5 File::Temp - return name and handle of a temporary file safely
9 use File::Temp qw/ tempfile tempdir /;
11 $dir = tempdir( CLEANUP => 1 );
12 ($fh, $filename) = tempfile( DIR => $dir );
14 ($fh, $filename) = tempfile( $template, DIR => $dir);
15 ($fh, $filename) = tempfile( $template, SUFFIX => '.dat');
21 use File::Temp qw/ :mktemp /;
23 ($fh, $file) = mkstemp( "tmpfileXXXXX" );
24 ($fh, $file) = mkstemps( "tmpfileXXXXXX", $suffix);
26 $tmpdir = mkdtemp( $template );
28 $unopened_file = mktemp( $template );
32 use File::Temp qw/ :POSIX /;
37 ($fh, $file) = tmpnam();
38 ($fh, $file) = tmpfile();
41 Compatibility functions:
43 $unopened_file = File::Temp::tempnam( $dir, $pfx );
47 Objects (NOT YET IMPLEMENTED):
51 $fh = new File::Temp($template);
52 $fname = $fh->filename;
58 C<File::Temp> can be used to create and open temporary files in a safe way.
59 The tempfile() function can be used to return the name and the open
60 filehandle of a temporary file. The tempdir() function can
61 be used to create a temporary directory.
63 The security aspect of temporary file creation is emphasized such that
64 a filehandle and filename are returned together. This helps guarantee that
65 a race condition can not occur where the temporary file is created by another process
66 between checking for the existence of the file and its
67 opening. Additional security levels are provided to check, for
68 example, that the sticky bit is set on world writable directories.
69 See L<"safe_level"> for more information.
71 For compatibility with popular C library functions, Perl implementations of
72 the mkstemp() family of functions are provided. These are, mkstemp(),
73 mkstemps(), mkdtemp() and mktemp().
75 Additionally, implementations of the standard L<POSIX|POSIX>
76 tmpnam() and tmpfile() functions are provided if required.
78 Implementations of mktemp(), tmpnam(), and tempnam() are provided,
79 but should be used with caution since they return only a filename
80 that was valid when function was called, so cannot guarantee
81 that the file will not exist by the time the caller opens the filename.
85 # 5.6.0 gives us S_IWOTH, S_IWGRP, our and auto-vivifying filehandls
86 # People would like a version on 5.005 so give them what they want :-)
91 use File::Path qw/ rmtree /;
93 use Errno qw( EEXIST ENOENT ENOTDIR EINVAL );
95 # Need the Symbol package if we are running older perl
96 require Symbol if $] < 5.006;
100 use vars qw($VERSION @EXPORT_OK %EXPORT_TAGS $DEBUG);
104 # We are exporting functions
106 use base qw/Exporter/;
108 # Export list - to allow fine tuning of export table
122 # Groups of functions for export
125 'POSIX' => [qw/ tmpnam tmpfile /],
126 'mktemp' => [qw/ mktemp mkstemp mkstemps mkdtemp/],
129 # add contents of these tags to @EXPORT
130 Exporter::export_tags('POSIX','mktemp');
136 # This is a list of characters that can be used in random filenames
138 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
139 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
140 0 1 2 3 4 5 6 7 8 9 _
143 # Maximum number of tries to make a temp file before failing
145 use constant MAX_TRIES => 10;
147 # Minimum number of X characters that should be in a template
148 use constant MINX => 4;
150 # Default template when no template supplied
152 use constant TEMPXXX => 'X' x 10;
154 # Constants for the security level
156 use constant STANDARD => 0;
157 use constant MEDIUM => 1;
158 use constant HIGH => 2;
160 # OPENFLAGS. If we defined the flag to use with Sysopen here this gives
161 # us an optimisation when many temporary files are requested
163 my $OPENFLAGS = O_CREAT | O_EXCL | O_RDWR;
165 for my $oflag (qw/FOLLOW BINARY LARGEFILE EXLOCK NOINHERIT TEMPORARY/) {
166 my ($bit, $func) = (0, "Fcntl::O_" . $oflag);
168 $OPENFLAGS |= $bit if eval { $bit = &$func(); 1 };
173 # INTERNAL ROUTINES - not to be used outside of package
175 # Generic routine for getting a temporary filename
176 # modelled on OpenBSD _gettemp() in mktemp.c
178 # The template must contain X's that are to be replaced
179 # with the random values
183 # TEMPLATE - string containing the XXXXX's that is converted
184 # to a random filename and opened if required
186 # Optionally, a hash can also be supplied containing specific options
187 # "open" => if true open the temp file, else just return the name
189 # "mkdir"=> if true, we are creating a temp directory rather than tempfile
191 # "suffixlen" => number of characters at end of PATH to be ignored.
193 # "open" and "mkdir" can not both be true
195 # The default options are equivalent to mktemp().
