Symbolize once when the handler itself faults

A fault inside the handler re-enters the printer, which interleaved a second
symbolized trace on the same fd and spent a second budget: 3.04s and two
overlapping reports, measured.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

.github/workflows/windows-build.yml

@@ -225,8 +225,9 @@ jobs:
 
           # Every gate here exits 77, so an all-skipped suite would report green having
           # tested nothing: pin the skips, and floor the passes in case the glob empties.
-          # footer-overflow skips on Windows (needs a path past MAX_PATH); crange pending #581.
-          expected_skips=" 01_engine-footer-overflow.test 48_local-crange-memresume.test 71_local-crange-repaircache.test"
+          # footer-overflow skips on Windows (needs a path past MAX_PATH); crange pending #581;
+          # webdav-mime needs a reapable background listener, which MSYS cannot give it.
+          expected_skips=" 01_engine-footer-overflow.test 48_local-crange-memresume.test 71_local-crange-repaircache.test 79_local-proxytrack-webdav-mime.test"
           [ "$pass" -ge 90 ] || { echo "::error::only $pass tests passed ($skip skipped)"; exit 1; }
           [ "$skipped" = "$expected_skips" ] || { echo "::error::unexpected skips:$skipped"; exit 1; }
           [ "$fail" -eq 0 ] || { echo "::error::failing:$failed"; exit 1; }

configure.ac

@@ -100,7 +100,8 @@ AX_CHECK_COMPILE_FLAG([-fstack-protector-strong], [DEFAULT_CFLAGS="$DEFAULT_CFLA
 	[AX_CHECK_COMPILE_FLAG([-fstack-protector], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fstack-protector"], [], [-Werror])], [-Werror])
 AX_CHECK_COMPILE_FLAG([-fstack-clash-protection], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fstack-clash-protection"], [], [-Werror])
 AX_CHECK_COMPILE_FLAG([-fcf-protection], [DEFAULT_CFLAGS="$DEFAULT_CFLAGS -fcf-protection"], [], [-Werror])
-AX_CHECK_LINK_FLAG([-Wl,--discard-all], [DEFAULT_LDFLAGS="$DEFAULT_LDFLAGS -Wl,--discard-all"])
+# No --discard-all: it drops the local symbols naming every static function, so
+# a trace misattributes them to the nearest surviving global. Costs 0.6% size.
 AX_CHECK_LINK_FLAG([-Wl,--no-undefined], [DEFAULT_LDFLAGS="$DEFAULT_LDFLAGS -Wl,--no-undefined"])
 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"])
@@ -127,8 +128,8 @@ AX_CHECK_LINK_FLAG([-pie], [LDFLAGS_PIE="-pie"])
 AC_SUBST([CFLAGS_PIE])
 AC_SUBST([LDFLAGS_PIE])
 
-## -rdynamic must be a link flag; DEFAULT_CFLAGS (AM_CPPFLAGS) never reaches the linker.
-AX_CHECK_LINK_FLAG([-rdynamic], [DEFAULT_LDFLAGS="$DEFAULT_LDFLAGS -rdynamic"])
+# Ties a crash trace from a stripped build back to its separate debug symbols.
+AX_CHECK_LINK_FLAG([-Wl,--build-id], [DEFAULT_LDFLAGS="$DEFAULT_LDFLAGS -Wl,--build-id"])
 
 ### Check for -fvisibility=hidden support
 gl_VISIBILITY

src/Makefile.am

@@ -32,7 +32,9 @@ AM_LDFLAGS = \
 
 bin_PROGRAMS = proxytrack httrack htsserver
 
-httrack_LDADD = $(THREADS_LIBS) libhttrack.la
+httrack_SOURCES = httrack.c htsbacktrace.c htsbacktrace.h
+# $(DL_LIBS): dladdr() in the crash handler, still in libdl on pre-2.34 glibc.
+httrack_LDADD = $(THREADS_LIBS) $(DL_LIBS) libhttrack.la
 htsserver_LDADD = $(THREADS_LIBS) $(SOCKET_LIBS) libhttrack.la
 proxytrack_LDADD = $(THREADS_LIBS) $(SOCKET_LIBS)
 

src/htsback.c

@@ -541,7 +541,7 @@ static int create_back_tmpfile(httrackp *opt, lien_back *const back,
                                const char *ext) {
   // do not use tempnam() but a regular filename
   back->tmpfile_buffer[0] = '\0';
-  if (back->url_sav != NULL && back->url_sav[0] != '\0') {
+  if (back->url_sav[0] != '\0') {
     snprintf(back->tmpfile_buffer, sizeof(back->tmpfile_buffer), "%s.%s",
              back->url_sav, ext);
     back->tmpfile = back->tmpfile_buffer;
@@ -887,8 +887,7 @@ int back_finalize(httrackp * opt, cache_back * cache, struct_back * sback,
               HTS_STAT.stat_bytes += back[p].r.size;
               HTS_STAT.stat_files++;
               hts_log_print(opt, LOG_TRACE, "added file %s%s => %s",
-                            back[p].url_adr, back[p].url_fil,
-                            back[p].url_sav != NULL ? back[p].url_sav : "");
+                            back[p].url_adr, back[p].url_fil, back[p].url_sav);
             }
             if ((!back[p].r.notmodified) && (opt->is_update)) {
               HTS_STAT.stat_updated_files++;    // page modifiée
@@ -2302,26 +2301,24 @@ int back_add(struct_back *sback, httrackp *opt, cache_back *cache,
               && slot_can_be_finalized(opt, &back[i]);
             int may_serialize = slot_can_be_cached_on_disk(&back[i]);
 
