commit a71ed489a2eea704d732cb2f1d11754dac26e84a
Author: Joshua Seigler <joshua.seigler@xpo.com>
Date:   Thu Jun 30 11:58:42 2016 -0400

    initial commit

diff --git a/.gitignore b/.gitignore
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+# https://git-scm.com/docs/gitignore
+# https://help.github.com/articles/ignoring-files
+# Example .gitignore files: https://github.com/github/gitignore
diff --git a/LICENSE.txt b/LICENSE.txt
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+++ b/LICENSE.txt
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+MIT License
+
+Copyright (c) 2016 Joshua Seigler
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
\ No newline at end of file
diff --git a/README.md b/README.md
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+++ b/README.md
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+# seigler/simple-php-buffer
+
+PHP file for basic file-based output buffering
+
+## Usage
+```php
+define('CACHE_PATH', sys_get_temp_dir().'/cache_'); // optional, cache-file location prefix
+define('CACHE_TIME', 5 * 60); // optional, seconds to cache the output
+require 'buffer.php';
+```
+
+This will send last-modified, expires, and etag headers. If a request includes theetag and
+modified-since parameters the script can return a 304 not modified.
+
+This uses output buffering, but it can't buffer headers. If you need to send out a header every time, cached or not, put that header code above the `require`.
+
+```php
+Header('Content-type: image/svg+xml; charset=utf-8');
+Header('Content-Disposition: inline; filename="fancy-chart-' . date('Y-m-d\THisT') . '.svg"');
+require 'buffer.php';
+
+// remaining code to generate the chart
+```
+
+## Credits
+
+* Based on http://www.the-art-of-web.com/php/buffer/
+
diff --git a/buffer.php b/buffer.php
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+++ b/buffer.php
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+<?php
+  // Based on code from The Art of Web: www.the-art-of-web.com
+  // Which was based on PHP code by Dennis Pallett: www.phpit.net
+
+  // location and prefix for cache files
+  defined('CACHE_PATH') or define('CACHE_PATH', sys_get_temp_dir().'/cache_');
+
+  // how long to keep the cache files (seconds)
+  defined('CACHE_TIME') or define('CACHE_TIME', 5 * 60);
+
+  // return location and name for cache file
+  function cache_file()
+  {
+    return CACHE_PATH . md5('buffer'.$_SERVER['REQUEST_URI']);
+  }
+
+  // display cached file if present and not expired
+  function cache_display()
+  {
+    $file = cache_file();
+
+    // check that cache file exists and is not too old
+    if(!file_exists($file)) return;
+    $last_modified_time = filemtime($file);
+    if($last_modified_time < time() - CACHE_TIME) return;
+    $etag = md5_file($file);
+
+    // always send headers
+    header("Last-Modified: ".gmdate("D, d M Y H:i:s", $last_modified_time)." GMT");
+    header("Etag: $etag");
+    header("Expires: ".gmdate("D, d M Y H:i:s", $last_modified_time + CACHE_TIME)." GMT");
+
+    // tell any caches that I really mean it with these other headers
+    header("Cache-Control: max-age=".CACHE_TIME.", must-revalidate");
+
+    // HTTP 304 and exit if not modified
+    if (@strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) == $last_modified_time ||
+        @trim($_SERVER['HTTP_IF_NONE_MATCH']) == $etag) {
+        header("HTTP/1.1 304 Not Modified");
+        exit;
+    }
+
+    // if so, display cache file and stop processing
+    readfile($file);
+    exit;
+  }
+
+  // write to cache file
+  function cache_page($content)
+  {
+    if(false !== ($f = @fopen(cache_file(), 'w'))) {
+      fwrite($f, $content);
+      fclose($f);
+    }
+    $last_modified_time = time();
+    $etag = md5_file('buffer'.$file);
+
+    // always send headers
+    header("Last-Modified: ".gmdate("D, d M Y H:i:s", $last_modified_time)." GMT");
+    header("Etag: $etag");
+    header("Expires: ".gmdate("D, d M Y H:i:s", $last_modified_time + CACHE_TIME)." GMT");
+
+    return $content;
+  }
+
+  // execution stops here if valid cache file found
+  cache_display();
+
+  // enable output buffering and create cache file
+  ob_start('cache_page');
+?>