From a109c9e35a040a7a8032c12ce7396bc949f3f735 Mon Sep 17 00:00:00 2001
From: ph10 <ph10@6239d852-aaf2-0410-a92c-79f79f948069>
Date: Tue, 26 Dec 2017 15:10:04 +0000
Subject: [PATCH 3/3] Fix \K issues in pcre2grep.
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git-svn-id: svn://vcs.exim.org/pcre2/code/trunk@896 6239d852-aaf2-0410-a92c-79f79f948069
Petr Písař: Ported to 10.30.
---
 RunGrepTest         | 11 +++++++++++
 src/pcre2grep.c     | 49 ++++++++++++++++++++++++++++++++++++++++++++-----
 testdata/grepoutput |  9 +++++++++

diff --git a/RunGrepTest b/RunGrepTest
index a7496cb..a26f677 100755
--- a/RunGrepTest
+++ b/RunGrepTest
@@ -630,6 +630,17 @@ echo "RC=$?" >>testtrygrep
 (cd $srcdir; $valgrind $vjs $pcre2grep -Mn -A2 'start[\s]+end' testdata/grepinputM) >>testtrygrep
 echo "RC=$?" >>testtrygrep
 
+echo "---------------------------- Test 125 -----------------------------" >>testtrygrep
+printf "abcd\n" >testNinputgrep
+$valgrind $vjs $pcre2grep --colour=always '(?<=\K.)' testNinputgrep >>testtrygrep
+echo "RC=$?" >>testtrygrep
+$valgrind $vjs $pcre2grep --colour=always '(?=.\K)' testNinputgrep >>testtrygrep
+echo "RC=$?" >>testtrygrep
+$valgrind $vjs $pcre2grep --colour=always '(?<=\K[ac])' testNinputgrep >>testtrygrep
+echo "RC=$?" >>testtrygrep
+$valgrind $vjs $pcre2grep --colour=always '(?=[ac]\K)' testNinputgrep >>testtrygrep
+echo "RC=$?" >>testtrygrep
+
 
 # Now compare the results.
 
diff --git a/src/pcre2grep.c b/src/pcre2grep.c
index e764313..02339f5 100644
--- a/src/pcre2grep.c
+++ b/src/pcre2grep.c
@@ -1607,7 +1607,7 @@ Returns:            nothing
 */
 
 static void
-do_after_lines(unsigned long int lastmatchnumber, char *lastmatchrestart, 
+do_after_lines(unsigned long int lastmatchnumber, char *lastmatchrestart,
   char *endptr, const char *printname)
 {
 if (after_context > 0 && lastmatchnumber > 0)
@@ -2764,11 +2764,38 @@ while (ptr < endptr)
       if ((multiline || do_colour) && !invert)
         {
         int plength;
+        PCRE2_SIZE endprevious;
+
+        /* The use of \K may make the end offset earlier than the start. In
+        this situation, swap them round. */
+
+        if (offsets[0] > offsets[1])
+          {
+          PCRE2_SIZE temp = offsets[0];
+          offsets[0] = offsets[1];
+          offsets[1] = temp;
+          }
+
         FWRITE_IGNORE(ptr, 1, offsets[0], stdout);
         print_match(ptr + offsets[0], offsets[1] - offsets[0]);
+
         for (;;)
           {
-          startoffset = offsets[1];  /* Advance after previous match. */
+          PCRE2_SIZE oldstartoffset = pcre2_get_startchar(match_data);
+
+          endprevious = offsets[1];
+          startoffset = endprevious;  /* Advance after previous match. */
+
+          /* If the pattern contained a lookbehind that included \K, it is
+          possible that the end of the match might be at or before the actual
+          starting offset we have just used. In this case, start one character
+          further on. */
+
+          if (startoffset <= oldstartoffset)
+            {
+            startoffset = oldstartoffset + 1;
+            if (utf) while ((ptr[startoffset] & 0xc0) == 0x80) startoffset++;
+            }
 
           /* If the current match ended past the end of the line (only possible
           in multiline mode), we must move on to the line in which it did end
@@ -2782,6 +2809,7 @@ while (ptr < endptr)
             filepos += (int)(linelength + endlinelength);
             linenumber++;
             startoffset -= (int)(linelength + endlinelength);
+            endprevious -= (int)(linelength + endlinelength);
             t = end_of_line(ptr, endptr, &endlinelength);
             linelength = t - ptr - endlinelength;
             length = (size_t)(endptr - ptr);
@@ -2797,7 +2825,18 @@ while (ptr < endptr)
           loop for any that may follow. */
 
           if (!match_patterns(ptr, length, options, startoffset, &mrc)) break;
-          FWRITE_IGNORE(ptr + startoffset, 1, offsets[0] - startoffset, stdout);
+
+          /* The use of \K may make the end offset earlier than the start. In
+          this situation, swap them round. */
+
+          if (offsets[0] > offsets[1])
+            {
+            PCRE2_SIZE temp = offsets[0];
+            offsets[0] = offsets[1];
+            offsets[1] = temp;
+            }
+
+          FWRITE_IGNORE(ptr + endprevious, 1, offsets[0] - endprevious, stdout);
           print_match(ptr + offsets[0], offsets[1] - offsets[0]);
           }
 
@@ -2805,8 +2844,8 @@ while (ptr < endptr)
         and its line-ending characters (if they matched the pattern), so there
         may be no more to print. */
 
-        plength = (int)((linelength + endlinelength) - startoffset);
-        if (plength > 0) FWRITE_IGNORE(ptr + startoffset, 1, plength, stdout);
+        plength = (int)((linelength + endlinelength) - endprevious);
+        if (plength > 0) FWRITE_IGNORE(ptr + endprevious, 1, plength, stdout);
         }
 
       /* Not colouring or multiline; no need to search for further matches. */
diff --git a/testdata/grepoutput b/testdata/grepoutput
index 7e963fb..e49c2b2 100644
--- a/testdata/grepoutput
+++ b/testdata/grepoutput
@@ -936,3 +936,12 @@ end
 16:start end in between start
 end
 RC=0
+---------------------------- Test 125 -----------------------------
+abcd
+RC=0
+abcd
+RC=0
+abcd
+RC=0
+abcd
+RC=0
-- 
2.13.6