-            hts_log_print(opt, LOG_DEBUG,
-                          "back[%03d]: may_clean=%d, may_finalize_disk=%d, may_serialize=%d:"
-                          LF "\t"
-                          "finalized(%d), status(%d), locked(%d), delayed(%d), test(%d), "
-                          LF "\t"
-                          "statuscode(%d), size(%d), is_write(%d), may_hypertext(%d), "
-                          LF "\t" "contenttype(%s), url(%s%s), save(%s)", i,
-                          may_clean, may_finalize, may_serialize,
-                          back[i].finalized, back[i].status, back[i].locked,
-                          IS_DELAYED_EXT(back[i].url_sav), back[i].testmode,
-                          back[i].r.statuscode, (int) back[i].r.size,
-                          back[i].r.is_write, may_be_hypertext_mime(opt,
-                                                                    back[i].r.
-                                                                    contenttype,
-                                                                    back[i].
-                                                                    url_fil),
-                          /* */
-                          back[i].r.contenttype, back[i].url_adr,
-                          back[i].url_fil,
-                          back[i].url_sav ? back[i].url_sav : "<null>");
+            hts_log_print(
+                opt, LOG_DEBUG,
+                "back[%03d]: may_clean=%d, may_finalize_disk=%d, "
+                "may_serialize=%d:" LF "\t"
+                "finalized(%d), status(%d), locked(%d), delayed(%d), "
+                "test(%d), " LF "\t"
+                "statuscode(%d), size(%d), is_write(%d), may_hypertext(%d), " LF
+                "\t"
+                "contenttype(%s), url(%s%s), save(%s)",
+                i, may_clean, may_finalize, may_serialize, back[i].finalized,
+                back[i].status, back[i].locked, IS_DELAYED_EXT(back[i].url_sav),
+                back[i].testmode, back[i].r.statuscode, (int) back[i].r.size,
+                back[i].r.is_write,
+                may_be_hypertext_mime(opt, back[i].r.contenttype,
+                                      back[i].url_fil),
+                /* */
+                back[i].r.contenttype, back[i].url_adr, back[i].url_fil,
+                back[i].url_sav);
           }
         }
       }
@@ -2857,7 +2854,8 @@ void back_wait(struct_back * sback, httrackp * opt, cache_back * cache,
               // new session
               back[i].r.ssl_con = SSL_new(openssl_ctx);
               if (back[i].r.ssl_con) {
-                const char* hostname = jump_protocol_const(back[i].url_adr);
+                /* non-const twin: the OpenSSL macro casts the qualifier away */
+                char *hostname = jump_protocol(back[i].url_adr);
                 // some servers expect the hostname on the clienthello (SNI TLS extension)
                 SSL_set_tlsext_host_name(back[i].r.ssl_con, hostname);
                 SSL_clear(back[i].r.ssl_con);

