strjoker: catastrophic backtracking on *-heavy filter patterns (#513)

* Fix catastrophic backtracking in the strjoker filter matcher

The recursive wildcard matcher re-explored the same (subject, pattern)
positions exponentially on *-heavy patterns against a non-matching
subject: 9 stars against 50 characters already took 149 seconds, about
7x per added star. Subjects come from crawled URLs, so a hostile site
could stall matching against a user's filters (ReDoS).

Memoize failures instead: one bit per (subject, pattern) offset pair,
checked before and recorded after each recursion, which bounds the
work polynomially. A pair that failed once fails forever (*size is
only written on the success path), so the memo is sound and the
matcher's semantics are unchanged; a differential run of 9000 random
pattern/subject/size cases old vs new is byte-identical. The bitmap
lives on the stack for common sizes, on the heap above 2 KB.

The engine test adds the pathological pattern (instant now, hung
before) plus a case where a later star's dead-end must re-extend an
earlier star, which guards against a single-backtrack-point rewrite.
A corpus seed lets the fuzz replay job cover the same shape.

Closes #501

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

* Broaden matching-system test coverage

Adds near-miss negative cases for the arms the filter tests skipped
(word order, exact tails, range boundaries, class case sensitivity,
empty star runs, descending ranges, *[param], rule ordering, failed
size tests), first coverage of mime: filters via a new
-#test=filtermime self-test, and a -#test=filtermemo differential:
20000 seeded random pattern/subject/size cases where the memoized
matcher must agree with a new no-memo oracle (strjoker_nomemo) on
result, *size and *size_flag, asserting both polarities occur.
Corrupting the memo indexing by hand makes the differential fail on
case 8, so it genuinely guards the memo.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

---------

Signed-off-by: Xavier Roche <roche@httrack.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/codeql.yml

@@ -43,6 +43,12 @@ jobs:
           languages: c-cpp
           build-mode: manual
           queries: security-extended
+          # fopen's umask-controlled 0666 is intended for mirror/cache/log
+          # output; the one credential file (cookies.txt) is kept 0600 on Unix.
+          config: |
+            query-filters:
+              - exclude:
+                  id: cpp/world-writable-file-creation
 
       # Manual build: CodeQL traces the compiler, so build exactly what ships.
       - name: Build

.gitignore

@@ -34,8 +34,9 @@ Makefile
 *.so.*
 *.a
 
-# make dist output.
+# make dist output; dist/ holds httrack-gh-release staging artifacts.
 /httrack-*.tar.gz
+/dist/
 
 # Editor / autotools backup files.
 *~

configure.ac

@@ -102,7 +102,8 @@ AX_CHECK_COMPILE_FLAG([-Wignored-qualifiers], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -
 AX_CHECK_COMPILE_FLAG([-Werror=attribute-warning], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -Werror=attribute-warning"])
 AX_CHECK_COMPILE_FLAG([-Werror=user-defined-warnings], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -Werror=user-defined-warnings"])
 AX_CHECK_COMPILE_FLAG([-fstrict-aliasing -Wstrict-aliasing], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fstrict-aliasing -Wstrict-aliasing"])
-AX_CHECK_COMPILE_FLAG([-fstack-protector], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fstack-protector"])
+AX_CHECK_COMPILE_FLAG([-fstack-protector-strong], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fstack-protector-strong"],
+	[AX_CHECK_COMPILE_FLAG([-fstack-protector], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fstack-protector"])])
 AX_CHECK_COMPILE_FLAG([-fstack-clash-protection], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fstack-clash-protection"])
 AX_CHECK_COMPILE_FLAG([-fcf-protection], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fcf-protection"])
 AX_CHECK_LINK_FLAG([-Wl,--discard-all], [DEFAULT_LDFLAGS="$DEFAULT_LDFLAGS -Wl,--discard-all"])
@@ -110,6 +111,13 @@ AX_CHECK_LINK_FLAG([-Wl,--no-undefined], [DEFAULT_LDFLAGS="$DEFAULT_LDFLAGS -Wl,
 AX_CHECK_LINK_FLAG([-Wl,-z,relro,-z,now], [DEFAULT_LDFLAGS="$DEFAULT_LDFLAGS -Wl,-z,relro,-z,now"])
 AX_CHECK_LINK_FLAG([-Wl,-z,noexecstack], [DEFAULT_LDFLAGS="$DEFAULT_LDFLAGS -Wl,-z,noexecstack"])
 
+# Fortify libc calls (=3, else =2) unless the toolchain predefines it; skip
+# sanitizer builds, whose interceptors want the unfortified calls.
+case "$CFLAGS" in
+*-fsanitize=*) ;;
+*) AX_ADD_FORTIFY_SOURCE ;;
+esac
+
 # Force libc back into DT_NEEDED for libraries that reach it only through
 # libhttrack (libhtsjava, the libtest callbacks), but only with a GNU-style
 # linker; Apple ld rejects these flags and links libSystem unconditionally.

fuzz/Makefile.am

@@ -1,7 +1,7 @@
 # libFuzzer harnesses; built only with --enable-fuzzers (requires clang).
 if FUZZERS
 noinst_PROGRAMS = fuzz-charset fuzz-meta fuzz-idna fuzz-entities \
-	fuzz-unescape fuzz-filters fuzz-url
+	fuzz-unescape fuzz-filters fuzz-url fuzz-header fuzz-cachendx
 endif
 
 AM_CPPFLAGS = \
@@ -23,6 +23,8 @@ fuzz_entities_SOURCES = fuzz-entities.c fuzz.h
 fuzz_unescape_SOURCES = fuzz-unescape.c fuzz.h
 fuzz_filters_SOURCES = fuzz-filters.c fuzz.h
 fuzz_url_SOURCES = fuzz-url.c fuzz.h
+fuzz_header_SOURCES = fuzz-header.c fuzz.h
+fuzz_cachendx_SOURCES = fuzz-cachendx.c fuzz.h
 
 # List corpus files explicitly: automake does not expand EXTRA_DIST globs.
 EXTRA_DIST = README.md run-fuzzers.sh \
@@ -34,5 +36,10 @@ EXTRA_DIST = README.md run-fuzzers.sh \
 	corpus/unescape/percent.txt \
 	corpus/filters/filter.bin corpus/filters/filter-size.bin \
 	corpus/filters/regress-empty-subject-unique.bin \
+	corpus/filters/redos-star-classes.bin \
 	corpus/url/http-url.txt corpus/url/relative-path.txt \
-	corpus/url/regress-file-empty-path.txt corpus/url/regress-long-path-abort.txt
+	corpus/url/regress-file-empty-path.txt corpus/url/regress-long-path-abort.txt \
+	corpus/header/full-response.txt corpus/header/redirect.txt \
+	corpus/cachendx/new-format.txt corpus/cachendx/old-format.txt \
+	corpus/cachendx/regress-overadvance.bin \
+	corpus/cachendx/regress-truncated-entry.bin

fuzz/corpus/cachendx/new-format.txt

@@ -0,0 +1,7 @@
+8
+CACHE-1.1
+28
+Mon, 01 Jan 2024 00:00:00 GMT
+www.example.com
+/index.html
+123

fuzz/corpus/cachendx/old-format.txt

@@ -0,0 +1,5 @@
+3
+1.0
+www.example.com
+/page
+5

fuzz/corpus/cachendx/regress-overadvance.bin

@@ -0,0 +1,2 @@
+32768
+CACHE-1.1

fuzz/corpus/cachendx/regress-truncated-entry.bin

@@ -0,0 +1,5 @@
+8
+CACHE-1.1
+1
+x
+www.example.com

fuzz/corpus/header/full-response.txt

@@ -0,0 +1,10 @@
+HTTP/1.1 200 OK
+Content-Type: text/html; charset=utf-8
+Content-Length: 1234
+Content-Encoding: gzip
+Last-Modified: Mon, 01 Jan 2024 00:00:00 GMT
+Etag: "abc"
+Location: http://example.com/x
+Set-Cookie: ID=42; path=/; domain=.example.com
+Content-Range: bytes 0-99/100
+Transfer-Encoding: chunked

fuzz/corpus/header/redirect.txt

@@ -0,0 +1,3 @@
+HTTP/1.0 301 Moved
+Location: /elsewhere
+Content-Disposition: attachment; filename="a.pdf"

fuzz/fuzz-cachendx.c

@@ -0,0 +1,65 @@
+/* ------------------------------------------------------------ */
+/*
+HTTrack Website Copier, Offline Browser for Windows and Unix
+Copyright (C) 2026 Xavier Roche and other contributors
+
+SPDX-License-Identifier: GPL-3.0-or-later
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+Ethical use: we kindly ask that you NOT use this software to harvest email
+addresses or to collect any other private information about people. Doing so
+would dishonor our work and waste the many hours we have spent on it.
+
+Please visit our Website: http://www.httrack.com
+*/
+
+/* Fuzz the cache-index (.ndx) parser: a corrupt or truncated index must not
+   walk the length-prefixed cache_brstr/cache_binput scan past the buffer.
+   Mirrors the -#C cache-listing scan (htscoremain.c). */
+#include "fuzz.h"
+#include "htscache.h"
+#include "htslib.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  char *buf = fuzz_strdup(data, size);
+  const char *const end = buf + size;
+  char firstline[256];
+  char *a = buf;
+
+  /* header: two length-prefixed fields (version, last-modified) */
+  a += cache_brstr(a, firstline, sizeof(firstline));
+  a += cache_brstr(a, firstline, sizeof(firstline));
+
+  /* body: newline-delimited host/file/position triples; the length-prefixed
+     scan must stay inside the buffer */
+  while (a != NULL && a < end) {
+    char BIGSTK line[HTS_URLMAXSIZE * 2];
+    char linepos[256];
+    int pos;
+
+    a = strchr(a + 1, '\n');
+    if (a == NULL)
+      break;
+    a++;
+    a += cache_binput(a, end, line, HTS_URLMAXSIZE);
+    a += cache_binput(a, end, line + strlen(line), HTS_URLMAXSIZE);
+    a += cache_binput(a, end, linepos, 200);
+    sscanf(linepos, "%d", &pos);
+    (void) pos;
+  }
+
+  freet(buf);
+  return 0;
+}

