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TMPFILE(3)	       FreeBSD Library Functions Manual		    TMPFILE(3)

NAME
     tempnam, tmpfile, tmpnam -- temporary file	routines

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <stdio.h>

     FILE *
     tmpfile(void);

     char *
     tmpnam(char *str);

     char *
     tempnam(const char	*tmpdir, const char *prefix);

DESCRIPTION
     The tmpfile() function returns a pointer to a stream associated with a
     file descriptor returned by the routine mkstemp(3).  The created file is
     unlinked before tmpfile() returns,	causing	the file to be automatically
     deleted when the last reference to	it is closed.  The file	is opened with
     the access	value `w+'.  The file is created in the	directory determined
     by	the environment	variable TMPDIR	if set.	 The default location if
     TMPDIR is not set is /tmp.

     The tmpnam() function returns a pointer to	a file name, in	the P_tmpdir
     directory,	which did not reference	an existing file at some indeterminate
     point in the past.	 P_tmpdir is defined in	the include file <stdio.h>.
     If	the argument str is non-NULL, the file name is copied to the buffer it
     references.  Otherwise, the file name is copied to	a static buffer.  In
     either case, tmpnam() returns a pointer to	the file name.

     The buffer	referenced by str is expected to be at least L_tmpnam bytes in
     length.  L_tmpnam is defined in the include file <stdio.h>.

     The tempnam() function is similar to tmpnam(), but	provides the ability
     to	specify	the directory which will contain the temporary file and	the
     file name prefix.

     The environment variable TMPDIR (if set), the argument tmpdir (if
     non-NULL),	the directory P_tmpdir,	and the	directory /tmp are tried, in
     the listed	order, as directories in which to store	the temporary file.

     The argument prefix, if non-NULL, is used to specify a file name prefix,
     which will	be the first part of the created file name.  The tempnam()
     function allocates	memory in which	to store the file name;	the returned
     pointer may be used as a subsequent argument to free(3).

RETURN VALUES
     The tmpfile() function returns a pointer to an open file stream on	suc-
     cess, and a NULL pointer on error.

     The tmpnam() and tempfile() functions return a pointer to a file name on
     success, and a NULL pointer on error.

ENVIRONMENT
     TMPDIR  [tempnam()	only] If set, the directory in which the temporary
	     file is stored.  TMPDIR is	ignored	for processes for which
	     issetugid(2) is true.

COMPATIBILITY
     These interfaces are provided from	System V and ANSI compatibility	only.

     Most historic implementations of these functions provide only a limited
     number of possible	temporary file names (usually 26) before file names
     will start	being recycled.	 System	V implementations of these functions
     (and of mktemp(3))	use the	access(2) system call to determine whether or
     not the temporary file may	be created.  This has obvious ramifications
     for setuid	or setgid programs, complicating the portable use of these
     interfaces	in such	programs.

     The tmpfile() interface should not	be used	in software expected to	be
     used on other systems if there is any possibility that the	user does not
     wish the temporary	file to	be publicly readable and writable.

ERRORS
     The tmpfile() function may	fail and set the global	variable errno for any
     of	the errors specified for the library functions fdopen(3) or
     mkstemp(3).

     The tmpnam() function may fail and	set errno for any of the errors	speci-
     fied for the library function mktemp(3).

     The tempnam() function may	fail and set errno for any of the errors spec-
     ified for the library functions malloc(3) or mktemp(3).

SEE ALSO
     mkstemp(3), mktemp(3)

STANDARDS
     The tmpfile() and tmpnam()	functions conform to ISO/IEC 9899:1990
     (``ISO C90'').

SECURITY CONSIDERATIONS
     The tmpnam() and tempnam()	functions are susceptible to a race condition
     occurring between the selection of	the file name and the creation of the
     file, which allows	malicious users	to potentially overwrite arbitrary
     files in the system, depending on the level of privilege of the running
     program.  Additionally, there is no means by which	file permissions may
     be	specified.  It is strongly suggested that mkstemp(3) be	used in	place
     of	these functions.  (See the FSA.)

FreeBSD	9.3			March 18, 2007			   FreeBSD 9.3

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ENVIRONMENT | COMPATIBILITY | ERRORS | SEE ALSO | STANDARDS | SECURITY CONSIDERATIONS

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