Merge origin/master (#763 landed)

Signed-off-by: Xavier Roche <roche@httrack.com>

# Conflicts:
#	src/htsback.c
#	tests/96_local-refetch-keep.test

.github/workflows/ci.yml

@@ -46,10 +46,32 @@ jobs:
       - name: Configure
         run: |
           set -euo pipefail
-          # Regenerate from configure.ac/Makefile.am to validate them; the
-          # committed generated files already let a plain checkout build.
+          # Regenerate: configure and the Makefile.in's are not tracked.
           autoreconf -fi
+          # Disabling zlib must fail here rather than at link with a pile of
+          # undefined minizip references (#735). Both spellings, so a rewrite
+          # cannot keep one and lose the other. Probed out-of-tree to leave
+          # nothing behind.
+          nozlib="$RUNNER_TEMP/nozlib"
+          for arg in --without-zlib --with-zlib=no; do
+            rm -rf "$nozlib" && mkdir -p "$nozlib"
+            if (cd "$nozlib" && "$GITHUB_WORKSPACE/configure" "$arg" >out.log 2>&1); then
+              echo "::error::configure $arg succeeded; it must be rejected"
+              exit 1
+            fi
+            # ... and for the stated reason, not an unrelated configure failure.
+            grep -q "zlib cannot be disabled" "$nozlib/out.log" \
+              || { cat "$nozlib/out.log"; exit 1; }
+          done
           ./configure
+          # Same dead end from the compile side. The bare compile is the
+          # control: without it a broken probe would pass vacuously.
+          hdr='#include "htsglobal.h"'
+          echo "$hdr" | $CC -I. -Isrc -fsyntax-only -xc -
+          if echo "$hdr" | $CC -DHTS_USEZLIB=0 -I. -Isrc -fsyntax-only -xc - 2>/dev/null; then
+            echo "::error::-DHTS_USEZLIB=0 compiled; htsglobal.h must reject it"
+            exit 1
+          fi
           # a missing decoder would silently drop the coding from Accept-Encoding
           grep -q "define HTS_USEBROTLI 1" config.h
           grep -q "define HTS_USEZSTD 1" config.h

configure.ac

@@ -175,7 +175,7 @@ AX_CHECK_ALIGNED_ACCESS_REQUIRED
 # check for various headers
 AC_CHECK_HEADERS([execinfo.h sys/ioctl.h])
 
-### zlib
+### zlib (mandatory)
 CHECK_ZLIB()
 
 ### brotli and zstd content codings (optional)

m4/check_zlib.m4

@@ -1,82 +1,33 @@
 dnl @synopsis CHECK_ZLIB()
 dnl
-dnl This macro searches for an installed zlib library. If nothing
-dnl was specified when calling configure, it searches first in /usr/local
-dnl and then in /usr. If the --with-zlib=DIR is specified, it will try
-dnl to find it in DIR/include/zlib.h and DIR/lib/libz.a. If --without-zlib
-dnl is specified, the library is not searched at all.
-dnl
-dnl If either the header file (zlib.h) or the library (libz) is not
-dnl found, the configuration exits on error, asking for a valid
-dnl zlib installation directory or --without-zlib.
-dnl
-dnl The macro defines the symbol HAVE_LIBZ if the library is found. You should
-dnl use autoheader to include a definition for this symbol in a config.h
-dnl file. Sample usage in a C/C++ source is as follows:
-dnl
-dnl   #ifdef HAVE_LIBZ
-dnl   #include <zlib.h>
-dnl   #endif /* HAVE_LIBZ */
-dnl
-dnl @version $Id$
-dnl @author Loic Dachary <loic@senga.org>
+dnl Look for zlib. It is a hard requirement, not an option: the cache and the
+dnl WARC output are zip/gzip containers, and the bundled minizip calls zlib
+dnl directly. --with-zlib=DIR points at a non-standard prefix.
 dnl
+dnl Adds -lz to LIBS and defines HAVE_LIBZ.
 
-AC_DEFUN([CHECK_ZLIB],
-#
-# Handle user hints
-#
-[AC_MSG_CHECKING(if zlib is wanted)
-AC_ARG_WITH(zlib,
-[  --with-zlib=DIR root directory path of zlib installation [defaults to
-                    /usr/local or /usr if not found in /usr/local]
-  --without-zlib to disable zlib usage completely],
-[if test "$withval" != no ; then
-  AC_MSG_RESULT(yes)
-  ZLIB_HOME="$withval"
-else
-  AC_MSG_RESULT(no)
-fi], [
-AC_MSG_RESULT(yes)
-ZLIB_HOME=/usr/local
-if test ! -f "${ZLIB_HOME}/include/zlib.h"
-then
-        ZLIB_HOME=/usr
+AC_DEFUN([CHECK_ZLIB], [
+AC_ARG_WITH([zlib],
+	[AS_HELP_STRING([--with-zlib=DIR],[root directory of the zlib installation])],
+	[zlib_want=$withval], [zlib_want=yes])
+if test "$zlib_want" = "no"; then
+	AC_MSG_ERROR([zlib cannot be disabled: the cache and the WARC output are zip/gzip containers, and the bundled minizip calls zlib directly])
 fi
-])
-
-#
-# Locate zlib, if wanted
-#
-if test -n "${ZLIB_HOME}"
-then
-        ZLIB_OLD_LDFLAGS=$LDFLAGS
-        ZLIB_OLD_CPPFLAGS=$LDFLAGS
-        LDFLAGS="$LDFLAGS -L${ZLIB_HOME}/lib"
-        CPPFLAGS="$CPPFLAGS -I${ZLIB_HOME}/include"
-        AC_LANG_SAVE
-        AC_LANG_C
-        AC_CHECK_LIB(z, inflateEnd, [zlib_cv_libz=yes], [zlib_cv_libz=no])
-        AC_CHECK_HEADER(zlib.h, [zlib_cv_zlib_h=yes], [zlib_cv_zlib_h=no])
-        AC_LANG_RESTORE
-        if test "$zlib_cv_libz" = "yes" -a "$zlib_cv_zlib_h" = "yes"
-        then
-                #
-                # If both library and header were found, use them
-                #
-                AC_CHECK_LIB(z, inflateEnd)
-                AC_MSG_CHECKING(zlib in ${ZLIB_HOME})
-                AC_MSG_RESULT(ok)
-        else
-                #
-                # If either header or library was not found, revert and bomb
-                #
-                AC_MSG_CHECKING(zlib in ${ZLIB_HOME})
-                LDFLAGS="$ZLIB_OLD_LDFLAGS"
-                CPPFLAGS="$ZLIB_OLD_CPPFLAGS"
-                AC_MSG_RESULT(failed)
-                AC_MSG_ERROR(either specify a valid zlib installation with --with-zlib=DIR or disable zlib usage with --without-zlib)
-        fi
+if test "$zlib_want" != "yes"; then
+	# An explicit prefix is authoritative: if the header is not under it,
+	# error rather than silently pick a system copy.
+	if test ! -f "$zlib_want/include/zlib.h"; then
+		AC_MSG_ERROR([zlib requested at $zlib_want but $zlib_want/include/zlib.h is missing])
+	fi
+	CPPFLAGS="$CPPFLAGS -I$zlib_want/include"
+	LDFLAGS="$LDFLAGS -L$zlib_want/lib"
+elif test -f /usr/local/include/zlib.h; then
+	# Where the BSD ports tree lands zlib, and not always searched by default.
+	CPPFLAGS="$CPPFLAGS -I/usr/local/include"
+	LDFLAGS="$LDFLAGS -L/usr/local/lib"
 fi
-
+AC_CHECK_HEADER([zlib.h], [],
+	[AC_MSG_ERROR([zlib.h not found; install the zlib development files or pass --with-zlib=DIR])])
+AC_CHECK_LIB([z], [inflateEnd], [],
+	[AC_MSG_ERROR([libz not found; install the zlib development files or pass --with-zlib=DIR])])
 ])

src/htsback.c

@@ -48,11 +48,6 @@ Please visit our Website: http://www.httrack.com
 #include "htsftp.h"
 #include "htscodec.h"
 #include "htsproxy.h"
-#if HTS_USEZLIB
-#include "htszlib.h"
-#else
-#error HTS_USEZLIB not defined
-#endif
 
