bin/47155: add mktemp zero arguments extension

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>Number:         47155
>Category:       bin
>Synopsis:       add mktemp zero arguments extension
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Sat Nov 03 04:45:00 +0000 2012
>Originator:     Eitan Adler
>Release:        trunk
>Organization:
FreeBSD
>Environment:
N/A
>Description:
FreeBSD and OpenBSD have already implemented the Sun/GNU extension of mktemp 
returning a path to a file in /tmp if mktemp is called without arguments.
>How-To-Repeat:

>Fix:
! Bring in a GNU/Sun/FreeBSD extension:
! If mktemp is called without an argument
! Return with a file in TMPDIR.
!
! Submitted by: Eitan Adler
!
Index: mktemp.1
===================================================================
RCS file: /cvsroot/src/usr.bin/mktemp/mktemp.1,v
retrieving revision 1.19
diff -u -r1.19 mktemp.1
--- mktemp.1    15 Aug 2009 20:44:56 -0000      1.19
+++ mktemp.1    3 Nov 2012 04:41:57 -0000
@@ -115,11 +115,12 @@
 .Fl t
 option value as filename prefix.
 .Pp
-At least one
-.Ar template
-argument or the
-.Fl t
-option must be present.
+If no arguments are passed or if only the
+.Fl d
+flag is passed
+.Nm behaves as if
+.Fl t Li tmp
+was supplied.
 .Pp
 .Nm
 is provided to allow shell scripts to safely use temporary files.
Index: mktemp.c
===================================================================
RCS file: /cvsroot/src/usr.bin/mktemp/mktemp.c,v
retrieving revision 1.11
diff -u -r1.11 mktemp.c
--- mktemp.c    15 Aug 2009 20:02:28 -0000      1.11
+++ mktemp.c    3 Nov 2012 04:41:57 -0000
@@ -100,6 +100,9 @@
        argc -= optind;
        argv += optind;
 
+       if (tflag == 0 && argc < 1)
+               tflag = 1;
+
        if (tflag) {
                if (tmpdir == NULL)
                        tmpdir = getenv("TMPDIR");