5 File::Temp - return name and handle of a temporary file safely
11 This module is designed to be portable across operating systems
12 and it currently supports Unix, VMS, DOS, OS/2 and Windows. When
13 porting to a new OS there are generally three main issues
14 that have to be solved:
20 Can the OS unlink an open file? If it can't then the
21 C<_can_unlink_opened_file> method should be modified.
25 Are the return values from C<stat> reliable? By default all the
26 return values from C<stat> are compared when unlinking a temporary
27 file using the filename and the handle. Operating systems other than
28 unix do not always have valid entries in all fields. If C<unlink0> fails
29 then the C<stat> comparison should be modified accordingly.
33 Security. Systems that can not support a test for the sticky bit
34 on a directory can not use the MEDIUM and HIGH security tests.
35 The C<_can_do_level> method should be modified accordingly.
43 use File::Temp qw/ tempfile tempdir /;
45 $dir = tempdir( CLEANUP => 1 );
46 ($fh, $filename) = tempfile( DIR => $dir );
48 ($fh, $filename) = tempfile( $template, DIR => $dir);
49 ($fh, $filename) = tempfile( $template, SUFFIX => '.dat');
55 use File::Temp qw/ :mktemp /;
57 ($fh, $file) = mkstemp( "tmpfileXXXXX" );
58 ($fh, $file) = mkstemps( "tmpfileXXXXXX", $suffix);
60 $tmpdir = mkdtemp( $template );
62 $unopened_file = mktemp( $template );
66 use File::Temp qw/ :POSIX /;
71 ($fh, $file) = tmpnam();
72 ($fh, $file) = tmpfile();
75 Compatibility functions:
77 $unopened_file = File::Temp::tempnam( $dir, $pfx );
81 Objects (NOT YET IMPLEMENTED):
85 $fh = new File::Temp($template);
86 $fname = $fh->filename;
92 C<File::Temp> can be used to create and open temporary files in a safe way.
93 The tempfile() function can be used to return the name and the open
94 filehandle of a temporary file. The tempdir() function can
95 be used to create a temporary directory.
97 The security aspect of temporary file creation is emphasized such that
98 a filehandle and filename are returned together. This helps guarantee
99 that a race condition can not occur where the temporary file is
100 created by another process between checking for the existence of the
101 file and its opening. Additional security levels are provided to
102 check, for example, that the sticky bit is set on world writable
103 directories. See L<"safe_level"> for more information.
105 For compatibility with popular C library functions, Perl implementations of
106 the mkstemp() family of functions are provided. These are, mkstemp(),
107 mkstemps(), mkdtemp() and mktemp().
109 Additionally, implementations of the standard L<POSIX|POSIX>
110 tmpnam() and tmpfile() functions are provided if required.
112 Implementations of mktemp(), tmpnam(), and tempnam() are provided,
113 but should be used with caution since they return only a filename
114 that was valid when function was called, so cannot guarantee
115 that the file will not exist by the time the caller opens the filename.
119 # 5.6.0 gives us S_IWOTH, S_IWGRP, our and auto-vivifying filehandls
120 # People would like a version on 5.005 so give them what they want :-)
125 use File::Path qw/ rmtree /;
127 use Errno qw( EEXIST ENOENT ENOTDIR EINVAL );
128 require VMS::Stdio if $^O eq 'VMS';
130 # Need the Symbol package if we are running older perl
131 require Symbol if $] < 5.006;
134 # use 'our' on v5.6.0
135 use vars qw($VERSION @EXPORT_OK %EXPORT_TAGS $DEBUG);
139 # We are exporting functions
141 use base qw/Exporter/;
143 # Export list - to allow fine tuning of export table
157 # Groups of functions for export
160 'POSIX' => [qw/ tmpnam tmpfile /],
161 'mktemp' => [qw/ mktemp mkstemp mkstemps mkdtemp/],
164 # add contents of these tags to @EXPORT
165 Exporter::export_tags('POSIX','mktemp');
171 # This is a list of characters that can be used in random filenames
173 my @CHARS = (qw/ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
174 a b c d e f g h i j k l m n o p q r s t u v w x y z
175 0 1 2 3 4 5 6 7 8 9 _
178 # Maximum number of tries to make a temp file before failing
180 use constant MAX_TRIES => 10;
182 # Minimum number of X characters that should be in a template
183 use constant MINX => 4;
185 # Default template when no template supplied
187 use constant TEMPXXX => 'X' x 10;
189 # Constants for the security level
191 use constant STANDARD => 0;
192 use constant MEDIUM => 1;
193 use constant HIGH => 2;
195 # OPENFLAGS. If we defined the flag to use with Sysopen here this gives
196 # us an optimisation when many temporary files are requested
198 my $OPENFLAGS = O_CREAT | O_EXCL | O_RDWR;
200 for my $oflag (qw/ FOLLOW BINARY LARGEFILE EXLOCK NOINHERIT /) {
201 my ($bit, $func) = (0, "Fcntl::O_" . $oflag);
203 $OPENFLAGS |= $bit if eval { $bit = &$func(); 1 };
206 # On some systems the O_TEMPORARY flag can be used to tell the OS
207 # to automatically remove the file when it is closed. This is fine
208 # in most cases but not if tempfile is called with UNLINK=>0 and
209 # the filename is requested -- in the case where the filename is to
210 # be passed to another routine. This happens on windows. We overcome
211 # this by using a second open flags variable
213 my $OPENTEMPFLAGS = $OPENFLAGS;
214 for my $oflag (qw/ TEMPORARY /) {
215 my ($bit, $func) = (0, "Fcntl::O_" . $oflag);
217 $OPENTEMPFLAGS |= $bit if eval { $bit = &$func(); 1 };
221 # INTERNAL ROUTINES - not to be used outside of package
223 # Generic routine for getting a temporary filename
224 # modelled on OpenBSD _gettemp() in mktemp.c
226 # The template must contain X's that are to be replaced
227 # with the random values
231 # TEMPLATE - string containing the XXXXX's that is converted
232 # to a random filename and opened if required
234 # Optionally, a hash can also be supplied containing specific options
235 # "open" => if true open the temp file, else just return the name
237 # "mkdir"=> if true, we are creating a temp directory rather than tempfile
239 # "suffixlen" => number of characters at end of PATH to be ignored.
