berkeley-abc · maliberty · Jun 3, 2026
diff --git a/src/misc/zlib/README b/src/misc/zlib/README
@@ -1,52 +1,51 @@
 ZLIB DATA COMPRESSION LIBRARY
 
-zlib 1.2.5 is a general purpose data compression library.  All the code is
-thread safe.  The data format used by the zlib library is described by RFCs
-(Request for Comments) 1950 to 1952 in the files
-http://www.ietf.org/rfc/rfc1950.txt (zlib format), rfc1951.txt (deflate format)
-and rfc1952.txt (gzip format).
+zlib 1.3.2 is a general purpose data compression library.  All the code is
+thread safe (though see the FAQ for caveats).  The data format used by the zlib
+library is described by RFCs (Request for Comments) 1950 to 1952 at
+https://datatracker.ietf.org/doc/html/rfc1950 (zlib format), rfc1951 (deflate
+format) and rfc1952 (gzip format).
 
 All functions of the compression library are documented in the file zlib.h
 (volunteer to write man pages welcome, contact zlib@gzip.org).  A usage example
-of the library is given in the file example.c which also tests that the library
-is working correctly.  Another example is given in the file minigzip.c.  The
-compression library itself is composed of all source files except example.c and
-minigzip.c.
+of the library is given in the file test/example.c which also tests that
+the library is working correctly.  Another example is given in the file
+test/minigzip.c.  The compression library itself is composed of all source
+files in the root directory.
 
 To compile all files and run the test program, follow the instructions given at
 the top of Makefile.in.  In short "./configure; make test", and if that goes
-well, "make install" should work for most flavors of Unix.  For Windows, use one
-of the special makefiles in win32/ or contrib/vstudio/ .  For VMS, use
+well, "make install" should work for most flavors of Unix.  For Windows, use
+one of the special makefiles in win32/ or contrib/vstudio/ .  For VMS, use
 make_vms.com.
 
 Questions about zlib should be sent to <zlib@gzip.org>, or to Gilles Vollant
 <info@winimage.com> for the Windows DLL version.  The zlib home page is
-http://zlib.net/ .  Before reporting a problem, please check this site to
+https://zlib.net/ .  Before reporting a problem, please check this site to
 verify that you have the latest version of zlib; otherwise get the latest
 version and check whether the problem still exists or not.
 
-PLEASE read the zlib FAQ http://zlib.net/zlib_faq.html before asking for help.
+PLEASE read the zlib FAQ https://zlib.net/zlib_faq.html before asking for help.
 
 Mark Nelson <markn@ieee.org> wrote an article about zlib for the Jan.  1997
 issue of Dr.  Dobb's Journal; a copy of the article is available at
-http://marknelson.us/1997/01/01/zlib-engine/ .
+https://zlib.net/nelson/ .
 
-The changes made in version 1.2.5 are documented in the file ChangeLog.
+The changes made in version 1.3.2 are documented in the file ChangeLog.
 
 Unsupported third party contributions are provided in directory contrib/ .
 
-zlib is available in Java using the java.util.zip package, documented at
-http://java.sun.com/developer/technicalArticles/Programming/compression/ .
+zlib is available in Java using the java.util.zip package. Follow the API
+Documentation link at: https://docs.oracle.com/search/?q=java.util.zip .
 
-A Perl interface to zlib written by Paul Marquess <pmqs@cpan.org> is available
-at CPAN (Comprehensive Perl Archive Network) sites, including
-http://search.cpan.org/~pmqs/IO-Compress-Zlib/ .
+A Perl interface to zlib and bzip2 written by Paul Marquess <pmqs@cpan.org>
+can be found at https://github.com/pmqs/IO-Compress .
 
 A Python interface to zlib written by A.M. Kuchling <amk@amk.ca> is
 available in Python 1.5 and later versions, see
-http://www.python.org/doc/lib/module-zlib.html .
+https://docs.python.org/3/library/zlib.html .
 
-zlib is built into tcl: http://wiki.tcl.tk/4610 .
+zlib is built into tcl: https://wiki.tcl-lang.org/page/zlib .
 