 #ifdef _WIN32
 #ifndef __cplusplus
@@ -590,12 +585,17 @@ static int create_back_tmpfile(httrackp *opt, lien_back *const back,
   return 0;
 }
 
-/* Move src onto dst; RENAME does not clobber an existing target on Windows. */
-static hts_boolean replace_file(const char *src, const char *dst) {
-  if (RENAME(src, dst) == 0)
-    return HTS_TRUE;
-  (void) UNLINK(dst);
-  return RENAME(src, dst) == 0 ? HTS_TRUE : HTS_FALSE;
+/* Did the fetch fail to produce a response, as opposed to the engine
+   deliberately passing the resource over? Only the latter may be purged. */
+static hts_boolean back_transfer_failed(const int statuscode) {
+  switch (statuscode) {
+  case STATUSCODE_TOO_BIG:
+  case STATUSCODE_EXCLUDED:
+  case STATUSCODE_TEST_OK:
+    return HTS_FALSE;
+  default:
+    return statuscode <= 0 ? HTS_TRUE : HTS_FALSE;
+  }
 }
 
 /* Commit or restore a re-fetch backup (#77 follow-up): a re-fetch over an
@@ -615,7 +615,7 @@ static void back_finalize_backup(httrackp *opt, lien_back *const back,
     }
     /* On failure keep the backup: an orphaned temp beats losing the good copy.
      */
-    if (!replace_file(back->tmpfile, back->url_sav))
+    if (!hts_rename_over(back->tmpfile, back->url_sav))
       hts_log_print(opt, LOG_WARNING | LOG_ERRNO,
                     "could not restore %s; previous copy kept as %s",
                     back->url_sav, back->tmpfile);
@@ -746,7 +746,7 @@ int back_finalize(httrackp * opt, cache_back * cache, struct_back * sback,
                                  "Read error when decompressing");
                     }
                     UNLINK(unpacked);
-                  } else if (replace_file(unpacked, back[p].url_sav)) {
+                  } else if (hts_rename_over(unpacked, back[p].url_sav)) {
                     /* The temp bypassed filecreate(), which is what chmods. */
 #ifndef _WIN32
                     chmod(back[p].url_sav, HTS_ACCESS_FILE);
@@ -1044,6 +1044,14 @@ int back_finalize(httrackp * opt, cache_back * cache, struct_back * sback,
   /* Aborted, error, or not ready: url_sav (if written) is broken; restore the
      previous copy from the backup. */
   back_finalize_backup(opt, &back[p], HTS_FALSE);
+  /* Note the surviving copy, or the end-of-update purge drops what this run
+     never managed to replace (#746). */
+  if (!back[p].testmode && back_transfer_failed(back[p].r.statuscode) &&
+      back[p].url_sav[0] != '\0' && fexist_utf8(back[p].url_sav)) {
+    filenote(&opt->state.strc, back[p].url_sav, NULL);
+    file_notify(opt, back[p].url_adr, back[p].url_fil, back[p].url_sav, 0, 0,
+                back[p].r.notmodified);
+  }
   return -1;
 }
 

src/htscodec.c

@@ -72,7 +72,7 @@ hts_codec hts_codec_parse(const char *encoding) {
     return HTS_CODEC_IDENTITY;
   if (strfield2(encoding, "gzip") || strfield2(encoding, "x-gzip") ||
       strfield2(encoding, "deflate") || strfield2(encoding, "x-deflate"))
-    return HTS_USEZLIB ? HTS_CODEC_DEFLATE : HTS_CODEC_UNSUPPORTED;
+    return HTS_CODEC_DEFLATE;
   if (strfield2(encoding, "br"))
     return HTS_USEBROTLI ? HTS_CODEC_BROTLI : HTS_CODEC_UNSUPPORTED;
   if (strfield2(encoding, "zstd"))
@@ -98,16 +98,11 @@ hts_codec hts_codec_parse(const char *encoding) {
 const char *hts_acceptencoding(hts_boolean compressible, hts_boolean secure) {
   if (!compressible)
     return "identity";
-#if HTS_USEZLIB
   /* br and zstd over TLS only, as browsers do: a cleartext intermediary that
      rewrites a coding it can not read would corrupt the mirror. */
   if (secure)
     return "gzip, deflate" HTS_AE_BROTLI HTS_AE_ZSTD ", identity;q=0.9";
   return "gzip, deflate, identity;q=0.9";
-#else
-  (void) secure;
-  return "identity";
-#endif
 }
 
 hts_boolean hts_codec_is_archive_ext(hts_codec codec, const char *ext) {
@@ -300,11 +295,7 @@ int hts_codec_unpack(hts_codec codec, const char *filename,
     return -1;
   switch (codec) {
   case HTS_CODEC_DEFLATE:
-#if HTS_USEZLIB
     return hts_zunpack(filename, newfile);
-#else
-    return -1;
-#endif
   case HTS_CODEC_BROTLI:
   case HTS_CODEC_ZSTD:
     break;
@@ -348,10 +339,8 @@ size_t hts_codec_head(hts_codec codec, const void *in, size_t in_len, void *out,
   if (in == NULL || in_len == 0 || out == NULL || out_len == 0)
     return 0;
   switch (codec) {
-#if HTS_USEZLIB
   case HTS_CODEC_DEFLATE:
     return hts_zhead(in, in_len, out, out_len);
-#endif
 #if HTS_USEBROTLI
   case HTS_CODEC_BROTLI:
     return codec_head_brotli(in, in_len, out, out_len);

src/htscore.c

@@ -1980,10 +1980,9 @@ int httpmirror(char *url1, httrackp * opt) {
           }
 
           // ATTENTION C'EST ICI QU'ON SAUVE LE FICHIER!!
-          // An empty body must not overwrite the file when the transfer failed
-          // (statuscode <= 0, e.g. an -M hard-stop): it would truncate a good
-          // copy to 0 (#77 follow-up).
-          if (r.adr != NULL || (r.size == 0 && r.statuscode > 0)) {
+          // A failed transfer has no body: r.adr holds debris from the aborted
+          // read, which would destroy the copy being re-fetched (#748).
+          if (r.statuscode > 0 && (r.adr != NULL || r.size == 0)) {
             file_notify(opt, urladr(), urlfil(), savename(), 1, 1, r.notmodified);
             if (filesave(opt, r.adr, (int) r.size, savename(), urladr(), urlfil()) !=
                 0) {
@@ -2693,7 +2692,11 @@ HTSEXT_API int structcheck(const char *path) {
       if (!S_ISDIR(st.st_mode)) {
 #if HTS_REMOVE_ANNOYING_INDEX
         if (S_ISREG(st.st_mode)) {      /* Regular file in place ; move it and create directory */
-          sprintf(tmpbuf, "%s.txt", file);
+          /* bounded here, not by the path-length guard far above */
+          if (!sprintfbuff(tmpbuf, "%s.txt", file)) {
+            errno = ENAMETOOLONG;
+            return -1;
+          }
           if (rename(file, tmpbuf) != 0) {      /* Can't rename regular file */
             return -1;
           }
@@ -2801,7 +2804,11 @@ HTSEXT_API int structcheck_utf8(const char *path) {
       if (!S_ISDIR(st.st_mode)) {
 #if HTS_REMOVE_ANNOYING_INDEX
         if (S_ISREG(st.st_mode)) {      /* Regular file in place ; move it and create directory */
-          sprintf(tmpbuf, "%s.txt", file);
+          /* bounded here, not by the path-length guard far above */
+          if (!sprintfbuff(tmpbuf, "%s.txt", file)) {
+            errno = ENAMETOOLONG;
+            return -1;
+          }
           if (RENAME(file, tmpbuf) != 0) {      /* Can't rename regular file */
             return -1;
           }
@@ -3821,11 +3828,12 @@ int htsAddLink(htsmoduleStruct * str, char *link) {
         strcpybuff(codebase, heap(ptr)->fil);
       else
         strcpybuff(codebase, heap(heap(ptr)->precedent)->fil);
-      a = codebase + strlen(codebase) - 1;
+      // empty codebase has no last char; codebase-1 would underflow
+      a = codebase[0] != '\0' ? codebase + strlen(codebase) - 1 : codebase;
       while((*a) && (*a != '/') && (a > codebase))
         a--;
       if (*a == '/')
-        *(a + 1) = '\0';        // couper
+        *(a + 1) = '\0';        // cut
     } else {                    // couper http:// éventuel
       if (strfield(codebase, "http://")) {
         char BIGSTK tempo[HTS_URLMAXSIZE * 2];