241 # "unlink_on_close" => indicates that, if possible, the OS should remove
242 # the file as soon as it is closed. Usually indicates
243 # use of the O_TEMPORARY flag to sysopen.
244 # Usually irrelevant on unix
246 # "open" and "mkdir" can not both be true
247 # "unlink_on_close" is not used when "mkdir" is true.
249 # The default options are equivalent to mktemp().
252 # filehandle - open file handle (if called with doopen=1, else undef)
253 # temp name - name of the temp file or directory
256 # ($fh, $name) = _gettemp($template, "open" => 1);
258 # for the current version, failures are associated with
259 # a carp to give the reason whilst debugging
263 croak 'Usage: ($fh, $name) = _gettemp($template, OPTIONS);'
264 unless scalar(@_) >= 1;
271 "unlink_on_close" => 0,
275 my $template = shift;
276 if (ref($template)) {
277 carp "File::Temp::_gettemp: template must not be a reference";
281 # Check that the number of entries on stack are even
282 if (scalar(@_) % 2 != 0) {
283 carp "File::Temp::_gettemp: Must have even number of options";
287 # Read the options and merge with defaults
288 %options = (%options, @_) if @_;
290 # Can not open the file and make a directory in a single call
291 if ($options{"open"} && $options{"mkdir"}) {
292 carp "File::Temp::_gettemp: doopen and domkdir can not both be true\n";
296 # Find the start of the end of the Xs (position of last X)
297 # Substr starts from 0
298 my $start = length($template) - 1 - $options{"suffixlen"};
300 # Check that we have at least MINX x X (eg 'XXXX") at the end of the string
301 # (taking suffixlen into account). Any fewer is insecure.
303 # Do it using substr - no reason to use a pattern match since
304 # we know where we are looking and what we are looking for
306 if (substr($template, $start - MINX + 1, MINX) ne 'X' x MINX) {
307 carp "File::Temp::_gettemp: The template must contain at least ". MINX ." 'X' characters\n";
311 # Replace all the X at the end of the substring with a
312 # random character or just all the XX at the end of a full string.
313 # Do it as an if, since the suffix adjusts which section to replace
314 # and suffixlen=0 returns nothing if used in the substr directly
315 # and generate a full path from the template
317 my $path = _replace_XX($template, $options{"suffixlen"});
320 # Split the path into constituent parts - eventually we need to check
321 # whether the directory exists
322 # We need to know whether we are making a temp directory
325 my ($volume, $directories, $file);
326 my $parent; # parent directory
327 if ($options{"mkdir"}) {
328 # There is no filename at the end
329 ($volume, $directories, $file) = File::Spec->splitpath( $path, 1);
331 # The parent is then $directories without the last directory
332 # Split the directory and put it back together again
333 my @dirs = File::Spec->splitdir($directories);
335 # If @dirs only has one entry that means we are in the current
338 $parent = File::Spec->curdir;
341 if ($^O eq 'VMS') { # need volume to avoid relative dir spec
342 $parent = File::Spec->catdir($volume, @dirs[0..$#dirs-1]);
345 # Put it back together without the last one
346 $parent = File::Spec->catdir(@dirs[0..$#dirs-1]);
348 # ...and attach the volume (no filename)
349 $parent = File::Spec->catpath($volume, $parent, '');
356 # Get rid of the last filename (use File::Basename for this?)
357 ($volume, $directories, $file) = File::Spec->splitpath( $path );
359 # Join up without the file part
360 $parent = File::Spec->catpath($volume,$directories,'');
362 # If $parent is empty replace with curdir
363 $parent = File::Spec->curdir
364 unless $directories ne '';
368 # Check that the parent directories exist
369 # Do this even for the case where we are simply returning a name
370 # not a file -- no point returning a name that includes a directory
371 # that does not exist or is not writable
373 unless (-d $parent && -w _) {
374 carp "File::Temp::_gettemp: Parent directory ($parent) is not a directory"
375 . " or is not writable\n";
379 # Check the stickiness of the directory and chown giveaway if required
380 # If the directory is world writable the sticky bit
383 if (File::Temp->safe_level == MEDIUM) {
384 unless (_is_safe($parent)) {
385 carp "File::Temp::_gettemp: Parent directory ($parent) is not safe (sticky bit not set when world writable?)";
388 } elsif (File::Temp->safe_level == HIGH) {
389 unless (_is_verysafe($parent)) {
390 carp "File::Temp::_gettemp: Parent directory ($parent) is not safe (sticky bit not set when world writable?)";
396 # Now try MAX_TRIES time to open the file
397 for (my $i = 0; $i < MAX_TRIES; $i++) {
399 # Try to open the file if requested
400 if ($options{"open"}) {
403 # If we are running before perl5.6.0 we can not auto-vivify
405 $fh = &Symbol::gensym;
408 # Try to make sure this will be marked close-on-exec
409 # XXX: Win32 doesn't respect this, nor the proper fcntl,
410 # but may have O_NOINHERIT. This may or may not be in Fcntl.
413 # Store callers umask
419 # Attempt to open the file
420 my $open_success = undef;
421 if ( $^O eq 'VMS' and $options{"unlink_on_close"} ) {
422 # make it auto delete on close by setting FAB$V_DLT bit
423 $fh = VMS::Stdio::vmssysopen($path, $OPENFLAGS, 0600, 'fop=dlt');
426 my $flags = ( $options{"unlink_on_close"} ?
