AOLserver Wiki - User contributions [en]

Ns returnfile

2008-08-20T00:55:12Z

Jcaruso: Minor clarification.

ns_returnfile 200 "application/zip" $filepath
ns_returnfile 200 [ns_guesstype $file] $filepath

==== Caveat programmor ====

ns_returnfile uses [[fastpath]] caching internally, and fastpath caching may fail to distinguish between two files on the same filesystem which have the same inode, mtime, and size (serving one file in lieu of the other). This can happen if a file is generated, returned to the user, and then deleted. For example, in the following sample code the second call to ns_returnfile will return /var/tmp/myfile rather than /var/tmp/myotherfile:

set file [open "/var/tmp/myfile" "w"]
puts $file "ABC123"
close $file
ns_returnfile 200 text/plain "/var/tmp/myfile"
ns_unlink -nocomplain "/var/tmp/myfile"

set file [open "/var/tmp/myotherfile" "w"]
puts $file "XYZ987"
close $file
ns_returnfile 200 text/plain "/var/tmp/myotherfile"
ns_unlink -nocomplain "/var/tmp/myotherfile"

When returning "dynamic" file data like this, a safer practice would be to use [[ns_return]] or ns_returnfp instead (since they don't use fastpath caching). For example:

set fd [open $myfile]
ns_return 200 [ns_guesstype $myfile] [read $fd]
close $fd

==== Want to name the file returned? ====

ns_set update [ns_conn outputheaders] content-disposition "attachment; filename=1.abc"

Ns returnfile

2008-08-19T23:07:32Z

Jcaruso:

ns_returnfile 200 "application/zip" $filepath
ns_returnfile 200 [ns_guesstype $file] $filepath

==== Caveat programmor ====

ns_returnfile uses [[fastpath]] caching internally, and fastpath caching may fail to distinguish between two files on the same filesystem which have the same inode, mtime, and size (serving one file in lieu of the other). This can happen if a file is generated, returned to the user, and then deleted. For example, in the following sample code the second call to ns_returnfile will return /var/tmp/myfile rather than /var/tmp/myotherfile:

set file [open "/var/tmp/myfile" "w"]
puts $file "ABC123"
close $file
ns_returnfile 200 text/plain "/var/tmp/myfile"
ns_unlink -nocomplain "/var/tmp/myfile"

set file [open "/var/tmp/myotherfile" "w"]
puts $file "XYZ987"
close $file
ns_returnfile 200 text/plain "/var/tmp/myotherfile"
ns_unlink -nocomplain "/var/tmp/myotherfile"

When returning "dynamic" file data like this, a safer practice would be to use [[ns_return]] or ns_returnfp instead. For example:

set fd [open $myfile]
ns_return 200 [ns_guesstype $myfile] [read $fd]
close $fd

==== Want to name the file returned? ====

ns_set update [ns_conn outputheaders] content-disposition "attachment; filename=1.abc"

Ns returnfile

2008-08-19T23:05:58Z

Jcaruso: Added a clearer explanation of the fastpath caching issue

ns_returnfile 200 "application/zip" $filepath
ns_returnfile 200 [ns_guesstype $file] $filepath

==== Caveat programmor ====

ns_returnfile uses [[fastpath]] caching internally, and fastpath caching may fail to distinguish between two files on the same filesystem which have the same inode, mtime, and size (serving one file in lieu of the other). This can happen if a file is generated, returned to the user, and then deleted. For example, in the following sample code the second call to ns_returnfile will return /var/tmp/myfile rather than /var/tmp/myotherfile:

set file [open "/var/tmp/myfile" "w"]
puts $file "ABC123"
close $file
ns_returnfile 200 text/plain "/var/tmp/myfile"
ns_unlink -nocomplain "/var/tmp/myfile"

set file [open "/var/tmp/myotherfile" "w"]
puts $file "XYZ987"
close $file
ns_returnfile 200 text/plain "/var/tmp/myotherfile"
ns_unlink -nocomplain "/var/tmp/myotherfile"

When returning "dynamic" file data like this, a safer practice would be to use [[ns_return]] or ns_returnfp instead. For example:

set fd [open $myfile]
ns_unlink $myfile; # So that nothing else can access the file from the filesystem
ns_return 200 [ns_guesstype $myfile] [read $fd]
close $fd

==== Want to name the file returned? ====

ns_set update [ns_conn outputheaders] content-disposition "attachment; filename=1.abc"