1TMPNAM(3)                  Linux Programmer's Manual                 TMPNAM(3)
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NAME

6       tmpnam, tmpnam_r - create a name for a temporary file
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SYNOPSIS

9       #include <stdio.h>
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11       char *tmpnam(char *s);
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DESCRIPTION

14       The  tmpnam()  function  returns  a pointer to a string that is a valid
15       filename, and such that a file with this name did  not  exist  at  some
16       point  in  time, so that naive programmers may think it a suitable name
17       for a temporary file.  If the argument s is NULL this name is generated
18       in an internal static buffer and may be overwritten by the next call to
19       tmpnam().  If s is not NULL, the name is copied to the character  array
20       (of  length  at  least  L_tmpnam)  pointed  to  by s and the value s is
21       returned in case of success.
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23       The pathname that is created, has a directory prefix  P_tmpdir.   (Both
24       L_tmpnam  and  P_tmpdir are defined in <stdio.h>, just like the TMP_MAX
25       mentioned below.)
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RETURN VALUE

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

32       No errors are defined.
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CONFORMING TO

35       SVr4,  4.3BSD,  C89, C99, POSIX.1-2001.  POSIX.1-2008 marks tmpnam() as
36       obsolete.
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NOTES

39       The tmpnam() function generates a different  string  each  time  it  is
40       called,  up to TMP_MAX times.  If it is called more than TMP_MAX times,
41       the behavior is implementation defined.
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43       Although tmpnam() generates names that are difficult to  guess,  it  is
44       nevertheless  possible  that  between  the time that tmpnam() returns a
45       pathname, and the time that the program opens it, another program might
46       create  that  pathname  using open(2), or create it as a symbolic link.
47       This can lead to security holes.  To avoid such possibilities, use  the
48       open(2)  O_EXCL  flag  to  open  the  pathname.   Or  better  yet,  use
49       mkstemp(3) or tmpfile(3).
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51       Portable applications that use threads cannot call tmpnam() with a NULL
52       argument  if  either  _POSIX_THREADS or _POSIX_THREAD_SAFE_FUNCTIONS is
53       defined.
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55       A POSIX draft proposed to use a function tmpnam_r() defined by
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57           char *
58           tmpnam_r(char *s)
59           {
60               return s ? tmpnam(s) : NULL;
61           }
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63       apparently as a warning not to use NULL.  A few systems  implement  it.
64       To  get  a  glibc  prototype  for this function, define _SVID_SOURCE or
65       _BSD_SOURCE before including <stdio.h>.
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BUGS

68       Never use this function.  Use mkstemp(3) or tmpfile(3) instead.
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SEE ALSO

71       mkstemp(3), mktemp(3), tempnam(3), tmpfile(3)
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COLOPHON

74       This page is part of release 3.22 of the Linux  man-pages  project.   A
75       description  of  the project, and information about reporting bugs, can
76       be found at http://www.kernel.org/doc/man-pages/.
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80                                  2008-08-06                         TMPNAM(3)
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