src/htsbacktrace.c

@@ -0,0 +1,238 @@
+/* ------------------------------------------------------------ */
+/*
+HTTrack Website Copier, Offline Browser for Windows and Unix
+Copyright (C) 1998 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
+*/
+
+/* ------------------------------------------------------------ */
+/* File: crash backtrace printer                                 */
+/* Author: Xavier Roche                                          */
+/* ------------------------------------------------------------ */
+
+/* Before every header: glibc gates dladdr() on it. */
+#if defined(__linux) && !defined(_GNU_SOURCE)
+#define _GNU_SOURCE
+#endif
+
+#include "htsbacktrace.h"
+
+#include "htsglobal.h"
+
+#include <stdlib.h>
+#include <string.h>
+#ifdef _WIN32
+#include <io.h> /* write */
+#endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#if (defined(__linux) && defined(HAVE_EXECINFO_H))
+#include <dlfcn.h>
+#include <errno.h>
+#include <execinfo.h>
+#include <signal.h>
+#include <time.h>
+#include <sys/wait.h>
+#define USES_BACKTRACE
+#endif
+
+#ifdef USES_BACKTRACE
+#define BT_MAX_FRAMES 64     /* frames we try to name */
+#define BT_MAX_MODULES 8     /* distinct modules, one child each */
+#define BT_HEX_SIZE 19       /* "0x" + 16 nibbles + NUL */
+#define BT_PATH_SIZE 1024    /* module path; longer is skipped */
+#define BT_WAIT_TICKS 300    /* 10ms ticks, shared: cap a slow child */
+#define BT_NO_SYMBOLIZER 127 /* child exit: execvp() found none */
+
+static hts_boolean symbolize_crash = HTS_TRUE;
+
+/* "0x"-prefixed hex: the handler must stay stdio-free. */
+static void print_hex(char *buffer, uintptr_t value) {
+  static const char digits[] = "0123456789abcdef";
+  size_t i = 2, a, b;
+
+  buffer[0] = '0';
+  buffer[1] = 'x';
+  do {
+    buffer[i++] = digits[value & 0xf];
+    value >>= 4;
+  } while (value != 0);
+  buffer[i] = '\0';
+  for (a = 2, b = i - 1; a < b; a++, b--) {
+    const char c = buffer[a];
+
+    buffer[a] = buffer[b];
+    buffer[b] = c;
+  }
+}
+
+/* HTS_FALSE if src does not fit: a truncated module path would point the
+   symbolizer at the wrong file. */
+static hts_boolean copy_bounded(char *dest, size_t size, const char *src) {
+  size_t i;
+
+  for (i = 0; i < size - 1 && src[i] != '\0'; i++) {
+    dest[i] = src[i];
+  }
+  dest[i] = '\0';
+  return src[i] == '\0' ? HTS_TRUE : HTS_FALSE;
+}
+
+/* Run the symbolizer on argv, output on fd, within *budget ticks. HTS_FALSE
+   only if none could be run at all; otherwise silent, the raw trace stands. */
+static hts_boolean spawn_symbolizer(char **argv, int fd, int *budget) {
+  const pid_t pid = fork();
+  int status = 0;
+
+  if (pid == -1)
+    return HTS_FALSE;
+  if (pid == 0) {
+    static char llvm_prog[] = "llvm-symbolizer";
+    static char llvm_opts[] = "-p";
+
+    dup2(fd, 1); /* both symbolizers write on stdout */
+    execvp(argv[0], argv);
+    argv[0] = llvm_prog; /* an LLVM-only install ships no addr2line */
+    argv[1] = llvm_opts;
+    execvp(argv[0], argv);
+    _exit(BT_NO_SYMBOLIZER);
+  }
+  for (; *budget > 0; (*budget)--) {
+    const struct timespec tick = {0, 10 * 1000 * 1000};
+    const pid_t reaped = waitpid(pid, &status, WNOHANG);
+
+    if (reaped == pid)
+      return WIFEXITED(status) && WEXITSTATUS(status) == BT_NO_SYMBOLIZER
+                 ? HTS_FALSE
+                 : HTS_TRUE;
+    if (reaped == -1 && errno != EINTR)
+      return HTS_TRUE;
+    nanosleep(&tick, NULL);
+  }
+  kill(pid, SIGKILL);
+  waitpid(pid, NULL, 0);
+  return HTS_TRUE;
+}
+
+/* Name the frames backtrace_symbols_fd() leaves as module+offset:
+   -fvisibility=hidden keeps them out of .dynsym, but DWARF has them. dladdr()
+   is not formally async-signal-safe; accepted, this path is already fatal. */
+static void symbolize_backtrace(void *const *stack, int size, int fd) {
+  static char prog[] = "addr2line";
+  static char opts[] = "-Cfipa";
+  static char dashe[] = "-e";
+  char hex[BT_MAX_FRAMES][BT_HEX_SIZE];
+  const void *base[BT_MAX_FRAMES];
+  const char *name[BT_MAX_FRAMES];
+  hts_boolean grouped[BT_MAX_FRAMES];
+  char module[BT_PATH_SIZE];
+  char *argv[4 + BT_MAX_FRAMES + 1];
+  int budget = BT_WAIT_TICKS;
+  int i, spawned;
+
+  if (size > BT_MAX_FRAMES)
+    size = BT_MAX_FRAMES;
+
+  for (i = 0; i < size; i++) {
+    Dl_info info;
+
+    grouped[i] = HTS_TRUE; /* skipped unless dladdr() places the frame */
+    if (dladdr(stack[i], &info) == 0 || info.dli_fname == NULL ||
+        info.dli_fname[0] == '\0')
+      continue;
+    base[i] = info.dli_fbase;
+    name[i] = info.dli_fname;
+    print_hex(hex[i], (uintptr_t) ((const char *) stack[i] -
+                                   (const char *) info.dli_fbase));
+    grouped[i] = HTS_FALSE;
+  }
+
+  /* One child per module: addr2line takes a single -e. Each frame is claimed
+     once, so argc cannot exceed argv[]. */
+  for (spawned = 0; spawned < BT_MAX_MODULES; spawned++) {
+    int first, j, argc = 0;
+
+    for (first = 0; first < size && grouped[first]; first++)
+      ;
+    if (first >= size)
+      break;
+    argv[argc++] = prog;
+    argv[argc++] = opts;
+    argv[argc++] = dashe;
+    argv[argc++] = module;
+    for (j = first; j < size; j++) {
+      if (grouped[j] || base[j] != base[first])
+        continue;
+      grouped[j] = HTS_TRUE;
+      argv[argc++] = hex[j];
+    }
+    argv[argc] = NULL;
+    /* access(): skip pseudo-modules like linux-vdso, which have no file and
+       would draw nothing but an addr2line complaint. */
+    if (copy_bounded(module, sizeof(module), name[first]) &&
+        access(module, R_OK) == 0) {
+      const size_t len = strlen(module);
+
+      /* addr2line -a prints offsets only: say which module they are in. */
+      (void) (write(fd, module, len) == (ssize_t) len);
+      (void) (write(fd, ":\n", 2) == 2);
+      if (!spawn_symbolizer(argv, fd, &budget))
+        break; /* no symbolizer: stop at one header */
+    }
+  }
+}
+#endif
+
+void hts_backtrace_init(void) {
+#ifdef USES_BACKTRACE
+  symbolize_crash =
+      getenv("HTTRACK_NO_SYMBOLIZE") == NULL ? HTS_TRUE : HTS_FALSE;
+#endif
+}
+
+void hts_print_backtrace(int fd) {
+#ifdef USES_BACKTRACE
+  void *stack[256];
+  const int size = backtrace(stack, sizeof(stack) / sizeof(stack[0]));
+
+  /* A fault inside the handler lands back here: symbolizing twice interleaves
+     two traces on fd and spends a second budget. */
+  static volatile sig_atomic_t entered = 0;
+
+  if (size != 0) {
+    backtrace_symbols_fd(stack, size, fd);
+    if (symbolize_crash && entered == 0) {
+      entered = 1;
+      symbolize_backtrace(stack, size, fd);
+      entered = 0;
+    }
+  }
+#else
+  const char msg[] = "No stack trace available on this OS :(\n";
+
+  if (write(fd, msg, sizeof(msg) - 1) != sizeof(msg) - 1) {
+    /* sorry GCC */
+  }
+#endif
+}