fuzz/fuzz-header.c

@@ -0,0 +1,74 @@
+/* ------------------------------------------------------------ */
+/*
+HTTrack Website Copier, Offline Browser for Windows and Unix
+Copyright (C) 2026 Xavier Roche and other contributors
+
+SPDX-License-Identifier: GPL-3.0-or-later
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+Ethical use: we kindly ask that you NOT use this software to harvest email
+addresses or to collect any other private information about people. Doing so
+would dishonor our work and waste the many hours we have spent on it.
+
+Please visit our Website: http://www.httrack.com
+*/
+
+/* Fuzz the HTTP response-header parser (htslib.c): treatfirstline on the
+   status line, treathead on each following header. Both consume raw bytes
+   off the wire and copy fields into fixed htsblk buffers; treathead also
+   mutates its line in place and drives cookie parsing. */
+#include "fuzz.h"
+#include "htslib.h"
+#include "htsbauth.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  char *buf = fuzz_strdup(data, size);
+  htsblk r;
+  t_cookie *cookie = calloct(1, sizeof(*cookie));
+  char *line = malloct(size + 1);
+  char *p = buf;
+  int first = 1;
+
+  memset(&r, 0, sizeof(r));
+  cookie->max_len = (int) sizeof(cookie->data);
+  r.location = malloct(HTS_URLMAXSIZE * 2);
+  r.location[0] = '\0';
+
+  /* feed one header line at a time, as the receive loop does */
+  while (p != NULL && *p != '\0') {
+    char *nl = strchr(p, '\n');
+    size_t n = (nl != NULL) ? (size_t) (nl - p) : strlen(p);
+    size_t i, len = 0;
+
+    /* binput drops every '\r' on the wire; mirror it */
+    for (i = 0; i < n; i++)
+      if (p[i] != '\r')
+        line[len++] = p[i];
+    line[len] = '\0';
+    if (first) {
+      treatfirstline(&r, line);
+      first = 0;
+    } else {
+      treathead(cookie, "www.example.com", "/", &r, line);
+    }
+    p = (nl != NULL) ? nl + 1 : NULL;
+  }
+
+  freet(r.location);
+  freet(line);
+  freet(cookie);
+  freet(buf);
+  return 0;
+}

fuzz/run-fuzzers.sh

@@ -2,8 +2,8 @@
 # Drive every built harness against its seed corpus.
 #   run-fuzzers.sh <build-fuzz-dir> check       deterministic replay (CI smoke)
 #   run-fuzzers.sh <build-fuzz-dir> [seconds]   timed mutation run (discovery)
-# Replay is crash/leak-only and never mutates, so it can't hit strjoker's
-# catastrophic backtracking; the timed mode can, hence the per-unit -timeout.
+# Replay is crash/leak-only and never mutates; the per-unit -timeout guards
+# both modes against pathological slowdowns (e.g. pre-#501 strjoker).
 set -euo pipefail
 
 srcdir=$(cd "$(dirname "$0")" && pwd)

m4/ax_add_fortify_source.m4

@@ -0,0 +1,119 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_add_fortify_source.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_ADD_FORTIFY_SOURCE
+#
+# DESCRIPTION
+#
+#   Check whether -D_FORTIFY_SOURCE=2 can be added to CPPFLAGS without macro
+#   redefinition warnings, other cpp warnings or linker. Some distributions
+#   (such as Ubuntu or Gentoo Linux) enable _FORTIFY_SOURCE globally in
+#   their compilers, leading to unnecessary warnings in the form of
+#
+#     <command-line>:0:0: error: "_FORTIFY_SOURCE" redefined [-Werror]
+#     <built-in>: note: this is the location of the previous definition
+#
+#   which is a problem if -Werror is enabled. This macro checks whether
+#   _FORTIFY_SOURCE is already defined, and if not, adds -D_FORTIFY_SOURCE=2
+#   to CPPFLAGS.
+#
+#   Newer mingw-w64 msys2 package comes with a bug in
+#   headers-git-7.0.0.5546.d200317d-1. It broke -D_FORTIFY_SOURCE support,
+#   and would need -lssp or -fstack-protector.  See
+#   https://github.com/msys2/MINGW-packages/issues/5803. Try to actually
+#   link it.
+#
+# LICENSE
+#
+#   Copyright (c) 2017 David Seifert <soap@gentoo.org>
+#   Copyright (c) 2019, 2023 Reini Urban <rurban@cpan.org>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 10
+
+AC_DEFUN([AX_ADD_FORTIFY_SOURCE],[
+    ac_save_cflags=$CFLAGS
+    ac_cwerror_flag=yes
+    AX_CHECK_COMPILE_FLAG([-Werror],[CFLAGS="$CFLAGS -Werror"])
+    ax_add_fortify_3_failed=
+    AC_MSG_CHECKING([whether to add -D_FORTIFY_SOURCE=3 to CPPFLAGS])
+    AC_LINK_IFELSE([
+        AC_LANG_PROGRAM([],
+            [[
+                #ifndef _FORTIFY_SOURCE
+                    return 0;
+                #else
+                    _FORTIFY_SOURCE_already_defined;
+                #endif
+            ]]
+        )],
+        AC_LINK_IFELSE([
+            AC_LANG_SOURCE([[
+                #define _FORTIFY_SOURCE 3
+                #include <string.h>
+                int main(void) {
+                    char *s = " ";
+                    strcpy(s, "x");
+                    return strlen(s)-1;
+                }
+              ]]
+            )],
+            [
+              AC_MSG_RESULT([yes])
+              CFLAGS=$ac_save_cflags
+              CPPFLAGS="$CPPFLAGS -D_FORTIFY_SOURCE=3"
+            ], [
+              AC_MSG_RESULT([no])
+              ax_add_fortify_3_failed=1
+            ],
+        ),
+        [
+          AC_MSG_RESULT([no])
+          ax_add_fortify_3_failed=1
+        ])
+    if test -n "$ax_add_fortify_3_failed"
+    then
+    AC_MSG_CHECKING([whether to add -D_FORTIFY_SOURCE=2 to CPPFLAGS])
+    AC_LINK_IFELSE([
+        AC_LANG_PROGRAM([],
+            [[
+                #ifndef _FORTIFY_SOURCE
+                    return 0;
+                #else
+                    _FORTIFY_SOURCE_already_defined;
+                #endif
+            ]]
+        )],
+        AC_LINK_IFELSE([
+            AC_LANG_SOURCE([[
+                #define _FORTIFY_SOURCE 2
+                #include <string.h>
+                int main(void) {
+                    char *s = " ";
+                    strcpy(s, "x");
+                    return strlen(s)-1;
+                }
+              ]]
+            )],
+            [
+              AC_MSG_RESULT([yes])
+              CFLAGS=$ac_save_cflags
+              CPPFLAGS="$CPPFLAGS -D_FORTIFY_SOURCE=2"
+            ], [
+              AC_MSG_RESULT([no])
+              CFLAGS=$ac_save_cflags
+            ],
+        ),
+        [
+          AC_MSG_RESULT([no])
+          CFLAGS=$ac_save_cflags
+        ])
+    fi
+])

man/httrack.1

@@ -3,7 +3,7 @@
 .\"
 .\" This file is generated by man/makeman.sh; do not edit by hand.
 .\" SPDX-License-Identifier: GPL-3.0-or-later
-.TH httrack 1 "27 June 2026" "httrack website copier"
+.TH httrack 1 "07 July 2026" "httrack website copier"
 .SH NAME
 httrack \- offline browser : copy websites to a local directory
 .SH SYNOPSIS
@@ -51,6 +51,7 @@ httrack \- offline browser : copy websites to a local directory
 [ \fB\-%T, \-\-utf8\-conversion\fR ]
 [ \fB\-bN, \-\-cookies[=N]\fR ]
 [ \fB\-%K, \-\-cookies\-file\fR ]
+[ \fB\-%Y, \-\-why\fR ]
 [ \fB\-u, \-\-check\-type[=N]\fR ]
 [ \fB\-j, \-\-parse\-java[=N]\fR ]
 [ \fB\-sN, \-\-robots[=N]\fR ]
@@ -218,6 +219,8 @@ links conversion to UTF\-8 (\-\-utf8\-conversion)
 accept cookies in cookies.txt (0=do not accept,* 1=accept) (\-\-cookies[=N])
 .IP \-%K
 load extra cookies from a Netscape cookies.txt (\-\-cookies\-file <param>)
+.IP \-%Y
+explain which filter rule accepts or rejects a URL, then exit (\-\-why <param>)
 .IP \-u
 check document type if unknown (cgi,asp..) (u0 don't check, * u1 check but /, u2 check always) (\-\-check\-type[=N])
 .IP \-j

src/htsalias.c

@@ -114,6 +114,8 @@ const char *hts_optalias[][4] = {
    "strip [host/pattern=]key1,key2,... from URLs"},
   {"cookies-file", "-%K", "param1",
    "load extra cookies from a Netscape cookies.txt"},
+  {"why", "-%Y", "param1",
+   "explain which filter rule accepts or rejects a URL, then exit"},
   {"pause", "-%G", "param1",
    "random pause of MIN[:MAX] seconds between files"},
   {"generate-errors", "-o", "single", ""},

src/htsbauth.c

@@ -307,14 +307,25 @@ int cookie_load(t_cookie * cookie, const char *fpath, const char *name) {
   return -1;
 }
 
-// écrire cookies.txt
-// !=0 : erreur
+/* Write cookies.txt; returns 0 on success. The jar holds live session
+   cookies, so keep it owner-only on Unix (Windows inherits folder ACLs). */
 int cookie_save(t_cookie * cookie, const char *name) {
   char catbuff[CATBUFF_SIZE];
 
   if (strnotempty(cookie->data)) {
     char BIGSTK line[8192];
+#ifdef _WIN32
     FILE *fp = fopen(fconv(catbuff, sizeof(catbuff), name), "wb");
+#else
+    const int fd = open(fconv(catbuff, sizeof(catbuff), name),
+                        O_WRONLY | O_CREAT | O_TRUNC, HTS_PROTECT_FILE);
+    FILE *fp = fd != -1 ? fdopen(fd, "wb") : NULL;
+
+    if (fd != -1 && fp == NULL)
+      close(fd);    /* fdopen failed: don't leak the descriptor */
+    if (fp != NULL) /* O_CREAT's mode skips pre-existing jars: tighten those */
+      (void) fchmod(fd, HTS_PROTECT_FILE);
+#endif
 
     if (fp) {
       char *a = cookie->data;

src/htscache.h

@@ -89,14 +89,11 @@ typedef enum {
    the involved files are absent. */
 void hts_cache_reconcile(httrackp *opt, hts_cache_reconcile_mode mode);
 