src/htsglobal.h

@@ -138,10 +138,11 @@ Please visit our Website: http://www.httrack.com
 #define HTS_DOSNAME 0
 #endif
 
-// utiliser zlib?
+// zlib is mandatory: the cache is a zip and minizip calls it regardless
 #ifndef HTS_USEZLIB
-// autoload
 #define HTS_USEZLIB 1
+#elif !HTS_USEZLIB
+#error HTS_USEZLIB=0 is not a supported configuration
 #endif
 
 // brotli and zstd content codings; off unless the build opted in (configure,

src/htslib.c

@@ -1131,12 +1131,10 @@ int http_sendhead(httrackp * opt, t_cookie * cookie, int mode,
 
       // Compression accepted ?
       if (retour->req.http11) {
-        hts_boolean compressible = HTS_FALSE;
+        hts_boolean compressible =
+            (!retour->req.range_used && !retour->req.nocompression);
         hts_boolean secure = HTS_FALSE;
 
-#if HTS_USEZLIB
-        compressible = (!retour->req.range_used && !retour->req.nocompression);
-#endif
 #if HTS_USEOPENSSL
         secure = retour->ssl ? HTS_TRUE : HTS_FALSE;
 #endif

src/htsname.c

@@ -43,9 +43,7 @@ Please visit our Website: http://www.httrack.com
 #include "htsencoding.h"
 #include "htssniff.h"
 #include "htscodec.h"
-#if HTS_USEZLIB
 #include "htszlib.h"
-#endif
 #include <ctype.h>
 #include <limits.h>
 

src/htsselftest.c

@@ -43,6 +43,7 @@ Please visit our Website: http://www.httrack.com
 
 #include "htsglobal.h"
 #include "htscore.h"
+#include "htsmodules.h"
 #include "htsback.h"
 #include "htsdefines.h"
 #include "htslib.h"
@@ -63,9 +64,7 @@ Please visit our Website: http://www.httrack.com
 #include "htswarc.h"
 #include "htschanges.h"
 #include "htssinglefile.h"
-#if HTS_USEZLIB
 #include "htszlib.h"
-#endif
 #if HTS_USEZSTD
 #include <zstd.h>
 #endif
@@ -2623,6 +2622,68 @@ static int st_savename(httrackp *opt, int argc, char **argv) {
   return 0;
 }
 
+/* an empty fil started htsAddLink's codebase walk before the buffer (#730) */
+static int st_addlink(httrackp *opt, int argc, char **argv) {
+  htsmoduleStruct BIGSTK str;
+  cache_back cache;
+  struct_back *sback;
+  hash_struct hash;
+  int ptr = 0;
+  int i;
+
+  (void) argc;
+  (void) argv;
+
+  memset(&cache, 0, sizeof(cache));
+  cache.hashtable = (void *) coucal_new(0);
+  sback = back_new(opt, opt->maxsoc * 32 + 1024);
+  /* same wiring as hts_mirror (htscore.c) */
+  hash_init(opt, &hash, opt->urlhack);
+  hash.liens = (const lien_url *const *const *) &opt->liens;
+  opt->hash = &hash;
+  hts_record_init(opt);
+
+  memset(&str, 0, sizeof(str));
+  str.opt = opt;
+  str.sback = sback;
+  str.cache = &cache;
+  str.hashptr = &hash;
+  str.ptr_ = &ptr;
+  str.addLink = htsAddLink;
+
+  /* [0] is the underflow; [1] and [2] are controls that the trim is unchanged.
+     A query-only link is the one that notices the trim at all: for the others
+     ident_url_relatif() re-derives the directory from the path it is given. */
+  for (i = 0; i < 3; i++) {
+    static const char *const fil[3] = {"", "/dir/page.html", "/dir/page.html"};
+    static const char *const lnk[3] = {"sub/page.html", "sub/page.html",
+                                       "?x=1"};
+    static const char *const want[3] = {
+        "untouched", "http://www.example.com/dir/sub/page.html",
+        "http://www.example.com/dir/?x=1"};
+    char BIGSTK loc[HTS_URLMAXSIZE * 2];
+    char BIGSTK link[HTS_URLMAXSIZE];
+
+    strcpybuff(loc, "untouched");
+    strcpybuff(link, lnk[i]);
+    str.localLink = loc;
+    str.localLinkSize = (int) sizeof(loc);
+    if (!hts_record_link(opt, "www.example.com", fil[i], "", "", "", ""))
+      return 1;
+    ptr = heap_top_index();
+    str.url_host = heap(ptr)->adr;
+    str.url_file = heap(ptr)->fil;
+    assertf(htsAddLink(&str, link) == 0); /* refused by the wizard either way */
+    if (strcmp(loc, want[i]) != 0) {
+      fprintf(stderr, "addlink[%d]: got '%s' want '%s'\n", i, loc, want[i]);
+      return 1;
+    }
+  }
+
+  printf("addlink self-test OK\n");
+  return 0;
+}
+
 static int st_cache(httrackp *opt, int argc, char **argv) {
   int err;
 
@@ -3264,6 +3325,81 @@ static int st_topindex(httrackp *opt, int argc, char **argv) {
   return 0;
 }
 
