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md5_file() calcule le MD5 du fichier


   filename

en utilisant l'algorithme »


    RSA Data Security, Inc. 
   MD5 Message-Digest Algorithm

, puis retourne la valeur ainsi calculée. Le résultat est un nombre de 32 caractères hexadécimaux.

hash_file() - Génère une valeur de hachage en utilisant le contenu d'un fichier donné

hash_init() - Initialise un contexte de hachage incrémental

md5() - Calcule le md5 d'une chaîne

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
     
     
      ;
      

      }
      

     
     
      ?>

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

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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