429 $open_success = sysopen($fh, $path, $flags, 0600);
431 if ( $open_success ) {
436 # Opened successfully - return file handle and name
443 # Error opening file - abort with error
444 # if the reason was anything but EEXIST
445 unless ($! == EEXIST) {
446 carp "File::Temp: Could not create temp file $path: $!";
450 # Loop round for another try
453 } elsif ($options{"mkdir"}) {
455 # Store callers umask
461 # Open the temp directory
462 if (mkdir( $path, 0700)) {
473 # Abort with error if the reason for failure was anything
475 unless ($! == EEXIST) {
476 carp "File::Temp: Could not create directory $path: $!";
480 # Loop round for another try
486 # Return true if the file can not be found
487 # Directory has been checked previously
489 return (undef, $path) unless -e $path;
491 # Try again until MAX_TRIES
495 # Did not successfully open the tempfile/dir
496 # so try again with a different set of random letters
497 # No point in trying to increment unless we have only
498 # 1 X say and the randomness could come up with the same
499 # file MAX_TRIES in a row.
501 # Store current attempt - in principal this implies that the
502 # 3rd time around the open attempt that the first temp file
503 # name could be generated again. Probably should store each
504 # attempt and make sure that none are repeated
506 my $original = $path;
507 my $counter = 0; # Stop infinite loop
512 # Generate new name from original template
513 $path = _replace_XX($template, $options{"suffixlen"});
517 } until ($path ne $original || $counter > $MAX_GUESS);
519 # Check for out of control looping
520 if ($counter > $MAX_GUESS) {
521 carp "Tried to get a new temp name different to the previous value $MAX_GUESS times.\nSomething wrong with template?? ($template)";
527 # If we get here, we have run out of tries
528 carp "Have exceeded the maximum number of attempts (".MAX_TRIES .
529 ") to open temp file/dir";
535 # Internal routine to return a random character from the
536 # character list. Does not do an srand() since rand()
537 # will do one automatically
539 # No arguments. Return value is the random character
541 # No longer called since _replace_XX runs a few percent faster if
542 # I inline the code. This is important if we are creating thousands of
547 $CHARS[ int( rand( $#CHARS ) ) ];
551 # Internal routine to replace the XXXX... with random characters
552 # This has to be done by _gettemp() every time it fails to
553 # open a temp file/dir
555 # Arguments: $template (the template with XXX),
556 # $ignore (number of characters at end to ignore)
558 # Returns: modified template
562 croak 'Usage: _replace_XX($template, $ignore)'
563 unless scalar(@_) == 2;
565 my ($path, $ignore) = @_;
567 # Do it as an if, since the suffix adjusts which section to replace
568 # and suffixlen=0 returns nothing if used in the substr directly
569 # Alternatively, could simply set $ignore to length($path)-1
570 # Don't want to always use substr when not required though.
573 substr($path, 0, - $ignore) =~ s/X(?=X*\z)/$CHARS[ int( rand( $#CHARS ) ) ]/ge;
575 $path =~ s/X(?=X*\z)/$CHARS[ int( rand( $#CHARS ) ) ]/ge;
581 # internal routine to check to see if the directory is safe
582 # First checks to see if the directory is not owned by the
583 # current user or root. Then checks to see if anyone else
584 # can write to the directory and if so, checks to see if
585 # it has the sticky bit set
587 # Will not work on systems that do not support sticky bit
589 #Args: directory path to check
590 # Returns true if the path is safe and false otherwise.
591 # Returns undef if can not even run stat() on the path
593 # This routine based on version written by Tom Christiansen
595 # Presumably, by the time we actually attempt to create the
596 # file or directory in this directory, it may not be safe
597 # anymore... Have to run _is_safe directly after the open.
604 my @info = stat($path);
605 return 0 unless scalar(@info);
606 return 1 if $^O eq 'VMS'; # owner delete control at file level
608 # Check to see whether owner is neither superuser (or a system uid) nor me
609 # Use the real uid from the $< variable
611 if ($info[4] > File::Temp->top_system_uid() && $info[4] != $<) {
613 Carp::cluck(sprintf "uid=$info[4] topuid=%s \$<=$< path='$path'",
614 File::Temp->top_system_uid());
616 carp "Directory owned neither by root nor the current user.";
620 # check whether group or other can write file
621 # use 066 to detect either reading or writing
622 # use 022 to check writability
623 # Do it with S_IWOTH and S_IWGRP for portability (maybe)
625 if (($info[2] & &Fcntl::S_IWGRP) || # Is group writable?
626 ($info[2] & &Fcntl::S_IWOTH) ) { # Is world writable?