198 # filehandle - open file handle (if called with doopen=1, else undef)
199 # temp name - name of the temp file or directory
202 # ($fh, $name) = _gettemp($template, "open" => 1);
204 # for the current version, failures are associated with
205 # a carp to give the reason whilst debugging
209 croak 'Usage: ($fh, $name) = _gettemp($template, OPTIONS);'
210 unless scalar(@_) >= 1;
220 my $template = shift;
221 if (ref($template)) {
222 carp "File::Temp::_gettemp: template must not be a reference";
226 # Check that the number of entries on stack are even
227 if (scalar(@_) % 2 != 0) {
228 carp "File::Temp::_gettemp: Must have even number of options";
232 # Read the options and merge with defaults
233 %options = (%options, @_) if @_;
235 # Can not open the file and make a directory in a single call
236 if ($options{"open"} && $options{"mkdir"}) {
237 carp "File::Temp::_gettemp: doopen and domkdir can not both be true\n";
241 # Find the start of the end of the Xs (position of last X)
242 # Substr starts from 0
243 my $start = length($template) - 1 - $options{"suffixlen"};
245 # Check that we have at least MINX x X (eg 'XXXX") at the end of the string
246 # (taking suffixlen into account). Any fewer is insecure.
248 # Do it using substr - no reason to use a pattern match since
249 # we know where we are looking and what we are looking for
251 if (substr($template, $start - MINX + 1, MINX) ne 'X' x MINX) {
252 carp "File::Temp::_gettemp: The template must contain at least ". MINX ." 'X' characters\n";
256 # Replace all the X at the end of the substring with a
257 # random character or just all the XX at the end of a full string.
258 # Do it as an if, since the suffix adjusts which section to replace
259 # and suffixlen=0 returns nothing if used in the substr directly
260 # and generate a full path from the template
262 my $path = _replace_XX($template, $options{"suffixlen"});
265 # Split the path into constituent parts - eventually we need to check
266 # whether the directory exists
267 # We need to know whether we are making a temp directory
270 my ($volume, $directories, $file);
271 my $parent; # parent directory
272 if ($options{"mkdir"}) {
273 # There is no filename at the end
274 ($volume, $directories, $file) = File::Spec->splitpath( $path, 1);
276 # The parent is then $directories without the last directory
277 # Split the directory and put it back together again
278 my @dirs = File::Spec->splitdir($directories);
280 # If @dirs only has one entry that means we are in the current
283 $parent = File::Spec->curdir;
286 if ($^O eq 'VMS') { # need volume to avoid relative dir spec
287 $parent = File::Spec->catdir($volume, @dirs[0..$#dirs-1]);
290 # Put it back together without the last one
291 $parent = File::Spec->catdir(@dirs[0..$#dirs-1]);
293 # ...and attach the volume (no filename)
294 $parent = File::Spec->catpath($volume, $parent, '');
301 # Get rid of the last filename (use File::Basename for this?)
302 ($volume, $directories, $file) = File::Spec->splitpath( $path );
304 # Join up without the file part
305 $parent = File::Spec->catpath($volume,$directories,'');
307 # If $parent is empty replace with curdir
308 $parent = File::Spec->curdir
309 unless $directories ne '';
313 # Check that the parent directories exist
314 # Do this even for the case where we are simply returning a name
315 # not a file -- no point returning a name that includes a directory
316 # that does not exist or is not writable
318 unless (-d $parent && -w _) {
319 carp "File::Temp::_gettemp: Parent directory ($parent) is not a directory"
320 . " or is not writable\n";
324 # Check the stickiness of the directory and chown giveaway if required
325 # If the directory is world writable the sticky bit
328 if (File::Temp->safe_level == MEDIUM) {
329 unless (_is_safe($parent)) {
330 carp "File::Temp::_gettemp: Parent directory ($parent) is not safe (sticky bit not set when world writable?)";
333 } elsif (File::Temp->safe_level == HIGH) {
334 unless (_is_verysafe($parent)) {
335 carp "File::Temp::_gettemp: Parent directory ($parent) is not safe (sticky bit not set when world writable?)";
341 # Calculate the flags that we wish to use for the sysopen
342 # Some of these are not always available
344 # if ($options{"open"}) {
346 # $openflags = O_CREAT | O_EXCL | O_RDWR;
348 # for my $oflag (qw/FOLLOW BINARY LARGEFILE EXLOCK NOINHERIT TEMPORARY/) {
349 # my ($bit, $func) = (0, "Fcntl::O_" . $oflag);
351 # $openflags |= $bit if eval { $bit = &$func(); 1 };
356 # Now try MAX_TRIES time to open the file
357 for (my $i = 0; $i < MAX_TRIES; $i++) {
359 # Try to open the file if requested
360 if ($options{"open"}) {
363 # If we are running before perl5.6.0 we can not auto-vivify
365 $fh = &Symbol::gensym;
368 # Try to make sure this will be marked close-on-exec
369 # XXX: Win32 doesn't respect this, nor the proper fcntl,
370 # but may have O_NOINHERIT. This may or may not be in Fcntl.
373 # Store callers umask
379 # Attempt to open the file
380 if ( sysopen($fh, $path, $OPENFLAGS, 0600) ) {
385 # Opened successfully - return file handle and name
392 # Error opening file - abort with error
393 # if the reason was anything but EEXIST
394 unless ($! == EEXIST) {
395 carp "File::Temp: Could not create temp file $path: $!";
399 # Loop round for another try
402 } elsif ($options{"mkdir"}) {
404 # Store callers umask
410 # Open the temp directory
411 if (mkdir( $path, 0700)) {
422 # Abort with error if the reason for failure was anything
424 unless ($! == EEXIST) {
425 carp "File::Temp: Could not create directory $path: $!";
429 # Loop round for another try
435 # Return true if the file can not be found
436 # Directory has been checked previously
438 return (undef, $path) unless -e $path;
440 # Try again until MAX_TRIES
444 # Did not successfully open the tempfile/dir
445 # so try again with a different set of random letters
446 # No point in trying to increment unless we have only
447 # 1 X say and the randomness could come up with the same
448 # file MAX_TRIES in a row.