 An experimental package to read and write files in .zip format, written on top
 of zlib by Gilles Vollant <info@winimage.com>, is available in the
@@ -64,15 +63,13 @@ Notes for some targets:
 - zlib doesn't work with gcc 2.6.3 on a DEC 3000/300LX under OSF/1 2.1 it works
   when compiled with cc.
 
-- On Digital Unix 4.0D (formely OSF/1) on AlphaServer, the cc option -std1 is
+- On Digital Unix 4.0D (formerly OSF/1) on AlphaServer, the cc option -std1 is
   necessary to get gzprintf working correctly. This is done by configure.
 
 - zlib doesn't work on HP-UX 9.05 with some versions of /bin/cc. It works with
   other compilers. Use "make test" to check your compiler.
 
-- gzdopen is not supported on RISCOS or BEOS.
-
-- For PalmOs, see http://palmzlib.sourceforge.net/
+- For PalmOs, see https://palmzlib.sourceforge.net/
 
 
 Acknowledgments:
@@ -84,7 +81,7 @@ Acknowledgments:
 
 Copyright notice:
 
- (C) 1995-2010 Jean-loup Gailly and Mark Adler
+ (C) 1995-2026 Jean-loup Gailly and Mark Adler
 
   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
@@ -108,7 +105,10 @@ Copyright notice:
 If you use the zlib library in a product, we would appreciate *not* receiving
 lengthy legal documents to sign.  The sources are provided for free but without
 warranty of any kind.  The library has been entirely written by Jean-loup
-Gailly and Mark Adler; it does not include third-party code.
+Gailly and Mark Adler; it does not include third-party code.  We make all
+contributions to and distributions of this project solely in our personal
+capacity, and are not conveying any rights to any intellectual property of
+any third parties.
 
 If you redistribute modified sources, we would appreciate that you include in
 the file ChangeLog history information documenting your changes.  Please read

diff --git a/src/misc/zlib/adler32.c b/src/misc/zlib/adler32.c
@@ -1,5 +1,5 @@
 /* adler32.c -- compute the Adler-32 checksum of a data stream
- * Copyright (C) 1995-2007 Mark Adler
+ * Copyright (C) 1995-2011, 2016 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
@@ -14,11 +14,8 @@
 
 ABC_NAMESPACE_IMPL_START
 
-#define local static
 
-local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2);
-
-#define BASE 65521UL    /* largest prime smaller than 65536 */
+#define BASE 65521U     /* largest prime smaller than 65536 */
 #define NMAX 5552
 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
 
@@ -28,44 +25,48 @@ local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2);
 #define DO8(buf,i)  DO4(buf,i); DO4(buf,i+4);
 #define DO16(buf)   DO8(buf,0); DO8(buf,8);
 
-/* use NO_DIVIDE if your processor does not do division in hardware */
+/* use NO_DIVIDE if your processor does not do division in hardware --
+   try it both ways to see which is faster */
 #ifdef NO_DIVIDE
-#  define MOD(a) \
+/* note that this assumes BASE is 65521, where 65536 % 65521 == 15
+   (thank you to John Reiser for pointing this out) */
+#  define CHOP(a) \
+    do { \
+        unsigned long tmp = a >> 16; \
+        a &= 0xffffUL; \
+        a += (tmp << 4) - tmp; \
+    } while (0)
+#  define MOD28(a) \
     do { \
-        if (a >= (BASE << 16)) a -= (BASE << 16); \
-        if (a >= (BASE << 15)) a -= (BASE << 15); \
-        if (a >= (BASE << 14)) a -= (BASE << 14); \
-        if (a >= (BASE << 13)) a -= (BASE << 13); \
-        if (a >= (BASE << 12)) a -= (BASE << 12); \
-        if (a >= (BASE << 11)) a -= (BASE << 11); \
-        if (a >= (BASE << 10)) a -= (BASE << 10); \
-        if (a >= (BASE << 9)) a -= (BASE << 9); \
-        if (a >= (BASE << 8)) a -= (BASE << 8); \
-        if (a >= (BASE << 7)) a -= (BASE << 7); \
-        if (a >= (BASE << 6)) a -= (BASE << 6); \
-        if (a >= (BASE << 5)) a -= (BASE << 5); \
-        if (a >= (BASE << 4)) a -= (BASE << 4); \
-        if (a >= (BASE << 3)) a -= (BASE << 3); \
-        if (a >= (BASE << 2)) a -= (BASE << 2); \
-        if (a >= (BASE << 1)) a -= (BASE << 1); \
+        CHOP(a); \
         if (a >= BASE) a -= BASE; \
     } while (0)
-#  define MOD4(a) \
+#  define MOD(a) \
     do { \
-        if (a >= (BASE << 4)) a -= (BASE << 4); \
-        if (a >= (BASE << 3)) a -= (BASE << 3); \
-        if (a >= (BASE << 2)) a -= (BASE << 2); \
-        if (a >= (BASE << 1)) a -= (BASE << 1); \
+        CHOP(a); \
+        MOD28(a); \
+    } while (0)
+#  define MOD63(a) \
+    do { /* this assumes a is not negative */ \
+        z_off64_t tmp = a >> 32; \
+        a &= 0xffffffffL; \
+        a += (tmp << 8) - (tmp << 5) + tmp; \
+        tmp = a >> 16; \
+        a &= 0xffffL; \
+        a += (tmp << 4) - tmp; \
+        tmp = a >> 16; \
+        a &= 0xffffL; \
+        a += (tmp << 4) - tmp; \
         if (a >= BASE) a -= BASE; \
     } while (0)
 #else
 #  define MOD(a) a %= BASE
-#  define MOD4(a) a %= BASE
+#  define MOD28(a) a %= BASE
+#  define MOD63(a) a %= BASE
 #endif
 