-int cache_writedata(FILE * cache_ndx, FILE * cache_dat, const char *str1,
-                    const char *str2, char *outbuff, int len);
-int cache_readdata(cache_back * cache, const char *str1, const char *str2,
-                   char **inbuff, int *len);
-
 void cache_rstr(FILE *fp, char *s, size_t s_size);
 char *cache_rstr_addr(FILE * fp);
 int cache_brstr(char *adr, char *s, size_t s_size);
+/* binput over a NUL-terminated buffer, bounded: no read starts at/past end. */
+int cache_binput(char *adr, const char *end, char *s, int max);
 int cache_brint(char *adr, int *i);
 void cache_rint(FILE * fp, int *i);
 void cache_rLLint(FILE * fp, LLint * i);

src/htscache_selftest.c

@@ -78,14 +78,6 @@ static void selftest_open_for_read(cache_back *cache, httrackp *opt) {
 }
 
 static void selftest_close(cache_back *cache) {
-  if (cache->dat != NULL) {
-    fclose(cache->dat);
-    cache->dat = NULL;
-  }
-  if (cache->ndx != NULL) {
-    fclose(cache->ndx);
-    cache->ndx = NULL;
-  }
   if (cache->zipOutput != NULL) {
     zipClose(cache->zipOutput,
              "Created by HTTrack Website Copier (cache self-test)");
@@ -989,26 +981,15 @@ int cache_reconcile_selftest(httrackp *opt, const char *dir) {
   failures +=
       reconcile_expect(opt, "hts-cache/old.zip", SOLID, "promote-zip-noop");
 
-  /* PROMOTE: a pure-legacy old generation is promoted too (was dead when no
-     zip cache existed) */
+  /* PROMOTE: the removed pre-3.31 legacy pair is left alone */
   reconcile_wipe(opt);
   reconcile_put(opt, "hts-cache/old.dat", SOLID);
   reconcile_put(opt, "hts-cache/old.ndx", TINY);
   hts_cache_reconcile(opt, CACHE_RECONCILE_PROMOTE);
-  failures += reconcile_expect(opt, "hts-cache/new.dat", SOLID, "promote-dat");
-  failures += reconcile_expect(opt, "hts-cache/new.ndx", TINY, "promote-dat");
-  failures += reconcile_expect(opt, "hts-cache/old.dat", -1, "promote-dat");
-
-  /* PROMOTE: a half-written legacy new pair is replaced by the old pair */
-  reconcile_wipe(opt);
-  reconcile_put(opt, "hts-cache/new.dat", TINY);
-  reconcile_put(opt, "hts-cache/old.dat", SOLID);
-  reconcile_put(opt, "hts-cache/old.ndx", TINY);
-  hts_cache_reconcile(opt, CACHE_RECONCILE_PROMOTE);
-  failures +=
-      reconcile_expect(opt, "hts-cache/new.dat", SOLID, "promote-dat-partial");
-  failures +=
-      reconcile_expect(opt, "hts-cache/new.ndx", TINY, "promote-dat-partial");
+  failures += reconcile_expect(opt, "hts-cache/new.dat", -1, "promote-dat");
+  failures += reconcile_expect(opt, "hts-cache/new.ndx", -1, "promote-dat");
+  failures += reconcile_expect(opt, "hts-cache/old.dat", SOLID, "promote-dat");
+  failures += reconcile_expect(opt, "hts-cache/old.ndx", TINY, "promote-dat");
 
   /* INTERRUPTED: no lock file, no action */
   reconcile_wipe(opt);
@@ -1058,7 +1039,7 @@ int cache_reconcile_selftest(httrackp *opt, const char *dir) {
   failures +=
       reconcile_expect(opt, "hts-cache/new.zip", MID, "interrupted-bignew");
 
-  /* INTERRUPTED: the legacy pair follows the same size rule (was dead code) */
+  /* INTERRUPTED: the removed pre-3.31 legacy pair is left alone */
   reconcile_wipe(opt);
   reconcile_put(opt, "hts-in_progress.lock", 0);
   reconcile_put(opt, "hts-cache/new.dat", TINY);
@@ -1067,9 +1048,13 @@ int cache_reconcile_selftest(httrackp *opt, const char *dir) {
   reconcile_put(opt, "hts-cache/old.ndx", MID);
   hts_cache_reconcile(opt, CACHE_RECONCILE_INTERRUPTED);
   failures +=
-      reconcile_expect(opt, "hts-cache/new.dat", SOLID, "interrupted-dat");
+      reconcile_expect(opt, "hts-cache/new.dat", TINY, "interrupted-dat");
   failures +=
-      reconcile_expect(opt, "hts-cache/new.ndx", MID, "interrupted-dat");
+      reconcile_expect(opt, "hts-cache/new.ndx", TINY, "interrupted-dat");
+  failures +=
+      reconcile_expect(opt, "hts-cache/old.dat", SOLID, "interrupted-dat");
+  failures +=
+      reconcile_expect(opt, "hts-cache/old.ndx", MID, "interrupted-dat");
 
   /* ROLLBACK: the old zip generation is restored (a zip cache used to lose
      its only good generation here) */
@@ -1089,17 +1074,18 @@ int cache_reconcile_selftest(httrackp *opt, const char *dir) {
   failures += reconcile_expect(opt, "hts-cache/new.lst", MID, "rollback-lst");
   failures += reconcile_expect(opt, "hts-cache/new.txt", MID, "rollback-txt");
 
-  /* ROLLBACK: full legacy generation incl. sidecars (historical behavior) */
+  /* ROLLBACK: sidecars restored, the removed pre-3.31 pair left alone */
   reconcile_wipe(opt);
   reconcile_put(opt, "hts-cache/new.dat", TINY);
-  reconcile_put(opt, "hts-cache/new.ndx", TINY);
   reconcile_put(opt, "hts-cache/old.dat", SOLID);
   reconcile_put(opt, "hts-cache/old.ndx", MID);
   reconcile_put(opt, "hts-cache/old.lst", MID);
   reconcile_put(opt, "hts-cache/old.txt", MID);
   hts_cache_reconcile(opt, CACHE_RECONCILE_ROLLBACK);
-  failures += reconcile_expect(opt, "hts-cache/new.dat", SOLID, "rollback-dat");
-  failures += reconcile_expect(opt, "hts-cache/new.ndx", MID, "rollback-dat");
+  failures += reconcile_expect(opt, "hts-cache/new.dat", TINY, "rollback-dat");
+  failures += reconcile_expect(opt, "hts-cache/new.ndx", -1, "rollback-dat");
+  failures += reconcile_expect(opt, "hts-cache/old.dat", SOLID, "rollback-dat");
+  failures += reconcile_expect(opt, "hts-cache/old.ndx", MID, "rollback-dat");
   failures += reconcile_expect(opt, "hts-cache/new.lst", MID, "rollback-dat");
   failures += reconcile_expect(opt, "hts-cache/new.txt", MID, "rollback-dat");
 
@@ -1113,6 +1099,101 @@ int cache_reconcile_selftest(httrackp *opt, const char *dir) {
   return failures;
 }
 
+/* The pre-3.31 .dat/.ndx import was removed: cache_init must refuse the
+   legacy pair, leave the files in place, and not flag an update run. */
+int cache_legacy_refused_selftest(httrackp *opt, const char *dir) {
+  int failures = 0;
+  int variant;
+
+  selftest_tag = "cache-legacy";
+  golden_setup(opt, dir);
+#ifdef _WIN32
+  mkdir(reconcile_st_path(opt, "hts-cache"));
+#else
+  mkdir(reconcile_st_path(opt, "hts-cache"), HTS_PROTECT_FOLDER);
+#endif
+
+  /* variant 0: old.dat/old.ndx (--update layout); 1: new.dat/new.ndx (ro) */
+  for (variant = 0; variant < 2; variant++) {
+    cache_back cache;
+    const char *const dat =
+        variant == 0 ? "hts-cache/old.dat" : "hts-cache/new.dat";
+    const char *const ndx =
+        variant == 0 ? "hts-cache/old.ndx" : "hts-cache/new.ndx";
+
+    reconcile_wipe(opt);
+    reconcile_put(opt, dat, 4096);
+    reconcile_put(opt, ndx, 4096);
+    opt->is_update = 0;
+    selftest_open(&cache, opt, /*ro*/ variant == 1);
+    if (cache_readable(&cache)) {
+      printf("cache-legacy: variant %d imported a removed format\n", variant);
+      failures++;
+    }
+    if (coucal_nitems(cache.hashtable) != 0) { /* no phantom index entries */
+      printf("cache-legacy: variant %d imported index entries\n", variant);
+      failures++;
+    }
+    if (opt->is_update) {
+      printf("cache-legacy: variant %d flagged an update\n", variant);
+      failures++;
+    }
+    if (fsize(reconcile_st_path(opt, dat)) != 4096 ||
+        fsize(reconcile_st_path(opt, ndx)) != 4096) {
+      printf("cache-legacy: variant %d touched the legacy files\n", variant);
+      failures++;
+    }
+    if (cache.lst != NULL) {
+      fclose(cache.lst);
+      cache.lst = NULL;
+    }
+    if (cache.txt != NULL) {
+      fclose(cache.txt);
+      cache.txt = NULL;
+    }
+    selftest_close(&cache);
+  }
+
+  /* a healthy zip must win over stray legacy files, with no refusal */
+  {
+    cache_back cache;
+    const char *const body = "<html>zip wins</html>";
+
+    reconcile_wipe(opt);
+    selftest_open_for_write(&cache, opt);
+    store_entry(opt, &cache, "example.com", "/", "example.com/index.html", 200,
+                "OK", "text/html", "utf-8", "", "", "", "", body, strlen(body));
+    selftest_close(&cache);
+    reconcile_put(opt, "hts-cache/old.ndx", 4096);
+    reconcile_put(opt, "hts-cache/old.dat", 4096);
+    selftest_open_for_read(&cache, opt);
+    if (!cache_readable(&cache)) {
+      printf("cache-legacy: stray legacy files shadowed the zip cache\n");
+      failures++;
+    }
+    failures +=
+        check_entry(opt, &cache, "example.com", "/", 200, "OK", "text/html",
+                    "utf-8", "", "", "", "", body, strlen(body));
+    if (fsize(reconcile_st_path(opt, "hts-cache/old.ndx")) != 4096 ||
+        fsize(reconcile_st_path(opt, "hts-cache/old.dat")) != 4096) {
+      printf("cache-legacy: zip-wins pass touched the legacy files\n");
+      failures++;
+    }
+    if (cache.lst != NULL) {
+      fclose(cache.lst);
+      cache.lst = NULL;
+    }
+    if (cache.txt != NULL) {
+      fclose(cache.txt);
+      cache.txt = NULL;
+    }
+    selftest_close(&cache);
+  }
+
+  reconcile_wipe(opt);
+  return failures;
+}
+
 /* --- read-side corruption injection --------------------------------------- */
 
