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php-db | 2002091

RE: [PHP-DB] External file integryti check From: Beau Lebens (B.Lebens <email protected>)
Date: 09/03/02

can't you just make the name of the file include a unique identifier of some
sort, or store each user's files in a different directory or something, to
make sure that they can't overwrite each other's (or their own) files?

Or would that not work in your app?

HTH

Beau

// -----Original Message-----
// From: Miguel Carvalho [mailto:miguel <email protected>]
// Sent: Tuesday, 3 September 2002 5:35 PM
// To: php-db <email protected>
// Subject: [PHP-DB] External file integryti check
//
//
// Hi, id'like to know the opinion about to ensure external
// file integrity.
//
// Scenario: A web application that uses binary files( images, PDF's ).
// On the database ( postgresql 7.2.2 ) i store the filename of
// the files.
//
// The files ( images only ) are taken from an internal machine
// when needed(
// via ftp ) or automatically at idle periods.If the image
// comes throuth ftp( requested by a user ),
// the image is downloaded to a temporary directory, a record
// is inserted
// into the database and the file get's moved to the final
// directory if it
// passed some tests.If no image is requested by a user, a
// script will download( rcp ) at night
// the files and then put those in the final directory.When a
// user request's a PDF, i create the PDF in realtime, using info.
// stored in the DB plus the image( store on filesystem ).
// My concern here is the folowing:
// let's imagine that an image file is overwriten with a new image( by
// mistake ). This is possible because users use some kind of
// ID to name
// the file. If this appens, the info stored in DB is out of sync in
// relation to the file stored in filesystem.
// To correct this issues i have three possibilities:
//
// 1 - Store the PDF's in the filesystem, and store the
// file date, time
// and CRC32 of the entire file in the database. This
// solution has a
// consequence... i will need lots of space in the server(
// each file is
// aprox. 2MB ). At night a script will validate the
// sync between the info stored in
// DB and the info on filesystem.
// 2 - Create the PDF when requested. When the PDF generated for the
// first time, i will store: image creation date, time,
// crc32 and some
// more dates, times and CRC32's of other information into
// the DB. At night a script will validate the sync
// between the info stored in
// DB and the info on filesystem.
// 3 - Run a script that is change file permissions( file
// is created with
// user owner of webserver) for those new records inserted
// to root. A script will be run, because i cant change
// ownership of a file on
// the fly with PHP( PHP security ).
// Those are my solution's, if any one has any comments or suggestion's
// please share it with us.Thank's
// Miguel Carvalho
//
//
//
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