450 # Store current attempt - in principal this implies that the
451 # 3rd time around the open attempt that the first temp file
452 # name could be generated again. Probably should store each
453 # attempt and make sure that none are repeated
455 my $original = $path;
456 my $counter = 0; # Stop infinite loop
461 # Generate new name from original template
462 $path = _replace_XX($template, $options{"suffixlen"});
466 } until ($path ne $original || $counter > $MAX_GUESS);
468 # Check for out of control looping
469 if ($counter > $MAX_GUESS) {
470 carp "Tried to get a new temp name different to the previous value $MAX_GUESS times.\nSomething wrong with template?? ($template)";
476 # If we get here, we have run out of tries
477 carp "Have exceeded the maximum number of attempts (".MAX_TRIES .
478 ") to open temp file/dir";
484 # Internal routine to return a random character from the
485 # character list. Does not do an srand() since rand()
486 # will do one automatically
488 # No arguments. Return value is the random character
490 # No longer called since _replace_XX runs a few percent faster if
491 # I inline the code. This is important if we are creating thousands of
496 $CHARS[ int( rand( $#CHARS ) ) ];
500 # Internal routine to replace the XXXX... with random characters
501 # This has to be done by _gettemp() every time it fails to
502 # open a temp file/dir
504 # Arguments: $template (the template with XXX),
505 # $ignore (number of characters at end to ignore)
507 # Returns: modified template
511 croak 'Usage: _replace_XX($template, $ignore)'
512 unless scalar(@_) == 2;
514 my ($path, $ignore) = @_;
516 # Do it as an if, since the suffix adjusts which section to replace
517 # and suffixlen=0 returns nothing if used in the substr directly
518 # Alternatively, could simply set $ignore to length($path)-1
519 # Don't want to always use substr when not required though.
522 substr($path, 0, - $ignore) =~ s/X(?=X*\z)/$CHARS[ int( rand( $#CHARS ) ) ]/ge;
524 $path =~ s/X(?=X*\z)/$CHARS[ int( rand( $#CHARS ) ) ]/ge;
530 # internal routine to check to see if the directory is safe
531 # First checks to see if the directory is not owned by the
532 # current user or root. Then checks to see if anyone else
533 # can write to the directory and if so, checks to see if
534 # it has the sticky bit set
536 # Will not work on systems that do not support sticky bit
538 #Args: directory path to check
539 # Returns true if the path is safe and false otherwise.
540 # Returns undef if can not even run stat() on the path
542 # This routine based on version written by Tom Christiansen
544 # Presumably, by the time we actually attempt to create the
545 # file or directory in this directory, it may not be safe
546 # anymore... Have to run _is_safe directly after the open.
553 my @info = stat($path);
554 return 0 unless scalar(@info);
555 return 1 if $^O eq 'VMS'; # owner delete control at file level
557 # Check to see whether owner is neither superuser (or a system uid) nor me
558 # Use the real uid from the $< variable
560 if ( $info[4] > File::Temp->top_system_uid() && $info[4] != $<) {
561 carp "Directory owned neither by root nor the current user";
565 # check whether group or other can write file
566 # use 066 to detect either reading or writing
567 # use 022 to check writability
568 # Do it with S_IWOTH and S_IWGRP for portability (maybe)
570 if (($info[2] & &Fcntl::S_IWGRP) || # Is group writable?
571 ($info[2] & &Fcntl::S_IWOTH) ) { # Is world writable?
572 return 0 unless -d _; # Must be a directory
573 return 0 unless -k _; # Must be sticky
579 # Internal routine to check whether a directory is safe
580 # for temp files. Safer than _is_safe since it checks for
581 # the possibility of chown giveaway and if that is a possibility
582 # checks each directory in the path to see if it is safe (with _is_safe)
584 # If _PC_CHOWN_RESTRICTED is not set, does the full test of each
589 # Need POSIX - but only want to bother if really necessary due to overhead
593 return 1 if $^O eq 'VMS'; # owner delete control at file level
595 # Should Get the value of _PC_CHOWN_RESTRICTED if it is defined
596 # and If it is not there do the extensive test
597 my $chown_restricted;
598 $chown_restricted = &POSIX::_PC_CHOWN_RESTRICTED()
599 if eval { &POSIX::_PC_CHOWN_RESTRICTED(); 1};
601 # If chown_resticted is set to some value we should test it
602 if (defined $chown_restricted) {
604 # Return if the current directory is safe
605 return _is_safe($path) if POSIX::sysconf( $chown_restricted );
609 # To reach this point either, the _PC_CHOWN_RESTRICTED symbol
610 # was not avialable or the symbol was there but chown giveaway
611 # is allowed. Either way, we now have to test the entire tree for
614 # Convert path to an absolute directory if required
615 unless (File::Spec->file_name_is_absolute($path)) {
616 $path = File::Spec->rel2abs($path);
619 # Split directory into components - assume no file
620 my ($volume, $directories, undef) = File::Spec->splitpath( $path, 1);
622 # Slightly less efficient than having a a function in File::Spec
623 # to chop off the end of a directory or even a function that
624 # can handle ../ in a directory tree
625 # Sometimes splitdir() returns a blank at the end
626 # so we will probably check the bottom directory twice in some cases
627 my @dirs = File::Spec->splitdir($directories);
629 # Concatenate one less directory each time around
630 foreach my $pos (0.. $#dirs) {
631 # Get a directory name
632 my $dir = File::Spec->catpath($volume,
633 File::Spec->catdir(@dirs[0.. $#dirs - $pos]),
637 print "TESTING DIR $dir\n" if $DEBUG;
639 # Check the directory
640 return 0 unless _is_safe($dir);
649 # internal routine to determine whether unlink works on this
650 # platform for files that are currently open.