src/htsbacktrace.h

@@ -0,0 +1,45 @@
+/* ------------------------------------------------------------ */
+/*
+HTTrack Website Copier, Offline Browser for Windows and Unix
+Copyright (C) 1998 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
+*/
+
+/* ------------------------------------------------------------ */
+/* File: crash backtrace printer                                 */
+/* Author: Xavier Roche                                          */
+/* ------------------------------------------------------------ */
+
+#ifndef HTSBACKTRACE_DEFH
+#define HTSBACKTRACE_DEFH
+
+/* Sample HTTRACK_NO_SYMBOLIZE before any crash: getenv() is not signal-safe.
+   Call once, from the process that installs the fatal-signal handlers. */
+void hts_backtrace_init(void);
+
+/* Write the calling thread's stack to fd, callable from a fatal signal handler:
+   raw frames first, then whatever an external symbolizer can name. Allocates
+   nothing; prints a one-line notice where the OS has no backtrace(). */
+void hts_print_backtrace(int fd);
+
+#endif

src/htscache.c

@@ -1441,7 +1441,7 @@ int cache_brstr(char *adr, char *s, size_t s_size) {
 
 /* binput bounded to a NUL-terminated buffer: refuse to start a read at or
    past `end`, so a prior over-advance can't walk a cache-index parse OOB. */
-int cache_binput(char *adr, const char *end, char *s, int max) {
+int cache_binput(const char *adr, const char *end, char *s, int max) {
   if (adr >= end) {
     s[0] = '\0';
     return 0;

src/htscache.h

@@ -93,7 +93,7 @@ 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_binput(const 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/htshelp.c

@@ -156,9 +156,7 @@ void help_wizard(httrackp * opt) {
   char *a;
 
   //
-  if (urls == NULL || mainpath == NULL || projname == NULL || stropt == NULL
-      || stropt2 == NULL || strwild == NULL || cmd == NULL || str == NULL
-      || argv == NULL) {
+  if (buffers == NULL) {
     fprintf(stderr, "* memory exhausted in %s, line %d\n", __FILE__, __LINE__);
     return;
   }
@@ -251,6 +249,7 @@ void help_wizard(httrackp * opt) {
       strcatbuff(stropt2, "--update ");
       break;
     case 0:
+      freet(buffers);
       return;
       break;
     }
@@ -315,8 +314,10 @@ void help_wizard(httrackp * opt) {
       fflush(stdout);
       linput(stdin, str, 250);
       if (strnotempty(str)) {
-        if (!((str[0] == 'y') || (str[0] == 'Y')))
+        if (!((str[0] == 'y') || (str[0] == 'Y'))) {
+          freet(buffers);
           return;
+        }
       }
       printf("\n");
 
@@ -340,7 +341,7 @@ void help_wizard(httrackp * opt) {
   }
 
   /* Free buffers */
-  free(buffers);
+  freet(buffers);
 #undef urls
 #undef mainpath
 #undef projname

src/htslib.c

@@ -704,18 +704,16 @@ T_SOC http_xfopen(httrackp *opt, int mode, int treat, int waitconnect,
   /* Check for errors */
   if (soc == INVALID_SOCKET) {
     if (retour) {
-      if (retour->msg) {
-        if (!strnotempty(retour->msg)) {
+      if (!strnotempty(retour->msg)) {
 #ifdef _WIN32
-          int last_errno = WSAGetLastError();
+        int last_errno = WSAGetLastError();
 
