md5_file

(PHP 4 >= 4.2.0, PHP 5, PHP 7)

md5_file — Calculates the md5 hash of a given file

Descrierea

md5_file ( string $filename , bool $binary = false ) : string|false

Calculates the MD5 hash of the file specified by the filename parameter using the » RSA Data Security, Inc. MD5 Message-Digest Algorithm, and returns that hash. The hash is a 32-character hexadecimal number.

Parametri

filename: The filename
binary: When true, returns the digest in raw binary format with a length of 16.

Valorile întoarse

Returns a string on success, false otherwise.

Exemple

Example #1 Usage example of md5_file()


<?php
$file = 'php-5.3.0alpha2-Win32-VC9-x64.zip';

echo 'MD5 file hash of ' . $file . ': ' . md5_file($file);
?>

A se vedea și

md5() - Calculate the md5 hash of a string
sha1_file() - Calculate the sha1 hash of a file
crc32() - Calculates the crc32 polynomial of a string

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User Contributed Notes 5 notes

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Chris ¶

15 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;
}
?>

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lukasamd at gmail dot com ¶

12 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

down

smartin ¶

16 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)

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potsed [at] gmail [dot] com ¶

17 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));
}

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-7

richard at interlink dot com dot au ¶

20 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));

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