pcre2/pcre2-10.33-Fix-lookbehind-within-lookahead-within-lookbehind-mi.patch

From 44c8382acfe0902b302e0d7a5b1c6d9ee9226a51 Mon Sep 17 00:00:00 2001
From: ph10 <ph10@6239d852-aaf2-0410-a92c-79f79f948069>
Date: Tue, 16 Jul 2019 15:06:21 +0000
Subject: [PATCH] Fix lookbehind within lookahead within lookbehind
 misbehaviour bug.
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git-svn-id: svn://vcs.exim.org/pcre2/code/trunk@1133 6239d852-aaf2-0410-a92c-79f79f948069
Petr Písař: Ported to 10.33.

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 src/pcre2_compile.c  | 58 +++++++++++++++++++++++++++++---------------
 testdata/testinput1  |  6 +++++
 testdata/testinput2  |  3 +++
 testdata/testoutput1 |  9 +++++++
 testdata/testoutput2 |  4 +++
 5 files changed, 61 insertions(+), 19 deletions(-)

diff --git a/src/pcre2_compile.c b/src/pcre2_compile.c
index f6e0a0b..2ae95ed 100644
--- a/src/pcre2_compile.c
+++ b/src/pcre2_compile.c
@@ -135,6 +135,8 @@ static BOOL
   set_lookbehind_lengths(uint32_t **, int *, int *, parsed_recurse_check *,
     compile_block *);
 
+static int
+  check_lookbehinds(uint32_t *, uint32_t **, compile_block *);
 
 
 /*************************************************
@@ -8997,15 +8999,15 @@ for (;; pptr++)
       }
     break;
 
-    /* Lookaheads can be ignored, but we must start the skip inside the group
-    so that it isn't treated as a group within the branch. */
+    /* Lookaheads do not contribute to the length of this branch, but they may
+    contain lookbehinds within them whose lengths need to be set. */
 
     case META_LOOKAHEAD:
     case META_LOOKAHEADNOT:
-    pptr = parsed_skip(pptr + 1, PSKIP_KET);
-    if (pptr == NULL) goto PARSED_SKIP_FAILED;
+    *errcodeptr = check_lookbehinds(pptr + 1, &pptr, cb);
+    if (*errcodeptr != 0) return -1;
 
-    /* Also ignore any qualifiers that follow a lookahead assertion. */
+    /* Ignore any qualifiers that follow a lookahead assertion. */
 
     switch (pptr[1])
       {
@@ -9319,20 +9321,28 @@ set_lookbehind_lengths() for each one. At the start, the errorcode is zero and
 the error offset is marked unset. The enables the functions above not to
 override settings from deeper nestings.
 
-Arguments cb      points to the compile block
-Returns:          0 on success, or an errorcode (cb->erroroffset will be set)
+This function is called recursively from get_branchlength() for lookaheads in
+order to process any lookbehinds that they may contain. It stops when it hits a
+non-nested closing parenthesis in this case, returning a pointer to it.
+
+Arguments
+  pptr    points to where to start (start of pattern or start of lookahead)
+  retptr  if not NULL, return the ket pointer here
+  cb      points to the compile block
+
+Returns:  0 on success, or an errorcode (cb->erroroffset will be set)
 */
 
 static int
-check_lookbehinds(compile_block *cb)
+check_lookbehinds(uint32_t *pptr, uint32_t **retptr, compile_block *cb)
 {
-uint32_t *pptr;
 int errorcode = 0;
 int loopcount = 0;
+int nestlevel = 0;
 
 cb->erroroffset = PCRE2_UNSET;
 
-for (pptr = cb->parsed_pattern; *pptr != META_END; pptr++)
+for (; *pptr != META_END; pptr++)
   {
   if (*pptr < META_END) continue;  /* Literal */
 
@@ -9346,14 +9356,30 @@ for (pptr = cb->parsed_pattern; *pptr != META_END; pptr++)
       pptr += 1;
     break;
 
