fmemopen.3: Small improvements to the description of open_memstream()

Make it a little more evident that the caller should not
pass a previously allocated buffer to open_memstream().

Reported-by: Rasmus Villemoes <Rasmus.Villemoes@decode.is>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/man3/fmemopen.3 b/man3/fmemopen.3
index c14587098d..bf6d78d42b 100644
--- a/man3/fmemopen.3
+++ b/man3/fmemopen.3
@@ -135,14 +135,18 @@ below).
 The
 .BR open_memstream ()
 function opens a stream for writing to a buffer.
-The buffer
-is dynamically allocated (as with
+The function dynamically allocates the buffer (in the manner of
 .BR malloc (3)),
-and automatically grows as required.
+and the buffer automatically grows as required.
 After closing the stream, the caller should
 .BR free (3)
 this buffer.
 
+The locations pointed to by
+.IR ptr
+and
+.I sizeloc
+are used to report the current location and size of the buffer.
 When the stream is closed
 .RB ( fclose (3))
 or flushed