+/* Build a path of exactly len chars under base; returns that length. */
+static size_t st_structcheck_longpath(char *dst, size_t dstsize,
+                                      const char *base, size_t len) {
+  size_t n = strlen(base);
+
+  assertf(len < dstsize && n + 2 <= len);
+  memmove(dst, base, n);
+  while (n < len) {
+    size_t seg = len - n - 1;
+
+    if (seg > 200) /* stay under the usual 255-byte component limit */
+      seg = len - n == 202 ? 199 : 200; /* never leave a bare separator */
+    dst[n++] = '/';
+    memset(dst + n, 'x', seg);
+    n += seg;
+  }
+  dst[n] = '\0';
+  return n;
+}
+
+/* The path guard, and the <name>.txt rename structcheck() performs when a
+   regular file sits where a directory has to go (#745). */
+static int st_structcheck(httrackp *opt, int argc, char **argv) {
+  char BIGSTK path[HTS_URLMAXSIZE * 2];
+  char BIGSTK target[HTS_URLMAXSIZE * 2];
+  FILE *fp;
+
+  (void) opt;
+  if (argc < 1) {
+    fprintf(stderr, "usage: -#test=structcheck <writable directory>\n");
+    return 1;
+  }
+
+  /* over the guard: refused before a single directory is created */
+  st_structcheck_longpath(path, sizeof(path), argv[0], HTS_URLMAXSIZE + 1);
+  errno = 0;
+  assertf(structcheck(path) == -1);
+  assertf(errno == EINVAL);
+  errno = 0;
+  assertf(structcheck_utf8(path) == -1);
+  assertf(errno == EINVAL);
+  {
+    char *const sep = strchr(path + strlen(argv[0]) + 1, '/');
+
+    assertf(sep != NULL);
+    sep[1] = '\0'; /* the outermost component it would have created */
+    assertf(!dir_exists(path));
+  }
+
+  /* a regular file where a directory belongs is renamed to <name>.txt */
+  snprintf(path, sizeof(path), "%s/sc", argv[0]);
+  fp = fopen(path, "wb");
+  assertf(fp != NULL);
+  fclose(fp);
+  snprintf(path, sizeof(path), "%s/sc/sub/", argv[0]);
+  assertf(structcheck(path) == 0);
+  assertf(dir_exists(path));
+  snprintf(target, sizeof(target), "%s/sc.txt", argv[0]);
+  assertf(fexist(target));
+
+  /* the utf-8 entry point carries the same rename */
+  snprintf(path, sizeof(path), "%s/u8", argv[0]);
+  fp = FOPEN(path, "wb");
+  assertf(fp != NULL);
+  fclose(fp);
+  snprintf(path, sizeof(path), "%s/u8/sub/", argv[0]);
+  assertf(structcheck_utf8(path) == 0);
+  assertf(dir_exists(path));
+  snprintf(target, sizeof(target), "%s/u8.txt", argv[0]);
+  assertf(fexist_utf8(target));
+
+  printf("structcheck self-test OK\n");
+  return 0;
+}
+
 /* Each inplace_escape_*() must equal escape_*() on a copy. */
 static int st_inplace_escape(httrackp *opt, int argc, char **argv) {
   /* >255 bytes forces the helper's malloct path, not the stack buffer */
@@ -3377,7 +3513,6 @@ static int st_status(httrackp *opt, int argc, char **argv) {
   return 0;
 }
 
-#if HTS_USEZLIB
 /* Deflate src->path at windowBits (16+ gzip, + zlib, - raw); 0 on success. */
 static int ae_write_packed(const char *path, int windowBits,
                            const unsigned char *src, size_t len) {
@@ -3451,7 +3586,6 @@ static int ae_write_collision(const char *path, const unsigned char *src,
   freet(buf);
   return ok ? 0 : 1;
 }
-#endif
 
 /* Write src[0..len) to path as-is; 0 on success. */
 static int ae_write_raw(const char *path, const unsigned char *src,
@@ -3501,7 +3635,6 @@ static int st_acceptencoding(httrackp *opt, int argc, char **argv) {
   assertf(strstr(on, "br") == NULL && strstr(on, "zstd") == NULL);
   assertf((strstr(tls, ", br") != NULL) == (HTS_USEBROTLI != 0));
   assertf((strstr(tls, "zstd") != NULL) == (HTS_USEZSTD != 0));
-#if HTS_USEZLIB
   if (argc >= 1) {
     static const int windowBits[] = {16 + MAX_WBITS, MAX_WBITS, -MAX_WBITS};
     const unsigned char small[] =
@@ -3580,10 +3713,6 @@ static int st_acceptencoding(httrackp *opt, int argc, char **argv) {
     }
     freet(body);
   }
-#else
-  (void) argc;
-  (void) argv;
-#endif
   printf("acceptencoding self-test OK: %s\n", on);
   return 0;
 }
@@ -3928,7 +4057,6 @@ static int st_sitemap(httrackp *opt, int argc, char **argv) {
     freet(big);
   }
 
-#if HTS_USEZLIB
   /* A highly compressible document decodes without running away: the ratio
      budget cannot bind (deflate tops out near 1032:1), so this pins the
      decompression path itself rather than the 64 MiB ceiling. */
@@ -3979,13 +4107,11 @@ static int st_sitemap(httrackp *opt, int argc, char **argv) {
     freet(z);
     freet(x);
   }
-#endif
 
   /* An unterminated <loc> at end of buffer must not read past it. */
   assertf(sm_scan("<urlset><loc>http://h.test/a", 100, &idx, &c) == 0);
   assertf(sm_scan("<urlset><lo", 100, &idx, &c) == 0);
 
-#if HTS_USEZLIB
   /* A gzip-framed document is decompressed before scanning. */
   {
     const char *const xml =
@@ -4015,7 +4141,6 @@ static int st_sitemap(httrackp *opt, int argc, char **argv) {
     assertf(hts_sitemap_scan(z, 4, 100, &idx, sm_take, &c) == -1);
     freet(z);
   }
-#endif
 
   /* robots.txt: only Sitemap: records, comments stripped, case-insensitive,
      and group-independent (no User-agent line needed). */
@@ -6089,6 +6214,116 @@ static int st_changes(httrackp *opt, int argc, char **argv) {
   return err;
 }
 
+/* #747: a thread is outstanding from the moment hts_newthread() returns, not
+   from the moment it starts running, or a wait right after the spawn joins
+   nothing. One thread per round is what makes the old bug visible: the wait
+   had to find the counter at zero, and a batch of spawns gives the earlier
+   threads time to raise it. Unfixed, one round in two caught it, so the round
+   count is what turns that into a reliable failure. */
+#define THREADWAIT_N 8
+#define THREADWAIT_ROUNDS 16
+#define THREADWAIT_SLEEP_MS 50
+#define THREADWAIT_GATE_MS 10000
+
+static htsmutex threadwait_lock = HTSMUTEX_INIT;
+static int threadwait_done = 0;
+static hts_boolean threadwait_gated = HTS_FALSE;
+
+static int threadwait_count(void) {
+  int n;
+
+  hts_mutexlock(&threadwait_lock);
+  n = threadwait_done;
+  hts_mutexrelease(&threadwait_lock);
+  return n;
+}
+
+static void threadwait_thread(void *arg) {
+  (void) arg;
+  Sleep(THREADWAIT_SLEEP_MS);
+  hts_mutexlock(&threadwait_lock);
+  threadwait_done++;
+  hts_mutexrelease(&threadwait_lock);
+}
+
+/* Stays outstanding until the gate clears, so wait_n() can be asked to leave a
+   known number of live threads behind. Bounded: a wait_n() that wrongly drains
+   them would otherwise never return, and hang the suite instead of failing. */
+static void threadwait_gated_thread(void *arg) {
+  int waited;
+
+  (void) arg;
+  for (waited = 0; waited < THREADWAIT_GATE_MS; waited += 10) {
+    hts_boolean gated;
+
+    hts_mutexlock(&threadwait_lock);
+    gated = threadwait_gated;
+    hts_mutexrelease(&threadwait_lock);
+    if (!gated)
+      break;
+    Sleep(10);
+  }
+  hts_mutexlock(&threadwait_lock);
+  threadwait_done++;
+  hts_mutexrelease(&threadwait_lock);
+}
+
+static int st_threadwait(httrackp *opt, int argc, char **argv) {
+  int err = 0;
+  int i, round;
+
+  (void) opt;
+  (void) argc;
+  (void) argv;
+
+  /* htsthread_wait() joins a thread spawned just before it */
+  for (round = 0; round < THREADWAIT_ROUNDS && !err; round++) {
+    hts_mutexlock(&threadwait_lock);
+    threadwait_done = 0;
+    hts_mutexrelease(&threadwait_lock);
+    if (hts_newthread(threadwait_thread, NULL) != 0) {
+      fprintf(stderr, "threadwait: cannot spawn\n");
+      return 1;
+    }
+    htsthread_wait();
+    if (threadwait_count() != 1) {
+      fprintf(stderr, "threadwait: round %d returned before the thread ran\n",
+              round);
+      err = 1;
+    }
+  }
+
+  /* htsthread_wait_n(n) leaves n behind rather than draining everything */
+  hts_mutexlock(&threadwait_lock);
+  threadwait_done = 0;
+  threadwait_gated = HTS_TRUE;
+  hts_mutexrelease(&threadwait_lock);
+  for (i = 0; i < THREADWAIT_N; i++) {
+    if (hts_newthread(threadwait_gated_thread, NULL) != 0) {
+      fprintf(stderr, "threadwait: cannot spawn a gated thread\n");
+      return 1;
+    }
+  }
+  htsthread_wait_n(THREADWAIT_N);
+  if (threadwait_count() != 0) {
+    fprintf(stderr, "threadwait: wait_n(%d) joined %d gated threads\n",
+            THREADWAIT_N, threadwait_count());
+    err = 1;
+  }
+  hts_mutexlock(&threadwait_lock);
+  threadwait_gated = HTS_FALSE;
+  hts_mutexrelease(&threadwait_lock);
+  htsthread_wait();
+  if (threadwait_count() != THREADWAIT_N) {
+    fprintf(stderr, "threadwait: wait left %d/%d gated threads running\n",
+            THREADWAIT_N - threadwait_count(), THREADWAIT_N);
+    err = 1;
+  }
+
+  printf("threadwait self-test: %s\n", err ? "FAIL" : "OK");
+  return err;
+}
+
 #define CHANGES_RACE_FILES 8
 #define CHANGES_RACE_ROUNDS 400
 
