md5_file

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

md5_file — Calcula o hash md5 de um arquivo

Descrição

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

Calcula o hash MD5 do arquivo especificado pelo parâmetro filename usando o » Algoritmo de Sintetização de Mensagem da RSA Data Security, Inc., e retorna esse hash. O hash é um número hexadecimal de 32 caracteres.

Parâmetros

filename: O nome do arquivo.
binary: Quando true, retorna a sintetização MD5 em formato binário bruto com um comprimento de 16 bytes.

Valor Retornado

Retorna uma string em caso de sucesso, false caso contrário.

Exemplos

Exemplo #1 Exemplo de uso de md5_file()

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

echo 'Hash MD5 do arquivo ' . $file . ': ' . md5_file($file);
?>

Veja Também

hash_file() - Generate a hash value using the contents of a given file
hash_init() - Initialize an incremental hashing context
md5() - Calculata o hash md5 de uma string

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Notas Enviadas por Usuários (em inglês) 3 notes

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100

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

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-5

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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