[PATCH] getttyent.3: Add description of the functions are not thread-safe

[Peng Haitao <penght-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>]

The function getttyent() returns a pointer to the static variable, so it is not
thread-safe. The functions setttyent() and endttyent() use a static variable "tf", 
so they are not thread-safe. The function getttynam() calls unsafe function 
getttyent(), so it is not thread-safe.

Signed-off-by: Peng Haitao <penght-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
---
 man3/getttyent.3 |   19 ++++++++++++++++++-
 1 files changed, 18 insertions(+), 1 deletions(-)

diff --git a/man3/getttyent.3 b/man3/getttyent.3
index 1cf8ebc..a4e9b17 100644
--- a/man3/getttyent.3
+++ b/man3/getttyent.3
@@ -1,7 +1,7 @@
 .\"  Copyright 2002 walter harms (walter.harms-jNDFPZUTrfTUvfpBxBsQfasoZZ7OtMbqG9Ur7JDdleE@public.gmane.org)
 .\"  Distributed under GPL
 .\"
-.TH GETTTYENT 3 2002-07-18  "GNU" "Linux Programmer's Manual"
+.TH GETTTYENT 3 2011-09-15  "GNU" "Linux Programmer's Manual"
 .SH NAME
 getttyent, getttynam, setttyent, endttyent \- get ttys file entry
 .SH SYNOPSIS
@@ -66,6 +66,23 @@ can be:
 #define TTY_ON     0x01  /* enable logins (start ty_getty program) */
 #define TTY_SECURE 0x02  /* allow UID 0 to login */
 .fi
+.SH ATTRIBUTES
+.SS Multithreading (see pthreads(7))
+The
+.BR getttyent ()
+returns a pointer to the static variable, so it is not thread-safe.
+.LP
+The
+.BR setttyent ()
+and
+.BR endttyent ()
+use a static variable, so they are not thread-safe.
+.LP
+The
+.BR getttynam ()
+calls thread-unsafe function
+.BR getttyent ()
+so it is not thread-safe.
 .SH "CONFORMING TO"
 Not in POSIX.1-2001.
 Present on the BSDs, and perhaps other systems.
-- 
1.7.1

-- 
Best Regards,
Peng Haitao

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