@@ -6103,11 +6338,8 @@ static void changes_race_notify(httrackp *opt, int n) {
   hts_changes_notify(opt, "race.example", fil, save, HTS_TRUE, HTS_FALSE);
 }
 
-/* htsthread_wait() counts a thread only once it is running, so it can return
-   before any of them started; join on our own counter instead. */
 static htsmutex changes_race_lock = HTSMUTEX_INIT;
 static int changes_race_started = 0;
-static int changes_race_live = 0;
 
 static int changes_race_count(int *which) {
   int n;
@@ -6127,9 +6359,6 @@ static void changes_race_thread(void *arg) {
   hts_mutexrelease(&changes_race_lock);
   for (i = 0; i < CHANGES_RACE_ROUNDS; i++)
     changes_race_notify(opt, i % CHANGES_RACE_FILES);
-  hts_mutexlock(&changes_race_lock);
-  changes_race_live--;
-  hts_mutexrelease(&changes_race_lock);
 }
 
 /* A transfer thread the crawl never joins (FTP) reaches hts_changes_notify()
@@ -6184,7 +6413,6 @@ static int st_changes_race(httrackp *opt, int argc, char **argv) {
      threads reaching a fresh one together race on the init itself. */
   hts_mutexlock(&changes_race_lock);
   changes_race_started = 0;
-  changes_race_live = 4;
   hts_mutexrelease(&changes_race_lock);
   for (i = 0; i < 4; i++) {
     if (hts_newthread(changes_race_thread, opt) != 0) {
@@ -6198,8 +6426,7 @@ static int st_changes_race(httrackp *opt, int argc, char **argv) {
   for (i = 0; i < 64; i++)
     hts_changes_report(opt, &out);
   hts_changes_close_opt(opt);
-  while (changes_race_count(&changes_race_live) > 0)
-    Sleep(10);
+  htsthread_wait();
 
   /* Sealed: a straggler must be dropped, not start a report nobody writes. */
   changes_race_notify(opt, CHANGES_RACE_FILES + 1);
@@ -6277,6 +6504,8 @@ static const struct selftest_entry {
      st_changes},
     {"changes-race", "<dir>", "--changes under a late transfer thread (#714)",
      st_changes_race},
+    {"threadwait", "", "htsthread_wait() joins threads spawned just before it",
+     st_threadwait},
     {"pause", "", "randomized inter-file pause target self-test", st_pause},
     {"relative", "<link> <curr-file>", "relative link between two paths",
      st_relative},
@@ -6307,6 +6536,8 @@ static const struct selftest_entry {
     {"fsize", "<dir>", "file size past the 2GB signed-32-bit wrap", st_fsize},
     {"growsize", "", "buffer capacity for a 64-bit file size (no int wrap)",
      st_growsize},
+    {"addlink", "", "htsAddLink codebase walk over an empty current path",
+     st_addlink},
     {"cache", "<dir>", "cache read/write round-trip self-test", st_cache},
     {"cacheindex", "", "cache-index (.ndx) parse must stay in bounds",
      st_cacheindex},
@@ -6330,6 +6561,9 @@ static const struct selftest_entry {
     {"useragent", "", "default User-Agent self-test", st_useragent},
     {"makeindex", "[dir]", "hts_finish_makeindex footer/refresh self-test",
      st_makeindex},
+    {"structcheck", "<dir>",
+     "structcheck path guard and the <name>.txt rename it performs",
+     st_structcheck},
     {"topindex", "[dir]",
      "hts_buildtopindex charset handling of a non-ASCII project dir",
      st_topindex},

src/htssinglefile.c

@@ -1108,13 +1108,8 @@ hts_boolean singlefile_rewrite_file(httrackp *opt, const char *root,
       (void) chmod(fconv(catbuff, sizeof(catbuff), StringBuff(tmp)),
                    HTS_ACCESS_FILE);
 #endif
-    if (ok) {
-      /* RENAME does not clobber an existing target on Windows. */
-      if (RENAME(StringBuff(tmp), page_path) != 0) {
-        (void) UNLINK(page_path);
-        ok = RENAME(StringBuff(tmp), page_path) == 0 ? HTS_TRUE : HTS_FALSE;
-      }
-    }
+    if (ok)
+      ok = hts_rename_over(StringBuff(tmp), page_path);
     if (!ok) {
       hts_log_print(opt, LOG_ERROR, "single-file: could not rewrite %s",
                     page_path);

src/htsthread.c

@@ -44,9 +44,18 @@ Please visit our Website: http://www.httrack.com
 #endif
 #endif
 
+/* Outstanding threads, counted at spawn rather than by the child at entry, so
+   that a caller which spawns and immediately waits still joins them (#747). */
 static int process_chain = 0;
 static htsmutex process_chain_mutex = HTSMUTEX_INIT;
 
+static void process_chain_add(int delta) {
+  hts_mutexlock(&process_chain_mutex);
+  process_chain += delta;
+  assertf(process_chain >= 0);
+  hts_mutexrelease(&process_chain_mutex);
+}
+
 HTSEXT_API void htsthread_wait(void) {
   htsthread_wait_n(0);
 }
@@ -99,20 +108,12 @@ static void *hts_entry_point(void *tharg)
   void *const arg = s_args->arg;
   void (*fun) (void *arg) = s_args->fun;
 
-  free(tharg);
-
-  hts_mutexlock(&process_chain_mutex);
-  process_chain++;
-  assertf(process_chain > 0);
-  hts_mutexrelease(&process_chain_mutex);
+  freet(tharg);
 
   /* run */
   fun(arg);
 
-  hts_mutexlock(&process_chain_mutex);
-  process_chain--;
-  assertf(process_chain >= 0);
-  hts_mutexrelease(&process_chain_mutex);
+  process_chain_add(-1);
 #ifdef _WIN32
   return 0;
 #else
@@ -122,18 +123,20 @@ static void *hts_entry_point(void *tharg)
 
