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md5_file

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

md5_file指定したファイルのMD5ハッシュ値を計算する

説明

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

» RSA Data Security, Inc. MD5 メッセージダイジェストアルゴリズムを用いて filenameパラメータで指定したファイルの MD5ハッシュを計算し、そのハッシュを返します。 ハッシュは、32 文字の 16 進数です。

パラメータ

filename

ファイル名

binary

true の場合、長さ 16 の生のバイナリフォーマットで ダイジェストを返します。

戻り値

成功時は文字列、そうでなければ false

例1 md5_file() の使用例

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

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

参考

  • hash_file() - ファイルの内容から、ハッシュ値を生成する
  • hash_init() - 段階的なハッシュコンテキストを初期化する
  • md5() - 文字列のmd5ハッシュ値を計算する

add a note

User Contributed Notes 3 notes

up
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;
}
?>
up
9
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)