Handle xdebug conflict on dump_on_limit feature (#68)

Author: arnaud-lb

.github/workflows/test.yml

@@ -56,6 +56,9 @@ jobs:
             - name: 'Build PHP'
               run: './ext/.github/workflows/test/build-php.sh'
 
+            - name: 'Install xdebug'
+              run: './ext/.github/workflows/test/build-xdebug.sh'
+
             - name: 'Build extension'
               run: './ext/.github/workflows/test/build-extension.sh'
 

.github/workflows/test/build-xdebug.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+set -e
+
+export PATH="$HOME/php/bin:$PATH"
+hash -r
+
+git clone --depth 1 --branch "3.1.2" "https://github.com/xdebug/xdebug.git"
+
+cd xdebug
+
+phpize
+./configure
+make
+sudo make install

.github/workflows/test/tests.sh

@@ -13,5 +13,9 @@ if [ "$MEMORY_CHECK" = "1" ]; then
       checkmem=-m
 fi
 
+# Hack to ensure that run-tests.php attempts to load xdebug as a zend_extension
+# This hack is necessary with PHP < 8.1
+sed -i "s/if (\$req_ext == 'opcache') {/if (\$req_ext == 'opcache' || \$req_ext == 'xdebug') {/" run-tests.php || true
+
 PHP=$(which php)
 REPORT_EXIT_STATUS=1 TEST_PHP_EXECUTABLE="$PHP" "$PHP" run-tests.php -q $checkmem --show-diff $showmem

memprof.c

@@ -217,6 +217,9 @@ static void (*old_zend_execute_internal)(zend_execute_data *execute_data_ptr, zv
 #endif
 
 static void (*old_zend_error_cb)(MEMPROF_ZEND_ERROR_CB_ARGS);
+static void (*rinit_zend_error_cb)(MEMPROF_ZEND_ERROR_CB_ARGS);
+static zend_bool zend_error_cb_overridden;
+static void memprof_zend_error_cb(MEMPROF_ZEND_ERROR_CB_ARGS);
 
 static PHP_INI_MH((*origOnChangeMemoryLimit)) = NULL;
 
@@ -718,8 +721,20 @@ static void * zend_realloc_handler(void * ptr, size_t size)
 	return result;
 }
 
+// Some extensions override zend_error_cb and don't call the previous
+// zend_error_cb, so memprof needs to be the last to override it
+static void memprof_late_override_error_cb() {
+	old_zend_error_cb = zend_error_cb;
+	zend_error_cb = memprof_zend_error_cb;
+	zend_error_cb_overridden = 1;
+}
+
 static void memprof_zend_execute(zend_execute_data *execute_data)
 {
+	if (UNEXPECTED(!zend_error_cb_overridden)) {
+		memprof_late_override_error_cb();
+	}
+
 	WITHOUT_MALLOC_TRACKING {
 
 		current_frame = get_or_create_frame(execute_data, current_frame);
@@ -740,6 +755,10 @@ static void memprof_zend_execute_internal(zend_execute_data *execute_data_ptr, z
 {
 	int ignore = 0;
 
+	if (UNEXPECTED(!zend_error_cb_overridden)) {
+		memprof_late_override_error_cb();
+	}
+
 	if (&execute_data_ptr->func->internal_function == &zend_pass_function) {
 		ignore = 1;
 	} else if (execute_data_ptr->func->common.function_name) {
@@ -1191,9 +1210,6 @@ PHP_MINIT_FUNCTION(memprof)
 		}
 	}
 
-	old_zend_error_cb = zend_error_cb;
-	zend_error_cb = memprof_zend_error_cb;
-
 	return SUCCESS;
 }
 /* }}} */
@@ -1231,6 +1247,9 @@ PHP_RINIT_FUNCTION(memprof)
 		memprof_enable(&MEMPROF_G(profile_flags));
 	}
 
+	rinit_zend_error_cb = zend_error_cb;
+	zend_error_cb_overridden = 0;
+
 	return SUCCESS;
 }
 /* }}} */
@@ -1243,6 +1262,8 @@ PHP_RSHUTDOWN_FUNCTION(memprof)
 		memprof_disable();
 	}
 
+	zend_error_cb = rinit_zend_error_cb;
+
 	return SUCCESS;
 }
 /* }}} */

tests/autodump-xdebug.phpt

@@ -0,0 +1,65 @@
+--TEST--
+autodump vs xdebug
+--EXTENSIONS--
+xdebug
+--INI--
+xdebug.mode=develop
+--ENV--
+MEMPROF_PROFILE=dump_on_limit
+--FILE--
+<?php
+
+$dir = sys_get_temp_dir() . '/' . microtime(true);
+var_dump($dir);
+var_dump(mkdir($dir));
+var_dump(memprof_enabled_flags());
+
+$buf = str_repeat("a", 5<<20);
+
+register_shutdown_function(function () use (&$buf, $dir) {
+    $buf = "";
+    var_dump(scandir($dir));
+});
+
+ini_set("memprof.output_dir", $dir);
+ini_set("memory_limit", 15<<20);
+
+function f() {
+    $a = [];
+    for (;;) {
+        $a[] = str_repeat("a", 1<<20);
+    }
+}
+
+f();
+--EXPECTF--
+%sautodump-xdebug.php:%d:
+string(%d) "/%s"
+%sautodump-xdebug.php:%d:
+bool(true)
+%sautodump-xdebug.php:%d:
+array(3) {
+  'enabled' =>
+  bool(true)
+  'native' =>
+  bool(false)
+  'dump_on_limit' =>
+  bool(true)
+}
+
+Fatal error: Allowed memory size of 15728640 bytes exhausted%S (tried to allocate %d bytes) (memprof dumped to %smemprof.callgrind%s) in %s on line%a
+
+Call Stack:
+    %s
+    %s
+    %s
+
+%sautodump-xdebug.php:%d:
+array(3) {
+  [0] =>
+  string(1) "."
+  [1] =>
+  string(2) ".."
+  [2] =>
+  string(%d) "memprof.callgrind.%s"
+}