[glib/wip/3v1n0/regex-pcre2-flags-fixes: 7/11] gregex: Handle the case we need to re-allocate the match data

[Marco Trevisan <marcotrevi src gnome org>]

commit 0e3f8fc3c1432a1cb00c437198e6f06ea052a9c1
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Tue Sep 6 18:26:12 2022 +0200

    gregex: Handle the case we need to re-allocate the match data
    
    In case PCRE2 returns an empty match
    
    This can be easily tested by initializing the initial match data to a
    value that is less than the expected match values (e.g. by calling
    pcre2_match_data_create (1, NULL)), but we can't do it in our tests
    without bigger changes.

 glib/gregex.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)
---
diff --git a/glib/gregex.c b/glib/gregex.c
index b886b24e2a..58f106419c 100644
--- a/glib/gregex.c
+++ b/glib/gregex.c
@@ -1075,6 +1075,19 @@ g_match_info_next (GMatchInfo  *match_info,
                    match_info->regex->pattern, match_error (match_info->matches));
       return FALSE;
     }
+  else if (match_info->matches == 0)
+    {
+      /* info->offsets is too small. */
+      match_info->n_offsets *= 2;
+      match_info->offsets = g_realloc_n (match_info->offsets,
+                                         match_info->n_offsets,
+                                         sizeof (gint));
+
+      pcre2_match_data_free (match_info->match_data);
+      match_info->match_data = pcre2_match_data_create (match_info->n_offsets, NULL);
+
+      return g_match_info_next (match_info, error);
+    }
   else if (match_info->matches == PCRE2_ERROR_NOMATCH)
     {
       /* We're done with this match info */