Remove dead HTS_USEZLIB guards now that zlib is mandatory

configure has rejected --without-zlib since #750, and htsglobal.h
#errors on a forced HTS_USEZLIB=0, so the macro can only ever be 1.
Collapse every #if/#ifdef HTS_USEZLIB guard (htsweb.c, htsname.c,
htslib.c, htszlib.c, htsselftest.c, htscodec.c) to its always-taken
branch; htsweb.c's guard used #ifdef where every other site used #if,
an inconsistency that no longer matters once the guard is gone.

htscodec.c's #else arms were a genuine zlib-free content-coding path
(Accept-Encoding: identity, hts_codec_unpack returning -1), not stubs.
Removed for consistency with the other nine guards: the cache
(htscache.c, proxy/store.c) already reaches minizip unconditionally
from ~60 call sites with no null backend, so a zlib-free build is not
actually reachable today regardless of this file.

No new test: this is dead-code removal with no behavior change.
Verified by differential build against master: htscodec.o and
htszlib.o are byte-identical; the other touched objects differ only
in __LINE__ immediates shifted by the removed guard lines (plus one
cosmetic objdump label-annotation artifact each in htsselftest.o and
htsweb.o, from string-literal pool reordering). Exported symbols in
libhttrack.so are unchanged. make check: 166/166 (158 pass, 8 skip).

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

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/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

@@ -63,9 +63,7 @@ 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
@@ -3377,7 +3375,6 @@ 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 +3448,6 @@ 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 +3497,6 @@ 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 +3575,6 @@ 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 +3919,6 @@ 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 +3969,11 @@ 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 +4003,6 @@ 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). */

src/htsweb.c

@@ -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

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