Fix msync calls beyond the end of the mapping

Fixed very infrequent errors of page alignment in msync calls.
Thanks to Chris Knipe for the bug report and to Richard Kettlewell for
the patch.

close #327

Author: Julien-Elie

CONTRIBUTORS

@@ -279,4 +279,5 @@ Tim Fardell, Remco Rijnders, David Binderman, Tony Evans, Christian Garbs,
 Jesse Rehmer, Colin Watson, Lauri Tirkkonen, Christian Mock, Marcus Jodorf,
 Richard Kettlewell, Yuriy M. Kaminskiy, Bill Parker, Thomas Hochstein,
 Tanguy Ortolo, Michael Baeuerle, Kevin Bowling, Andreas Kempe, Hauke Lampe,
-Enrik Berkhan, Nigel Reed, Christian Clauss, Roberto Corrado, Roman Donchenko
+Enrik Berkhan, Nigel Reed, Christian Clauss, Roberto Corrado, Roman Donchenko,
+Chris Knipe

doc/pod/news.pod

@@ -35,6 +35,13 @@ to Roman Donchenko for the code simplification and cleaning.
 
 =item *
 
+Fixed very infrequent errors of memory mapping when updating the F<active>
+file or using the tradindexed overview method, as well as when updating the
+F<history> file with I<nfswriter> set to true.  Thanks to Chris Knipe for the
+bug report and to Richard Kettlewell for the patch.
+
+=item *
+
 Fixed the rotation of the F<perl-nocem.log> file generated when syslog is not
 available or the B<-l> flag used with B<perl-nocem>: the contents of this log
 file was mistakenly appended to F<news.notice> by B<scanlogs>.

frontends/cnfsstat.in

@@ -615,7 +615,7 @@ sub get_cycbuff_info {
         my $pagesize = 16384;
         my $minartoffset = int($len / ($blksz * 8)) + 512;
         # Align upwards:
-        $minartoffset = ($minartoffset + $pagesize) & ~($pagesize - 1);
+        $minartoffset = ($minartoffset + $pagesize - 1) & ~($pagesize - 1);
 
         if ($cyclenum == 0 && $free == $minartoffset) {
             # The cycbuff has no articles yet.

lib/mmap.c

@@ -1,7 +1,10 @@
 /*
 **  Manipulation routines for memory-mapped pages.
 **
-**  Written by Alex Kiernan (alex.kiernan@thus.net)
+**  Written by Alex Kiernan <alex.kiernan@thus.net> in 2002.
+**
+**  Various bug fixes, code and documentation improvements
+**  in 2002-2004, 2007, 2021-2023, 2025.
 */
 
 #include "portable/system.h"
@@ -27,7 +30,7 @@ inn__msync_page(void *p, size_t length, int flags)
     } else {
         const size_t mask = ~(size_t) (pagesize - 1);
         char *start = (char *) ((uintptr_t) p & mask);
-        char *end = (char *) (((uintptr_t) p + length + pagesize) & mask);
+        char *end = (char *) (((uintptr_t) p + length + pagesize - 1) & mask);
 
         return msync(start, end - start, flags);
     }

storage/cnfs/cnfs.c

@@ -760,8 +760,8 @@ CNFSinit_disks(CYCBUFF *cycbuff)
         /*
         ** The minimum article offset will be the size of the bitfield itself,
         ** len / (blocksize * 8), plus however many additional blocks the
-        *CYCBUFF
-        ** external header occupies ... then round up to the next block.
+        ** *CYCBUFF external header occupies... then round up to the next
+        ** block.
         */
         minartoffset = cycbuff->len / (cycbuff->blksz * 8) + CNFS_BEFOREBITF;
         tonextblock =
@@ -1002,11 +1002,10 @@ CNFSread_config(void)
 static void
 cnfs_mapcntl(void *p, size_t length, int flags)
 {
-    char *start, *end;
+    const size_t mask = ~(size_t) (pagesize - 1);
+    char *start = (char *) ((uintptr_t) p & mask);
+    char *end = (char *) (((uintptr_t) p + length + pagesize - 1) & mask);
 
-    start = (char *) ((uintptr_t) p & ~(size_t) (pagesize - 1));
-    end = (char *) (((uintptr_t) p + length + pagesize)
-                    & ~(size_t) (pagesize - 1));
     if (flags == MS_INVALIDATE) {
         msync(start, end - start, flags);
     } else {