 /* canary read back intact after each corruption; victim gets the byte surgery

src/htscache_selftest.h

@@ -60,6 +60,10 @@ int cache_write_failure_selftest(httrackp *opt, const char *dir);
    under <dir>. Returns the failed-check count. */
 int cache_reconcile_selftest(httrackp *opt, const char *dir);
 
+/* Verify cache_init refuses a pre-3.31 .dat/.ndx cache without touching it.
+   Returns the number of failed checks (0 = pass). */
+int cache_legacy_refused_selftest(httrackp *opt, const char *dir);
+
 /* Inject read-side corruption (zip byte surgery: bad size, header, deflate)
    under <dir> and assert every case degrades to STATUSCODE_INVALID without
    tainting a sibling entry. */

src/htscore.c

@@ -138,14 +138,6 @@ RUN_CALLBACK0(opt, end); \
       freet(cache.use);                                                        \
       cache.use = NULL;                                                        \
     }                                                                          \
-    if (cache.dat) {                                                           \
-      fclose(cache.dat);                                                       \
-      cache.dat = NULL;                                                        \
-    }                                                                          \
-    if (cache.ndx) {                                                           \
-      fclose(cache.ndx);                                                       \
-      cache.ndx = NULL;                                                        \
-    }                                                                          \
     if (cache.zipOutput) {                                                     \
       zipClose(cache.zipOutput,                                                \
                "Created by HTTrack Website Copier/" HTTRACK_VERSION);          \
@@ -155,10 +147,6 @@ RUN_CALLBACK0(opt, end); \
       unzClose(cache.zipInput);                                                \
       cache.zipInput = NULL;                                                   \
     }                                                                          \
-    if (cache.olddat) {                                                        \
-      fclose(cache.olddat);                                                    \
-      cache.olddat = NULL;                                                     \
-    }                                                                          \
     if (cache.lst) {                                                           \
       fclose(cache.lst);                                                       \
       cache.lst = opt->state.strc.lst = NULL;                                  \
@@ -488,32 +476,11 @@ void hts_finish_makeindex(httrackp *opt, int *makeindex_done,
   *makeindex_done = 1;
 }
 
-/* Flush the parsed HTML output buffer to disk, skipping the rewrite when the
- * on-disk MD5 is unchanged. */
+/* Flush the parsed HTML output buffer to disk. */
 void hts_finish_html_file(httrackp *opt, cache_back *cache, htsblk *r,
                           FILE **fp, const char *ht_buff, size_t ht_len,
                           const char *adr, const char *fil, const char *save) {
-  char digest[32 + 2];
-  off_t fsize_old =
-      fsize(fconv(OPT_GET_BUFF(opt), OPT_GET_BUFF_SIZE(opt), save));
-  int ok = 0;
-
-  digest[0] = '\0';
-  domd5mem(ht_buff, ht_len, digest, 1);
-  if (fsize_old == (off_t) ht_len) {
-    int mlen = 0;
-    char *mbuff;
-
-    cache_readdata(cache, "//[HTML-MD5]//", save, &mbuff, &mlen);
-    if (mlen)
-      mbuff[mlen] = '\0';
-    if ((mlen == 32) && (strcmp(((mbuff != NULL) ? mbuff : ""), digest) == 0)) {
-      ok = 1;
-      hts_log_print(opt, LOG_DEBUG, "File not re-written (md5): %s", save);
-    }
-    freet(mbuff);
-  }
-  if (!ok) {
+  {
     file_notify(opt, adr, fil, save, 1, 1, r->notmodified);
     *fp = filecreate(&opt->state.strc, save);
     if (*fp) {
@@ -545,13 +512,7 @@ void hts_finish_html_file(httrackp *opt, cache_back *cache, htsblk *r,
       if (fcheck)
         hts_log_print(opt, LOG_ERROR, "* * Fatal write error, giving up");
     }
-  } else {
-    file_notify(opt, adr, fil, save, 0, 0, r->notmodified);
-    filenote(&opt->state.strc, save, NULL);
   }
-  if (cache->ndx)
-    cache_writedata(cache->ndx, cache->dat, "//[HTML-MD5]//", save, digest,
-                    (int) strlen(digest));
 }
 
 /* does it look like XML ? (SVG et al.) */
@@ -846,6 +807,52 @@ int httpmirror(char *url1, httrackp * opt) {
       }
     }                           // while
 
+    /* --why: print which filter rule decides for this URL, then stop */
+    if (StringNotEmpty(opt->why_url)) {
+      char BIGSTK url[HTS_URLMAXSIZE * 2];
+      lien_adrfil af;
+
+      if (strstr(StringBuff(opt->why_url), ":/") == NULL)
+        snprintf(url, sizeof(url), "http://%s", StringBuff(opt->why_url));
+      else
+        strcpybuff(url, StringBuff(opt->why_url));
+      if (ident_url_absolute(url, &af) < 0) {
+        printf("--why: unable to parse URL %s" LF, StringBuff(opt->why_url));
+      } else {
+        char BIGSTK l[HTS_URLMAXSIZE * 2], lfull[HTS_URLMAXSIZE * 2];
+        int jok, jokDepth = 0;
+
+        /* the two forms the wizard tests */
+        strcpybuff(l, jump_identification_const(af.adr));
+        if (*af.fil != '/')
+          strcatbuff(l, "/");
+        strcatbuff(l, af.fil);
+        if (!link_has_authority(af.adr))
+          strcpybuff(lfull, "http://");
+        else
+          lfull[0] = '\0';
+        strcatbuff(lfull, af.adr);
+        if (*af.fil != '/')
+          strcatbuff(lfull, "/");
+        strcatbuff(lfull, af.fil);
+        jok = fa_strjoker_dual(/*url */ 0, filters, filptr, lfull, l, NULL,
+                               NULL, &jokDepth);
+        if (jok > 0)
+          printf("%s: accepted by rule #%d (%s)" LF, url, jokDepth + 1,
+                 filters[jokDepth]);
+        else if (jok < 0)
+          printf("%s: rejected by rule #%d (%s)" LF, url, jokDepth + 1,
+                 filters[jokDepth]);
+        else
+          printf("%s: no filter rule matches; the wizard decides "
+                 "(same-site links are followed by default)" LF,
+                 url);
+      }
+      freet(primary);
+      XH_extuninit;
+      return 1;
+    }
+
     /* load URL file list */
     /* OPTIMIZED for fast load */
     if (StringNotEmpty(opt->filelist)) {

src/htscore.h

@@ -193,7 +193,7 @@ struct cache_back {
   /* */
   int type;
   int ro;                   /**< read-only: no new cache is written */
-  FILE *dat, *ndx, *olddat; /**< new data, new index, old data files */
+
   char *use;                /**< in-memory list of cached adr+fil keys */
   FILE *lst;                /**< file list, used for purge */
   FILE *txt;                /**< human-readable file list (info) */
@@ -288,12 +288,12 @@ struct filecreate_params {
 
 /* True if a new cache is being written (plain or zip backend). */
 HTS_STATIC int cache_writable(cache_back * cache) {
-  return (cache != NULL && (cache->dat != NULL || cache->zipOutput != NULL));
+  return (cache != NULL && cache->zipOutput != NULL);
 }
 
 /* True if an old cache is available to read (plain or zip backend). */
 HTS_STATIC int cache_readable(cache_back * cache) {
-  return (cache != NULL && (cache->olddat != NULL || cache->zipInput != NULL));
+  return (cache != NULL && cache->zipInput != NULL);
 }
 
 #endif

src/htscoremain.c

@@ -1803,6 +1803,23 @@ static int hts_main_internal(int argc, char **argv, httrackp * opt) {
                   StringCopy(opt->cookies_file, argv[na]);
                 }
                 break;
+              case 'Y': // why: explain the filter verdict for a URL, no crawl
+                if ((na + 1 >= argc) || (argv[na + 1][0] == '-')) {
+                  HTS_PANIC_PRINTF("Option why needs a blank space and a URL");
+                  printf(
+                      "Example: --why \"http://www.example.com/file.zip\"\n");
+                  htsmain_free();
+                  return -1;
+                } else {
+                  na++;
+                  if (strlen(argv[na]) >= HTS_URLMAXSIZE) {
+                    HTS_PANIC_PRINTF("why URL too long");
+                    htsmain_free();
+                    return -1;
+                  }
+                  StringCopy(opt->why_url, argv[na]);
+                }
+                break;
               case 'G': // pause: randomized inter-file delay MIN[:MAX] seconds
                 if ((na + 1 >= argc) || (argv[na + 1][0] == '-')) {
                   HTS_PANIC_PRINTF("Option pause needs a blank space and a "
@@ -1936,18 +1953,20 @@ static int hts_main_internal(int argc, char **argv, httrackp * opt) {
                     char BIGSTK url[HTS_URLMAXSIZE * 2];
                     char linepos[256];
                     int pos;
-                    char *cacheNdx =
-                      readfile(fconcat
-                               (OPT_GET_BUFF(opt), OPT_GET_BUFF_SIZE(opt), StringBuff(opt->path_log),
-                                "hts-cache/new.ndx"));
+                    LLint cacheNdxLen = 0;
+                    char *cacheNdx = readfile2(
+                        fconcat(OPT_GET_BUFF(opt), OPT_GET_BUFF_SIZE(opt),
+                                StringBuff(opt->path_log), "hts-cache/new.ndx"),
+                        &cacheNdxLen);
                     cache_init(&cache, opt);    /* load cache */
                     if (cacheNdx != NULL) {
                       char firstline[256];
                       char *a = cacheNdx;
+                      const char *const end = cacheNdx + cacheNdxLen;
 
