fixed throwing errors in exists-check functions (#54) [Closes #52]

Suppresses warning triggered by `stat`/`lstat` when file does not exit.

By injecting another error handler which resets error reporting the
suppressed warning gets caught and does not appear in error logs.

As certain testing frameworks establish error handlers to pick up
on suppressed errors, exceptions and warnings, the warning generated
by `stat`/`lstat` when provided an unknown path is recorded.

src/NativeWrapper.php

@@ -198,14 +198,19 @@ public function unlink(string $path): bool
 
 	public function url_stat(string $path, int $flags)
 	{
+		if ($flags & STREAM_URL_STAT_QUIET) {
+			set_error_handler(static fn(): bool => true);
+		}
 		try {
 			$func = $flags & STREAM_URL_STAT_LINK ? 'lstat' : 'stat';
-			return $flags & STREAM_URL_STAT_QUIET
-				? @$this->native($func, $path)
-				: $this->native($func, $path);
+			return $this->native($func, $path);
 		} catch (\RuntimeException $e) {
 			// SplFileInfo::isFile throws exception
 			return false;
+		} finally {
+			if ($flags & STREAM_URL_STAT_QUIET) {
+				restore_error_handler();
+			}
 		}
 	}
 

tests/BypassFinals/overloaded.exists_check.phpt

@@ -0,0 +1,76 @@
+<?php
+
+// test that overloaded "exists-check" functions (see php-src/ext/standard/filestat.c) must not invoke the error handler
+
+declare(strict_types=1);
+
+use Tester\Assert;
+
+require __DIR__ . '/../../vendor/autoload.php';
+
+Tester\Environment::setup();
+
+DG\BypassFinals::enable();
+
+
+function thoroughErrorHandler(): void
+{
+	throw new Exception('This must not happen');
+}
+
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	file_exists('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_writable('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_readable('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_executable('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_file('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_dir('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_link('unknown');
+
+	restore_error_handler();
+});