627 return 0 unless -d _; # Must be a directory
628 return 0 unless -k _; # Must be sticky
634 # Internal routine to check whether a directory is safe
635 # for temp files. Safer than _is_safe since it checks for
636 # the possibility of chown giveaway and if that is a possibility
637 # checks each directory in the path to see if it is safe (with _is_safe)
639 # If _PC_CHOWN_RESTRICTED is not set, does the full test of each
644 # Need POSIX - but only want to bother if really necessary due to overhead
648 return 1 if $^O eq 'VMS'; # owner delete control at file level
650 # Should Get the value of _PC_CHOWN_RESTRICTED if it is defined
651 # and If it is not there do the extensive test
652 my $chown_restricted;
653 $chown_restricted = &POSIX::_PC_CHOWN_RESTRICTED()
654 if eval { &POSIX::_PC_CHOWN_RESTRICTED(); 1};
656 # If chown_resticted is set to some value we should test it
657 if (defined $chown_restricted) {
659 # Return if the current directory is safe
660 return _is_safe($path) if POSIX::sysconf( $chown_restricted );
664 # To reach this point either, the _PC_CHOWN_RESTRICTED symbol
665 # was not avialable or the symbol was there but chown giveaway
666 # is allowed. Either way, we now have to test the entire tree for
669 # Convert path to an absolute directory if required
670 unless (File::Spec->file_name_is_absolute($path)) {
671 $path = File::Spec->rel2abs($path);
674 # Split directory into components - assume no file
675 my ($volume, $directories, undef) = File::Spec->splitpath( $path, 1);
677 # Slightly less efficient than having a a function in File::Spec
678 # to chop off the end of a directory or even a function that
679 # can handle ../ in a directory tree
680 # Sometimes splitdir() returns a blank at the end
681 # so we will probably check the bottom directory twice in some cases
682 my @dirs = File::Spec->splitdir($directories);
684 # Concatenate one less directory each time around
685 foreach my $pos (0.. $#dirs) {
686 # Get a directory name
687 my $dir = File::Spec->catpath($volume,
688 File::Spec->catdir(@dirs[0.. $#dirs - $pos]),
692 print "TESTING DIR $dir\n" if $DEBUG;
694 # Check the directory
695 return 0 unless _is_safe($dir);
704 # internal routine to determine whether unlink works on this
705 # platform for files that are currently open.
706 # Returns true if we can, false otherwise.
708 # Currently WinNT, OS/2 and VMS can not unlink an opened file
709 # On VMS this is because the O_EXCL flag is used to open the
710 # temporary file. Currently I do not know enough about the issues
711 # on VMS to decide whether O_EXCL is a requirement.
713 sub _can_unlink_opened_file {
715 if ($^O eq 'MSWin32' || $^O eq 'os2' || $^O eq 'VMS' || $^O eq 'dos') {
723 # internal routine to decide which security levels are allowed
724 # see safe_level() for more information on this
726 # Controls whether the supplied security level is allowed
728 # $cando = _can_do_level( $level )
735 # Always have to be able to do STANDARD
736 return 1 if $level == STANDARD;
738 # Currently, the systems that can do HIGH or MEDIUM are identical
739 if ( $^O eq 'MSWin32' || $^O eq 'os2' || $^O eq 'cygwin' || $^O eq 'dos') {
747 # This routine sets up a deferred unlinking of a specified
748 # filename and filehandle. It is used in the following cases:
749 # - Called by unlink0 if an opened file can not be unlinked
750 # - Called by tempfile() if files are to be removed on shutdown
751 # - Called by tempdir() if directories are to be removed on shutdown
754 # _deferred_unlink( $fh, $fname, $isdir );
756 # - filehandle (so that it can be expclicitly closed if open
757 # - filename (the thing we want to remove)
758 # - isdir (flag to indicate that we are being given a directory)
759 # [and hence no filehandle]
761 # Status is not referred to since all the magic is done with an END block
764 # Will set up two lexical variables to contain all the files to be
765 # removed. One array for files, another for directories
766 # They will only exist in this block
767 # This means we only have to set up a single END block to remove all files
768 # @files_to_unlink contains an array ref with the filehandle and filename
769 my (@files_to_unlink, @dirs_to_unlink);
771 # Set up an end block to use these arrays
774 foreach my $file (@files_to_unlink) {
775 # close the filehandle without checking its state
776 # in order to make real sure that this is closed
777 # if its already closed then I dont care about the answer
778 # probably a better way to do this
779 close($file->[0]); # file handle is [0]
781 if (-f $file->[1]) { # file name is [1]
782 unlink $file->[1] or warn "Error removing ".$file->[1];
786 foreach my $dir (@dirs_to_unlink) {
788 rmtree($dir, $DEBUG, 1);
795 # This is the sub called to register a file for deferred unlinking
796 # This could simply store the input parameters and defer everything
797 # until the END block. For now we do a bit of checking at this
798 # point in order to make sure that (1) we have a file/dir to delete
799 # and (2) we have been called with the correct arguments.
800 sub _deferred_unlink {
802 croak 'Usage: _deferred_unlink($fh, $fname, $isdir)'
803 unless scalar(@_) == 3;
805 my ($fh, $fname, $isdir) = @_;
807 warn "Setting up deferred removal of $fname\n"
810 # If we have a directory, check that it is a directory
815 # Directory exists so store it
816 # first on VMS turn []foo into [.foo] for rmtree
817 $fname = VMS::Filespec::vmspath($fname) if $^O eq 'VMS';
818 push (@dirs_to_unlink, $fname);
821 carp "Request to remove directory $fname could not be completed since it does not exist!\n";
828 # file exists so store handle and name for later removal
829 push(@files_to_unlink, [$fh, $fname]);
832 carp "Request to remove file $fname could not be completed since it is not there!\n";
844 This section describes the recommended interface for generating
845 temporary files and directories.
851 This is the basic function to generate temporary files.
852 The behaviour of the file can be changed using various options:
854 ($fh, $filename) = tempfile();
856 Create a temporary file in the directory specified for temporary
857 files, as specified by the tmpdir() function in L<File::Spec>.
859 ($fh, $filename) = tempfile($template);
861 Create a temporary file in the current directory using the supplied
862 template. Trailing `X' characters are replaced with random letters to
863 generate the filename. At least four `X' characters must be present
866 ($fh, $filename) = tempfile($template, SUFFIX => $suffix)
868 Same as previously, except that a suffix is added to the template
869 after the `X' translation. Useful for ensuring that a temporary
870 filename has a particular extension when needed by other applications.
871 But see the WARNING at the end.
873 ($fh, $filename) = tempfile($template, DIR => $dir);
875 Translates the template as before except that a directory name
878 ($fh, $filename) = tempfile($template, UNLINK => 1);
880 Return the filename and filehandle as before except that the file is
881 automatically removed when the program exits. Default is for the file
882 to be removed if a file handle is requested and to be kept if the
883 filename is requested.
