An empty $HOME sends webhttrack's base path and httrack.ini to the root

PR #619 fixed hts_gethome() for an exported-but-empty $HOME, where getenv()
returns "" rather than NULL and the old NULL-only check let "~/foo" collapse
into the absolute "/foo". The same shape lives in two static clones that the
fix missed; htsserver's is live.

With HOME= exported, htsserver renders /websites as the default base path,
reads /.httrack.ini on the first request of every session, and writes
/.httrack.ini when a mirror starts. Running as root that last one lands a file
at the filesystem root; otherwise it silently fails on EACCES.

The clones cannot just call hts_gethome(): it is hidden by -fvisibility=hidden
(nm reports it as a local "t" in libhttrack.so), so htsserver cannot reach it
even though it links the library, and proxytrack does not link libhttrack at
all. Exporting it would grow the public ABI for no other caller, so each copy
keeps its own body. proxytrack's is dead today and fixed anyway: this bug got a
second round precisely because one copy kept the old shape.

Test 63 drives htsserver and reads the base path back out of the rendered UI,
since a static in htsserver.h is out of reach of the -#test registry. It pins a
real HOME too, or the empty case would also pass against a gethomedir() that
ignored the environment and always answered ".".

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

src/htsserver.h

@@ -164,13 +164,12 @@ HTS_UNUSED static int linputsoc_t(T_SOC soc, char *s, int max, int timeout) {
   return -1;
 }
 
+/* Same contract as hts_gethome(), which is hidden and out of reach from here */
 static const char *gethomedir(void) {
   const char *home = getenv("HOME");
 
-  if (home)
-    return home;
-  else
-    return ".";
+  /* An empty $HOME would put the base path and httrack.ini at the root */
+  return strnotempty(home) ? home : ".";
 }
 static int linput_cpp(FILE * fp, char *s, int max) {
   int rlen = 0;

src/proxy/proxytrack.h

@@ -107,13 +107,12 @@ HTS_UNUSED static void proxytrack_print_log(const char *severity, const char *fo
 	"<!-- _-._.--._._-._.--._._-._.--._._-._.--._._-._.--._. -->\r\n" \
 	"<!-- End Disable IE Friendly HTTP Error Messages -->\r\n"
 
+/* Same contract as hts_gethome(): proxytrack does not link libhttrack */
 HTS_UNUSED static const char *gethomedir(void) {
   const char *home = getenv("HOME");
 
-  if (home)
-    return home;
-  else
-    return ".";
+  /* An empty $HOME would resolve a relative path against the root */
+  return strnotempty(home) ? home : ".";
 }
 
 HTS_UNUSED static int linput(FILE * fp, char *s, int max) {

tests/63_webhttrack-home.test

@@ -0,0 +1,88 @@
+#!/bin/bash
+#
+# htsserver's $HOME lookup, through the web UI it actually renders. An exported
+# but empty $HOME must not resolve the default base path against the root.
+
+set -euo pipefail
+
+testdir=$(cd "$(dirname "$0")" && pwd)
+distdir=${top_srcdir:-$(cd "${testdir}/.." && pwd)}
+distdir=$(cd "${distdir}" && pwd)
+
+fail() {
+    echo "FAIL: $*" >&2
+    exit 1
+}
+
+command -v htsserver >/dev/null || fail "no htsserver in PATH"
+# Mirror local-crawl.sh's skip-with-77: the Debian buildd chroot has no python3.
+command -v python3 >/dev/null || {
+    echo "python3 not found; skipping" >&2
+    exit 77
+}
+
+srv=
+cleanup() {
+    test -z "${srv}" || kill -9 "${srv}" 2>/dev/null || true
+}
+trap cleanup EXIT HUP INT QUIT PIPE TERM
+
+log=$(mktemp)
+trap 'cleanup; rm -f "${log}"' EXIT
+
+# Ask htsserver for its rendered default base path, under the given $HOME
+# ("-" = leave $HOME unset).
+pathfor() {
+    local homeval=$1 port url got
+    port=$(python3 -c 'import socket
+s = socket.socket()
+s.bind(("127.0.0.1", 0))
+print(s.getsockname()[1])
+s.close()')
+
+    : >"${log}"
+    (
+        # htsserver ignores SIGTERM/SIGTTOU handling from the harness shell
+        trap '' TERM TTOU
+        if test "${homeval}" = -; then unset HOME; else export HOME="${homeval}"; fi
+        exec htsserver "${distdir}/" --port "${port}" >"${log}" 2>&1
+    ) &
+    srv=$!
+
+    for _ in $(seq 1 40); do
+        url=$(sed -n 's/^URL=//p' "${log}" 2>/dev/null) && test -n "${url}" && break
+        kill -0 "${srv}" 2>/dev/null || break
+        sleep 0.25
+    done
+    test -n "${url:-}" || fail "htsserver did not come up: $(cat "${log}")"
+
+    # The UI is served ISO-8859-1, so keep python out of text mode.
+    got=$(python3 -c 'import re, sys, urllib.request
+body = urllib.request.urlopen(sys.argv[1] + "server/step2.html", timeout=20).read()
+m = re.search(br"name=\"path\" value=\"([^\"]*)\"", body)
+print(m.group(1).decode("latin-1") if m else "")' "${url}")
+
+    kill -9 "${srv}" 2>/dev/null || true
+    wait "${srv}" 2>/dev/null || true
+    srv=
+    test -n "${got}" || fail "no path field in the rendered step2.html"
+    echo "${got}"
+}
+
+check() {
+    local desc=$1 homeval=$2 want=$3 got
+    got=$(pathfor "${homeval}")
+    test "${got}" = "${want}" || fail "${desc}: want ${want}, got ${got}"
+    echo "ok: ${desc} -> ${got}"
+}
+
+# A real HOME must reach the page, or the two cases below are vacuous: they
+# also pass when gethomedir() ignores the environment and always answers ".".
+check 'a set HOME is used' /nonexistent/hts-home /nonexistent/hts-home/websites
+
+# Exported but empty is the regression: getenv() returns "", not NULL, so a
+# bare NULL check let the base path collapse onto /websites.
+check 'an empty HOME' '' ./websites
+check 'an unset HOME' - ./websites
+
+echo "PASS"

tests/Makefile.am

@@ -143,6 +143,7 @@ TESTS = \
 	59_local-tls-stall.test \
 	60_crawl-log-salvage.test \
 	61_webhttrack-locale.test \
-	62_lang-integrity.test
+	62_lang-integrity.test \
+	63_webhttrack-home.test
 
 CLEANFILES = check-network_sh.cache