-          sprintf(retour->msg, "Connect error: %s", strerror(last_errno));
+        sprintf(retour->msg, "Connect error: %s", strerror(last_errno));
 #else
-          int last_errno = errno;
+        int last_errno = errno;
 
-          sprintf(retour->msg, "Connect error: %s", strerror(last_errno));
+        sprintf(retour->msg, "Connect error: %s", strerror(last_errno));
 #endif
-        }
       }
     }
   }
@@ -2207,7 +2205,7 @@ T_SOC newhttp_addr(httrackp *opt, const char *_iadr, htsblk *retour, int port,
 #if DEBUG
       printf("erreur gethostbyname\n");
 #endif
-      if (retour && retour->msg) {
+      if (retour != NULL) {
 #ifdef _WIN32
         snprintf(retour->msg, sizeof(retour->msg),
                  "Unable to get server's address: %s", error);
@@ -2238,7 +2236,7 @@ T_SOC newhttp_addr(httrackp *opt, const char *_iadr, htsblk *retour, int port,
     DEBUG_W("socket()=%d\n" _(int) soc);
 #endif
     if (soc == INVALID_SOCKET) {
-      if (retour && retour->msg) {
+      if (retour != NULL) {
 #ifdef _WIN32
         int last_errno = WSAGetLastError();
 
@@ -2262,17 +2260,8 @@ T_SOC newhttp_addr(httrackp *opt, const char *_iadr, htsblk *retour, int port,
                              &bind_addr, &error) == NULL
           || bind(soc, &SOCaddr_sockaddr(bind_addr), 
                   SOCaddr_size(bind_addr)) != 0) {
-        if (retour && retour->msg) {
-#ifdef _WIN32
-          snprintf(retour->msg, sizeof(retour->msg),
-                   "Unable to bind the specificied server address: %s",
-                   error);
-#else
-          snprintf(retour->msg, sizeof(retour->msg),
-                   "Unable to bind the specificied server address: %s",
-                   error);
-#endif
-        }
+        snprintf(retour->msg, sizeof(retour->msg),
+                 "Unable to bind the specificied server address: %s", error);
         deletesoc(soc);
         return INVALID_SOCKET;
       }
@@ -2319,7 +2308,7 @@ T_SOC newhttp_addr(httrackp *opt, const char *_iadr, htsblk *retour, int port,
 #if HDEBUG
         printf("unable to connect!\n");
 #endif
-        if (retour != NULL && retour->msg) {
+        if (retour != NULL) {
 #ifdef _WIN32
           const int last_errno = WSAGetLastError();
 
@@ -3019,7 +3008,7 @@ int finput(T_SOC fd, char *s, int max) {
 }
 
 // Like linput, but in memory (optimized)
-int binput(char *buff, char *s, int max) {
+int binput(const char *buff, char *s, int max) {
   int count = 0;
   int destCount = 0;
 

src/htslib.h

@@ -262,7 +262,7 @@ HTS_INLINE void time_rfc822_local(char *s, struct tm *A);
 
 HTS_INLINE int sendc(htsblk * r, const char *s);
 int finput(T_SOC fd, char *s, int max);
-int binput(char *buff, char *s, int max);
+int binput(const char *buff, char *s, int max);
 int linput(FILE * fp, char *s, int max);
 int linputsoc(T_SOC soc, char *s, int max);
 int linputsoc_t(T_SOC soc, char *s, int max, int timeout);

src/htsselftest.c

@@ -2488,17 +2488,20 @@ static int st_cookies(httrackp *opt, int argc, char **argv) {
     static t_cookie ck2;
     htsblk r;
     char host[600];
+    char line[64]; /* treathead NUL-cuts the header in place: never a literal */
 
     memset(&r, 0, sizeof(r));
     memset(host, 'a', sizeof(host) - 1);
     host[sizeof(host) - 1] = '\0';
     ck2.max_len = (int) sizeof(ck2.data);
     ck2.data[0] = '\0';
-    treathead(&ck2, host, "/", &r, "Set-Cookie: SID=1; path=/");
+    strcpybuff(line, "Set-Cookie: SID=1; path=/");
+    treathead(&ck2, host, "/", &r, line);
     if (strnotempty(ck2.data)) // oversize-host cookie was not dropped
       err = 1;
     /* control: a normal host still yields a cookie through treathead */
-    treathead(&ck2, dom, "/", &r, "Set-Cookie: SID=1; path=/");
+    strcpybuff(line, "Set-Cookie: SID=1; path=/");
+    treathead(&ck2, dom, "/", &r, line);
     if (strstr(ck2.data, "SID") == NULL) // guard wrongly dropped a valid cookie
       err = 1;
   }
@@ -2988,7 +2991,7 @@ static int ae_write_packed(const char *path, int windowBits,
     deflateEnd(&strm);
     return 1;
   }
-  strm.next_in = (Bytef *) src;
+  strm.next_in = (const Bytef *) src;
   strm.avail_in = (uInt) len;
   do {
     size_t n;