 /* create a thread */
 HTSEXT_API int hts_newthread(void (*fun) (void *arg), void *arg) {
-  hts_thread_s *s_args = malloc(sizeof(hts_thread_s));
+  hts_thread_s *s_args = malloct(sizeof(hts_thread_s));
 
   assertf(s_args != NULL);
   s_args->arg = arg;
   s_args->fun = fun;
+  process_chain_add(1);
 #ifdef _WIN32
   {
     unsigned int idt;
     HANDLE handle =
       (HANDLE) _beginthreadex(NULL, 0, hts_entry_point, s_args, 0, &idt);
     if (handle == 0) {
-      free(s_args);
+      process_chain_add(-1);
+      freet(s_args);
       return -1;
     } else {
       /* detach the thread from the main process so that is can be independent */
@@ -151,7 +154,8 @@ HTSEXT_API int hts_newthread(void (*fun) (void *arg), void *arg) {
         || pthread_attr_setstacksize(&attr, stackSize) != 0
         || (retcode =
             pthread_create(&handle, &attr, hts_entry_point, s_args)) != 0) {
-      free(s_args);
+      process_chain_add(-1);
+      freet(s_args);
       return -1;
     } else {
       /* detach the thread from the main process so that is can be independent */

src/htstools.c

@@ -1443,3 +1443,15 @@ HTSEXT_API hts_boolean hts_findissystem(find_handle find) {
   }
   return 0;
 }
+
+hts_boolean hts_rename_over(const char *src, const char *dst) {
+  char csrc[CATBUFF_SIZE], cdst[CATBUFF_SIZE];
+
+  fconv(csrc, sizeof(csrc), src);
+  fconv(cdst, sizeof(cdst), dst);
+  if (RENAME(csrc, cdst) == 0)
+    return HTS_TRUE;
+  /* RENAME does not clobber an existing target on Windows. */
+  (void) UNLINK(cdst);
+  return RENAME(csrc, cdst) == 0 ? HTS_TRUE : HTS_FALSE;
+}

src/htstools.h

@@ -137,6 +137,10 @@ HTSEXT_API hts_boolean hts_findisdir(find_handle find);
 HTSEXT_API hts_boolean hts_findisfile(find_handle find);
 HTSEXT_API hts_boolean hts_findissystem(find_handle find);
 
+/* Move src onto dst, replacing an existing dst; HTS_TRUE on success. Both
+   paths are fconv()'d. */
+hts_boolean hts_rename_over(const char *src, const char *dst);
+
 #endif
 
 #endif

src/htswarc.c

@@ -964,16 +964,6 @@ static zipFile wacz_zip_open(const char *path) {
   return zipOpen2_64(path, 0 /*create*/, NULL, &ff);
 }
 
-/* Move src onto dst (UTF-8/Windows-safe); RENAME won't clobber on Windows, so
-   fall back to unlink+rename. Returns 0 on success. */
-static int wacz_rename_over(const char *src, const char *dst) {
-  char cs[CATBUFF_SIZE], cd[CATBUFF_SIZE];
-  if (RENAME(fconv(cs, sizeof(cs), src), fconv(cd, sizeof(cd), dst)) == 0)
-    return 0;
-  (void) UNLINK(fconv(cd, sizeof(cd), dst));
-  return RENAME(fconv(cs, sizeof(cs), src), fconv(cd, sizeof(cd), dst));
-}
-
 /* Package the segment(s) + .cdx + a generated pages.jsonl into <base>.wacz at
    crawl end (the archive file(s) and .cdx are already closed on disk). */
 static void warc_wacz_package(warc_writer *w) {
@@ -1092,7 +1082,7 @@ static void warc_wacz_package(warc_writer *w) {
     hts_log_print(w->opt, LOG_WARNING,
                   "WACZ: packaging failed, kept existing %s untouched",
                   waczpath);
-  } else if (wacz_rename_over(tmppath, waczpath) != 0) {
+  } else if (!hts_rename_over(tmppath, waczpath)) {
     (void) UNLINK(fconv(catbuff, sizeof(catbuff), tmppath));
     hts_log_print(w->opt, LOG_WARNING | LOG_ERRNO,
                   "WACZ: could not finalize %s", waczpath);

src/htsweb.c

@@ -101,8 +101,8 @@ static void htsweb_sig_brpipe(int code) {
   /* ignore */
 }
 
-/* Number of background threads */
-static int background_threads = 0;
+/* Threads that never return; no wait may count on them draining. */
+static int nonjoinable_threads = 0;
 
 /* Server/client ping handling */
 static htsmutex pingMutex = HTSMUTEX_INIT;
@@ -224,9 +224,7 @@ int main(int argc, char *argv[]) {
 #ifdef HTS_USESWF
   smallserver_setkey("USESWF", "1");
 #endif
-#ifdef HTS_USEZLIB
   smallserver_setkey("USEZLIB", "1");
-#endif
 #ifdef _WIN32
   smallserver_setkey("WIN32", "1");
 #endif
@@ -299,15 +297,19 @@ int main(int argc, char *argv[]) {
 
   /* pinger */
   if (parentPid > 0) {
-    hts_newthread(client_ping, (void *) (uintptr_t) parentPid);
-    background_threads++; /* Do not wait for this thread! */
+    if (hts_newthread(client_ping, (void *) (uintptr_t) parentPid) == 0) {
+#ifndef _WIN32
+      nonjoinable_threads++; /* client_ping() only ever leaves through exit() */
+#endif
+    }
     smallserver_setpinghandler(pingHandler, NULL);
   }
 
   /* launch */
   ret = help_server(argv[1], defaultPort, bindAddr);
 
-  htsthread_wait_n(background_threads - 1);
+  /* Drain everything a mirror may still have in flight, the pinger aside. */
+  htsthread_wait_n(nonjoinable_threads);
   hts_uninit();
 
 #ifdef _WIN32
@@ -382,7 +384,6 @@ void webhttrack_main(char *cmd) {
   commandRunning = 1;
   DEBUG(fprintf(stderr, "commandRunning=1\n"));
   hts_newthread(back_launch_cmd, (void *) strdup(cmd));
-  background_threads++; /* Do not wait for this thread! */
 }
 
 void webhttrack_lock(void) {
@@ -423,8 +424,8 @@ static int webhttrack_runmain(httrackp * opt, int argc, char **argv) {
   /* Rock'in! */
   ret = hts_main2(argc, argv, opt);
 
-  /* Wait for pending threads to finish */
-  htsthread_wait_n(background_threads);
+  /* Wait for pending threads to finish; the pinger and this thread stay. */
+  htsthread_wait_n(nonjoinable_threads + 1);
 
   return ret;
 }

src/htszlib.c

@@ -40,7 +40,6 @@ Please visit our Website: http://www.httrack.com
 #include "htscodec.h"
 #include "htszlib.h"
 
-#if HTS_USEZLIB
 /* zlib */
 /*
 #include <zlib.h>
@@ -274,4 +273,3 @@ const char *hts_get_zerror(int err) {
     break;
   }
 }
-#endif

src/httrack.c

@@ -306,8 +306,8 @@ int main(int argc, char **argv) {
     fprintf(stderr, "* %s\n", hts_errmsg(opt));
   }
   global_opt = NULL;
+  htsthread_wait(); /* pending threads still read opt */
   hts_free_opt(opt);
-  htsthread_wait();             /* wait for pending threads */
   hts_uninit();
 