                       a += cache_brstr(a, firstline, sizeof(firstline));
                       a += cache_brstr(a, firstline, sizeof(firstline));
-                      while(a != NULL) {
+                      while (a != NULL && a < end) {
                         a = strchr(a + 1, '\n');        /* start of line */
                         if (a) {
                           htsblk r;
@@ -1955,15 +1974,15 @@ static int hts_main_internal(int argc, char **argv, httrackp * opt) {
                           /* */
                           a++;
                           /* read "host/file" */
-                          a += binput(a, afs.af.adr, HTS_URLMAXSIZE);
-                          a += binput(a, afs.af.fil, HTS_URLMAXSIZE);
+                          a += cache_binput(a, end, afs.af.adr, HTS_URLMAXSIZE);
+                          a += cache_binput(a, end, afs.af.fil, HTS_URLMAXSIZE);
                           url[0] = '\0';
                           if (!link_has_authority(afs.af.adr))
                             strcatbuff(url, "http://");
                           strcatbuff(url, afs.af.adr);
                           strcatbuff(url, afs.af.fil);
                           /* read position */
-                          a += binput(a, linepos, 200);
+                          a += cache_binput(a, end, linepos, 200);
                           sscanf(linepos, "%d", &pos);
                           if (!hasFilter
                               || (strjoker(url, filter, NULL, NULL) != NULL)

src/htsfilters.c

@@ -48,6 +48,7 @@ Please visit our Website: http://www.httrack.com
 #include "htsbase.h"
 #include "htslib.h"
 #include <ctype.h>
+#include <stdint.h>
 /* END specific definitions */
 
 // à partir d'un tableau de {"+*.toto","-*.zip","+*.tata"} définit si nom est autorisé
@@ -94,16 +95,107 @@ int fa_strjoker(int type, char **filters, int nfil, const char *nom, LLint * siz
   return verdict;
 }
 
-// supercomparateur joker (tm)
-// compare a et b (b=avec joker dedans), case insensitive [voir CI]
-// renvoi l'adresse de la première lettre de la chaine
-// (càd *[..]toto.. renvoi adresse de toto dans la chaine)
-// accepte les délires du genre www.*.*/ * / * truc*.*
-// cet algo est 'un peu' récursif mais ne consomme pas trop de tm
-// * = toute lettre
-// --?-- : spécifique à HTTrack et aux ?
+int fa_strjoker_dual(int type, char **filters, int nfil, const char *nom1,
+                     const char *nom2, LLint *size, int *size_flag,
+                     int *depth) {
+  int depth1 = 0, depth2 = 0;
+  int flag1 = 0, flag2 = 0;
+  LLint sz1 = 0, sz2 = 0;
+  int jok1, jok2, use1;
+
+  if (size) {
+    sz1 = *size;
+    sz2 = *size;
+  }
+  jok1 = fa_strjoker(type, filters, nfil, nom1, size ? &sz1 : NULL,
+                     size_flag ? &flag1 : NULL, &depth1);
+  jok2 = fa_strjoker(type, filters, nfil, nom2, size ? &sz2 : NULL,
+                     size_flag ? &flag2 : NULL, &depth2);
+  use1 = jok2 == 0 || (jok1 != 0 && depth1 >= depth2);
+  if (size)
+    *size = use1 ? sz1 : sz2;
+  if (size_flag)
+    *size_flag = use1 ? flag1 : flag2;
+  if (depth)
+    *depth = use1 ? depth1 : depth2;
+  return use1 ? jok1 : jok2;
+}
+
+/* Failure memo for the recursive matcher: one bit per (chaine, joker) offset
+   pair keeps star-heavy patterns polynomial instead of exponential (#501). */
+typedef struct strjoker_memo {
+  const char *chaine0, *joker0; /* offsets are relative to these bases */
+  size_t stride;                /* strlen(joker0) + 1 */
+  unsigned char *failed;        /* failed-pair bitmap; NULL: no memo */
+} strjoker_memo;
+
+static const char *strjoker_impl(const strjoker_memo *memo, const char *chaine,
+                                 const char *joker, LLint *size,
+                                 int *size_flag);
+
+/* A pair that failed once fails forever (*size is only written on the success
+   path), so record NULL results and cut the re-exploration. */
+static const char *strjoker_rec(const strjoker_memo *memo, const char *chaine,
+                                const char *joker, LLint *size,
+                                int *size_flag) {
+  size_t bit = 0;
+  const char *adr;
+
+  if (memo->failed) {
+    bit = (size_t) (chaine - memo->chaine0) * memo->stride +
+          (size_t) (joker - memo->joker0);
+    if (memo->failed[bit >> 3] & (unsigned char) (1u << (bit & 7)))
+      return NULL;
+  }
+  adr = strjoker_impl(memo, chaine, joker, size, size_flag);
+  if (adr == NULL && memo->failed)
+    memo->failed[bit >> 3] |= (unsigned char) (1u << (bit & 7));
+  return adr;
+}
+
+// wildcard comparator: match chaine against joker (pattern), case-insensitive
+// returns the address of the first matched letter past any leading joker
+// (ie. *[..]toto.. returns the address of toto within chaine), NULL on mismatch
 HTS_INLINE const char *strjoker(const char *chaine, const char *joker,
                                 LLint *size, int *size_flag) {
+  strjoker_memo memo = {chaine, joker, 0, NULL};
+  unsigned char stackbits[2048];
+  hts_boolean onheap = HTS_FALSE;
+  const char *adr;
+
+  if (chaine != NULL && joker != NULL) {
+    const size_t n1 = strlen(chaine) + 1;
+
+    memo.stride = strlen(joker) + 1;
+    if (n1 <= (SIZE_MAX - 7) / memo.stride) { // overflow-safe bitmap size
+      const size_t bytes = (n1 * memo.stride + 7) / 8;
+
+      if (bytes <= sizeof(stackbits)) {
+        memset(stackbits, 0, bytes);
+        memo.failed = stackbits;
+      } else {
+        memo.failed = (unsigned char *) calloct(bytes, 1);
+        onheap = memo.failed != NULL ? HTS_TRUE : HTS_FALSE;
+      }
+    }
+  }
+  adr = strjoker_rec(&memo, chaine, joker, size, size_flag);
+  if (onheap)
+    freet(memo.failed);
+  return adr;
+}
+
+/* Test-only oracle: the same matcher without the failure memo. */
+const char *strjoker_nomemo(const char *chaine, const char *joker, LLint *size,
+                            int *size_flag) {
+  const strjoker_memo memo = {chaine, joker, 0, NULL};
+
+  return strjoker_rec(&memo, chaine, joker, size, size_flag);
+}
+
+static const char *strjoker_impl(const strjoker_memo *memo, const char *chaine,
+                                 const char *joker, LLint *size,
+                                 int *size_flag) {
   if (strnotempty(joker) == 0) {        // fin de chaine joker
     if (strnotempty(chaine) == 0)       // fin aussi pour la chaine: ok
       return chaine;
@@ -277,7 +369,7 @@ HTS_INLINE const char *strjoker(const char *chaine, const char *joker,
 
       // tester sans le joker (pas ()+ mais ()*)
       if (!unique) {
-        if ((adr = strjoker(chaine, joker + jmp, size, size_flag))) {
+        if ((adr = strjoker_rec(memo, chaine, joker + jmp, size, size_flag))) {
           return adr;
         }
       }
@@ -289,7 +381,8 @@ HTS_INLINE const char *strjoker(const char *chaine, const char *joker,
         max = strnotempty(chaine) ? 1 : 0; /* empty chaine: no char to eat */
       while(i < (int) max) {
         if (pass[(int) (unsigned char) chaine[i]]) {    // caractère autorisé
-          if ((adr = strjoker(chaine + i + 1, joker + jmp, size, size_flag))) {
+          if ((adr = strjoker_rec(memo, chaine + i + 1, joker + jmp, size,
+                                  size_flag))) {
             return adr;
           }
           i++;
@@ -299,7 +392,8 @@ HTS_INLINE const char *strjoker(const char *chaine, const char *joker,
 
       // tester chaîne vide
       if (i != max + 2)         // avant c'est ok
-        if ((adr = strjoker(chaine + max, joker + jmp, size, size_flag)))
+        if ((adr = strjoker_rec(memo, chaine + max, joker + jmp, size,
+                                size_flag)))
           return adr;
 
       return NULL;              // perdu
@@ -321,7 +415,7 @@ HTS_INLINE const char *strjoker(const char *chaine, const char *joker,
       // comparaison ok?
       if (ok) {
         // continuer la comparaison.
-        if (strjoker(chaine + jmp, joker + jmp, size, size_flag))
+        if (strjoker_rec(memo, chaine + jmp, joker + jmp, size, size_flag))
           return chaine;        // retourner 1e lettre
       }
 

src/htsfilters.h

@@ -41,8 +41,17 @@ Please visit our Website: http://www.httrack.com
 
 int fa_strjoker(int type, char **filters, int nfil, const char *nom, LLint * size,
                 int *size_flag, int *depth);
+/* fa_strjoker() on both URL forms the engine builds (nom1 full, nom2 without
+   scheme); the match latest in the list wins, a "don't know" verdict defers.
+   Returns the merged verdict; the out-params carry the winner's values. */
+int fa_strjoker_dual(int type, char **filters, int nfil, const char *nom1,
+                     const char *nom2, LLint *size, int *size_flag, int *depth);
 HTS_INLINE const char *strjoker(const char *chaine, const char *joker, LLint * size,
                           int *size_flag);
+/* strjoker() without the failure memo (exponential worst case); test-only
+   oracle for the memoized matcher. */
+const char *strjoker_nomemo(const char *chaine, const char *joker, LLint *size,
+                            int *size_flag);
 const char *strjokerfind(const char *chaine, const char *joker);
 #endif
 

src/htsglobal.h

@@ -422,9 +422,10 @@ typedef int T_SOC;
 #endif
 
 /* Permission bits for created folders and files (mkdir and chmod).
-   PROTECT_FOLDER is owner-only. With HTS_ACCESS set (the default) the ACCESS_
-   modes also grant group/other read; otherwise they stay owner-only. */
+   PROTECT_FOLDER/FILE are owner-only. With HTS_ACCESS set (the default) the
+   ACCESS_ modes also grant group/other read; otherwise they stay owner-only. */
 #define HTS_PROTECT_FOLDER (S_IRUSR | S_IWUSR | S_IXUSR)
+#define HTS_PROTECT_FILE (S_IRUSR | S_IWUSR)
 