src/htstools.c

@@ -1318,19 +1318,19 @@ HTSEXT_API hts_boolean hts_findnext(find_handle find) {
   if (find) {
 #ifdef _WIN32
     if ((FindNextFileA(find->handle, &find->hdata)))
-      return 1;
+      return HTS_TRUE;
 #else
     char catbuff[CATBUFF_SIZE];
 
     memset(&(find->filestat), 0, sizeof(find->filestat));
     if ((find->dirp = readdir(find->hdir)))
-      if (find->dirp->d_name)
-        if (!STAT
-            (concat(catbuff, sizeof(catbuff), find->path, find->dirp->d_name), &find->filestat))
-          return 1;
+      if (!STAT(
+              concat(catbuff, sizeof(catbuff), find->path, find->dirp->d_name),
+              &find->filestat))
+        return HTS_TRUE;
 #endif
   }
-  return 0;
+  return HTS_FALSE;
 }
 
 HTSEXT_API int hts_findclose(find_handle find) {

src/httrack.c

@@ -46,6 +46,7 @@ Please visit our Website: http://www.httrack.com
 #include "httrack.h"
 #include "htslib.h"
 #include "htscharset.h" // after htslib.h: winsock2.h must precede windows.h
+#include "htsbacktrace.h"
 
 /* Static definitions */
 static int fexist(const char *s);
@@ -72,10 +73,6 @@ static int linput(FILE * fp, char *s, int max);
 #include <sys/ioctl.h>
 #endif
 #include <ctype.h>
-#if (defined(__linux) && defined(HAVE_EXECINFO_H))
-#include <execinfo.h>
-#define USES_BACKTRACE
-#endif
 /* END specific definitions */
 
 static void __cdecl htsshow_init(t_hts_callbackarg * carg);
@@ -880,21 +877,6 @@ static void sig_doback(int blind) {     // mettre en backing
 #undef FD_ERR
 #define FD_ERR 2
 
-static void print_backtrace(void) {
-#ifdef USES_BACKTRACE
-  void *stack[256];
-  const int size = backtrace(stack, sizeof(stack)/sizeof(stack[0]));
-  if (size != 0) {
-    backtrace_symbols_fd(stack, size, FD_ERR);
-  }
-#else
-  const char msg[] = "No stack trace available on this OS :(\n";
-  if (write(FD_ERR, msg, sizeof(msg) - 1) != sizeof(msg) - 1) {
-    /* sorry GCC */
-  }
-#endif
-}
-
 static size_t print_num(char *buffer, int num) {
   size_t i, j;
   if (num < 0) {
@@ -928,7 +910,7 @@ static void sig_fatal(int code) {
   size += print_num(&buffer[size], code);
   buffer[size++] = '\n';
   (void) (write(FD_ERR, buffer, size) == size);
-  print_backtrace();
+  hts_print_backtrace(FD_ERR);
   (void) (write(FD_ERR, msgreport, sizeof(msgreport) - 1)
     == sizeof(msgreport) - 1);
   abort();
@@ -951,6 +933,7 @@ static void sig_leave(int code) {
 }
 
 static void signal_handlers(void) {
+  hts_backtrace_init();
 #ifdef _WIN32
   signal(SIGINT, sig_leave);    // ^C
   signal(SIGTERM, sig_finish);  // kill <process>

src/httrack.vcxproj

@@ -100,6 +100,7 @@
 
   <ItemGroup>
     <ClCompile Include="httrack.c" />
+    <ClCompile Include="htsbacktrace.c" />
   </ItemGroup>
 
   <!-- Pulls in libhttrack.lib and builds it first. -->

src/libhttrack.vcxproj

@@ -59,9 +59,10 @@
   <ItemDefinitionGroup>
     <ClCompile>
       <!-- LIBHTTRACK_EXPORTS turns HTSEXT_API into __declspec(dllexport); ZLIB_DLL
-           imports zlib from its DLL. HTS_USEBROTLI/HTS_USEZSTD enable the br and
-           zstd content codings. Windows 7 floor, matching WinHTTrack. -->
-      <PreprocessorDefinitions>WIN32;_WINDOWS;_MBCS;_USRDLL;LIBHTTRACK_EXPORTS;ZLIB_DLL;HTS_USEBROTLI=1;HTS_USEZSTD=1;WINVER=0x0601;_WIN32_WINNT=0x0601;_CRT_SECURE_NO_WARNINGS;_CRT_NONSTDC_NO_DEPRECATE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+           imports zlib from its DLL, ZLIB_CONST makes its next_in const as the
+           autotools build does. HTS_USEBROTLI/HTS_USEZSTD enable the br and zstd
+           content codings. Windows 7 floor, matching WinHTTrack. -->
+      <PreprocessorDefinitions>WIN32;_WINDOWS;_MBCS;_USRDLL;LIBHTTRACK_EXPORTS;ZLIB_DLL;ZLIB_CONST;HTS_USEBROTLI=1;HTS_USEZSTD=1;WINVER=0x0601;_WIN32_WINNT=0x0601;_CRT_SECURE_NO_WARNINGS;_CRT_NONSTDC_NO_DEPRECATE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <AdditionalIncludeDirectories>$(MSBuildThisFileDirectory);$(MSBuildThisFileDirectory)coucal;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <WarningLevel>Level3</WarningLevel>
       <MultiProcessorCompilation>true</MultiProcessorCompilation>

