Fix regex substring capture variables for null matches (again). Bug 2933

Broken-by: 59d66fdc13f0

3 files changed, 14 insertions, 15 deletions

diff --git a/src/src/exim.c b/src/src/exim.c
index 47a685aa7..16c0184e0 100644
--- a/src/src/exim.c
+++ b/src/src/exim.c
@@ -127,16 +127,15 @@ BOOL yield;
 
 if ((yield = (res >= 0)))
   {
+  PCRE2_SIZE * ovec = pcre2_get_ovector_pointer(md);
   res = pcre2_get_ovector_count(md);
   expand_nmax = setup < 0 ? 0 : setup + 1;
   for (int matchnum = setup < 0 ? 0 : 1; matchnum < res; matchnum++)
     {
-    PCRE2_SIZE len;
-    pcre2_substring_get_bynumber(md, matchnum,
-      (PCRE2_UCHAR **)&expand_nstring[expand_nmax], &len);
-    if (!expand_nstring[expand_nmax])
-      { expand_nstring[expand_nmax] = US""; len = 0; }
-    expand_nlength[expand_nmax++] = (int)len;
+    int off = matchnum * 2;
+    int len = ovec[off + 1] - ovec[off];
+    expand_nstring[expand_nmax] = string_copyn(subject + ovec[off], len);
+    expand_nlength[expand_nmax++] = len;
     }
   expand_nmax--;
   }
diff --git a/src/src/malware.c b/src/src/malware.c
index 423a5b692..01dd455ba 100644
--- a/src/src/malware.c
+++ b/src/src/malware.c
@@ -310,16 +310,16 @@ m_pcre_exec(const pcre2_code * cre, uschar * text)
 {
 pcre2_match_data * md = pcre2_match_data_create(2, pcre_gen_ctx);
 int i = pcre2_match(cre, text, PCRE2_ZERO_TERMINATED, 0, 0, md, pcre_gen_mtc_ctx);
-PCRE2_UCHAR * substr = NULL;
-PCRE2_SIZE slen;
+uschar * substr = NULL;
 
 if (i >= 2)				/* Got it */
   {
-  pcre2_substring_get_bynumber(md, 1, &substr, &slen);	/* uses same ctx as md */
-  if (!substr) substr = US"";
+  PCRE2_SIZE * ovec = pcre2_get_ovector_pointer(md);
+  int len = ovec[3] - ovec[2];
+  substr = string_copyn(text + ovec[2], len);
   }
 /* pcre2_match_data_free(md);	gen ctx needs no free */
-return US substr;
+return substr;
 }
 
 static const pcre2_code *
diff --git a/src/src/regex.c b/src/src/regex.c
index b401ba0d7..210620f26 100644
--- a/src/src/regex.c
+++ b/src/src/regex.c
@@ -79,10 +79,10 @@ for (pcre_list * ri = re_list_head; ri; ri = ri->next)
 
     for (int nn = 1; nn < n; nn++)
       {
-      PCRE2_UCHAR * cstr;
-      PCRE2_SIZE cslen;
-      pcre2_substring_get_bynumber(md, nn, &cstr, &cslen);	/* uses same ctx as md */
-      regex_vars[nn-1] = cstr ? CUS cstr : CUS"";
+      PCRE2_SIZE * ovec = pcre2_get_ovector_pointer(md);
+      int off = nn * 2;
+      int len = ovec[off + 1] - ovec[off];
+      regex_vars[nn-1] = string_copyn(linebuffer + ovec[off], len);
       }
 
     return OK;