885 If the template is not specified, a template is always
886 automatically generated. This temporary file is placed in tmpdir()
887 (L<File::Spec>) unless a directory is specified explicitly with the
890 $fh = tempfile( $template, DIR => $dir );
892 If called in scalar context, only the filehandle is returned
893 and the file will automatically be deleted when closed (see
894 the description of tmpfile() elsewhere in this document).
895 This is the preferred mode of operation, as if you only
896 have a filehandle, you can never create a race condition
897 by fumbling with the filename. On systems that can not unlink
898 an open file (for example, Windows NT) the file is marked for
899 deletion when the program ends (equivalent to setting UNLINK to 1).
901 (undef, $filename) = tempfile($template, OPEN => 0);
903 This will return the filename based on the template but
904 will not open this file. Cannot be used in conjunction with
905 UNLINK set to true. Default is to always open the file
906 to protect from possible race conditions. A warning is issued
907 if warnings are turned on. Consider using the tmpnam()
908 and mktemp() functions described elsewhere in this document
909 if opening the file is not required.
911 Options can be combined as required.
917 # Can not check for argument count since we can have any
922 "DIR" => undef, # Directory prefix
923 "SUFFIX" => '', # Template suffix
924 "UNLINK" => 0, # Do not unlink file on exit
925 "OPEN" => 1, # Open file
928 # Check to see whether we have an odd or even number of arguments
929 my $template = (scalar(@_) % 2 == 1 ? shift(@_) : undef);
931 # Read the options and merge with defaults
932 %options = (%options, @_) if @_;
934 # First decision is whether or not to open the file
935 if (! $options{"OPEN"}) {
937 warn "tempfile(): temporary filename requested but not opened.\nPossibly unsafe, consider using tempfile() with OPEN set to true\n"
942 if ($options{"DIR"} and $^O eq 'VMS') {
944 # on VMS turn []foo into [.foo] for concatenation
945 $options{"DIR"} = VMS::Filespec::vmspath($options{"DIR"});
948 # Construct the template
950 # Have a choice of trying to work around the mkstemp/mktemp/tmpnam etc
951 # functions or simply constructing a template and using _gettemp()
952 # explicitly. Go for the latter
954 # First generate a template if not defined and prefix the directory
955 # If no template must prefix the temp directory
956 if (defined $template) {
957 if ($options{"DIR"}) {
959 $template = File::Spec->catfile($options{"DIR"}, $template);
965 if ($options{"DIR"}) {
967 $template = File::Spec->catfile($options{"DIR"}, TEMPXXX);
971 $template = File::Spec->catfile(File::Spec->tmpdir, TEMPXXX);
978 $template .= $options{"SUFFIX"};
982 croak "Error in tempfile() using $template"
983 unless (($fh, $path) = _gettemp($template,
984 "open" => $options{'OPEN'},
986 "unlink_on_close" => $options{'UNLINK'},
987 "suffixlen" => length($options{'SUFFIX'}),
990 # Set up an exit handler that can do whatever is right for the
991 # system. Do not check return status since this is all done with
993 _deferred_unlink($fh, $path, 0) if $options{"UNLINK"};
998 if ($options{'OPEN'}) {
1001 return (undef, $path);
1006 # Unlink the file. It is up to unlink0 to decide what to do with
1007 # this (whether to unlink now or to defer until later)
1008 unlink0($fh, $path) or croak "Error unlinking file $path using unlink0";
1010 # Return just the filehandle.
1019 This is the recommended interface for creation of temporary directories.
1020 The behaviour of the function depends on the arguments:
1022 $tempdir = tempdir();
1024 Create a directory in tmpdir() (see L<File::Spec|File::Spec>).
1026 $tempdir = tempdir( $template );
1028 Create a directory from the supplied template. This template is
1029 similar to that described for tempfile(). `X' characters at the end
1030 of the template are replaced with random letters to construct the
1031 directory name. At least four `X' characters must be in the template.
1033 $tempdir = tempdir ( DIR => $dir );
1035 Specifies the directory to use for the temporary directory.
1036 The temporary directory name is derived from an internal template.
1038 $tempdir = tempdir ( $template, DIR => $dir );
1040 Prepend the supplied directory name to the template. The template
1041 should not include parent directory specifications itself. Any parent
1042 directory specifications are removed from the template before
1043 prepending the supplied directory.
1045 $tempdir = tempdir ( $template, TMPDIR => 1 );
1047 Using the supplied template, creat the temporary directory in
1048 a standard location for temporary files. Equivalent to doing
1050 $tempdir = tempdir ( $template, DIR => File::Spec->tmpdir);
1052 but shorter. Parent directory specifications are stripped from the
1053 template itself. The C<TMPDIR> option is ignored if C<DIR> is set
1054 explicitly. Additionally, C<TMPDIR> is implied if neither a template
1055 nor a directory are supplied.
1057 $tempdir = tempdir( $template, CLEANUP => 1);
1059 Create a temporary directory using the supplied template, but
1060 attempt to remove it (and all files inside it) when the program
1061 exits. Note that an attempt will be made to remove all files from
1062 the directory even if they were not created by this module (otherwise
1063 why ask to clean it up?). The directory removal is made with
1064 the rmtree() function from the L<File::Path|File::Path> module.
1065 Of course, if the template is not specified, the temporary directory
1066 will be created in tmpdir() and will also be removed at program exit.
