here too.

>                  if (g_pattern_match_string(pat, rd->name) ||
>                      g_pattern_match_string(pat, rd_lower)) {
> +#else
> +                if (g_pattern_spec_match_string(pat, rd->name) ||
> +                    g_pattern_spec_match_string(pat, rd_lower)) {
> +#endif

Rather than putting this ifdef in the middle of this function,
I think it would be easier to read if we abstract out a function
which does the pattern matching and whose body calls the right
glib function depending on glib version. We generally call these
functions the same as the glib function but with a _qemu suffix
(compare the ones in include/glib-compat.h), so here that would
be g_pattern_spec_match_string_qemu().

>                      Register *reg = init_vcpu_register(rd);
>                      g_ptr_array_add(registers, reg);
>
> @@ -336,7 +341,7 @@ static GPtrArray *registers_init(int vcpu_index)
>                      if (disas_assist) {
>                          g_mutex_lock(&add_reg_name_lock);
>                          if (!g_ptr_array_find(all_reg_names, reg->name, 
> NULL)) {
> -                            g_ptr_array_add(all_reg_names, reg->name);
> +                            g_ptr_array_add(all_reg_names, 
> (gpointer)reg->name);
>                          }
>                          g_mutex_unlock(&add_reg_name_lock);
>                      }

thanks
-- PMM