651 # Returns true if we can, false otherwise.
653 # Currently WinNT, OS/2 and VMS can not unlink an opened file
654 # On VMS this is because the O_EXCL flag is used to open the
655 # temporary file. Currently I do not know enough about the issues
656 # on VMS to decide whether O_EXCL is a requirement.
658 sub _can_unlink_opened_file {
660 if ($^O eq 'MSWin32' || $^O eq 'os2' || $^O eq 'VMS') {
668 # internal routine to decide which security levels are allowed
669 # see safe_level() for more information on this
671 # Controls whether the supplied security level is allowed
673 # $cando = _can_do_level( $level )
680 # Always have to be able to do STANDARD
681 return 1 if $level == STANDARD;
683 # Currently, the systems that can do HIGH or MEDIUM are identical
684 if ( $^O eq 'MSWin32' || $^O eq 'os2') {
692 # This routine sets up a deferred unlinking of a specified
693 # filename and filehandle. It is used in the following cases:
694 # - Called by unlink0 if an opened file can not be unlinked
695 # - Called by tempfile() if files are to be removed on shutdown
696 # - Called by tempdir() if directories are to be removed on shutdown
699 # _deferred_unlink( $fh, $fname, $isdir );
701 # - filehandle (so that it can be expclicitly closed if open
702 # - filename (the thing we want to remove)
703 # - isdir (flag to indicate that we are being given a directory)
704 # [and hence no filehandle]
706 # Status is not referred to since all the magic is done with and END block
709 # Will set up two lexical variables to contain all the files to be
710 # removed. One array for files, another for directories
711 # They will only exist in this block
712 # This means we only have to set up a single END block to remove all files
713 # @files_to_unlink contains an array ref with the filehandle and filename
714 my (@files_to_unlink, @dirs_to_unlink);
716 # Set up an end block to use these arrays
719 foreach my $file (@files_to_unlink) {
720 # close the filehandle without checking its state
721 # in order to make real sure that this is closed
722 # if its already closed then I dont care about the answer
723 # probably a better way to do this
724 close($file->[0]); # file handle is [0]
726 if (-f $file->[1]) { # file name is [1]
727 unlink $file->[1] or warn "Error removing ".$file->[1];
731 foreach my $dir (@dirs_to_unlink) {
733 rmtree($dir, $DEBUG, 1);
740 # This is the sub called to register a file for deferred unlinking
741 # This could simply store the input parameters and defer everything
742 # until the END block. For now we do a bit of checking at this
743 # point in order to make sure that (1) we have a file/dir to delete
744 # and (2) we have been called with the correct arguments.
745 sub _deferred_unlink {
747 croak 'Usage: _deferred_unlink($fh, $fname, $isdir)'
748 unless scalar(@_) == 3;
750 my ($fh, $fname, $isdir) = @_;
752 warn "Setting up deferred removal of $fname\n"
755 # If we have a directory, check that it is a directory
760 # Directory exists so store it
761 push (@dirs_to_unlink, $fname);
764 carp "Request to remove directory $fname could not be completed since it does not exists!\n";
771 # file exists so store handle and name for later removal
772 push(@files_to_unlink, [$fh, $fname]);
775 carp "Request to remove file $fname could not be completed since it is not there!\n";
787 This section describes the recommended interface for generating
788 temporary files and directories.
794 This is the basic function to generate temporary files.
795 The behaviour of the file can be changed using various options:
797 ($fh, $filename) = tempfile();
799 Create a temporary file in the directory specified for temporary
800 files, as specified by the tmpdir() function in L<File::Spec>.
802 ($fh, $filename) = tempfile($template);
804 Create a temporary file in the current directory using the supplied
805 template. Trailing `X' characters are replaced with random letters to
806 generate the filename. At least four `X' characters must be present
809 ($fh, $filename) = tempfile($template, SUFFIX => $suffix)
811 Same as previously, except that a suffix is added to the template
812 after the `X' translation. Useful for ensuring that a temporary
813 filename has a particular extension when needed by other applications.
814 But see the WARNING at the end.
816 ($fh, $filename) = tempfile($template, DIR => $dir);
818 Translates the template as before except that a directory name
821 If the template is not specified, a template is always
822 automatically generated. This temporary file is placed in tmpdir()
823 (L<File::Spec>) unless a directory is specified explicitly with the
826 $fh = tempfile( $template, DIR => $dir );
828 If called in scalar context, only the filehandle is returned
829 and the file will automatically be deleted when closed (see
830 the description of tmpfile() elsewhere in this document).
831 This is the preferred mode of operation, as if you only
832 have a filehandle, you can never create a race condition
833 by fumbling with the filename. On systems that can not unlink
834 an open file (for example, Windows NT) the file is marked for
835 deletion when the program ends (equivalent to setting UNLINK to 1).
