[glib/wip/3v1n0/regex-pcre2-flags-fixes: 3/7] regex: Compute the offsets size based on match results

[Marco Trevisan <marcotrevi src gnome org>]

commit d2e59a5d5e895b40b1fdd6e6bf2aef4e76fab6a6
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Tue Sep 6 19:05:24 2022 +0200

    regex: Compute the offsets size based on match results
    
    While the ovector count would include all the allocated space, we only
    care about the actual match values, so avoid wasting allocations and
    just use the ones we need to hold the offsets.

 glib/gregex.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)
---
diff --git a/glib/gregex.c b/glib/gregex.c
index cf86f0fe0d..8a3be9076b 100644
--- a/glib/gregex.c
+++ b/glib/gregex.c
@@ -832,10 +832,20 @@ recalc_match_offsets (GMatchInfo *match_info,
                       GError     **error)
 {
   PCRE2_SIZE *ovector;
+  uint32_t ovector_size = 0;
   uint32_t pre_n_offset;
   uint32_t i;
 
-  if (pcre2_get_ovector_count (match_info->match_data) > G_MAXUINT32 / 2)
+  g_assert (!IS_PCRE2_ERROR (match_info->matches));
+
+  if (match_info->matches == PCRE2_ERROR_PARTIAL)
+    ovector_size = 1;
+  else if (match_info->matches > 0)
+    ovector_size = match_info->matches;
+
+  g_assert (ovector_size != 0);
+
+  if (pcre2_get_ovector_count (match_info->match_data) < ovector_size)
     {
       g_set_error (error, G_REGEX_ERROR, G_REGEX_ERROR_MATCH,
                    _("Error while matching regular expression %s: %s"),
@@ -844,7 +854,7 @@ recalc_match_offsets (GMatchInfo *match_info,
     }
 
   pre_n_offset = match_info->n_offsets;
-  match_info->n_offsets = pcre2_get_ovector_count (match_info->match_data) * 2;
+  match_info->n_offsets = ovector_size * 2;
   ovector = pcre2_get_ovector_pointer (match_info->match_data);
 
   if (match_info->n_offsets != pre_n_offset)
@@ -2387,7 +2397,7 @@ g_regex_match_all_full (const GRegex      *regex,
                        _("Error while matching regular expression %s: %s"),
                        regex->pattern, match_error (info->matches));
         }
-      else if (info->matches > 0)
+      else if (info->matches != PCRE2_ERROR_NOMATCH)
         {
           if (!recalc_match_offsets (info, error))
             info->matches = PCRE2_ERROR_NOMATCH;