 #if HTS_ACCESS
 #define HTS_ACCESS_FILE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)

src/htshelp.c

@@ -543,6 +543,7 @@ void help(const char *app, int more) {
   infomsg("Spider options:");
   infomsg("  bN accept cookies in cookies.txt (0=do not accept,* 1=accept)");
   infomsg(" %K  load extra cookies from a Netscape cookies.txt");
+  infomsg(" %Y  explain which filter rule accepts or rejects a URL, then exit");
   infomsg
     ("  u  check document type if unknown (cgi,asp..) (u0 don't check, * u1 check but /, u2 check always)");
   infomsg

src/htslib.c

@@ -1562,7 +1562,7 @@ void treathead(t_cookie * cookie, const char *adr, const char *fil, htsblk * ret
       }
       // An empty/whitespace Content-Type value yields no token: keep the
       // sentinel default rather than reading an uninitialized tempo.
-      if (sscanf(rcvd + p, "%s", tempo) == 1) {
+      if (sscanf(rcvd + p, "%1099s", tempo) == 1) { // tempo[1100], server data
         if (strlen(tempo) < sizeof(retour->contenttype) - 2) // pas trop long!!
           strcpybuff(retour->contenttype, tempo);
         else
@@ -1657,11 +1657,11 @@ void treathead(t_cookie * cookie, const char *adr, const char *fil, htsblk * ret
         if (a)
           *a = '\0';
       }
-      sscanf(a, "%s", tempo);
-      if (strlen(tempo) < 64)   // pas trop long!!
+      // Bound to tempo[1100]; no token => leave empty, don't read uninit tempo.
+      if (sscanf(a, "%1099s", tempo) == 1 && strlen(tempo) < 64)
         strcpybuff(retour->contentencoding, tempo);
       else
-        retour->contentencoding[0] = '\0';      // erreur
+        retour->contentencoding[0] = '\0';
 #if HTS_USEZLIB
       /* Check known encodings */
       if (retour->contentencoding[0]) {
@@ -6006,6 +6006,7 @@ HTSEXT_API httrackp *hts_create_opt(void) {
   StringCopy(opt->footer, HTS_DEFAULT_FOOTER);
   StringCopy(opt->strip_query, "");
   StringCopy(opt->cookies_file, "");
+  StringCopy(opt->why_url, "");
   opt->pause_min_ms = 0;
   opt->pause_max_ms = 0;
   opt->ftp_proxy = HTS_TRUE;
@@ -6153,6 +6154,7 @@ HTSEXT_API void hts_free_opt(httrackp * opt) {
     StringFree(opt->mod_blacklist);
     StringFree(opt->strip_query);
     StringFree(opt->cookies_file);
+    StringFree(opt->why_url);
 
     StringFree(opt->path_html);
     StringFree(opt->path_html_utf8);

src/htsopt.h

@@ -536,6 +536,8 @@ struct httrackp {
                                  (--cookies-file) */
   int pause_min_ms; /**< inter-file pause lower bound, ms (0=off, #185) */
   int pause_max_ms; /**< inter-file pause upper bound, ms */
+  String why_url;   /**< URL to diagnose (--why): print the deciding filter rule
+                         and exit without crawling */
 };
 
 /* Running statistics for a mirror. */

src/htsselftest.c

@@ -46,6 +46,7 @@ Please visit our Website: http://www.httrack.com
 #include "htsdefines.h"
 #include "htslib.h"
 #include "htsparse.h"
+#include "htscache.h"
 #include "htscache_selftest.h"
 #include "htsdns_selftest.h"
 #include "htscharset.h"
@@ -620,6 +621,125 @@ static int st_filtersize(httrackp *opt, int argc, char **argv) {
   return 0;
 }
 
+/* Mime-type filter verdict via fa_strjoker(type=1): only mime: rules apply. */
+static int st_filtermime(httrackp *opt, int argc, char **argv) {
+  int verdict;
+
+  (void) opt;
+  if (argc < 2) {
+    fprintf(stderr, "filtermime: needs <mime> <filter> [filter...]\n");
+    return 1;
+  }
+  verdict = fa_strjoker(1, &argv[1], argc - 1, argv[0], NULL, NULL, NULL);
+  printf("verdict=%s\n", verdict > 0   ? "allowed"
+                         : verdict < 0 ? "forbidden"
+                                       : "unknown");
+  return 0;
+}
+
+/* SplitMix64: deterministic, platform-independent case generator. */
+static uint64_t st_mix64(uint64_t *state) {
+  uint64_t z = (*state += UINT64_C(0x9E3779B97F4A7C15));
+
+  z = (z ^ (z >> 30)) * UINT64_C(0xBF58476D1CE4B5B9);
+  z = (z ^ (z >> 27)) * UINT64_C(0x94D049BB133111EB);
+  return z ^ (z >> 31);
+}
+
+/* Differential test: memoized strjoker vs the no-memo oracle on seeded random
+   pattern/subject/size cases must agree on result, *size and *size_flag. */
+static int st_filtermemo(httrackp *opt, int argc, char **argv) {
+  static const char *const pieces[] = {
+      "a",       "b",        "A",    "c",      ".",       "/",
+      "?",       "*",        "*[a]", "*[ab]",  "*[a-c]",  "*[A-Z]",
+      "*[<5]",   "*[>5]",    "*(a)", "*(a,b)", "*[file]", "*[path]",
+      "*[name]", "*[param]", "*[]",  "*[\\a]", "*[a-"};
+  static const char subject_chars[] = "abAc./?";
+  uint64_t rng = UINT64_C(0x501);
+  int iters = 20000, matched = 0, unmatched = 0;
+  int it;
+
+  (void) opt;
+  if (argc >= 1)
+    sscanf(argv[0], "%d", &iters);
+  for (it = 0; it < iters; it++) {
+    char pat[64], str[16];
+    size_t pl = 0;
+    const int npieces = (int) (st_mix64(&rng) % 5);
+    const int slen = (int) (st_mix64(&rng) % 13);
+    const int szsel = (int) (st_mix64(&rng) % 4); /* none/unknown/3/20 */
+    LLint sz1, sz2, off1, off2;
+    int i, flag1 = 0, flag2 = 0;
+    char *hpat, *hstr;
+    const char *adr;
+
+    for (i = 0; i < npieces; i++) {
+      const char *p =
+          pieces[st_mix64(&rng) % (sizeof(pieces) / sizeof(pieces[0]))];
+      const size_t len = strlen(p);
+
+      if (len >= sizeof(pat) - pl)
+        break;
+      memcpy(pat + pl, p, len);
+      pl += len;
+    }
+    pat[pl] = '\0';
+    for (i = 0; i < slen; i++)
+      str[i] = subject_chars[st_mix64(&rng) % (sizeof(subject_chars) - 1)];
+    str[slen] = '\0';
+    sz1 = sz2 = (szsel <= 1) ? -1 : (szsel == 2) ? 3 : 20;
+    /* exact-size heap copies per run so a sanitizer traps any over-read */
+    hpat = strdupt(pat);
+    hstr = strdupt(str);
+    adr = strjoker(hstr, hpat, szsel ? &sz1 : NULL, szsel ? &flag1 : NULL);
+    off1 = adr != NULL ? (LLint) (adr - hstr) : -1;
+    freet(hpat);
+    freet(hstr);
+    hpat = strdupt(pat);
+    hstr = strdupt(str);
+    adr =
+        strjoker_nomemo(hstr, hpat, szsel ? &sz2 : NULL, szsel ? &flag2 : NULL);
+    off2 = adr != NULL ? (LLint) (adr - hstr) : -1;
+    freet(hpat);
+    freet(hstr);
+    if (off1 != off2 || sz1 != sz2 || flag1 != flag2) {
+      printf("filtermemo MISMATCH pat=[%s] str=[%s] szsel=%d: "
+             "off %d/%d size %d/%d flag %d/%d\n",
+             pat, str, szsel, (int) off1, (int) off2, (int) sz1, (int) sz2,
+             flag1, flag2);
+      return 1;
+    }
+    if (off1 >= 0)
+      matched++;
+    else
+      unmatched++;
+  }
+  /* both polarities must actually occur or the test proves nothing */
+  assertf(matched > 0 && unmatched > 0);
+  printf("filtermemo: %d cases OK\n", iters);
+  return 0;
+}
+
+/* Merged two-form filter verdict via fa_strjoker_dual (see htsfilters.h). */
+static int st_filterdual(httrackp *opt, int argc, char **argv) {
+  int depth = -1, verdict;
+
+  (void) opt;
+  if (argc < 3) {
+    fprintf(stderr,
+            "filterdual: needs <string1> <string2> <filter> [filter...]\n");
+    return 1;
+  }
+  verdict = fa_strjoker_dual(0, &argv[2], argc - 2, argv[0], argv[1], NULL,
+                             NULL, &depth);
+  printf("verdict=%s rule=%d\n",
+         verdict > 0   ? "allowed"
+         : verdict < 0 ? "forbidden"
+                       : "unknown",
+         depth);
+  return 0;
+}
+
 static int st_simplify(httrackp *opt, int argc, char **argv) {
   (void) opt;
   if (argc < 1) {
@@ -1143,6 +1263,26 @@ static int st_header(httrackp *opt, int argc, char **argv) {
     treathead(NULL, "www.example.com", "/", &r, line);
   }
   printf("contenttype=%s cdispo=%s\n", r.contenttype, r.cdispo);
+  printf("contentencoding=%s\n", r.contentencoding);
+  return 0;
+}
+
+/* An over-long header value must not overflow treathead's tempo[1100]. */
+static int st_headerlong(httrackp *opt, int argc, char **argv) {
+  htsblk r;
+  char BIGSTK line[HTS_URLMAXSIZE * 2];
+  const char *const name = argc >= 1 ? argv[0] : "Content-Type:";
+  const int pad = 1500; /* > tempo[1100] */
+  size_t n;
+
+  (void) opt;
+  memset(&r, 0, sizeof(r));
+  n = (size_t) snprintf(line, sizeof(line), "%s ", name);
+  memset(line + n, 'a', pad);
+  line[n + pad] = '\0';
+  treathead(NULL, "www.example.com", "/", &r, line);
+  printf("contenttype_len=%d contentencoding_len=%d\n",
+         (int) strlen(r.contenttype), (int) strlen(r.contentencoding));
   return 0;
 }
 