837 (undef, $filename) = tempfile($template, OPEN => 0);
839 This will return the filename based on the template but
840 will not open this file. Cannot be used in conjunction with
841 UNLINK set to true. Default is to always open the file
842 to protect from possible race conditions. A warning is issued
843 if warnings are turned on. Consider using the tmpnam()
844 and mktemp() functions described elsewhere in this document
845 if opening the file is not required.
851 # Can not check for argument count since we can have any
856 "DIR" => undef, # Directory prefix
857 "SUFFIX" => '', # Template suffix
858 "UNLINK" => 0, # Unlink file on exit
859 "OPEN" => 1, # Do not open file
862 # Check to see whether we have an odd or even number of arguments
863 my $template = (scalar(@_) % 2 == 1 ? shift(@_) : undef);
865 # Read the options and merge with defaults
866 %options = (%options, @_) if @_;
868 # First decision is whether or not to open the file
869 if (! $options{"OPEN"}) {
871 warn "tempfile(): temporary filename requested but not opened.\nPossibly unsafe, consider using tempfile() with OPEN set to true\n"
876 # Construct the template
878 # Have a choice of trying to work around the mkstemp/mktemp/tmpnam etc
879 # functions or simply constructing a template and using _gettemp()
880 # explicitly. Go for the latter
882 # First generate a template if not defined and prefix the directory
883 # If no template must prefix the temp directory
884 if (defined $template) {
885 if ($options{"DIR"}) {
887 $template = File::Spec->catfile($options{"DIR"}, $template);
893 if ($options{"DIR"}) {
895 $template = File::Spec->catfile($options{"DIR"}, TEMPXXX);
899 $template = File::Spec->catfile(File::Spec->tmpdir, TEMPXXX);
906 $template .= $options{"SUFFIX"};
910 croak "Error in tempfile() using $template"
911 unless (($fh, $path) = _gettemp($template,
912 "open" => $options{'OPEN'},
914 "suffixlen" => length($options{'SUFFIX'}),
917 # Set up an exit handler that can do whatever is right for the
918 # system. Do not check return status since this is all done with
920 _deferred_unlink($fh, $path, 0) if $options{"UNLINK"};
925 if ($options{'OPEN'}) {
928 return (undef, $path);
933 # Unlink the file. It is up to unlink0 to decide what to do with
934 # this (whether to unlink now or to defer until later)
935 unlink0($fh, $path) or croak "Error unlinking file $path using unlink0";
937 # Return just the filehandle.
946 This is the recommended interface for creation of temporary directories.
947 The behaviour of the function depends on the arguments:
949 $tempdir = tempdir();
951 Create a directory in tmpdir() (see L<File::Spec|File::Spec>).
953 $tempdir = tempdir( $template );
955 Create a directory from the supplied template. This template is
956 similar to that described for tempfile(). `X' characters at the end
957 of the template are replaced with random letters to construct the
958 directory name. At least four `X' characters must be in the template.
960 $tempdir = tempdir ( DIR => $dir );
962 Specifies the directory to use for the temporary directory.
963 The temporary directory name is derived from an internal template.
965 $tempdir = tempdir ( $template, DIR => $dir );
967 Prepend the supplied directory name to the template. The template
968 should not include parent directory specifications itself. Any parent
969 directory specifications are removed from the template before
970 prepending the supplied directory.
972 $tempdir = tempdir ( $template, TMPDIR => 1 );
974 Using the supplied template, creat the temporary directory in
975 a standard location for temporary files. Equivalent to doing
977 $tempdir = tempdir ( $template, DIR => File::Spec->tmpdir);
979 but shorter. Parent directory specifications are stripped from the
980 template itself. The C<TMPDIR> option is ignored if C<DIR> is set
981 explicitly. Additionally, C<TMPDIR> is implied if neither a template
982 nor a directory are supplied.
984 $tempdir = tempdir( $template, CLEANUP => 1);
986 Create a temporary directory using the supplied template, but
987 attempt to remove it (and all files inside it) when the program
988 exits. Note that an attempt will be made to remove all files from
989 the directory even if they were not created by this module (otherwise
990 why ask to clean it up?). The directory removal is made with
991 the rmtree() function from the L<File::Path|File::Path> module.
992 Of course, if the template is not specified, the temporary directory
993 will be created in tmpdir() and will also be removed at program exit.