src/proxy/proxytrack.c

@@ -771,7 +771,7 @@ static PT_Element proxytrack_process_DAV_Request(PT_Indexes indexes,
                   PT_ReadIndex(indexes, StringBuff(itemUrl) + 1, FETCH_HEADERS);
                 if (file != NULL && file->statuscode == HTTP_OK) {
                   size = file->size;
-                  if (file->lastmodified) {
+                  if (file->lastmodified[0] != '\0') {
                     timestamp = get_time_rfc822(file->lastmodified);
                   }
                   if (timestamp == (time_t) 0) {
@@ -785,7 +785,7 @@ static PT_Element proxytrack_process_DAV_Request(PT_Indexes indexes,
                     }
                     timestamp = timestampRep;
                   }
-                  if (file->contenttype) {
+                  if (file->contenttype[0] != '\0') {
                     mimeType = file->contenttype;
                   }
                 }

tests/79_local-proxytrack-webdav-mime.test

@@ -0,0 +1,90 @@
+#!/bin/bash
+#
+# proxytrack's WebDAV PROPFIND fallback must behave identically whether or not
+# the cache entry supplies Content-Type and Last-Modified.
+
+set -euo pipefail
+
+: "${top_srcdir:=..}"
+# shellcheck source=tests/testlib.sh
+. "$top_srcdir/tests/testlib.sh"
+
+python=$(find_python) || {
+    echo "python3 missing, skipping"
+    exit 77
+}
+command -v curl >/dev/null 2>&1 || {
+    echo "curl missing, skipping"
+    exit 77
+}
+# First test to run proxytrack as a live server, and MSYS cannot reap a native
+# listener: the orphan wedged the whole Windows suite for 48 minutes (#595).
+if is_windows; then
+    echo "windows: cannot reap a backgrounded proxytrack, skipping"
+    exit 77
+fi
+
+dir=$(mktemp -d)
+ptpid=
+cleanup() {
+    stop_server "$ptpid"
+    rm -rf "$dir"
+}
+trap cleanup EXIT
+
+# Neither header is present, so file->contenttype and ->lastmodified stay "".
+printf 'HTTP/1.1 200 OK\r\nContent-Length: 5\r\n\r\n' >"$dir/hdr"
+printf 'hello' >"$dir/body"
+alen=$(($(wc -c <"$dir/hdr") + $(wc -c <"$dir/body")))
+{
+    printf 'filedesc://t.arc 0.0.0.0 20250101000000 text/plain 200 - - 0 t.arc 9\n'
+    printf '2 0 test\n'
+    printf '\n\n'
+    printf 'http://example.com/page.html 0.0.0.0 20250101000000 text/html 200 - - 0 t.arc %d\n' "$alen"
+    cat "$dir/hdr" "$dir/body"
+} >"$dir/in.arc"
+
+freeport() {
+    "$python" -c 'import socket; s=socket.socket(); s.bind(("127.0.0.1",0)); print(s.getsockname()[1]); s.close()'
+}
+proxyport=$(freeport)
+icpport=$(freeport)
+
+proxytrack "127.0.0.1:$proxyport" "127.0.0.1:$icpport" "$dir/in.arc" >"$dir/pt.log" 2>&1 &
+ptpid=$!
+waited=0
+until grep -qE "HTTP Proxy installed on|Unable to (initialize a temporary server|create the server)" "$dir/pt.log"; do
+    kill -0 "$ptpid" 2>/dev/null || {
+        echo "FAIL: proxytrack exited before listening"
+        cat "$dir/pt.log"
+        exit 1
+    }
+    test "$waited" -lt 50 || {
+        echo "FAIL: proxytrack never announced its listen port"
+        exit 1
+    }
+    sleep 0.1
+    waited=$((waited + 1))
+done
+grep -q "HTTP Proxy installed on" "$dir/pt.log" || {
+    echo "FAIL: proxytrack failed to bind"
+    cat "$dir/pt.log"
+    exit 1
+}
+
+# --max-time: an unbounded read here would wedge the runner rather than fail
+curl -s --max-time 30 -X PROPFIND -H "Depth: 1" \
+    "http://127.0.0.1:$proxyport/webdav/example.com/" >"$dir/resp.xml"
+
+grep -q '<getcontenttype>application/octet-stream</getcontenttype>' "$dir/resp.xml" || {
+    echo "FAIL: missing Content-Type did not fall back to application/octet-stream"
+    cat "$dir/resp.xml"
+    exit 1
+}
+grep -q '<getlastmodified>Wed, 01 Jan 2025 00:00:00 GMT</getlastmodified>' "$dir/resp.xml" || {
+    echo "FAIL: missing Last-Modified did not fall back to the index timestamp"
+    cat "$dir/resp.xml"
+    exit 1
+}
+
+echo "OK: WebDAV listing falls back correctly for an entry with no Content-Type/Last-Modified"