 #ifdef _WIN32

tests/01_engine-addlink.test

@@ -0,0 +1,7 @@
+#!/bin/bash
+#
+# an empty current path underflowed htsAddLink's codebase walk (#730).
+
+set -euo pipefail
+
+httrack -O /dev/null -#test=addlink | grep -q "addlink self-test OK"

tests/01_engine-structcheck.test

@@ -0,0 +1,12 @@
+#!/bin/bash
+#
+# structcheck(): the path-length guard, and the <name>.txt rename that once
+# built its target with an unbounded sprintf (#745).
+
+set -euo pipefail
+
+dir=$(mktemp -d)
+trap 'rm -rf "$dir"' EXIT
+
+httrack -O /dev/null -#test=structcheck "$dir" |
+    grep -q "structcheck self-test OK"

tests/01_engine-threadwait.test

@@ -0,0 +1,28 @@
+#!/bin/bash
+#
+
+set -euo pipefail
+
+tmpdir=$(mktemp -d "${TMPDIR:-/tmp}/httrack_threadwait_st.XXXXXX") || exit 1
+trap 'rm -rf "$tmpdir"' EXIT HUP INT QUIT PIPE TERM
+
+# No pipe into grep: SIGPIPE would mask a failing exit status.
+expect_ok() {
+    local label="$1" out
+    shift
+    out=$("$@" 2>&1) || {
+        echo "FAIL: ${label} exited non-zero: ${out}"
+        exit 1
+    }
+    case "$out" in
+    *"${label}: OK"*) ;;
+    *)
+        echo "FAIL: ${out}"
+        exit 1
+        ;;
+    esac
+}
+
+# A thread is outstanding from the moment hts_newthread() returns, so a wait
+# that follows the spawn joins it, and wait_n(n) still leaves n behind (#747).
+expect_ok "threadwait self-test" httrack -O "${tmpdir}/o1" -#test=threadwait

tests/43_local-update-truncate.test

@@ -18,6 +18,7 @@ set -euo pipefail
 bash "$top_srcdir/tests/local-crawl.sh" \
     --rerun-args '--update -M400000' \
     --log-found 'More than 400000 bytes have been transferred.. giving up' \
+    --log-not-found 'could not restore' \
     --found bigtrunc/slow.bin \
     --file-min-bytes bigtrunc/slow.bin 655360 \
     --file-min-bytes bigtrunc/fast.bin 655360 \

tests/65_port-siblings.test

@@ -79,6 +79,29 @@ done
 # 65535 is a valid port the old "< 65535" bound refused
 web_accepted 65535
 
+# --- htsserver returns from main() instead of blocking at exit -------------
+# The exit wait must exclude exactly the threads that never return (#753).
+# $tmp has no lang.def, so the server fails right after announcing and main()
+# reaches the wait on its own; rc, not EXITED, carries the verdict.
+
+web_exits() {
+    local rc=0
+
+    : >"$tmp/exit.log"
+    run_with_timeout 30 htsserver "$tmp" "$@" >"$tmp/exit.log" 2>&1 || rc=$?
+    grep -q "^EXITED" "$tmp/exit.log" ||
+        ! echo "FAIL: #753: htsserver ${*:-(no options)} never finished serving" || exit 1
+    # exactly 1, not merely "not 124": a crash or an assertf abort also escapes
+    # the wait, and would otherwise read as a pass
+    test "$rc" -eq 1 ||
+        ! echo "FAIL: #753: htsserver ${*:-(no options)} exited $rc, want 1" || exit 1
+}
+
+# no pinger: the excluded count went negative
+web_exits
+# a pinger, which never returns and so must stay excluded
+web_exits --ppid $$
+
 # --- proxytrack <proxy-addr:port> <ICP-addr:port> --------------------------
 # A bad argument falls through to the usage screen; it had no range check at
 # all, so 65616 quietly listened on port 80. A valid one binds and blocks.

tests/74_local-warc-wacz.test

@@ -5,11 +5,16 @@
 # real gate: STORE-mode entries, the fixed layout, recomputed sha256 digests and
 # the datapackage-digest chain (plus py-wacz/pywb when importable). The crawl
 # skips cleanly on a build without OpenSSL (no conformant SHA-256 -> no package).
+#
+# The cacheless second pass repackages over the .wacz the first one left: the
+# clobber, not the happy rename, is what breaks when a platform refuses to
+# rename onto an existing file (#726).
 
 set -eu
 
 : "${top_srcdir:=..}"
 
 bash "$top_srcdir/tests/local-crawl.sh" --errors 0 --wacz-validate \
+    --rerun-args '-C0' --log-not-found 'could not finalize' \
     --found 'mini304/index.html' --found 'mini304/page.html' \
     httrack 'BASEURL/mini304/index.html' --warc-file warc-out --wacz

tests/93_local-changes.test

@@ -94,10 +94,7 @@ expect_counts_match() {
     echo "OK"
 }
 lines() { printf '%s\n' "$@" | sort; }
-# A connection killed before the status line surfaces differently per platform
-# (macOS truncates the file, #748; Linux leaves it), so reset.bin is asserted on
-# its own and kept out of the exact lists.
-listed_but_reset() { listed "$1" | grep -v '/reset\.bin$' | sort; }
+digest() { cksum <"$1" | tr -d '[:space:]'; }
 
 # --- pass 1: nothing to compare against --------------------------------------
 httrack "${common[@]}" -O "$out" --purge-old=0 "${base}/changes/index.html" \
@@ -120,6 +117,7 @@ grep -aq "first crawl" "${out}/hts-log.txt" || {
 }
 
 host="127.0.0.1_${port}"
+resetdigest=$(digest "${out}/${host}/changes/reset.bin")
 # A leftover from some earlier failed attempt, at a name pass 2 fetches for the
 # first time: on disk, but never part of the previous mirror, so it is new.
 printf 'leftover junk' >"${out}/${host}/changes/fresh.html"
@@ -144,21 +142,19 @@ expect "gone is doomed.html and the old redirect target" \
 expect "changed is exactly the four moved resources" \
     "$(lines "${host}/changes/coded.bin" "${host}/changes/index.html" \
         "${host}/changes/moved.bin" "${host}/changes/moved.html")" \
-    "$(listed_but_reset changed)"
+    "$(listed changed | sort)"
 # Re-served byte for byte, 200, no Last-Modified, no ETag. flaky.bin gets there
 # through a failed transfer and a retry, so its file is notified twice;
 # redirtarget.html arrives behind a 302. sized.html has a byte-identical
 # payload, but the rewritten link to the renamed redirect target makes the file
-# on disk change length.
-expect "unchanged is exactly the six stable resources" \
+# on disk change length. reset.bin never completes a transfer (#746), so its
+# previous copy stands.
+expect "unchanged is exactly the seven stable resources" \
     "$(lines "${host}/changes/codedstable.bin" "${host}/changes/flaky.bin" \
-        "${host}/changes/redirtarget.html" "${host}/changes/sized.html" \
-        "${host}/changes/stable.bin" "${host}/changes/stable.html")" \
-    "$(listed_but_reset unchanged)"
-# reset.bin never completes a transfer, so it drops out of new.lst with its
-# mirrored copy still there. Whatever else it is, it is not a deletion.
-expect "a failed re-fetch is never reported gone" "" \
-    "$(listed gone | grep '/reset\.bin$' || true)"
+        "${host}/changes/redirtarget.html" "${host}/changes/reset.bin" \
+        "${host}/changes/sized.html" "${host}/changes/stable.bin" \
+        "${host}/changes/stable.html")" \
+    "$(listed unchanged | sort)"
 expect_counts_match "pass 2 counts match its lists"
 
 # Every mirrored file appears once and only once, across all four buckets.
@@ -192,19 +188,15 @@ test -f "${out}/${host}/changes/doomed.html" || {
     exit 1
 }
 echo "OK"
-printf '[a failed transfer keeps its file] ..\t'
-test -f "${out}/${host}/changes/reset.bin" || {
-    echo "FAIL: reset.bin lost its previous copy"
-    exit 1
-}
-echo "OK"
+expect "a failed transfer keeps its bytes" "$resetdigest" \
+    "$(digest "${out}/${host}/changes/reset.bin")"
 
