Fix GH-7875: mails are sent even if failure to log throws exception

We explicitly check for an exception after the logging attempt, and
bail out in that case.

Co-authored-by: Tim Düsterhus <timwolla@googlemail.com>

Closes GH-7878.

NEWS

@@ -16,6 +16,10 @@ PHP                                                                        NEWS
 - Sockets:
   . Fixed ext/sockets build on Haiku. (David Carlier)
 
+- Standard:
+  . Fixed bug GH-7875 (mails are sent even if failure to log throws exception).
+    (cmb)
+
 20 Jan 2022, PHP 8.0.15
 
 - Core:

ext/standard/mail.c

@@ -473,6 +473,10 @@ PHPAPI int php_mail(const char *to, const char *subject, const char *message, co
 		efree(logline);
 	}
 
+	if (EG(exception)) {
+		MAIL_RET(0);
+	}
+
 	if (PG(mail_x_header)) {
 		const char *tmp = zend_get_executed_filename();
 		zend_string *f;

ext/standard/tests/mail/gh7875.phpt

@@ -0,0 +1,35 @@
+--TEST--
+GH-7875 (mails are sent even if failure to log throws exception)
+--INI--
+sendmail_path={MAIL:{PWD}/gh7875.mail.out}
+mail.log={PWD}/gh7875.mail.log
+--FILE--
+<?php
+function exception_error_handler($severity, $message, $file, $line) {
+    if (!(error_reporting() & $severity)) {
+        return;
+    }
+    throw new ErrorException($message, 0, $severity, $file, $line);
+}
+set_error_handler("exception_error_handler");
+
+touch(__DIR__ . "/gh7875.mail.log");
+chmod(__DIR__ . "/gh7875.mail.log", 0444);
+
+try {
+	mail('recipient@example.com', 'Subject', 'Body', []);
+	echo 'Not Reached';
+} catch (\Exception $e) {
+	echo $e->getMessage(), PHP_EOL;
+    var_dump(file_exists(__DIR__ . "/gh7875.mail.out"));
+}
+?>
+--CLEAN--
+<?php
+@chmod(__DIR__ . "/gh7875.mail.log", 0644);
+@unlink(__DIR__ . "/gh7875.mail.log");
+@unlink(__DIR__ . "/gh7875.mail.out");
+?>
+--EXPECTF--
+mail(%s): Failed to open stream: Permission denied
+bool(false)