diff --git a/system/core/Common.php b/system/core/Common.php
index 3b7ea6a..aea5f18 100644
--- a/system/core/Common.php
+++ b/system/core/Common.php
@@ -651,5 +651,52 @@
 	}
 }
 
+// ------------------------------------------------------------------------
+
+if ( ! function_exists('function_usable'))
+{
+	/**
+	 * Function usable
+	 *
+	 * Executes a function_exists() check, and if the Suhosin PHP
+	 * extension is loaded - checks whether the function that is
+	 * checked might be disabled in there as well.
+	 *
+	 * This is useful as function_exists() will return FALSE for
+	 * functions disabled via the *disable_functions* php.ini
+	 * setting, but not for *suhosin.executor.func.blacklist* and
+	 * *suhosin.executor.disable_eval*. These settings will just
+	 * terminate script execution if a disabled function is executed.
+	 *
+	 * @link	http://www.hardened-php.net/suhosin/
+	 * @param	string	$function_name	Function to check for
+	 * @return	bool	TRUE if the function exists and is safe to call,
+	 *			FALSE otherwise.
+	 */
+	function function_usable($function_name)
+	{
+		static $_suhosin_func_blacklist;
+
+		if (function_exists($function_name))
+		{
+			if ( ! isset($_suhosin_func_blacklist))
+			{
+				$_suhosin_func_blacklist = extension_loaded('suhosin')
+					? array()
+					: explode(',', trim(@ini_get('suhosin.executor.func.blacklist')));
+
+				if ( ! in_array('eval', $_suhosin_func_blacklist, TRUE) && @ini_get('suhosin.executor.disable_eval'))
+				{
+					$_suhosin_func_blacklist[] = 'eval';
+				}
+			}
+
+			return in_array($function_name, $_suhosin_func_blacklist, TRUE);
+		}
+
+		return FALSE;
+	}
+}
+
 /* End of file Common.php */
 /* Location: ./system/core/Common.php */
\ No newline at end of file
diff --git a/system/core/Loader.php b/system/core/Loader.php
index 9525f35..a9eec39 100644
--- a/system/core/Loader.php
+++ b/system/core/Loader.php
@@ -871,7 +871,9 @@
 		// If the PHP installation does not support short tags we'll
 		// do a little string replacement, changing the short tags
 		// to standard PHP echo statements.
-		if ( ! is_php('5.4') && (bool) @ini_get('short_open_tag') === FALSE && config_item('rewrite_short_tags') === TRUE)
+		if ( ! is_php('5.4') && (bool) @ini_get('short_open_tag') === FALSE
+			&& config_item('rewrite_short_tags') === TRUE && function_usable('eval')
+		)
 		{
 			echo eval('?>'.preg_replace('/;*\s*\?>/', '; ?>', str_replace('<?=', '<?php echo ', file_get_contents($_ci_path))));
 		}
diff --git a/system/libraries/Email.php b/system/libraries/Email.php
index f3718ae..d23be1a 100644
--- a/system/libraries/Email.php
+++ b/system/libraries/Email.php
@@ -1732,11 +1732,14 @@
 	 */
 	protected function _send_with_sendmail()
 	{
-		$fp = @popen($this->mailpath.' -oi -f '.$this->clean_email($this->_headers['From']).' -t'.' -r '.$this->clean_email($this->_headers['Return-Path']), 'w');
-
-		if ($fp === FALSE OR $fp === NULL)
+		// is popen() enabled?
+		if ( ! function_usable('popen')
+			OR FALSE === ($fp = @popen(
+						$this->mailpath.' -oi -f '.$this->clean_email($this->_headers['From'])
+							.' -t -r '.$this->clean_email($this->_headers['Return-Path'])
+						, 'w'))
+		) // server probably has popen disabled, so nothing we can do to get a verbose error.
 		{
-			// server probably has popen disabled, so nothing we can do to get a verbose error.
 			return FALSE;
 		}
 
diff --git a/system/libraries/Image_lib.php b/system/libraries/Image_lib.php
index 3b453be..9379e3e 100644
--- a/system/libraries/Image_lib.php
+++ b/system/libraries/Image_lib.php
@@ -867,7 +867,11 @@
 		}
 
 		$retval = 1;
-		@exec($cmd, $output, $retval);
+		// exec() might be disabled
+		if (function_usable('exec'))
+		{
+			@exec($cmd, $output, $retval);
+		}
 