 # --- pass 3: the same run with purging on ------------------------------------
 httrack "${common[@]}" -O "$out" --update "${base}/changes/index.html" \
     >"${tmpdir}/log3" 2>&1
 expect "the report says files were purged" "true" "$(field purged)"
 expect "gone is the page that only pass 2 linked" \
-    "${host}/changes/transient.html" "$(listed_but_reset gone)"
+    "${host}/changes/transient.html" "$(listed gone | sort)"
 printf '[a purged file is off disk] ..\t'
 test ! -f "${out}/${host}/changes/transient.html" || {
     echo "FAIL: transient.html survived --purge-old"

tests/96_local-refetch-keep.test

@@ -0,0 +1,25 @@
+#!/bin/bash
+#
+# A re-fetch cut mid-header must leave the mirrored file alone (#748) and keep
+# it out of the update purge (#746). err.bin is the control, an HTTP 500 on the
+# same resource already surviving both; stay.bin answers normally with a new
+# body, so a fix that stopped overwriting anything fails.
+
+set -euo pipefail
+
+: "${top_srcdir:=..}"
+
+bash "$top_srcdir/tests/local-crawl.sh" \
+    --rerun-args '--update' \
+    --log-found 'after 2 retries at link .*keep/page\.html' \
+    --log-found 'after 2 retries at link .*keep/data\.bin' \
+    --file-matches 'keep/page.html' 'KEEP-PAGE-V1' \
+    --file-not-matches 'keep/page.html' 'HTTP/1\.0 200' \
+    --file-matches 'keep/data.bin' 'KEEP-BIN-V1' \
+    --file-not-matches 'keep/data.bin' 'HTTP/1\.0 200' \
+    --file-min-bytes 'keep/data.bin' 2048 \
+    --file-matches 'keep/err.bin' 'KEEP-ERR-V1' \
+    --file-min-bytes 'keep/err.bin' 2048 \
+    --file-matches 'keep/stay.bin' 'KEEP-STAY-V2' \
+    --file-min-bytes 'keep/stay.bin' 2048 \
+    httrack 'BASEURL/keep/index.html' --retries=2

tests/Makefile.am

@@ -30,6 +30,7 @@ TEST_EXTENSIONS = .test
 TEST_LOG_COMPILER = $(BASH)
 TESTS = \
 	00_runnable.test \
+	01_engine-addlink.test \
 	01_engine-changes.test \
 	01_engine-charset.test \
 	01_engine-cmdline.test \
@@ -81,7 +82,9 @@ TESTS = \
 	01_engine-status.test \
 	01_engine-stripquery.test \
 	01_engine-strsafe.test \
+	01_engine-structcheck.test \
 	01_engine-syscharset.test \
+	01_engine-threadwait.test \
 	01_engine-topindex.test \
 	01_engine-urlhack.test \
 	01_engine-unescape-bounds.test \
@@ -194,6 +197,7 @@ TESTS = \
 	92_local-proxytrack-ndx-fields.test \
 	93_local-changes.test \
 	94_local-single-file.test \
-	95_local-sitemap.test
+	95_local-sitemap.test \
+	96_local-refetch-keep.test
 
 CLEANFILES = check-network_sh.cache

tests/local-crawl.sh

@@ -57,6 +57,8 @@ rerun_dead=
 tmpdir=
 serverpid=
 crawlpid=
+wacz_poisoned=
+wacz_poison="stale-wacz-that-a-second-pass-must-replace"
 
 function warning {
     echo "** $*" >&2
@@ -272,6 +274,14 @@ if test -n "$warc_validate"; then
     test -z "$w1" || cp "$w1" "${tmpdir}/warc-pass1.gz"
 fi
 
+# Poison the first-pass .wacz when a second pass follows: repackaging moves the
+# new archive over it, so the marker must be gone afterwards (#726). Poisoning
+# beats comparing the two packages, which can come out byte-identical.
+if test -n "$wacz_validate" && test -n "${rerun}${rerun_args}"; then
+    wacz_poisoned=$(find "$mirrorroot" -maxdepth 2 -name '*.wacz' 2>/dev/null | sort | tail -n1)
+    test -z "$wacz_poisoned" || echo "$wacz_poison" >"$wacz_poisoned"
+fi
+
 # --- optional second pass: re-mirror into the same dir (cache/update path) ----
 if test -n "$rerun"; then
     info "re-running httrack (update pass)"
@@ -416,6 +426,12 @@ if test -n "$wacz_validate"; then
         fi
         die "no .wacz file produced under $mirrorroot"
     fi
+    if test -n "$wacz_poisoned"; then
+        info "checking the second pass replaced the .wacz"
+        grep -q "$wacz_poison" "$wacz_poisoned" 2>/dev/null &&
+            die "stale .wacz kept: $wacz_poisoned"
+        result "OK"
+    fi
     validator=$(nativepath "${testdir}/wacz-validate.py")
     info "validating WACZ package"
     "$python" "$validator" "$(nativepath "$wacz")" >&2 || die "WACZ validation failed"

tests/local-server.py

@@ -1000,6 +1000,62 @@ class Handler(SimpleHTTPRequestHandler):
         v = 1 if self.refetch_pass() == 1 else 2
         self.send_raw(b"<html><body><p>STAY-V%d</p></body></html>" % v, "text/html")
 
+    # --- re-fetch cut mid-header, so nothing is stored (#746, #748) ---------
+    KEEP_PAGE = b"<html><body><p>KEEP-PAGE-V1</p></body></html>"
+    KEEP_BIN = b"KEEP-BIN-V1\n" + b"\x51\x52\x53\x54" * 512
+    KEEP_ERR = b"KEEP-ERR-V1\n" + b"\x61\x62\x63\x64" * 512
+
+    def send_cut_headers(self):
+        """Hang up mid-header: the response never becomes parseable."""
+        self.close_connection = True
+        try:
+            self.wfile.write(b"HTTP/1.0 200 OK\r\nContent-Ty")
+            self.wfile.flush()
+        except OSError:
+            pass
+        self.connection.close()
+
+    def route_keep_index(self):
+        self.refetch_pass()
+        self.send_html(
+            '\t<a href="page.html">page</a>\n'
+            '\t<a href="data.bin">data</a>\n'
+            '\t<a href="err.bin">err</a>\n'
+            '\t<a href="stay.bin">stay</a>\n'
+        )
+
+    def route_keep_page(self):
+        if self.refetch_pass() == 1:
+            self.send_raw(self.KEEP_PAGE, "text/html")
+        else:
+            self.send_cut_headers()
+
+    def route_keep_data(self):
+        if self.refetch_pass() == 1:
+            self.send_raw(self.KEEP_BIN, "application/octet-stream")
+        else:
+            self.send_cut_headers()
+
+    # Control: an HTTP error on the same resource already keeps the copy, so
+    # the cut-header routes above must end up indistinguishable from it.
+    def route_keep_err(self):
+        if self.refetch_pass() == 1:
+            self.send_raw(self.KEEP_ERR, "application/octet-stream")
+        else:
+            self.send_response(500)
+            self.send_header("Content-Type", "text/html")
+            self.send_header("Content-Length", "0")
+            self.end_headers()
+
+    # Control: answers normally, with a new body on pass 2, so a fix that
+    # stopped overwriting mirrored files altogether would be caught.
+    def route_keep_stay(self):
+        v = 1 if self.refetch_pass() == 1 else 2
+        self.send_raw(
+            b"KEEP-STAY-V%d\n" % v + b"\x71\x72\x73\x74" * 512,
+            "application/octet-stream",
+        )
+
     # Echo what httrack advertised, so a crawl can assert the header.
     def route_codec_ae(self):
         self.send_raw(
@@ -1950,6 +2006,11 @@ class Handler(SimpleHTTPRequestHandler):
         "/uptrunc/page.html": route_uptrunc_page,
         "/uptrunc/file.bin": route_uptrunc_file,
         "/uptrunc/stay.html": route_uptrunc_stay,
+        "/keep/index.html": route_keep_index,
+        "/keep/page.html": route_keep_page,
+        "/keep/data.bin": route_keep_data,
+        "/keep/err.bin": route_keep_err,
+        "/keep/stay.bin": route_keep_stay,
         "/types/index.html": route_types_index,
         "/types/control.php": route_types,
         "/types/photo.png": route_types,