PHP CodeIgnitor: Files

With PHP, it is possible to upload files to the server.

Create an Upload-File Form

To allow users to upload files from a form can be very useful.

Look at the following HTML form for uploading files:

<html>

<body>

<form action="upload_file.php" method="post"

enctype="multipart/form-data">

<label for="file">Filename:</label>

<input type="file" name="file" id="file" />

<br />

<input type="submit" name="submit" value="Submit" />

</form>

</body>

</html>

Notice the following about the HTML form above:

The enctype attribute of the <form> tag specifies which content-type to use when submitting the form. "multipart/form-data" is used when a form requires binary data, like the contents of a file, to be uploaded
The type="file" attribute of the <input> tag specifies that the input should be processed as a file. For example, when viewed in a browser, there will be a browse-button next to the input field

Note: Allowing users to upload files is a big security risk. Only permit trusted users to perform file uploads.

Create The Upload Script

The "upload_file.php" file contains the code for uploading a file:

<?php

if ($_FILES["file"]["error"] > 0)

  {

  echo "Error: " . $_FILES["file"]["error"] . "<br />";

  }

else

  {

  echo "Upload: " . $_FILES["file"]["name"] . "<br />";

  echo "Type: " . $_FILES["file"]["type"] . "<br />";

  echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";

  echo "Stored in: " . $_FILES["file"]["tmp_name"];

  }

?>

By using the global PHP $_FILES array you can upload files from a client computer to the remote server.

The first parameter is the form's input name and the second index can be either "name", "type", "size", "tmp_name" or "error". Like this:

$_FILES["file"]["name"] - the name of the uploaded file
$_FILES["file"]["type"] - the type of the uploaded file
$_FILES["file"]["size"] - the size in bytes of the uploaded file
$_FILES["file"]["tmp_name"] - the name of the temporary copy of the file stored on the server
$_FILES["file"]["error"] - the error code resulting from the file upload

This is a very simple way of uploading files. For security reasons, you should add restrictions on what the user is allowed to upload.

Restrictions on Upload

In this script we add some restrictions to the file upload. The user may only upload .gif or .jpeg files and the file size must be under 20 kb:

<?php

if ((($_FILES["file"]["type"] == "image/gif")

|| ($_FILES["file"]["type"] == "image/jpeg")

|| ($_FILES["file"]["type"] == "image/pjpeg"))

&& ($_FILES["file"]["size"] < 20000))

  {

  if ($_FILES["file"]["error"] > 0)

    {

    echo "Error: " . $_FILES["file"]["error"] . "<br />";

    }

  else

    {

    echo "Upload: " . $_FILES["file"]["name"] . "<br />";

    echo "Type: " . $_FILES["file"]["type"] . "<br />";

    echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";

    echo "Stored in: " . $_FILES["file"]["tmp_name"];

    }

  }

else

  {

  echo "Invalid file";

  }

?>

Note: For IE to recognize jpg files the type must be pjpeg, for FireFox it must be jpeg.

Saving the Uploaded File

The examples above create a temporary copy of the uploaded files in the PHP temp folder on the server.

The temporary copied files disappears when the script ends. To store the uploaded file we need to copy it to a different location:

<?php

if ((($_FILES["file"]["type"] == "image/gif")

|| ($_FILES["file"]["type"] == "image/jpeg")

|| ($_FILES["file"]["type"] == "image/pjpeg"))

&& ($_FILES["file"]["size"] < 20000))

  {

  if ($_FILES["file"]["error"] > 0)

    {

    echo "Return Code: " . $_FILES["file"]["error"] . "<br />";

    }

  else

    {

    echo "Upload: " . $_FILES["file"]["name"] . "<br />";

    echo "Type: " . $_FILES["file"]["type"] . "<br />";

    echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";

    echo "Temp file: " . $_FILES["file"]["tmp_name"] . "<br />";

    if (file_exists("upload/" . $_FILES["file"]["name"]))

      {

      echo $_FILES["file"]["name"] . " already exists. ";

      }

    else

      {

      move_uploaded_file($_FILES["file"]["tmp_name"],

      "upload/" . $_FILES["file"]["name"]);

      echo "Stored in: " . "upload/" . $_FILES["file"]["name"];

      }

    }

  }

else

  {

  echo "Invalid file";

  }

?>

The script above checks if the file already exists, if it does not, it copies the file to the specified folder.

Note: This example saves the file to a new folder called "upload"

The fopen() function is used to open files in PHP.

Opening a File

The fopen() function is used to open files in PHP.

The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened:

<html>

<body>

<?php

$file=fopen("welcome.txt","r");

?>

</body>

</html>

The file may be opened in one of the following modes:

Modes	Description
r	Read only. Starts at the beginning of the file
r+	Read/Write. Starts at the beginning of the file
w	Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist
w+	Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist
a	Append. Opens and writes to the end of the file or creates a new file if it doesn't exist
a+	Read/Append. Preserves file content by writing to the end of the file
x	Write only. Creates a new file. Returns FALSE and an error if file already exists
x+	Read/Write. Creates a new file. Returns FALSE and an error if file already exists

Note: If the fopen() function is unable to open the specified file, it returns 0 (false).

Example

The following example generates a message if the fopen() function is unable to open the specified file:

<html>

<body>

<?php

$file=fopen("welcome.txt","r") or exit("Unable to open file!");

?>

</body>

</html>

Closing a File

The fclose() function is used to close an open file:

<?php

$file = fopen("test.txt","r");

//some code to be executed

fclose($file);

?>

Check End-of-file

The feof() function checks if the "end-of-file" (EOF) has been reached.

The feof() function is useful for looping through data of unknown length.

Note: You cannot read from files opened in w, a, and x mode!

if (feof($file)) echo "End of file";

Reading a File Line by Line

The fgets() function is used to read a single line from a file.

Note: After a call to this function the file pointer has moved to the next line.

Example

The example below reads a file line by line, until the end of file is reached:

<?php

$file = fopen("welcome.txt", "r") or exit("Unable to open file!");

//Output a line of the file until the end is reached

while(!feof($file))

  {

  echo fgets($file). "<br />";

  }

fclose($file);

?>

Reading a File Character by Character

The fgetc() function is used to read a single character from a file.

Note: After a call to this function the file pointer moves to the next character.

Example

The example below reads a file character by character, until the end of file is reached:

<?php

$file=fopen("welcome.txt","r") or exit("Unable to open file!");

while (!feof($file))

  {

  echo fgetc($file);

  }

fclose($file);

?>

PHP CodeIgnitor

Sunday, 10 July 2011

Create an Upload-File Form

Create The Upload Script

Restrictions on Upload

Saving the Uploaded File

PHP :: File Handling

Opening a File

Example

Closing a File

Check End-of-file

Reading a File Line by Line

Example

Reading a File Character by Character

Example