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x SuSE Linux 13.1-RELEASEx
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
Note: Avoid use of tmpnam(); use mkstemp(3) or tmpfile(3) instead.
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.
ATTRIBUTES
Multithreading (see pthreads(7))
The tmpnam() function is thread-safe with exceptions. It is not
thread-safe if called with a NULL parameter.
The tmpnam_r() function is thread-safe.
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 from <stdio.h>, define
_SVID_SOURCE or _BSD_SOURCE (before including any header file).
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 3.69 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
http://www.kernel.org/doc/man-pages/.
2014-02-27 TMPNAM(3)
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