tests/80_engine-crash-symbolize.test

@@ -0,0 +1,97 @@
+#!/bin/bash
+# A fatal signal prints the raw backtrace, then names the frames
+# backtrace_symbols_fd() leaves as module+offset (-fvisibility=hidden hides them).
+set -eu
+
+testdir=$(cd "$(dirname "$0")" && pwd)
+# shellcheck source=tests/testlib.sh
+. "${testdir}/testlib.sh"
+
+if is_windows; then
+    echo "no backtrace() on Windows; skipping" >&2
+    exit 77
+fi
+command -v httrack >/dev/null || {
+    echo "could not find httrack" >&2
+    exit 1
+}
+
+tmpdir=$(mktemp -d "${TMPDIR:-/tmp}/httrack_symbolize.XXXXXX") || exit 1
+trap 'rm -rf "$tmpdir"' EXIT HUP INT QUIT PIPE TERM
+out="${tmpdir}/trace"
+raw="${tmpdir}/trace-optout"
+overflow="this string is far too long for the buffer"
+# A frame glibc could not name. Stop at the offset: it prints the trailing
+# "[0xADDR]" with or without a leading space depending on its version.
+rawframe='(+0x[0-9a-f][0-9a-f]*)'
+
+# The strsafe selftest aborts on purpose, which lands in sig_fatal.
+rc=0
+run_with_timeout 60 httrack -#test=strsafe overflow "$overflow" >"$out" 2>&1 || rc=$?
+test "$rc" -ne 124 || {
+    echo "the crash handler did not finish within the deadline" >&2
+    exit 1
+}
+
+grep -q '^Caught signal ' "$out" || {
+    echo "no 'Caught signal' line:" >&2
+    cat "$out" >&2
+    exit 1
+}
+if grep -q 'No stack trace available on this OS' "$out"; then
+    echo "no backtrace() on this platform; skipping" >&2
+    exit 77
+fi
+# Unconditional and first: symbolizing must never cost the raw trace.
+grep -q "$rawframe" "$out" || {
+    echo "raw module+offset frames are gone:" >&2
+    cat "$out" >&2
+    exit 1
+}
+
+command -v addr2line >/dev/null || {
+    echo "addr2line not installed; skipping" >&2
+    exit 77
+}
+
+# Control: resolve the same frames ourselves, so a stripped build cannot turn
+# the assertion below into a vacuous pass.
+oracle="${tmpdir}/oracle"
+sed -n 's/^\([^(]*\)(+\(0x[0-9a-f]*\)).*$/\1 \2/p' "$out" |
+    while read -r mod off; do
+        test -f "$mod" || continue
+        addr2line -Cfip -e "$mod" "$off" 2>/dev/null || true
+    done >"$oracle"
+grep -qE 'st_strsafe|strcpy_safe_' "$oracle" || {
+    echo "addr2line names no hidden symbol in this build; skipping" >&2
+    exit 77
+}
+
+# The payload. Dropping the raw frames first is what makes it specific: both
+# names are static, so .dynsym could never have carried them. Not anchored on
+# the "0xOFF:" line, the inline chain puts the name on either half.
+grep -v "$rawframe" "$out" | grep -qE 'st_strsafe|strcpy_safe_' || {
+    echo "the handler did not name the hidden frames:" >&2
+    cat "$out" >&2
+    exit 1
+}
+
+# Opt-out: raw trace kept, nothing spawned.
+export HTTRACK_NO_SYMBOLIZE=1
+rc=0
+run_with_timeout 60 httrack -#test=strsafe overflow "$overflow" >"$raw" 2>&1 || rc=$?
+unset HTTRACK_NO_SYMBOLIZE
+test "$rc" -ne 124 || {
+    echo "the opt-out run did not finish within the deadline" >&2
+    exit 1
+}
+grep -q "$rawframe" "$raw" || {
+    echo "the opt-out lost the raw trace:" >&2
+    cat "$raw" >&2
+    exit 1
+}
+! grep -q '^0x[0-9a-f]*: ' "$raw" || {
+    echo "the opt-out still symbolized:" >&2
+    cat "$raw" >&2
+    exit 1
+}

tests/Makefile.am

@@ -174,6 +174,8 @@ TESTS = \
 	75_engine-longpath-posix.test \
 	76_cli-resize.test \
 	77_webhttrack-redirect.test \
-	78_webhttrack-sid.test
+	78_webhttrack-sid.test \
+	79_local-proxytrack-webdav-mime.test \
+	80_engine-crash-symbolize.test
 
 CLEANFILES = check-network_sh.cache