1001 # Can not check for argument count since we can have any
1006 "CLEANUP" => 0, # Remove directory on exit
1007 "DIR" => '', # Root directory
1008 "TMPDIR" => 0, # Use tempdir with template
1011 # Check to see whether we have an odd or even number of arguments
1012 my $template = (scalar(@_) % 2 == 1 ? shift(@_) : undef );
1014 # Read the options and merge with defaults
1015 %options = (%options, @_) if @_;
1017 # Modify or generate the template
1019 # Deal with the DIR and TMPDIR options
1020 if (defined $template) {
1022 # Need to strip directory path if using DIR or TMPDIR
1023 if ($options{'TMPDIR'} || $options{'DIR'}) {
1025 # Strip parent directory from the filename
1027 # There is no filename at the end
1028 my ($volume, $directories, undef) = File::Spec->splitpath( $template, 1);
1030 # Last directory is then our template
1031 $template = (File::Spec->splitdir($directories))[-1];
1033 # Prepend the supplied directory or temp dir
1034 if ($options{"DIR"}) {
1036 $template = File::Spec->catfile($options{"DIR"}, $template);
1038 } elsif ($options{TMPDIR}) {
1041 $template = File::Spec->catdir(File::Spec->tmpdir, $template);
1049 if ($options{"DIR"}) {
1051 $template = File::Spec->catdir($options{"DIR"}, TEMPXXX);
1055 $template = File::Spec->catdir(File::Spec->tmpdir, TEMPXXX);
1061 # Create the directory
1064 if ($^O eq 'VMS') { # dir names can end in delimiters
1065 $template =~ m/([\.\]:>]+)$/;
1066 $suffixlen = length($1);
1068 croak "Error in tempdir() using $template"
1069 unless ((undef, $tempdir) = _gettemp($template,
1072 "suffixlen" => $suffixlen,
1075 # Install exit handler; must be dynamic to get lexical
1076 if ( $options{'CLEANUP'} && -d $tempdir) {
1077 _deferred_unlink(undef, $tempdir, 1);
1080 # Return the dir name
1087 =head1 MKTEMP FUNCTIONS
1089 The following functions are Perl implementations of the
1090 mktemp() family of temp file generation system calls.
1096 Given a template, returns a filehandle to the temporary file and the name
1099 ($fh, $name) = mkstemp( $template );
1101 In scalar context, just the filehandle is returned.
1103 The template may be any filename with some number of X's appended
1104 to it, for example F</tmp/temp.XXXX>. The trailing X's are replaced
1105 with unique alphanumeric combinations.
1113 croak "Usage: mkstemp(template)"
1116 my $template = shift;
1119 croak "Error in mkstemp using $template"
1120 unless (($fh, $path) = _gettemp($template,
1127 return ($fh, $path);
1137 Similar to mkstemp(), except that an extra argument can be supplied
1138 with a suffix to be appended to the template.
1140 ($fh, $name) = mkstemps( $template, $suffix );
1142 For example a template of C<testXXXXXX> and suffix of C<.dat>
1143 would generate a file similar to F<testhGji_w.dat>.
1145 Returns just the filehandle alone when called in scalar context.
1151 croak "Usage: mkstemps(template, suffix)"
1155 my $template = shift;
1158 $template .= $suffix;
1161 croak "Error in mkstemps using $template"
1162 unless (($fh, $path) = _gettemp($template,
1165 "suffixlen" => length($suffix),
1169 return ($fh, $path);
1178 Create a directory from a template. The template must end in
1179 X's that are replaced by the routine.
1181 $tmpdir_name = mkdtemp($template);
1183 Returns the name of the temporary directory created.
1184 Returns undef on failure.
1186 Directory must be removed by the caller.
1194 croak "Usage: mkdtemp(template)"
1197 my $template = shift;
1199 if ($^O eq 'VMS') { # dir names can end in delimiters
1200 $template =~ m/([\.\]:>]+)$/;
1201 $suffixlen = length($1);
1203 my ($junk, $tmpdir);
1204 croak "Error creating temp directory from template $template\n"
1205 unless (($junk, $tmpdir) = _gettemp($template,
1208 "suffixlen" => $suffixlen,
1217 Returns a valid temporary filename but does not guarantee
1218 that the file will not be opened by someone else.
1220 $unopened_file = mktemp($template);
1222 Template is the same as that required by mkstemp().
1228 croak "Usage: mktemp(template)"
1231 my $template = shift;
1233 my ($tmpname, $junk);
1234 croak "Error getting name to temp file from template $template\n"
1235 unless (($junk, $tmpname) = _gettemp($template,
1246 =head1 POSIX FUNCTIONS
1248 This section describes the re-implementation of the tmpnam()
1249 and tmpfile() functions described in L<POSIX>
1250 using the mkstemp() from this module.
1252 Unlike the L<POSIX|POSIX> implementations, the directory used
1253 for the temporary file is not specified in a system include
1254 file (C<P_tmpdir>) but simply depends on the choice of tmpdir()
1255 returned by L<File::Spec|File::Spec>. On some implementations this
1256 location can be set using the C<TMPDIR> environment variable, which
1258 If this is a problem, simply use mkstemp() and specify a template.
1264 When called in scalar context, returns the full name (including path)
1265 of a temporary file (uses mktemp()). The only check is that the file does
1266 not already exist, but there is no guarantee that that condition will
1271 When called in list context, a filehandle to the open file and
1272 a filename are returned. This is achieved by calling mkstemp()
1273 after constructing a suitable template.
1275 ($fh, $file) = tmpnam();
1277 If possible, this form should be used to prevent possible
1280 See L<File::Spec/tmpdir> for information on the choice of temporary
1281 directory for a particular operating system.
1287 # Retrieve the temporary directory name
1288 my $tmpdir = File::Spec->tmpdir;
1290 croak "Error temporary directory is not writable"
1293 # Use a ten character template and append to tmpdir
1294 my $template = File::Spec->catfile($tmpdir, TEMPXXX);
1297 return mkstemp($template);
1299 return mktemp($template);
1306 In scalar context, returns the filehandle of a temporary file.
1310 The file is removed when the filehandle is closed or when the program
1311 exits. No access to the filename is provided.
1317 # Simply call tmpnam() in an array context
1318 my ($fh, $file) = tmpnam();
1320 # Make sure file is removed when filehandle is closed
1321 unlink0($fh, $file) or croak "Unable to unlink temporary file: $!";
1329 =head1 ADDITIONAL FUNCTIONS
1331 These functions are provided for backwards compatibility
1332 with common tempfile generation C library functions.