 /* ========================================================================= */
-uLong ZEXPORT adler32(uLong adler, const Bytef *buf, uInt len)
-{
+uLong ZEXPORT adler32_z(uLong adler, const Bytef *buf, z_size_t len) {
     unsigned long sum2;
     unsigned n;
 
@@ -96,7 +97,7 @@ uLong ZEXPORT adler32(uLong adler, const Bytef *buf, uInt len)
         }
         if (adler >= BASE)
             adler -= BASE;
-        MOD4(sum2);             /* only added so many BASE's */
+        MOD28(sum2);            /* only added so many BASE's */
         return adler | (sum2 << 16);
     }
 
@@ -132,37 +133,43 @@ uLong ZEXPORT adler32(uLong adler, const Bytef *buf, uInt len)
 }
 
 /* ========================================================================= */
-local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2)
-{
+uLong ZEXPORT adler32(uLong adler, const Bytef *buf, uInt len) {
+    return adler32_z(adler, buf, len);
+}
+
+/* ========================================================================= */
+local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2) {
     unsigned long sum1;
     unsigned long sum2;
     unsigned rem;
 
+    /* for negative len, return invalid adler32 as a clue for debugging */
+    if (len2 < 0)
+        return 0xffffffffUL;
+
     /* the derivation of this formula is left as an exercise for the reader */
-    rem = (unsigned)(len2 % BASE);
+    MOD63(len2);                /* assumes len2 >= 0 */
+    rem = (unsigned)len2;
     sum1 = adler1 & 0xffff;
     sum2 = rem * sum1;
     MOD(sum2);
     sum1 += (adler2 & 0xffff) + BASE - 1;
     sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;
     if (sum1 >= BASE) sum1 -= BASE;
     if (sum1 >= BASE) sum1 -= BASE;
-    if (sum2 >= (BASE << 1)) sum2 -= (BASE << 1);
+    if (sum2 >= ((unsigned long)BASE << 1)) sum2 -= ((unsigned long)BASE << 1);
     if (sum2 >= BASE) sum2 -= BASE;
     return sum1 | (sum2 << 16);
 }
 
 /* ========================================================================= */
-uLong ZEXPORT adler32_combine(uLong adler1, uLong adler2, z_off_t len2)
-{
+uLong ZEXPORT adler32_combine(uLong adler1, uLong adler2, z_off_t len2) {
     return adler32_combine_(adler1, adler2, len2);
 }
 
-uLong ZEXPORT adler32_combine64(uLong adler1, uLong adler2, z_off64_t len2)
-{
+uLong ZEXPORT adler32_combine64(uLong adler1, uLong adler2, z_off64_t len2) {
     return adler32_combine_(adler1, adler2, len2);
 }
 
-
 ABC_NAMESPACE_IMPL_END