Break global loop in pcre2test if matching returns the same substring.

src/pcre2test.c

@@ -4426,24 +4426,38 @@ if ((dat_datctl.control & CTL_JITVERIFY) != 0 && jit_stack == NULL)
    PCRE2_JIT_STACK_ASSIGN(compiled_code, jit_callback, NULL);
    }
 
+/* Adjust match_data according to size of offsets required. */
+
+if (dat_datctl.oveccount <= max_oveccount)
+  {
+  SETFLD(match_data, oveccount, dat_datctl.oveccount);
+  }
+else
+  {
+  max_oveccount = dat_datctl.oveccount;
+  PCRE2_MATCH_DATA_FREE(match_data);
+  PCRE2_MATCH_DATA_CREATE(match_data, max_oveccount, NULL);
+  }
+     
 /* Loop for global matching */
 
 for (gmatched = 0;; gmatched++)
   {
   int capcount;
+  PCRE2_SIZE *ovector;
+  PCRE2_SIZE ovecsave[2]; 
+
   jit_was_used = FALSE;
+  ovector = FLD(match_data, ovector);
   
-  /* Adjust match_data according to size of offsets required. */
+  /* After the first time round a global loop, save the current ovector[0,1] so
+  that we can check that they do change each time. Otherwise a matching bug 
+  that returns the same string causes an infinite loop. It has happened! */
 
-  if (dat_datctl.oveccount <= max_oveccount)
+  if (gmatched > 0)
     {  
-    SETFLD(match_data, oveccount, dat_datctl.oveccount);
+    ovecsave[0] = ovector[0];
-    }
+    ovecsave[1] = ovector[1];  
-  else
-    {
-    max_oveccount = dat_datctl.oveccount;
-    PCRE2_MATCH_DATA_FREE(match_data);
-    PCRE2_MATCH_DATA_CREATE(match_data, max_oveccount, NULL);
     } 
    
   /* Do timing if required. */
@@ -4538,7 +4552,7 @@ for (gmatched = 0;; gmatched++)
       }
     }
 
-  /* The result of the match is in now capcount. First handle a successful
+  /* The result of the match is now in capcount. First handle a successful
   match. */
 
   if (capcount >= 0)
@@ -4546,7 +4560,6 @@ for (gmatched = 0;; gmatched++)
     int i;
     uint8_t *nptr;
     BOOL showallused;
-    PCRE2_SIZE *ovector;
     PCRE2_SIZE leftchar = FLD(match_data, leftchar);
     PCRE2_SIZE rightchar = FLD(match_data, rightchar);
 
@@ -4555,16 +4568,30 @@ for (gmatched = 0;; gmatched++)
     if (capcount > (int)dat_datctl.oveccount)
       {
       fprintf(outfile,
-        "** PCRE error: returned count %d is too big for ovector count %d\n",
+        "** PCRE2 error: returned count %d is too big for ovector count %d\n",
         capcount, dat_datctl.oveccount);
       capcount = dat_datctl.oveccount;
       if ((dat_datctl.control & CTL_ANYGLOB) != 0)
         {
         fprintf(outfile, "** Global loop abandoned\n");
-        pat_patctl.options &= ~CTL_ANYGLOB;        /* Break g/G loop */
+        dat_datctl.control &= ~CTL_ANYGLOB;        /* Break g/G loop */
         }
       }
       
+    /* If this is not the first time round a global loop, check that the 
+    returned string has changed. If not, there is a bug somewhere and we must 
+    break the loop because it will go on for ever. We know that for a global
+    match there must be at least two elements in the ovector. This is checked 
+    above. */
+    
+    if (gmatched > 0 && ovecsave[0] == ovector[0] && ovecsave[1] == ovector[1])
+      {
+      fprintf(outfile,  
+        "** PCRE2 error: global repeat returned the same string as previous\n");
+      fprintf(outfile, "** Global loop abandoned\n");
+      dat_datctl.control &= ~CTL_ANYGLOB;        /* Break g/G loop */
+      }   
+
     /* "allcaptures" requests showing of all captures in the pattern, to check
     unset ones at the end. It may be set on the pattern or the data. Implement
     by setting capcount to the maximum. */
@@ -4581,7 +4608,6 @@ for (gmatched = 0;; gmatched++)
     /* Output the captured substrings. Note that, for the matched string,
     the use of \K in an assertion can make the start later than the end. */
 
-    ovector = FLD(match_data, ovector);
     for (i = 0; i < 2*capcount; i += 2)
       {
       PCRE2_SIZE lleft, lmiddle, lright;