@@ -1350,6 +1490,78 @@ static int st_cache(httrackp *opt, int argc, char **argv) {
   return err;
 }
 
+/* A corrupt cache index (.ndx) must not walk the length-prefixed scan past
+   the buffer. Checks the two primitives the loader is built from. */
+static int st_cacheindex(httrackp *opt, int argc, char **argv) {
+  int fail = 0;
+
+  (void) opt;
+  (void) argc;
+  (void) argv;
+
+  /* A length prefix that overstates the bytes present must bound the advance
+     to the buffer, not trust the declared length. */
+  {
+    static const char src[] = "32768\nCACHE-1.1";
+    const size_t len = sizeof(src) - 1;
+    char *buf = malloct(len + 1);
+    char s[256];
+    int off;
+
+    memcpy(buf, src, len + 1);
+    off = cache_brstr(buf, s, sizeof(s));
+    if (off > (int) len) {
+      printf("cacheindex: over-advance off=%d len=%d\n", off, (int) len);
+      fail = 1;
+    }
+    if (strcmp(s, "CACHE-1.1") != 0) {
+      printf("cacheindex: value=%s\n", s);
+      fail = 1;
+    }
+    freet(buf);
+  }
+
+  /* cache_binput reads a field while in bounds, but refuses one starting at
+     or past end-of-buffer. */
+  {
+    char buf[8] = "ab\ncd";
+    const char *const end = buf + 5;
+    char s[16];
+
+    if (cache_binput(buf, end, s, sizeof(s)) != 3 || strcmp(s, "ab") != 0)
+      fail = 1; /* normal read: "ab" then the '\n', 3 bytes consumed */
+    if (cache_binput(end, end, s, sizeof(s)) != 0 || s[0] != '\0')
+      fail = 1;
+  }
+
+  /* Drive the full loader scan over a truncated index: a declared length that
+     overshoots plus a half-written entry. ASan aborts here on the pre-fix
+     scan; the cursor must never leave the buffer. */
+  {
+    static const char src[] = "9\nCACHE-1.1\n99\nwww.example.com\n/a";
+    const size_t len = sizeof(src) - 1;
+    char *buf = malloct(len + 1);
+    const char *const end = buf + len;
+    char line[256];
+    char *a = buf;
+
+    memcpy(buf, src, len + 1);
+    a += cache_brstr(a, line, sizeof(line));
+    a += cache_brstr(a, line, sizeof(line));
+    while (a != NULL && a < end) {
+      a = strchr(a + 1, '\n');
+      if (a == NULL)
+        break;
+      a++;
+      a += cache_binput(a, end, line, sizeof(line));
+    }
+    freet(buf);
+  }
+
+  printf("cacheindex: %s\n", fail ? "FAIL" : "OK");
+  return fail;
+}
+
 static int st_cache_golden(httrackp *opt, int argc, char **argv) {
   int regen, err;
 
@@ -1387,6 +1599,18 @@ static int st_cache_corrupt(httrackp *opt, int argc, char **argv) {
   return err;
 }
 
+static int st_cache_legacy(httrackp *opt, int argc, char **argv) {
+  int err;
+
+  if (argc < 1) {
+    fprintf(stderr, "cache-legacy: needs a directory\n");
+    return 1;
+  }
+  err = cache_legacy_refused_selftest(opt, argv[0]);
+  printf("cache-legacy: %s\n", err ? "FAIL" : "OK");
+  return err;
+}
+
 static int st_reconcile(httrackp *opt, int argc, char **argv) {
   int err;
 
@@ -1438,6 +1662,26 @@ static int st_cookies(httrackp *opt, int argc, char **argv) {
     err = 1;
   if (strstr(hdr, "junk") != NULL) // wrong-domain cookie leaked
     err = 1;
+#ifndef _WIN32
+  /* the jar holds live session cookies: cookie_save must keep it 0600 */
+  {
+    const char *jar = "st-cookies-jar.txt";
+    struct stat st;
+
+    (void) UNLINK(jar);
+    assertf(cookie_save(&cookie, jar) == 0);
+    assertf(stat(jar, &st) == 0);
+    assertf((st.st_mode & 07777) == HTS_PROTECT_FILE);
+    assertf(st.st_size > 0); /* mode-only checks would pass an empty jar */
+    /* a pre-existing world-readable jar must be tightened, not kept */
+    assertf(chmod(jar, 0644) == 0);
+    assertf(cookie_save(&cookie, jar) == 0);
+    assertf(stat(jar, &st) == 0);
+    assertf((st.st_mode & 07777) == HTS_PROTECT_FILE);
+    assertf(st.st_size > 0);
+    (void) UNLINK(jar);
+  }
+#endif
   printf("cookie-header: %s\n", err ? "FAIL" : "OK");
   if (err)
     printf("  got: %s\n", hdr);
@@ -2134,6 +2378,12 @@ static const struct selftest_entry {
     {"filtersize", "<size> <string> <filter>...",
      "size-aware filter verdict (negative size = unknown/scan time)",
      st_filtersize},
+    {"filtermime", "<mime> <filter>...",
+     "mime-type filter verdict (fa_strjoker type=1)", st_filtermime},
+    {"filtermemo", "[iterations]",
+     "memoized vs unmemoized matcher differential", st_filtermemo},
+    {"filterdual", "<string1> <string2> <filter>...",
+     "merged two-form filter verdict (fa_strjoker_dual)", st_filterdual},
     {"simplify", "<path>", "collapse ./ and ../ in a path", st_simplify},
     {"stripquery", "", "--strip-query pattern/key stripping self-test",
      st_stripquery},
@@ -2163,17 +2413,24 @@ static const struct selftest_entry {
     {"identurl", "<url>", "split an absolute URL into (adr, fil)", st_identurl},
     {"header", "<raw-header-line> ...", "response header-line parsing",
      st_header},
+    {"headerlong", "[header-name:]",
+     "over-long header value must not overflow the parse scratch",
+     st_headerlong},
     {"savename", "<fil> <content-type> [key=value ...]",
      "local save-name for a URL", st_savename},
     {"sniff", "<content-type> <hex:..|text>", "MIME magic consistency",
      st_sniff},
     {"cache", "<dir>", "cache read/write round-trip self-test", st_cache},
+    {"cacheindex", "", "cache-index (.ndx) parse must stay in bounds",
+     st_cacheindex},
     {"cache-golden", "<dir> [regen]", "frozen cache-format read self-test",
      st_cache_golden},
     {"cache-writefail", "<dir>", "cache write-failure handling self-test",
      st_cache_writefail},
     {"reconcile", "<dir>", "cache generation reconcile policy self-test",
      st_reconcile},
+    {"cache-legacy", "<dir>", "pre-3.31 legacy cache refusal self-test",
+     st_cache_legacy},
     {"cache-corrupt", "<dir>", "cache read-side corruption self-test",
      st_cache_corrupt},
     {"dns", "", "DNS resolver/cache self-test", st_dns},

src/htswizard.c

@@ -524,28 +524,11 @@ static int hts_acceptlink_(httrackp * opt, int ptr,
 
         // filters, 0=sait pas 1=ok -1=interdit
         {
-          int jokDepth1 = 0, jokDepth2 = 0;
-          int jok1 = 0, jok2 = 0;
+          int jokDepth = 0;
 
-          jok1 =
-            fa_strjoker( /*url */ 0, _FILTERS, *_FILTERS_PTR, lfull, NULL, NULL,
-                        &jokDepth1);
-          jok2 =
-            fa_strjoker( /*url */ 0, _FILTERS, *_FILTERS_PTR, l, NULL, NULL,
-                        &jokDepth2);
-          if (jok2 == 0) {      // #2 doesn't know
-            jok = jok1;         // then, use #1
-            mdepth = _FILTERS[jokDepth1];
-          } else if (jok1 == 0) {       // #1 doesn't know
-            jok = jok2;         // then, use #2
-            mdepth = _FILTERS[jokDepth2];
-          } else if (jokDepth1 >= jokDepth2) {  // #1 matching rule is "after" #2, then it is prioritary
-            jok = jok1;
-            mdepth = _FILTERS[jokDepth1];
-          } else {              // #2 matching rule is "after" #1, then it is prioritary
-            jok = jok2;
-            mdepth = _FILTERS[jokDepth2];
-          }
+          jok = fa_strjoker_dual(/*url */ 0, _FILTERS, *_FILTERS_PTR, lfull, l,
+                                 NULL, NULL, &jokDepth);
+          mdepth = _FILTERS[jokDepth];
         }
 
         if (jok == 1) {         // autorisé
@@ -965,34 +948,10 @@ int hts_testlinksize(httrackp * opt, const char *adr, const char *fil, LLint siz
 
       // filters, 0=sait pas 1=ok -1=interdit
       {
-        int jokDepth1 = 0, jokDepth2 = 0;
-        int jok1 = 0, jok2 = 0;
-        LLint sz1 = size, sz2 = size;
-        int size_flag1 = 0, size_flag2 = 0;
-
-        jok1 =
-          fa_strjoker( /*url */ 0, *opt->filters.filters, *opt->filters.filptr,
-                      lfull, &sz1, &size_flag1, &jokDepth1);
-        jok2 =
-          fa_strjoker( /*url */ 0, *opt->filters.filters, *opt->filters.filptr,
-                      l, &sz2, &size_flag2, &jokDepth2);
-        if (jok2 == 0) {        // #2 doesn't know
-          jok = jok1;           // then, use #1
-          sz = sz1;
-          size_flag = size_flag1;
-        } else if (jok1 == 0) { // #1 doesn't know
-          jok = jok2;           // then, use #2
-          sz = sz2;
-          size_flag = size_flag2;
-        } else if (jokDepth1 >= jokDepth2) {    // #1 matching rule is "after" #2, then it is prioritary
-          jok = jok1;
-          sz = sz1;
-          size_flag = size_flag1;
-        } else {                // #2 matching rule is "after" #1, then it is prioritary
-          jok = jok2;
-          sz = sz2;
-          size_flag = size_flag2;
-        }
+        sz = size;
+        jok = fa_strjoker_dual(/*url */ 0, *opt->filters.filters,
+                               *opt->filters.filptr, lfull, l, &sz, &size_flag,
+                               NULL);
       }
 
