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md5_file

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

md5_fileCalcola l'hash md5 del file dato

Descrizione

md5_file(string $filename, bool $raw_output = false): string

Calcola l'hash MD5 del file specificato dal parametro filename utilizzando il » RSA Data Security, Inc. MD5 Message-Digest Algorithm, e restituendo quell'hash. L'hash è un numero esadecimale di 32 caratteri.

Elenco dei parametri

filename

Il nome del file

raw_output

Quando true, restituisce il digest nel formato binario raw con una dimensione di 16.

Valori restituiti

Restituisce una stringa in caso di successo, false in caso contrario.

Esempi

Example #1 Esempio di uso di md5_file()

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

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

Vedere anche:

  • md5() - Calcola il valore md5 di una stringa
  • sha1_file() - Calcola l'hash sha1 di un file
  • crc32() - Calcola il crc32 polinomiale di una stringa

add a note

User Contributed Notes 5 notes

up
99
Chris
14 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
8
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
up
-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)
up
-6
potsed [at] gmail [dot] com
16 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
-20
richard at interlink dot com dot au
19 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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