TMPFILE(2) System Calls Manual TMPFILE(2)NAME
tmpfile, tmpnam - Stdio temporary files
SYNOPSIS
#include <stdio.h>
FILE *tmpfile(void)
char *tmpnam(char *s)
DESCRIPTION
Tmpfile creates a temporary file that will automatically be removed when the file is closed or the program exits. The return value is a
Stdio FILE* opened in update mode (see fopen(2)).
Tmpnam generates a string that is a valid file name and that is not the same as the name of an existing file. If s is zero, it returns a
pointer to a string which may be overwritten by subsequent calls to tmpnam. If s is non-zero, it should point to an array of at least
L_tmpnam (defined in <stdio.h>) characters, and the answer will be copied there.
FILES
/tmp/tf000000000000
template for tmpfile file names.
/tmp/tn000000000000
template for tmpnam file names.
SOURCE
/sys/src/libstdio
BUGS
The files created by tmpfile are not removed until exits(2) is executed; in particular, they are not removed on fclose or if the program
terminates abnormally.
TMPFILE(2)
Check Out this Related Man Page
TMPFILE(3) BSD 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 indeter-
minate 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 success, 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 specified for the library function mktemp(3).
The tempnam() function may fail and set errno for any of the errors specified 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.
BSD March 18, 2007 BSD