| .\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl) |
| .\" |
| .\" %%%LICENSE_START(VERBATIM) |
| .\" Permission is granted to make and distribute verbatim copies of this |
| .\" manual provided the copyright notice and this permission notice are |
| .\" preserved on all copies. |
| .\" |
| .\" Permission is granted to copy and distribute modified versions of this |
| .\" manual under the conditions for verbatim copying, provided that the |
| .\" entire resulting derived work is distributed under the terms of a |
| .\" permission notice identical to this one. |
| .\" |
| .\" Since the Linux kernel and libraries are constantly changing, this |
| .\" manual page may be incorrect or out-of-date. The author(s) assume no |
| .\" responsibility for errors or omissions, or for damages resulting from |
| .\" the use of the information contained herein. The author(s) may not |
| .\" have taken the same level of care in the production of this manual, |
| .\" which is licensed free of charge, as they might when working |
| .\" professionally. |
| .\" |
| .\" Formatted or processed versions of this manual, if unaccompanied by |
| .\" the source, must acknowledge the copyright and authors of this work. |
| .\" %%%LICENSE_END |
| .\" |
| .\" 2003-11-15, aeb, added tmpnam_r |
| .\" |
| .TH TMPNAM 3 2016-03-15 "" "Linux Programmer's Manual" |
| .SH NAME |
| tmpnam, tmpnam_r \- create a name for a temporary file |
| .SH SYNOPSIS |
| .nf |
| .B #include <stdio.h> |
| .sp |
| .BI "char *tmpnam(char *" s ); |
| .fi |
| .SH DESCRIPTION |
| .B Note: |
| Avoid use of |
| .BR tmpnam (); |
| use |
| .BR mkstemp (3) |
| or |
| .BR tmpfile (3) |
| instead. |
| |
| The |
| .BR 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 |
| .I s |
| is NULL, this name is generated in an internal static buffer |
| and may be overwritten by the next call to |
| .BR tmpnam (). |
| If |
| .I s |
| is not NULL, the name is copied to the character array (of length |
| at least |
| .IR L_tmpnam ) |
| pointed to by |
| .I s |
| and the value |
| .I s |
| is returned in case of success. |
| .LP |
| The pathname that is created, has a directory prefix |
| .IR P_tmpdir . |
| (Both |
| .I L_tmpnam |
| and |
| .I P_tmpdir |
| are defined in |
| .IR <stdio.h> , |
| just like the |
| .B TMP_MAX |
| mentioned below.) |
| .SH RETURN VALUE |
| The |
| .BR tmpnam () |
| function returns a pointer to a unique temporary |
| filename, or NULL if a unique name cannot be generated. |
| .SH ERRORS |
| No errors are defined. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lb lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR tmpnam () |
| T} Thread safety MT-Unsafe race:tmpnam/!s |
| T{ |
| .BR tmpnam_r () |
| T} Thread safety MT-Safe |
| .TE |
| .SH CONFORMING TO |
| SVr4, 4.3BSD, C89, C99, POSIX.1-2001. |
| POSIX.1-2008 marks |
| .BR tmpnam () |
| as obsolete. |
| .SH NOTES |
| The |
| .BR tmpnam () |
| function generates a different string each time it is called, |
| up to |
| .B TMP_MAX |
| times. |
| If it is called more than |
| .B TMP_MAX |
| times, |
| the behavior is implementation defined. |
| .LP |
| Although |
| .BR tmpnam () |
| generates names that are difficult to guess, |
| it is nevertheless possible that between the time that |
| .BR tmpnam () |
| returns a pathname, and the time that the program opens it, |
| another program might create that pathname using |
| .BR open (2), |
| or create it as a symbolic link. |
| This can lead to security holes. |
| To avoid such possibilities, use the |
| .BR open (2) |
| .B O_EXCL |
| flag to open the pathname. |
| Or better yet, use |
| .BR mkstemp (3) |
| or |
| .BR tmpfile (3). |
| .LP |
| Portable applications that use threads cannot call |
| .BR tmpnam () |
| with a NULL argument if either |
| .B _POSIX_THREADS |
| or |
| .B _POSIX_THREAD_SAFE_FUNCTIONS |
| is defined. |
| .LP |
| A POSIX draft proposed to use a function |
| .BR tmpnam_r () |
| defined by |
| .sp |
| .nf |
| .in +4n |
| char * |
| tmpnam_r(char *s) |
| { |
| return s ? tmpnam(s) : NULL; |
| } |
| .in |
| .fi |
| .sp |
| apparently as a warning not to use NULL. |
| A few systems implement it and an implementation is provided in glibc. |
| .SH BUGS |
| Never use this function. |
| Use |
| .BR mkstemp (3) |
| or |
| .BR tmpfile (3) |
| instead. |
| .SH SEE ALSO |
| .BR mkstemp (3), |
| .BR mktemp (3), |
| .BR tempnam (3), |
| .BR tmpfile (3) |