From ffd63aedad3c0eb08ebb27103e5f242f8732dc0c Mon Sep 17 00:00:00 2001

From: Paul Eggert <eggert@cs.ucla.edu>

Date: Tue, 24 Jul 2018 10:18:28 -0700

Subject: cmp: fix bug in -b diagnostic

Problem reported by mancha (Bug#32249).

* src/cmp.c (count_newlines): Restore old value of sentinel.

* tests/cmp: Test for the bug.

---

 src/cmp.c |  2 ++

 tests/cmp | 10 ++++++++++

 2 files changed, 12 insertions(+)

diff --git a/src/cmp.c b/src/cmp.c

index 04638e3..2811392 100644

--- a/src/cmp.c

+++ b/src/cmp.c

@@ -639,9 +639,11 @@ count_newlines (char *buf, size_t bufsize)

   size_t count = 0;

   char *p;

   char *lim = buf + bufsize;

+  char ch = *lim;

   *lim = '\n';

   for (p = buf; (p = rawmemchr (p, '\n')) != lim; p++)

     count++;

+  *lim = ch;

   return count;

 }

diff --git a/tests/cmp b/tests/cmp

index 160c1ea..ca0fe5e 100755

--- a/tests/cmp

+++ b/tests/cmp

@@ -208,4 +208,14 @@ done >out1

 compare exp1 out1 || fail=1

+printf 'bad\n' >bad

+printf 'bug\n' >bug

+echo LC_ALL=C cmp -b bad bug

+LC_ALL=C cmp -b bad bug

+test $? -eq 1 || fail=1

+case `LC_ALL=C cmp -b bad bug` in

+  'bad bug differ: byte 2, line 1 is '*' a '*' u') ;;

+  *) echo 'expected cmp -b to report a and u'; fail=1;;

+esac

+

 Exit $fail

-- 

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