From: Jim Meyering <jim@meyering.net>
Date: Sat, 24 Jun 2000 07:37:44 +0000 (+0000)
Subject: (sysv_sum_file): Avoid overflowing 32-bit accumulator
X-Git-Tag: FILEUTILS-4_0v~18
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=a6e6a1e05b5ea28e8f8b3696c0e7748923cb1da4;p=thirdparty%2Fcoreutils.git

(sysv_sum_file): Avoid overflowing 32-bit accumulator
on files larger than 256 MB.
---

diff --git a/src/sum.c b/src/sum.c
index b012182c85..745093109f 100644
--- a/src/sum.c
+++ b/src/sum.c
@@ -176,6 +176,9 @@ sysv_sum_file (const char *file, int print_name)
 
       for (i = 0; i < bytes_read; i++)
 	checksum += buf[i];
+      /* Reduce checksum mod 0xffff, to avoid overflow.  */
+      checksum = (checksum & 0xffff) + (checksum >> 16);
+
       total_bytes += bytes_read;
     }