1334 They are not exported and must be addressed using the full package
1341 Return the name of a temporary file in the specified directory
1342 using a prefix. The file is guaranteed not to exist at the time
1343 the function was called, but such guarantees are good for one
1344 clock tick only. Always use the proper form of C<sysopen>
1345 with C<O_CREAT | O_EXCL> if you must open such a filename.
1347 $filename = File::Temp::tempnam( $dir, $prefix );
1349 Equivalent to running mktemp() with $dir/$prefixXXXXXXXX
1350 (using unix file convention as an example)
1352 Because this function uses mktemp(), it can suffer from race conditions.
1358 croak 'Usage tempnam($dir, $prefix)' unless scalar(@_) == 2;
1360 my ($dir, $prefix) = @_;
1362 # Add a string to the prefix
1363 $prefix .= 'XXXXXXXX';
1365 # Concatenate the directory to the file
1366 my $template = File::Spec->catfile($dir, $prefix);
1368 return mktemp($template);
1374 =head1 UTILITY FUNCTIONS
1376 Useful functions for dealing with the filehandle and filename.
1382 Given an open filehandle and the associated filename, make a safe
1383 unlink. This is achieved by first checking that the filename and
1384 filehandle initially point to the same file and that the number of
1385 links to the file is 1 (all fields returned by stat() are compared).
1386 Then the filename is unlinked and the filehandle checked once again to
1387 verify that the number of links on that file is now 0. This is the
1388 closest you can come to making sure that the filename unlinked was the
1389 same as the file whose descriptor you hold.
1391 unlink0($fh, $path) or die "Error unlinking file $path safely";
1393 Returns false on error. The filehandle is not closed since on some
1394 occasions this is not required.
1396 On some platforms, for example Windows NT, it is not possible to
1397 unlink an open file (the file must be closed first). On those
1398 platforms, the actual unlinking is deferred until the program ends and
1399 good status is returned. A check is still performed to make sure that
1400 the filehandle and filename are pointing to the same thing (but not at
1401 the time the end block is executed since the deferred removal may not
1402 have access to the filehandle).
1404 Additionally, on Windows NT not all the fields returned by stat() can
1405 be compared. For example, the C<dev> and C<rdev> fields seem to be different
1406 and also. Also, it seems that the size of the file returned by stat()
1407 does not always agree, with C<stat(FH)> being more accurate than
1408 C<stat(filename)>, presumably because of caching issues even when
1409 using autoflush (this is usually overcome by waiting a while after
1410 writing to the tempfile before attempting to C<unlink0> it).
1412 Finally, on NFS file systems the link count of the file handle does
1413 not always go to zero immediately after unlinking. Currently, this
1414 command is expected to fail on NFS disks.
1420 croak 'Usage: unlink0(filehandle, filename)'
1421 unless scalar(@_) == 2;
1424 my ($fh, $path) = @_;
1426 warn "Unlinking $path using unlink0\n"
1429 # Stat the filehandle
1432 if ($fh[3] > 1 && $^W) {
1433 carp "unlink0: fstat found too many links; SB=@fh";
1437 my @path = stat $path;
1440 carp "unlink0: $path is gone already" if $^W;
1444 # this is no longer a file, but may be a directory, or worse
1446 confess "panic: $path is no longer a file: SB=@fh";
1449 # Do comparison of each member of the array
1450 # On WinNT dev and rdev seem to be different
1451 # depending on whether it is a file or a handle.
1452 # Cannot simply compare all members of the stat return
1453 # Select the ones we can use
1454 my @okstat = (0..$#fh); # Use all by default
1455 if ($^O eq 'MSWin32') {
1456 @okstat = (1,2,3,4,5,7,8,9,10);
1457 } elsif ($^O eq 'VMS') {
1458 @okstat = (0,1,2,3,4,5,7,8,9,10);
1459 } elsif ($^O eq 'os2') {
1460 @okstat = (0, 2..10, 13..$#fh);
1463 # Now compare each entry explicitly by number
1465 print "Comparing: $_ : $fh[$_] and $path[$_]\n" if $DEBUG;
1466 # Use eq rather than == since on OS/2 elements 11 and 12 return
1467 # the empty string rather than a null. This is fine since we
1468 # are only comparing integers.
1469 unless ($fh[$_] eq $path[$_]) {
1470 warn "Did not match $_ element of stat\n" if $DEBUG;
1475 # attempt remove the file (does not work on some platforms)
1476 if (_can_unlink_opened_file()) {
1477 # XXX: do *not* call this on a directory; possible race
1478 # resulting in recursive removal
1479 croak "unlink0: $path has become a directory!" if -d $path;
1480 unlink($path) or return 0;
1482 # Stat the filehandle
1485 print "Link count = $fh[3] \n" if $DEBUG;
1487 # Make sure that the link count is zero
1488 return ( $fh[3] == 0 ? 1 : 0);
1491 _deferred_unlink($fh, $path, 0);
1499 =head1 PACKAGE VARIABLES
1501 These functions control the global state of the package.
1507 Controls the lengths to which the module will go to check the safety of the
1508 temporary file or directory before proceeding.
1515 Do the basic security measures to ensure the directory exists and
1516 is writable, that the umask() is fixed before opening of the file,
1517 that temporary files are opened only if they do not already exist, and
1518 that possible race conditions are avoided. Finally the L<unlink0|"unlink0">
1519 function is used to remove files safely.
