Utilities: Split out buildBacktrace function from logBacktrace.

git-svn-id: https://simplesamlphp.googlecode.com/svn/trunk@791 44740490-163a-0410-bde0-09ae8108e29a

lib/SimpleSAML/Utilities.php

@@ -271,63 +271,69 @@ class SimpleSAML_Utilities {
 	}
 	
 
-	
-
-	/* This function dumps a backtrace to the error log.
+	/**
+	 * Build a backtrace.
 	 *
-	 * The log is in the following form:
-	 *  BT: (0) <filename>:<line> (<current function>)
-	 *  BT: (1) <filename>:<line> (<previous fucntion>)
-	 *  ...
-	 *  BT: (N) <filename>:<line> (N/A)
+	 * This function takes in an exception and optionally a start depth, and
+	 * builds a backtrace from that depth. The backtrace is returned as an
+	 * array of strings, where each string represents one level in the stack.
 	 *
-	 * The log starts at the function which calls logBacktrace().
+	 * @param Exception $exception  The exception.
+	 * @param int $startDepth  The depth we should print the backtrace from.
+	 * @return array  The backtrace as an array of strings.
 	 */
-	public static function logBacktrace() {
+	public static function buildBacktrace(Exception $exception, $startDepth = 0) {
 
-		/* Get the backtrace. */
-		$bt = debug_backtrace();
+		assert('is_int($startDepth)');
 
-		/* Variable to hold the stack depth. */
-		$depth = 0;
+		$bt = array();
 
-		/* PHP stores the backtrace as a list of function calls.
-		 * This means that $bt[0]['function'] contains the function
-		 * which is called, while $bt[0]['line'] contains the line
-		 * the function was called from.
-		 *
-		 * To get the form of bactrace we want, we are going to use
-		 * $bt[i+1] to get the function and $bt[i] to get the file
-		 * name and the line number.
-		 */
+		/* Position in the top function on the stack. */
+		$pos = $exception->getFile() . ':' . $exception->getLine();
 
-		for($i = 0; $i < count($bt); $i++) {
-			$file = $bt[$i]['file'];
-			$line = $bt[$i]['line'];
+		foreach($exception->getTrace() as $t) {
 
-			/* We can't get a function name or class for the source
-			 * of the first call.
-			 */
-			if($i == count($bt) - 1) {
-				$function = 'N/A';
-				$class = NULL;
+			$function = $t['function'];
+			if(array_key_exists('class', $t)) {
+				$function = $t['class'] . '::' . $function;
+			}
+
+			$bt[] = $pos . ' (' . $function . ')';
+
+			if(array_key_exists('file', $t)) {
+				$pos = $t['file'] . ':' . $t['line'];
 			} else {
-				$function = $bt[$i+1]['function'];
-				$class = $bt[$i+1]['class'];
+				$pos = '[builtin]';
+			}
 		}
 
-			/* Attach the class name to the function name if
-			 * we have a class name.
-			 */
-			if($class !== NULL) {
-				$function = $class  . '::' . $function;
+		$bt[] = $pos . ' (N/A)';
+
+		/* Remove $startDepth elements from the top of the backtrace. */
+		$bt = array_slice($bt, $startDepth);
+
+		return $bt;
 	}
 
 
-			error_log('BT: (' . $depth . ') ' . $file . ':' .
-			          $line . ' (' . $function . ')');
+	/**
+	 * This function dumps a backtrace to the error log.
+	 *
+	 * The log is in the following form:
+	 *  BT: (0) <filename>:<line> (<current function>)
+	 *  BT: (1) <filename>:<line> (<previous fucntion>)
+	 *  ...
+	 *  BT: (N) <filename>:<line> (N/A)
+	 *
+	 * The log starts at the function which calls logBacktrace().
+	 */
+	public static function logBacktrace() {
+
+		$e = new Exception();
 
-			$depth++;
+		$bt = self::buildBackTrace($e, 1);
+		foreach($bt as $depth => $t) {
+			error_log('BT: (' . $depth . ') ' . $t);
 		}
 	}