       // log

tests/01_engine-cacheindex.test

@@ -0,0 +1,10 @@
+#!/bin/bash
+#
+
+set -euo pipefail
+
+# Cache-index (.ndx) parse must stay inside the buffer on a corrupt length
+# prefix (ASan aborts here on the pre-fix binary; the OK check gates the
+# non-sanitized build too).
+
+test "$(httrack -O /dev/null -#test=cacheindex)" == 'cacheindex: OK'

tests/01_engine-filter.test

@@ -131,3 +131,64 @@ match '*.aspx' 'page.aspx?y=2'
 # empty subject against a unique-match allow-all pattern (heap over-read regress)
 nomatch_empty '*(('
 nomatch_empty '**(('
+
+# near-miss negatives: word order, exact tails, range boundaries, class case
+nomatch 'foo*bar' 'foobaz'
+nomatch '*foo*bar' 'barfoo' # both words present, wrong order
+nomatch '*.gif' 'a.gifx'    # trailing junk after the extension
+nomatch '*.gif' 'a.gi'
+nomatch '*[b-y]' 'a'
+nomatch '*[b-y]' 'z'
+nomatch '*[a-z].txt' 'B.txt' # classes are case-sensitive...
+match 'FoO*' 'foobar'        # ...literals are not
+
+# a star may match an empty run, but never skip a required literal
+match '*[0-9].gif' '.gif'
+nomatch '*[0-9].gif' 'x.gif'
+
+# a descending range *[c-a] is an empty class, not c..a reversed
+match '*[c-a]x' 'x'
+nomatch '*[c-a]x' 'cx'
+
+# *[param] is all-or-nothing on '?': spans everything after one, else nothing
+match 'a*[param]' 'a?x=1'
+nomatch 'a*[param]' 'ab?x=1'
+
+# the latest matching rule wins, regardless of sign
+fsize 'verdict=forbidden size_flag=0' -1 a.gif '+*.gif' '-*.gif'
+fsize 'verdict=allowed size_flag=0' -1 a.gif '-*.gif' '+*.gif'
+
+# a failed size test sets size_flag but leaves the rule unmatched
+fsize 'verdict=unknown size_flag=1' 5 foo.jpg '-*.jpg*[>10]'
+
+# mime filters (-#test=filtermime = fa_strjoker type=1): only mime: rules
+# apply to a mime type, and mime: rules never apply to a URL
+fmime() {
+    local want="$1"
+    shift
+    test "$(httrack -O /dev/null -#test=filtermime "$@")" == "verdict=$want" || exit 1
+}
+fmime allowed 'image/png' '+mime:image/*'
+fmime unknown 'text/html' '+mime:image/*'
+fmime forbidden 'image/png' '+mime:image/*' '-mime:image/png' # last wins
+fmime allowed 'image/png' '-mime:image/png' '+mime:image/*'
+fmime unknown 'image/png' '+image/*'                               # URL rule: skipped
+fsize 'verdict=unknown size_flag=0' -1 'image/png' '+mime:image/*' # and vice versa
+
+# memoized vs no-memo differential over seeded random patterns and subjects,
+# matching and non-matching (the self-test asserts both polarities occurred)
+test "$(httrack -O /dev/null -#test=filtermemo)" == "filtermemo: 20000 cases OK" || exit 1
+
+# star-heavy non-match must stay polynomial (#501); 400 chars also exercises
+# the heap-allocated memo. timeout (where available) turns a hang into a FAIL.
+with_timeout() {
+    if command -v timeout >/dev/null; then timeout 60 "$@"; else "$@"; fi
+}
+pat=$(printf '*[a]%.0s' $(seq 1 12))b
+subj=$(printf 'a%.0s' $(seq 1 400))
+test "$(with_timeout httrack -O /dev/null -#test=filter "$pat" "$subj")" == "$subj does NOT match $pat" || exit 1
+
+# a later star's class dead-end must re-extend the earlier star, not give up
+# (guards against a single-backtrack-point matcher rewrite)
+match '*[aX]X*[a]Y' 'aXaXaY'
+nomatch '*[aX]X*[a]Y' 'aXbXaY'

tests/01_engine-filterdual.test

@@ -0,0 +1,20 @@
+#!/bin/bash
+#
+
+set -euo pipefail
+
+# fa_strjoker_dual: merged verdict on the two URL forms the engine tests;
+# the match latest in the filter list wins, an unknown verdict defers.
+
+fdual() {
+    local want="$1"
+    shift
+    test "$(httrack -O /dev/null -#test=filterdual "$@")" == "$want" || exit 1
+}
+
+fdual 'verdict=unknown rule=0' zzz yyy '+a*'     # neither form matches
+fdual 'verdict=forbidden rule=0' aaa zzz '-a*'   # only form 1 matches
+fdual 'verdict=forbidden rule=0' zzz aaa '-a*'   # only form 2 matches
+fdual 'verdict=forbidden rule=1' a b '+a*' '-b*' # later rule wins (form 2)
+fdual 'verdict=forbidden rule=1' b a '+a*' '-b*' # later rule wins (form 1)
+fdual 'verdict=allowed rule=0' a aa '+a*'        # tie: form 1 wins

tests/01_engine-header.test

@@ -27,3 +27,16 @@ hdr 'contenttype= cdispo=report.pdf' \
 # Path components in the filename are dropped on the wire (RFC 2616).
 hdr 'contenttype= cdispo=evil.pdf' \
     'Content-Disposition: attachment; filename="../../evil.pdf"'
+
+# An over-long header value must not overflow the parse scratch (ASan aborts
+# here on the pre-fix binary).
+test "$(httrack -O /dev/null -#test=headerlong 'Content-Type:')" \
+    == 'contenttype_len=32 contentencoding_len=0'
+test "$(httrack -O /dev/null -#test=headerlong 'Content-Encoding:')" \
+    == 'contenttype_len=0 contentencoding_len=0'
+
+# An empty Content-Encoding yields no token: leave it empty, don't read the
+# uninitialized scratch (MSan aborts here on the pre-fix binary).
+enc() { httrack -O /dev/null -#test=header "$1" | grep '^contentencoding='; }
+test "$(enc 'Content-Encoding:')" == 'contentencoding='
+test "$(enc 'Content-Encoding: gzip')" == 'contentencoding=gzip'

tests/01_zlib-cache-legacy.test

@@ -0,0 +1,23 @@
+#!/bin/bash
+#
+# The pre-3.31 .dat/.ndx cache import was removed: cache_init must refuse the
+# legacy pair and leave the files untouched (httrack -#test=cache-legacy <dir>).
+
+set -eu
+
+dir=$(mktemp -d)
+trap 'rm -rf "$dir"' EXIT
+
+# the refusal errors land on stdout (no log file); pin them and the verdict
+out=$(httrack -#test=cache-legacy "$dir" 2>/dev/null)
+cnt=$(printf '%s\n' "$out" | grep -c 'no longer supported' || true)
+test "$cnt" = 2 || {
+    echo "expected 2 refusal messages, got $cnt" >&2
+    exit 1
+}
+out=$(printf '%s\n' "$out" | tail -n1)
+
+test "$out" = "cache-legacy: OK" || {
+    echo "expected 'cache-legacy: OK', got: $out" >&2
+    exit 1
+}

tests/40_local-why.test

@@ -0,0 +1,35 @@
+#!/bin/bash
+#
+
+set -euo pipefail
+
+# --why: report which +/- filter rule decides for a URL, without crawling.
+
+tmpdir="$(mktemp -d)"
+trap 'rm -rf "$tmpdir"' EXIT
+
+why() {
+    local want="$1" out
+    shift
+    out="$(httrack -O "$tmpdir/p" -q "$@" |
+        grep -E 'accepted|rejected|no filter|unable')"
+    test "$out" == "$want" || {
+        echo "want: $want"
+        echo "got : $out"
+        exit 1
+    }
+}
+
+base=http://www.example.com
+why "$base/x.zip: rejected by rule #2 (-*.zip)" \
+    --why "$base/x.zip" "$base/" '+*.png' '-*.zip'
+why "$base/a.png: accepted by rule #1 (+*.png)" \
+    --why "$base/a.png" "$base/" '+*.png' '-*.zip'
+why "$base/i.html: no filter rule matches; the wizard decides (same-site links are followed by default)" \
+    --why "$base/i.html" "$base/" '+*.png' '-*.zip'
+# scheme-less input gets the same http:// default as primary URLs
+why "$base/x.zip: rejected by rule #2 (-*.zip)" \
+    --why "www.example.com/x.zip" "$base/" '+*.png' '-*.zip'
+# the rule latest in the list decides
+why "$base/x.zip: accepted by rule #3 (+*x.zip)" \
+    --why "$base/x.zip" "$base/" '+*.png' '-*.zip' '+*x.zip'

tests/Makefile.am

@@ -35,8 +35,10 @@ TESTS = \
 	01_engine-entities.test \
 	01_engine-filelist.test \
 	01_engine-filter.test \
+	01_engine-filterdual.test \
 	01_engine-ftp-line.test \
 	01_engine-ftp-userpass.test \
+	01_engine-cacheindex.test \
 	01_engine-hashtable.test \
 	01_engine-header.test \
 	01_engine-idna.test \
@@ -66,6 +68,7 @@ TESTS = \
 	01_zlib-acceptencoding.test \
 	01_zlib-cache.test \
 	01_zlib-cache-corrupt.test \
+	01_zlib-cache-legacy.test \
 	01_zlib-cache-golden.test \
 	01_zlib-cache-writefail.test \
 	01_zlib-savename-cached.test \
@@ -105,6 +108,7 @@ TESTS = \
 	36_local-bigcrawl.test \
 	37_local-cache-outage.test \
 	38_local-update-304.test \
-	39_local-delayed-cancel.test
+	39_local-delayed-cancel.test \
+	40_local-why.test
 
 CLEANFILES = check-network_sh.cache