1074 # Can not check for argument count since we can have any
1079 "CLEANUP" => 0, # Remove directory on exit
1080 "DIR" => '', # Root directory
1081 "TMPDIR" => 0, # Use tempdir with template
1084 # Check to see whether we have an odd or even number of arguments
1085 my $template = (scalar(@_) % 2 == 1 ? shift(@_) : undef );
1087 # Read the options and merge with defaults
1088 %options = (%options, @_) if @_;
1090 # Modify or generate the template
1092 # Deal with the DIR and TMPDIR options
1093 if (defined $template) {
1095 # Need to strip directory path if using DIR or TMPDIR
1096 if ($options{'TMPDIR'} || $options{'DIR'}) {
1098 # Strip parent directory from the filename
1100 # There is no filename at the end
1101 $template = VMS::Filespec::vmspath($template) if $^O eq 'VMS';
1102 my ($volume, $directories, undef) = File::Spec->splitpath( $template, 1);
1104 # Last directory is then our template
1105 $template = (File::Spec->splitdir($directories))[-1];
1107 # Prepend the supplied directory or temp dir
1108 if ($options{"DIR"}) {
1110 $template = File::Spec->catfile($options{"DIR"}, $template);
1112 } elsif ($options{TMPDIR}) {
1115 $template = File::Spec->catdir(File::Spec->tmpdir, $template);
1123 if ($options{"DIR"}) {
1125 $template = File::Spec->catdir($options{"DIR"}, TEMPXXX);
1129 $template = File::Spec->catdir(File::Spec->tmpdir, TEMPXXX);
1135 # Create the directory
1138 if ($^O eq 'VMS') { # dir names can end in delimiters
1139 $template =~ m/([\.\]:>]+)$/;
1140 $suffixlen = length($1);
1142 croak "Error in tempdir() using $template"
1143 unless ((undef, $tempdir) = _gettemp($template,
1146 "suffixlen" => $suffixlen,
1149 # Install exit handler; must be dynamic to get lexical
1150 if ( $options{'CLEANUP'} && -d $tempdir) {
1151 _deferred_unlink(undef, $tempdir, 1);
1154 # Return the dir name
1161 =head1 MKTEMP FUNCTIONS
1163 The following functions are Perl implementations of the
1164 mktemp() family of temp file generation system calls.
1170 Given a template, returns a filehandle to the temporary file and the name
1173 ($fh, $name) = mkstemp( $template );
1175 In scalar context, just the filehandle is returned.
1177 The template may be any filename with some number of X's appended
1178 to it, for example F</tmp/temp.XXXX>. The trailing X's are replaced
1179 with unique alphanumeric combinations.
1187 croak "Usage: mkstemp(template)"
1190 my $template = shift;
1193 croak "Error in mkstemp using $template"
1194 unless (($fh, $path) = _gettemp($template,
1201 return ($fh, $path);
1211 Similar to mkstemp(), except that an extra argument can be supplied
1212 with a suffix to be appended to the template.
1214 ($fh, $name) = mkstemps( $template, $suffix );
1216 For example a template of C<testXXXXXX> and suffix of C<.dat>
1217 would generate a file similar to F<testhGji_w.dat>.
1219 Returns just the filehandle alone when called in scalar context.
1225 croak "Usage: mkstemps(template, suffix)"
1229 my $template = shift;
1232 $template .= $suffix;
1235 croak "Error in mkstemps using $template"
1236 unless (($fh, $path) = _gettemp($template,
1239 "suffixlen" => length($suffix),
1243 return ($fh, $path);
1252 Create a directory from a template. The template must end in
1253 X's that are replaced by the routine.
1255 $tmpdir_name = mkdtemp($template);
1257 Returns the name of the temporary directory created.
1258 Returns undef on failure.
1260 Directory must be removed by the caller.
1268 croak "Usage: mkdtemp(template)"
1271 my $template = shift;
1273 if ($^O eq 'VMS') { # dir names can end in delimiters
1274 $template =~ m/([\.\]:>]+)$/;
1275 $suffixlen = length($1);
1277 my ($junk, $tmpdir);
1278 croak "Error creating temp directory from template $template\n"
1279 unless (($junk, $tmpdir) = _gettemp($template,
1282 "suffixlen" => $suffixlen,
1291 Returns a valid temporary filename but does not guarantee
1292 that the file will not be opened by someone else.
1294 $unopened_file = mktemp($template);
1296 Template is the same as that required by mkstemp().
1302 croak "Usage: mktemp(template)"
1305 my $template = shift;
1307 my ($tmpname, $junk);
1308 croak "Error getting name to temp file from template $template\n"
1309 unless (($junk, $tmpname) = _gettemp($template,
1320 =head1 POSIX FUNCTIONS
1322 This section describes the re-implementation of the tmpnam()
1323 and tmpfile() functions described in L<POSIX>
1324 using the mkstemp() from this module.
1326 Unlike the L<POSIX|POSIX> implementations, the directory used
1327 for the temporary file is not specified in a system include
1328 file (C<P_tmpdir>) but simply depends on the choice of tmpdir()
1329 returned by L<File::Spec|File::Spec>. On some implementations this
1330 location can be set using the C<TMPDIR> environment variable, which
1332 If this is a problem, simply use mkstemp() and specify a template.
1338 When called in scalar context, returns the full name (including path)
1339 of a temporary file (uses mktemp()). The only check is that the file does
1340 not already exist, but there is no guarantee that that condition will
1345 When called in list context, a filehandle to the open file and
1346 a filename are returned. This is achieved by calling mkstemp()
1347 after constructing a suitable template.
1349 ($fh, $file) = tmpnam();
1351 If possible, this form should be used to prevent possible
1354 See L<File::Spec/tmpdir> for information on the choice of temporary
1355 directory for a particular operating system.