+    case META_KET:
+    if (--nestlevel < 0)
+      {
+      if (retptr != NULL) *retptr = pptr;
+      return 0;
+      }
+    break;
+
+    case META_ATOMIC:
+    case META_CAPTURE:
+    case META_COND_ASSERT:
+    case META_LOOKAHEAD:
+    case META_LOOKAHEADNOT:
+    case META_NOCAPTURE:
+    case META_SCRIPT_RUN:
+    nestlevel++;
+    break;
+
     case META_ACCEPT:
     case META_ALT:
     case META_ASTERISK:
     case META_ASTERISK_PLUS:
     case META_ASTERISK_QUERY:
-    case META_ATOMIC:
     case META_BACKREF:
-    case META_CAPTURE:
     case META_CIRCUMFLEX:
     case META_CLASS:
     case META_CLASS_EMPTY:
@@ -9361,14 +9387,9 @@ for (pptr = cb->parsed_pattern; *pptr != META_END; pptr++)
     case META_CLASS_END:
     case META_CLASS_NOT:
     case META_COMMIT:
-    case META_COND_ASSERT:
     case META_DOLLAR:
     case META_DOT:
     case META_FAIL:
-    case META_KET:
-    case META_LOOKAHEAD:
-    case META_LOOKAHEADNOT:
-    case META_NOCAPTURE:
     case META_PLUS:
     case META_PLUS_PLUS:
     case META_PLUS_QUERY:
@@ -9378,7 +9399,6 @@ for (pptr = cb->parsed_pattern; *pptr != META_END; pptr++)
     case META_QUERY_QUERY:
     case META_RANGE_ESCAPED:
     case META_RANGE_LITERAL:
-    case META_SCRIPT_RUN:
     case META_SKIP:
     case META_THEN:
     break;
@@ -9879,7 +9899,7 @@ lengths. */
 
 if (has_lookbehind)
   {
-  errorcode = check_lookbehinds(&cb);
+  errorcode = check_lookbehinds(cb.parsed_pattern, NULL, &cb);
   if (errorcode != 0) goto HAD_CB_ERROR;
   }
 
diff --git a/testdata/testinput1 b/testdata/testinput1
index 4d9ec5a..ee9354b 100644
--- a/testdata/testinput1
+++ b/testdata/testinput1
@@ -6365,4 +6365,10 @@ ef) x/x,mark
 /(?(DEFINE)(a|ab))(?1){1}+c/
     abc    
 
+/(?<=(?=.(?<=x)))/aftertext
+    abx
+
+/(?<=(?=(?<=a)))b/
+    ab
+
 # End of testinput1 
diff --git a/testdata/testinput2 b/testdata/testinput2
index 9412bf6..d85fc5f 100644
--- a/testdata/testinput2
+++ b/testdata/testinput2
@@ -5597,4 +5597,7 @@ a)"xI
 # Multiplication overflow
 /(X{65535})(?<=\1{32770})/
 
+/(?<=(?=.(?<=x)))/
+    ab\=ph
+
 # End of testinput2
diff --git a/testdata/testoutput1 b/testdata/testoutput1
index fffb8ec..c9bfea8 100644
--- a/testdata/testoutput1
+++ b/testdata/testoutput1
@@ -10081,4 +10081,13 @@ No match
     abc    
 No match
 
+/(?<=(?=.(?<=x)))/aftertext
+    abx
+ 0: 
+ 0+ x
+
+/(?<=(?=(?<=a)))b/
+    ab
+ 0: b
+
 # End of testinput1 
diff --git a/testdata/testoutput2 b/testdata/testoutput2
index 950095f..6405e26 100644
--- a/testdata/testoutput2
+++ b/testdata/testoutput2
@@ -16948,6 +16948,10 @@ Failed: error 187 at offset 15: lookbehind assertion is too long
 /(X{65535})(?<=\1{32770})/
 Failed: error 187 at offset 10: lookbehind assertion is too long
 
+/(?<=(?=.(?<=x)))/
+    ab\=ph
+No match
+
 # End of testinput2
 Error -70: PCRE2_ERROR_BADDATA (unknown error number)
 Error -62: bad serialized data
-- 
2.20.1