1523 In addition to the STANDARD security, the output directory is checked
1524 to make sure that it is owned either by root or the user running the
1525 program. If the directory is writable by group or by other, it is then
1526 checked to make sure that the sticky bit is set.
1528 Will not work on platforms that do not support the C<-k> test
1533 In addition to the MEDIUM security checks, also check for the
1534 possibility of ``chown() giveaway'' using the L<POSIX|POSIX>
1535 sysconf() function. If this is a possibility, each directory in the
1536 path is checked in turn for safeness, recursively walking back to the
1539 For platforms that do not support the L<POSIX|POSIX>
1540 C<_PC_CHOWN_RESTRICTED> symbol (for example, Windows NT) it is
1541 assumed that ``chown() giveaway'' is possible and the recursive test
1546 The level can be changed as follows:
1548 File::Temp->safe_level( File::Temp::HIGH );
1550 The level constants are not exported by the module.
1552 Currently, you must be running at least perl v5.6.0 in order to
1553 run with MEDIUM or HIGH security. This is simply because the
1554 safety tests use functions from L<Fcntl|Fcntl> that are not
1555 available in older versions of perl. The problem is that the version
1556 number for Fcntl is the same in perl 5.6.0 and in 5.005_03 even though
1557 they are different versions.
1559 On systems that do not support the HIGH or MEDIUM safety levels
1560 (for example Win NT or OS/2) any attempt to change the level will
1561 be ignored. The decision to ignore rather than raise an exception
1562 allows portable programs to be written with high security in mind
1563 for the systems that can support this without those programs failing
1564 on systems where the extra tests are irrelevant.
1566 If you really need to see whether the change has been accepted
1567 simply examine the return value of C<safe_level>.
1569 $newlevel = File::Temp->safe_level( File::Temp::HIGH );
1570 die "Could not change to high security"
1571 if $newlevel != File::Temp::HIGH;
1576 # protect from using the variable itself
1577 my $LEVEL = STANDARD;
1582 if (($level != STANDARD) && ($level != MEDIUM) && ($level != HIGH)) {
1583 carp "safe_level: Specified level ($level) not STANDARD, MEDIUM or HIGH - ignoring\n";
1585 # Dont allow this on perl 5.005 or earlier
1586 if ($] < 5.006 && $level != STANDARD) {
1587 # Cant do MEDIUM or HIGH checks
1588 croak "Currently requires perl 5.006 or newer to do the safe checks";
1590 # Check that we are allowed to change level
1591 # Silently ignore if we can not.
1592 $LEVEL = $level if _can_do_level($level);
1601 This is the highest UID on the current system that refers to a root
1602 UID. This is used to make sure that the temporary directory is
1603 owned by a system UID (C<root>, C<bin>, C<sys> etc) rather than
1606 This is required since on many unix systems C</tmp> is not owned
1609 Default is to assume that any UID less than or equal to 10 is a root
1612 File::Temp->top_system_uid(10);
1613 my $topid = File::Temp->top_system_uid;
1615 This value can be adjusted to reduce security checking if required.
1616 The value is only relevant when C<safe_level> is set to MEDIUM or higher.
1623 my $TopSystemUID = 10;
1624 sub top_system_uid {
1628 croak "top_system_uid: UIDs should be numeric"
1629 unless $newuid =~ /^\d+$/s;
1630 $TopSystemUID = $newuid;
1632 return $TopSystemUID;
1638 For maximum security, endeavour always to avoid ever looking at,
1639 touching, or even imputing the existence of the filename. You do not
1640 know that that filename is connected to the same file as the handle
1641 you have, and attempts to check this can only trigger more race
1642 conditions. It's far more secure to use the filehandle alone and
1643 dispense with the filename altogether.
1645 If you need to pass the handle to something that expects a filename
1646 then, on a unix system, use C<"/dev/fd/" . fileno($fh)> for arbitrary
1647 programs, or more generally C<< "+<=&" . fileno($fh) >> for Perl
1648 programs. You will have to clear the close-on-exec bit on that file
1649 descriptor before passing it to another process.
1651 use Fcntl qw/F_SETFD F_GETFD/;
1652 fcntl($tmpfh, F_SETFD, 0)
1653 or die "Can't clear close-on-exec flag on temp fh: $!\n";
1657 Originally began life in May 1999 as an XS interface to the system
1658 mkstemp() function. In March 2000, the mkstemp() code was
1659 translated to Perl for total control of the code's
1660 security checking, to ensure the presence of the function regardless of
1661 operating system and to help with portability.
1665 L<POSIX/tmpnam>, L<POSIX/tmpfile>, L<File::Spec>, L<File::Path>
1667 See L<File::MkTemp> for a different implementation of temporary
1672 Tim Jenness E<lt>t.jenness@jach.hawaii.eduE<gt>
1674 Copyright (C) 1999, 2000 Tim Jenness and the UK Particle Physics and
1675 Astronomy Research Council. All Rights Reserved. This program is free
1676 software; you can redistribute it and/or modify it under the same
1677 terms as Perl itself.
1679 Original Perl implementation loosely based on the OpenBSD C code for
1680 mkstemp(). Thanks to Tom Christiansen for suggesting that this module
1681 should be written and providing ideas for code improvements and
1682 security enhancements.