Mention that basename(3) and dirname(3) will change in the future.

Update the existing manual pages for basename(3) and dirname(3) to
mention that in future versions of FreeBSD, these functions will no
longer use internal buffers for storing the results.

MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D7356

2 files changed, 16 insertions, 7 deletions

diff --git a/lib/libc/gen/basename.3 b/lib/libc/gen/basename.3
index 859f1047f84e..6de009448bda 100644
--- a/lib/libc/gen/basename.3
+++ b/lib/libc/gen/basename.3
@@ -16,7 +16,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 28, 2016
+.Dd July 29, 2016
 .Dt BASENAME 3
 .Os
 .Sh NAME
@@ -61,8 +61,16 @@ function
 returns a pointer to internal storage space allocated on the first call
 that will be overwritten
 by subsequent calls.
+.Pp
+Other vendor implementations of
+.Fn basename
+may store their result in the input buffer,
+making it safe to use in multithreaded applications.
+Future versions of
+.Fx
+will follow this approach as well.
 .Fn basename_r
-is therefore preferred for threaded applications.
+will then become obsolete.
 .Sh RETURN VALUES
 On successful completion,
 .Fn basename
diff --git a/lib/libc/gen/dirname.3 b/lib/libc/gen/dirname.3
index 19e45add0ad5..6685618a9869 100644
--- a/lib/libc/gen/dirname.3
+++ b/lib/libc/gen/dirname.3
@@ -16,7 +16,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 28, 2016
+.Dd July 29, 2016
 .Dt DIRNAME 3
 .Os
 .Sh NAME
@@ -56,10 +56,11 @@ by subsequent calls.
 .Pp
 Other vendor implementations of
 .Fn dirname
-may modify the contents of the string passed to
-.Fn dirname ;
-this should be taken into account when writing code which calls this function
-if portability is desired.
+may store their result in the input buffer,
+making it safe to use in multithreaded applications.
+Future versions of
+.Fx
+will follow this approach as well.
 .Sh RETURN VALUES
 On successful completion,
 .Fn dirname