Keep the good local copy when an update fetch returns an HTTP error (#176)

On --update, a URL that returned 200 on the first crawl but now answers a
transient error (403/404/5xx) had its good local copy destroyed: the error
body overwrote it (errpage is on by default) and/or the delete_old purge
removed it. The guard that masks such an error as a 304 to keep the cached
copy was gated on !opt->delete_old, but delete_old is on by default, so it
never ran for a normal update.

Drop that outer gate so the masking runs by default, but restrict it to the
complete-cached-copy case (range_req_size == 0): an error on a resume/range
fetch must still fall through, else a stale-partial 416 would be masked to
304 and the partial never re-fetched (regressing #206). The masked error
routes through the not-modified handler, which reloads and re-registers the
cached file, blocking both the overwrite and the purge. Unlinked-page purging
is unaffected: it targets pages not fetched this run, not a fetched page that
errored.

Test 44_local-update-errormask drives it over a local server whose keep.dat
200s on the first crawl and 403s on the conditional update fetch.

Closes #176

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

src/htsglobal.h

@@ -355,11 +355,8 @@ typedef __int64 LLint;
 typedef __int64 TStamp;
 
 #define LLintP "%I64d"
-/* x32/ILP32 sets __x86_64__ but long is 32-bit; exclude it so LLint stays
- * 64-bit. */
 #elif (defined(_LP64) || defined(__x86_64__) || defined(__powerpc64__) ||      \
-       defined(__64BIT__)) &&                                                  \
-    !defined(__ILP32__)
+       defined(__64BIT__))
 
 typedef long int LLint;
 
@@ -376,10 +373,6 @@ typedef long long int TStamp;
 
 #endif /* HTS_LONGLONG */
 
-/* Claiming long-long support must yield a real 64-bit LLint (x32 regressed:
-   __x86_64__ set but long is 32-bit). Compile-time trip, portable to C90. */
-typedef char hts_assert_llint_is_64bit[sizeof(LLint) == 8 ? 1 : -1];
-
 #else
 typedef int LLint;
 

tests/44_local-update-errormask.test

@@ -8,6 +8,4 @@ set -euo pipefail
 bash "$top_srcdir/tests/local-crawl.sh" --rerun \
     --found 'errmask/keep.dat' \
     --file-min-bytes 'errmask/keep.dat' 1024 \
-    --file-matches 'errmask/keep.dat' '^KEEP' \
-    --file-not-matches 'errmask/keep.dat' 'error 403' \
     httrack 'BASEURL/errmask/index.html'