suse man page for tmpnam

TMPNAM(3)						     Linux Programmer's Manual							 TMPNAM(3)

NAME
       tmpnam, tmpnam_r - create a name for a temporary file

SYNOPSIS
       #include <stdio.h>

       char *tmpnam(char *s);

DESCRIPTION
       The  tmpnam()  function	returns  a pointer to a string that is a valid filename, and such that a file with this name did not exist at some
       point in time, so that naive programmers may think it a suitable name for a temporary file.  If the argument s is NULL this name is  gener-
       ated in an internal static buffer and may be overwritten by the next call to tmpnam().  If s is not NULL, the name is copied to the charac-
       ter array (of length at least L_tmpnam) pointed to by s and the value s is returned in case of success.

       The pathname that is created, has a directory prefix P_tmpdir.  (Both L_tmpnam and P_tmpdir are defined in <stdio.h>, just like the TMP_MAX
       mentioned below.)

RETURN VALUE
       The tmpnam() function returns a pointer to a unique temporary filename, or NULL if a unique name cannot be generated.

ERRORS
       No errors are defined.

CONFORMING TO
       SVr4, 4.3BSD, C89, C99, POSIX.1-2001.  POSIX.1-2008 marks tmpnam() as obsolete.

NOTES
       The  tmpnam()  function generates a different string each time it is called, up to TMP_MAX times.  If it is called more than TMP_MAX times,
       the behavior is implementation defined.

       Although tmpnam() generates names that are difficult to guess, it is nevertheless possible that between the time that  tmpnam()	returns  a
       pathname,  and  the  time  that	the program opens it, another program might create that pathname using open(2), or create it as a symbolic
       link.  This can lead to security holes.	To avoid such possibilities, use the open(2) O_EXCL flag to open the pathname.	Or better yet, use
       mkstemp(3) or tmpfile(3).

       Portable  applications  that use threads cannot call tmpnam() with a NULL argument if either _POSIX_THREADS or _POSIX_THREAD_SAFE_FUNCTIONS
       is defined.

       A POSIX draft proposed to use a function tmpnam_r() defined by

	   char *
	   tmpnam_r(char *s)
	   {
	       return s ? tmpnam(s) : NULL;
	   }

       apparently as a warning not to use NULL.  A few systems implement it.  To get a glibc prototype for this function, define  _SVID_SOURCE	or
       _BSD_SOURCE before including <stdio.h>.

BUGS
       Never use this function.  Use mkstemp(3) or tmpfile(3) instead.

SEE ALSO
       mkstemp(3), mktemp(3), tempnam(3), tmpfile(3)

COLOPHON
       This  page is part of release 3.25 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

								    2008-08-06								 TMPNAM(3)