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md5_file

(PHP 4 >= 4.2.0, PHP 5)

md5_fileCalcola l'hash md5 del file dato

Descrizione

string md5_file ( string $filename [, bool $raw_output ] )

Calcola l'hash md5 del file filename utilizzando l' » RSA Data Security, Inc. MD5 Message-Digest Algorithm, e lo restituisce. L'hash prodotto è un numero esadecimale di 32 caratteri. Se il secondo parametro raw_output è impostato a TRUE, il valore md5 è restituito nel formato binario raw con una lunghezza di 16 caratteri.

Nota: Il parametro opzionale raw_output è stato aggiunto in PHP 5.0.0, e come default vale FALSE

Questa funzione ha il medesimo scopo dell'utilità di linea di comando md5sum.

Vedere anche md5(), crc32() e sha1_file().

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User Contributed Notes 6 notes

up
13
Chris
4 years ago
If you just need to find out if two files are identical, comparing file hashes can be inefficient, especially on large files.  There's no reason to read two whole files and do all the math if the second byte of each file is different.  If you don't need to store the hash value for later use, there may not be a need to calculate the hash value just to compare files.  This can be much faster:

<?php
define
('READ_LEN', 4096);

if(
files_identical('file1.txt', 'file2.txt'))
    echo
'files identical';
else
    echo
'files not identical';

//   pass two file names
//   returns TRUE if files are the same, FALSE otherwise
function files_identical($fn1, $fn2) {
    if(
filetype($fn1) !== filetype($fn2))
        return
FALSE;

    if(
filesize($fn1) !== filesize($fn2))
        return
FALSE;

    if(!
$fp1 = fopen($fn1, 'rb'))
        return
FALSE;

    if(!
$fp2 = fopen($fn2, 'rb')) {
       
fclose($fp1);
        return
FALSE;
    }

   
$same = TRUE;
    while (!
feof($fp1) and !feof($fp2))
        if(
fread($fp1, READ_LEN) !== fread($fp2, READ_LEN)) {
           
$same = FALSE;
            break;
        }

    if(
feof($fp1) !== feof($fp2))
       
$same = FALSE;

   
fclose($fp1);
   
fclose($fp2);

    return
$same;
}
?>
up
6
potsed [at] gmail [dot] com
7 years ago
Heres a function to give an md5 for an entire directory..

function MD5_DIR($dir)
{
    if (!is_dir($dir))
    {
        return false;
    }
   
    $filemd5s = array();
    $d = dir($dir);

    while (false !== ($entry = $d->read()))
    {
        if ($entry != '.' && $entry != '..')
        {
             if (is_dir($dir.'/'.$entry))
             {
                 $filemd5s[] = MD5_DIR($dir.'/'.$entry);
             }
             else
             {
                 $filemd5s[] = md5_file($dir.'/'.$entry);
             }
         }
    }
    $d->close();
    return md5(implode('', $filemd5s));
}
up
5
smartin
6 years ago
In response to using exec instead for performance (Nov 13 2007 post), It looks like the performance depends on the size of the file.  See the results below using the same script from the original post.  The first hash is with md5_file and the second is with openssl md5.

With a 1MB file:
Hash = df1555ec0c2d7fcad3a03770f9aa238a; time = 0.005006
Hash = df1555ec0c2d7fcad3a03770f9aa238a; time = 0.01498

With a 2MB file:

Hash = 4387904830a4245a8ab767e5937d722c; time = 0.010393
Hash = 4387904830a4245a8ab767e5937d722c; time = 0.016691

With a 10MB file:

Hash = b89f948e98f3a113dc13fdbd3bdb17ef; time = 0.241907
Hash = b89f948e98f3a113dc13fdbd3bdb17ef; time = 0.037597

Performance seems to change proportionally with the file size.  Judging from the previous post's default file name (.mov) he/she was probably dealing with a large file.  These are just quick tests and far from a perfect benchmark, but you might want to test your own files before assuming that the openssl solution is faster (ie, if working with small text files vs. movies, etc)
up
3
lukasamd at gmail dot com
2 years ago
It's faster to use md5sum than openssl md5:

<?php
$begin
= microtime(true);

$file_path = '../backup_file1.tar.gz';
$result = explode("  ", exec("md5sum $file_path"));
echo
"Hash = ".$result[0]."<br />";

# Here 7 other big files (20-300 MB)

$end = microtime(true) - $begin;
echo
"Time = $end";
# Time = 4.4475841522217

#Method with openssl
# Time = 12.1463856900543
?>

About 3x faster
up
2
richard at interlink dot com dot au
9 years ago
For those of you with PHP 4 that want to output the "raw" 128 bit hash, all you need to do is send it to pack to convert the hex string into the raw output.

ie:
$filename="checkthisfile.bin";
$rawhash=pack("H*",md5_file($filename));
up
-23
tommuhler at yahoo dot com
8 months ago
Sorry for voting Chris's code down.

It is great, but there are some brackets missing.  If you add more complex conditions than just a mere echo in the top IF ... ELSE structure please include the curly braces ... otherwise php  will choke.

<?php
define
('READ_LEN', 4096);

if(
files_identical('file1.txt', 'file2.txt')) {
    echo
'files identical';
} else {
    echo
'files not identical';
}

//   pass two file names
//   returns TRUE if files are the same, FALSE otherwise
function files_identical($fn1, $fn2) {
    if(
filetype($fn1) !== filetype($fn2))
        return
FALSE;

    if(
filesize($fn1) !== filesize($fn2))
        return
FALSE;

    if(!
$fp1 = fopen($fn1, 'rb'))
        return
FALSE;

    if(!
$fp2 = fopen($fn2, 'rb')) {
       
fclose($fp1);
        return
FALSE;
    }

   
$same = TRUE;
    while (!
feof($fp1) and !feof($fp2))
        if(
fread($fp1, READ_LEN) !== fread($fp2, READ_LEN)) {
           
$same = FALSE;
            break;
        }

    if(
feof($fp1) !== feof($fp2))
       
$same = FALSE;

   
fclose($fp1);
   
fclose($fp2);

    return
$same;
}
?>
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