Re: Idea for a new extensions: checksum_from_file()

Ah, never seen hash extension. But there is no function, handeling offsets internaly. hash_update could use offsets... but this isnt performant. Why handeling this filedata within the php script? Thats the way, i allready handel this without "hash". Can you give me an example to made this command performant with the hash functions for an 600 MB file? In my example/idea, you dont have to read all into an variable to create the checksum, only the php_extension do this transparent. Maybe its an idea to add such a feature to the hash-extension. // My idea: // all filedata is handeled transparent, only the checksums are returned. checksum_from_file($file, array('crc32', 'md5'), 512, -128, array($this, 'updateProcess', 1024)); I dont need the raw filedata in my script... i only need the checksum. I think, done in c this is mutch faster, isnt it? With "hash_update" you have read the whole file using while (!feof($fp)) { $buffer = fgets($fp, 65536); hash_update($ctx, $buffer); } Not really performant, isnt it? Regards, Andreas Johannes Schlueter wrote: > > Hi Andreas, > > since PHP 5.2.1 PHP bundles the hash extension, see php.net/hash which > includes way more hashing algorithms (see hash_algos()) and a > hash_file() function and should full-fill all your needs. > > johannes > > On Sun, 2007-06-24 at 02:16 -0700, ecc wrote: >> Hi, >> >> there are 3 checksums supported in php. (md5, crc32 and sha1, Mabye there >> are more...) >> >> md5 and sha1 allready have an *_file function available, crc32 dont have >> them. crc32 dont have this function in the latest php version. >> >> These *_file functions are usefull in the most cases, but have a very big >> disadvantage. They could not handle header offsets. >> >> Theses header offsets arent trivial, because e.g. MP3 files also contains >> an >> header. (In this case, its not really an header, because its an offset at >> the end of the MP3 file containing the meta-informations ID3). So if you >> parse the checksum of an MP3, you allway get the wrong checksum, because >> the >> song is the same in the most cases, but only the meta-infos are changed. >> This isnt the best example, but it shows you the problem. >> >> This is my implementation idea (pseudocode). >> >> // get crc32 and md5 checksums from $file, begin at byte 512 and stop 128 >> bytes before fileend. >> // call method "updateProcess" everytime if 1024 bytes for file are >> processed! (eg. for php-gtk2) >> checksum_from_file($file, array('crc32', 'md5'), 512, -128, >> array($this, >> 'updateProcess', 1024)); >> >> public function checksum_from_file($file= false, $checksum_type = false, >> $start_offset=false, $end_offset=false, $callback = false) { >> $checksums = array(); >> // get data >> return $checksums; >> } >> >> $file should be contain a filename, a filehandle or and something like >> this >> z:/test.zip#filename.php >> So the creation of temp-copys of e.g. zip content could be transparent >> done >> without managing this externaly. >> >> This extension have to parse files bigger than 600 MB. So, the funktion >> have >> to be ready for this. (file_get_contents crash in this cases :-)) >> >> Now, i have to read the complete filecontent to the memory using a php >> buildin function and create an checksum by this string, because i´ve had >> to >> manage the header offsets. Not really performant, and very very slow for >> large files > 64 MB >> >> Regards, >> Andreas >> http://www.php-gtk.eu/apps/emucontrolcenter >> >> Here an overview of the allready implemented checksum function in php. >> >> string md5_file ( string $filename [, bool $raw_output] ) >> http://de2.php.net/manual/de/function.md5-file.php >> >> string sha1_file ( string $filename [, bool $raw_output] ) >> http://de2.php.net/manual/de/function.sha1-file.php >> >> int crc32 ( string $str ) >> http://de2.php.net/manual/de/function.crc32.php > > -- > PECL development discussion Mailing List (http://pecl.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > > -- View this message in context: http://www.nabble.com/Idea-for-a-new-extensions%3A-checksum_from_file%28%29-tf3971680.html#a11274130 Sent from the Pecl - Dev mailing list archive at Nabble.com.