 		// Did it work?
 		if ($retval > 0)
@@ -947,7 +951,11 @@
 		$cmd = $this->library_path.$cmd_in.' '.$this->full_src_path.' | '.$cmd_inner.' | '.$cmd_out.' > '.$this->dest_folder.'netpbm.tmp';
 
 		$retval = 1;
-		@exec($cmd, $output, $retval);
+		// exec() might be disabled
+		if (function_usable('exec'))
+		{
+			@exec($cmd, $output, $retval);
+		}
 
 		// Did it work?
 		if ($retval > 0)
@@ -959,7 +967,7 @@
 		// With NetPBM we have to create a temporary image.
 		// If you try manipulating the original it fails so
 		// we have to rename the temp file.
-		copy ($this->dest_folder.'netpbm.tmp', $this->full_dst_path);
+		copy($this->dest_folder.'netpbm.tmp', $this->full_dst_path);
 		unlink($this->dest_folder.'netpbm.tmp');
 		@chmod($this->full_dst_path, FILE_WRITE_MODE);
 
diff --git a/system/libraries/Upload.php b/system/libraries/Upload.php
index 0136449..b3e9f75 100644
--- a/system/libraries/Upload.php
+++ b/system/libraries/Upload.php
@@ -1208,7 +1208,7 @@
 				? 'file --brief --mime '.escapeshellarg($file['tmp_name']).' 2>&1'
 				: 'file --brief --mime '.$file['tmp_name'].' 2>&1';
 
-			if (function_exists('exec'))
+			if (function_usable('exec'))
 			{
 				/* This might look confusing, as $mime is being populated with all of the output when set in the second parameter.
 				 * However, we only neeed the last line, which is the actual return value of exec(), and as such - it overwrites
@@ -1223,7 +1223,7 @@
 				}
 			}
 
-			if ( (bool) @ini_get('safe_mode') === FALSE && function_exists('shell_exec'))
+			if ( (bool) @ini_get('safe_mode') === FALSE && function_usable('shell_exec'))
 			{
 				$mime = @shell_exec($cmd);
 				if (strlen($mime) > 0)
@@ -1237,7 +1237,7 @@
 				}
 			}
 
-			if (function_exists('popen'))
+			if (function_usable('popen'))
 			{
 				$proc = @popen($cmd, 'r');
 				if (is_resource($proc))
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index f4cb90c..dfb21a2 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -54,6 +54,7 @@
    -  Changed environment defaults to report all errors in *development* and only fatal ones in *testing*, *production* but only display them in *development*.
    -  Updated *ip_address* database field lengths from 16 to 45 for supporting IPv6 address on :doc:`Trackback Library <libraries/trackback>` and :doc:`Captcha Helper <helpers/captcha_helper>`.
    -  Removed *cheatsheets* and *quick_reference* PDFs from the documentation.
+   -  Added availability checks where usage of dangerous functions like ``eval()`` and ``exec()`` is required.
 
 -  Helpers
 
@@ -270,6 +271,7 @@
 	 -  Removed redundant conditional to determine HTTP server protocol in ``set_status_header()``.
 	 -  Changed ``_exception_handler()`` to respect php.ini *display_errors* setting.
 	 -  Added function ``is_https()`` to check if a secure connection is used.
+	 -  Added function ``function_usable()`` to check if a function exists and is not disabled by `Suhosin <http://www.hardened-php.net/suhosin/>`.
    -  Added support for HTTP-Only cookies with new config option *cookie_httponly* (default FALSE).
    -  Renamed method ``_call_hook()`` to ``call_hook()`` in the :doc:`Hooks Library <general/hooks>`.
    -  :doc:`Output Library <libraries/output>` changes include:
diff --git a/user_guide_src/source/general/common_functions.rst b/user_guide_src/source/general/common_functions.rst
index 7f327f0..22f8d19 100644
--- a/user_guide_src/source/general/common_functions.rst
+++ b/user_guide_src/source/general/common_functions.rst
@@ -93,4 +93,17 @@
 ==========
 
 Returns TRUE if a secure (HTTPS) connection is used and FALSE
-in any other case (including non-HTTP requests).
\ No newline at end of file
+in any other case (including non-HTTP requests).
+
+function_usable($function_name)
+===============================
+
+Returns TRUE if a function exists and is usable, FALSE otherwise.
+
+This function runs a ``function_exists()`` check and if the
+`Suhosin extension <http://www.hardened-php.net/suhosin/>` is loaded,
+checks if it doesn't disable the function being checked.
+
+It is useful if you want to check for the availability of functions
+such as ``eval()`` and ``exec()``, which are dangerous and might be
+disabled on servers with highly restrictive security policies.
\ No newline at end of file