sort: avoid unaligned access.

* src/sort.c (fillbuf): When enlarging the line buffer, ensure that
the new size is a multiple of "sizeof (struct line)".  This avoids
alignment problems when indexing from the end of the buffer.
Problem reported by Andreas Schwab in
<http://lists.gnu.org/archive/html/bug-coreutils/2007-07/msg00158.html>.

ChangeLog

@@ -1,3 +1,12 @@
+2007-07-23  Paul Eggert  <eggert@cs.ucla.edu>
+
+	sort: avoid unaligned access.
+	* src/sort.c (fillbuf): When enlarging the line buffer, ensure that
+	the new size is a multiple of "sizeof (struct line)".  This avoids
+	alignment problems when indexing from the end of the buffer.
+	Problem reported by Andreas Schwab in
+	<http://lists.gnu.org/archive/html/bug-coreutils/2007-07/msg00158.html>.
+
 2007-07-23  Jim Meyering  <jim@meyering.net>
 
 	Update all copyright notices to use the newer form (e.g., remove

src/sort.c

@@ -1488,9 +1488,14 @@ fillbuf (struct buffer *buf, FILE *fp, char const *file)
 	  return true;
 	}
 
-      /* The current input line is too long to fit in the buffer.
-	 Double the buffer size and try again.  */
-      buf->buf = X2REALLOC (buf->buf, &buf->alloc);
+      {
+	/* The current input line is too long to fit in the buffer.
+	   Double the buffer size and try again, keeping it properly
+	   aligned.  */
+	size_t line_alloc = buf->alloc / sizeof (struct line);
+	buf->buf = x2nrealloc (buf->buf, &line_alloc, sizeof (struct line));
+	buf->alloc = line_alloc * sizeof (struct line);
+      }
     }
 }