1361 # Retrieve the temporary directory name
1362 my $tmpdir = File::Spec->tmpdir;
1364 croak "Error temporary directory is not writable"
1367 # Use a ten character template and append to tmpdir
1368 my $template = File::Spec->catfile($tmpdir, TEMPXXX);
1371 return mkstemp($template);
1373 return mktemp($template);
1380 In scalar context, returns the filehandle of a temporary file.
1384 The file is removed when the filehandle is closed or when the program
1385 exits. No access to the filename is provided.
1391 # Simply call tmpnam() in a list context
1392 my ($fh, $file) = tmpnam();
1394 # Make sure file is removed when filehandle is closed
1395 unlink0($fh, $file) or croak "Unable to unlink temporary file: $!";
1403 =head1 ADDITIONAL FUNCTIONS
1405 These functions are provided for backwards compatibility
1406 with common tempfile generation C library functions.
1408 They are not exported and must be addressed using the full package
1415 Return the name of a temporary file in the specified directory
1416 using a prefix. The file is guaranteed not to exist at the time
1417 the function was called, but such guarantees are good for one
1418 clock tick only. Always use the proper form of C<sysopen>
1419 with C<O_CREAT | O_EXCL> if you must open such a filename.
1421 $filename = File::Temp::tempnam( $dir, $prefix );
1423 Equivalent to running mktemp() with $dir/$prefixXXXXXXXX
1424 (using unix file convention as an example)
1426 Because this function uses mktemp(), it can suffer from race conditions.
1432 croak 'Usage tempnam($dir, $prefix)' unless scalar(@_) == 2;
1434 my ($dir, $prefix) = @_;
1436 # Add a string to the prefix
1437 $prefix .= 'XXXXXXXX';
1439 # Concatenate the directory to the file
1440 my $template = File::Spec->catfile($dir, $prefix);
1442 return mktemp($template);
1448 =head1 UTILITY FUNCTIONS
1450 Useful functions for dealing with the filehandle and filename.
1456 Given an open filehandle and the associated filename, make a safe
1457 unlink. This is achieved by first checking that the filename and
1458 filehandle initially point to the same file and that the number of
1459 links to the file is 1 (all fields returned by stat() are compared).
1460 Then the filename is unlinked and the filehandle checked once again to
1461 verify that the number of links on that file is now 0. This is the
1462 closest you can come to making sure that the filename unlinked was the
1463 same as the file whose descriptor you hold.
1465 unlink0($fh, $path) or die "Error unlinking file $path safely";
1467 Returns false on error. The filehandle is not closed since on some
1468 occasions this is not required.
1470 On some platforms, for example Windows NT, it is not possible to
1471 unlink an open file (the file must be closed first). On those
1472 platforms, the actual unlinking is deferred until the program ends and
1473 good status is returned. A check is still performed to make sure that
1474 the filehandle and filename are pointing to the same thing (but not at
1475 the time the end block is executed since the deferred removal may not
1476 have access to the filehandle).
1478 Additionally, on Windows NT not all the fields returned by stat() can
1479 be compared. For example, the C<dev> and C<rdev> fields seem to be
1480 different. Also, it seems that the size of the file returned by stat()
1481 does not always agree, with C<stat(FH)> being more accurate than
1482 C<stat(filename)>, presumably because of caching issues even when
1483 using autoflush (this is usually overcome by waiting a while after
1484 writing to the tempfile before attempting to C<unlink0> it).
1486 Finally, on NFS file systems the link count of the file handle does
1487 not always go to zero immediately after unlinking. Currently, this
1488 command is expected to fail on NFS disks.
1494 croak 'Usage: unlink0(filehandle, filename)'
1495 unless scalar(@_) == 2;
1498 my ($fh, $path) = @_;
1500 warn "Unlinking $path using unlink0\n"
1503 # Stat the filehandle
1506 if ($fh[3] > 1 && $^W) {
1507 carp "unlink0: fstat found too many links; SB=@fh";
1511 my @path = stat $path;
1514 carp "unlink0: $path is gone already" if $^W;
1518 # this is no longer a file, but may be a directory, or worse
1520 confess "panic: $path is no longer a file: SB=@fh";
1523 # Do comparison of each member of the array
1524 # On WinNT dev and rdev seem to be different
1525 # depending on whether it is a file or a handle.
1526 # Cannot simply compare all members of the stat return
1527 # Select the ones we can use
1528 my @okstat = (0..$#fh); # Use all by default
1529 if ($^O eq 'MSWin32') {
1530 @okstat = (1,2,3,4,5,7,8,9,10);
1531 } elsif ($^O eq 'os2') {
1532 @okstat = (0, 2..$#fh);
1533 } elsif ($^O eq 'VMS') { # device and file ID are sufficient
1535 } elsif ($^O eq 'dos') {
1536 @okstat = (0,2..7,11..$#fh);
1539 # Now compare each entry explicitly by number
1541 print "Comparing: $_ : $fh[$_] and $path[$_]\n" if $DEBUG;
1542 # Use eq rather than == since rdev, blksize, and blocks (6, 11,
1543 # and 12) will be '' on platforms that do not support them. This
1544 # is fine since we are only comparing integers.
1545 unless ($fh[$_] eq $path[$_]) {
1546 warn "Did not match $_ element of stat\n" if $DEBUG;
1551 # attempt remove the file (does not work on some platforms)
1552 if (_can_unlink_opened_file()) {
1553 # XXX: do *not* call this on a directory; possible race
1554 # resulting in recursive removal
1555 croak "unlink0: $path has become a directory!" if -d $path;
1556 unlink($path) or return 0;
1558 # Stat the filehandle
1561 print "Link count = $fh[3] \n" if $DEBUG;
1563 # Make sure that the link count is zero
1564 # - Cygwin provides deferred unlinking, however,
1565 # on Win9x the link count remains 1
1566 return ( $fh[3] == 0 or $^O eq 'cygwin' ? 1 : 0);
1569 _deferred_unlink($fh, $path, 0);
1577 =head1 PACKAGE VARIABLES
1579 These functions control the global state of the package.
1585 Controls the lengths to which the module will go to check the safety of the
1586 temporary file or directory before proceeding.
