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Date: Sun, 30 Dec 2001 01:04:54 +1100 (EST)
From: "Tim J. Robbins" <tim@robbins.dropbear.id.au>
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Subject: docs/33298: memcpy(3) could suggest memmove for overlapping copies
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>Number:         33298
>Category:       docs
>Synopsis:       memcpy(3) could suggest memmove for overlapping copies
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sat Dec 29 06:20:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     Tim J. Robbins
>Release:        FreeBSD 4.5-PRERELEASE i386
>Organization:
>Environment:
System: FreeBSD raven.robbins.dropbear.id.au 4.5-PRERELEASE FreeBSD 4.5-PRERELEASE #2: Thu Dec 27 22:09:06 EST 2001 tim@raven.robbins.dropbear.id.au:/usr/obj/usr/src/sys/RAVEN i386


	
>Description:
From memcpy(3):
BUGS
     In this implementation memcpy() is implemented using bcopy(3), and there-
     fore the strings may overlap.  On other systems, copying overlapping
     strings may produce surprises.  A simpler solution is to not use
     memcpy().

Using memmove() is simpler than not using memcpy().

>How-To-Repeat:
man 3 memcpy
>Fix:

--- memcpy.3.old	Sun Dec 30 00:55:49 2001
+++ memcpy.3	Sun Dec 30 00:59:20 2001
@@ -82,5 +82,10 @@
 .Xr bcopy 3 ,
 and therefore the strings may overlap.
 On other systems, copying overlapping strings may produce surprises.
-A simpler solution is to not use
-.Fn memcpy .
+Programs intended to be portable should use
+.Fn memmove
+when
+.Fa src
+and
+.Fa dst
+may overlap.


.. or something to that effect.
>Release-Note:
>Audit-Trail:
>Unformatted:

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