1593 Do the basic security measures to ensure the directory exists and
1594 is writable, that the umask() is fixed before opening of the file,
1595 that temporary files are opened only if they do not already exist, and
1596 that possible race conditions are avoided. Finally the L<unlink0|"unlink0">
1597 function is used to remove files safely.
1601 In addition to the STANDARD security, the output directory is checked
1602 to make sure that it is owned either by root or the user running the
1603 program. If the directory is writable by group or by other, it is then
1604 checked to make sure that the sticky bit is set.
1606 Will not work on platforms that do not support the C<-k> test
1611 In addition to the MEDIUM security checks, also check for the
1612 possibility of ``chown() giveaway'' using the L<POSIX|POSIX>
1613 sysconf() function. If this is a possibility, each directory in the
1614 path is checked in turn for safeness, recursively walking back to the
1617 For platforms that do not support the L<POSIX|POSIX>
1618 C<_PC_CHOWN_RESTRICTED> symbol (for example, Windows NT) it is
1619 assumed that ``chown() giveaway'' is possible and the recursive test
1624 The level can be changed as follows:
1626 File::Temp->safe_level( File::Temp::HIGH );
1628 The level constants are not exported by the module.
1630 Currently, you must be running at least perl v5.6.0 in order to
1631 run with MEDIUM or HIGH security. This is simply because the
1632 safety tests use functions from L<Fcntl|Fcntl> that are not
1633 available in older versions of perl. The problem is that the version
1634 number for Fcntl is the same in perl 5.6.0 and in 5.005_03 even though
1635 they are different versions.
1637 On systems that do not support the HIGH or MEDIUM safety levels
1638 (for example Win NT or OS/2) any attempt to change the level will
1639 be ignored. The decision to ignore rather than raise an exception
1640 allows portable programs to be written with high security in mind
1641 for the systems that can support this without those programs failing
1642 on systems where the extra tests are irrelevant.
1644 If you really need to see whether the change has been accepted
1645 simply examine the return value of C<safe_level>.
1647 $newlevel = File::Temp->safe_level( File::Temp::HIGH );
1648 die "Could not change to high security"
1649 if $newlevel != File::Temp::HIGH;
1654 # protect from using the variable itself
1655 my $LEVEL = STANDARD;
1660 if (($level != STANDARD) && ($level != MEDIUM) && ($level != HIGH)) {
1661 carp "safe_level: Specified level ($level) not STANDARD, MEDIUM or HIGH - ignoring\n";
1663 # Dont allow this on perl 5.005 or earlier
1664 if ($] < 5.006 && $level != STANDARD) {
1665 # Cant do MEDIUM or HIGH checks
1666 croak "Currently requires perl 5.006 or newer to do the safe checks";
1668 # Check that we are allowed to change level
1669 # Silently ignore if we can not.
1670 $LEVEL = $level if _can_do_level($level);
1679 This is the highest UID on the current system that refers to a root
1680 UID. This is used to make sure that the temporary directory is
1681 owned by a system UID (C<root>, C<bin>, C<sys> etc) rather than
1684 This is required since on many unix systems C</tmp> is not owned
1687 Default is to assume that any UID less than or equal to 10 is a root
1690 File::Temp->top_system_uid(10);
1691 my $topid = File::Temp->top_system_uid;
1693 This value can be adjusted to reduce security checking if required.
1694 The value is only relevant when C<safe_level> is set to MEDIUM or higher.
1701 my $TopSystemUID = 10;
1702 sub top_system_uid {
1706 croak "top_system_uid: UIDs should be numeric"
1707 unless $newuid =~ /^\d+$/s;
1708 $TopSystemUID = $newuid;
1710 return $TopSystemUID;
1716 For maximum security, endeavour always to avoid ever looking at,
1717 touching, or even imputing the existence of the filename. You do not
1718 know that that filename is connected to the same file as the handle
1719 you have, and attempts to check this can only trigger more race
1720 conditions. It's far more secure to use the filehandle alone and
1721 dispense with the filename altogether.
1723 If you need to pass the handle to something that expects a filename
1724 then, on a unix system, use C<"/dev/fd/" . fileno($fh)> for arbitrary
1725 programs, or more generally C<< "+<=&" . fileno($fh) >> for Perl
1726 programs. You will have to clear the close-on-exec bit on that file
1727 descriptor before passing it to another process.
1729 use Fcntl qw/F_SETFD F_GETFD/;
1730 fcntl($tmpfh, F_SETFD, 0)
1731 or die "Can't clear close-on-exec flag on temp fh: $!\n";
1735 Originally began life in May 1999 as an XS interface to the system
1736 mkstemp() function. In March 2000, the OpenBSD mkstemp() code was
1737 translated to Perl for total control of the code's
1738 security checking, to ensure the presence of the function regardless of
1739 operating system and to help with portability.
1743 L<POSIX/tmpnam>, L<POSIX/tmpfile>, L<File::Spec>, L<File::Path>
1745 See L<File::MkTemp> for a different implementation of temporary
1750 Tim Jenness E<lt>t.jenness@jach.hawaii.eduE<gt>
1752 Copyright (C) 1999, 2000 Tim Jenness and the UK Particle Physics and
1753 Astronomy Research Council. All Rights Reserved. This program is free
1754 software; you can redistribute it and/or modify it under the same
1755 terms as Perl itself.
1757 Original Perl implementation loosely based on the OpenBSD C code for
1758 mkstemp(). Thanks to Tom Christiansen for suggesting that this module
1759 should be written and providing ideas for code improvements and
1760 security enhancements.