From 0e6c0654ed06751ced134515f7629c40bd979d7f Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Sat, 23 Nov 2019 13:01:33 +0100
Subject: Fix #78862: link() silently truncates after a null byte on Windows

Since link() is supposed to accepts paths (i.e. strings without NUL
bytes), we must not accept arbitrary strings.
---
 ext/standard/link_win32.c                           |  2 +-
 ext/standard/tests/file/windows_links/bug78862.phpt | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 ext/standard/tests/file/windows_links/bug78862.phpt

diff --git a/ext/standard/link_win32.c b/ext/standard/link_win32.c
index b46dee6a26..0197ec02af 100644
--- a/ext/standard/link_win32.c
+++ b/ext/standard/link_win32.c
@@ -211,7 +211,7 @@ PHP_FUNCTION(link)
 
 	/*First argument to link function is the target and hence should go to frompath
 	  Second argument to link function is the link itself and hence should go to topath */
-	if (zend_parse_parameters(ZEND_NUM_ARGS(), "ss", &frompath, &frompath_len, &topath, &topath_len) == FAILURE) {
+	if (zend_parse_parameters(ZEND_NUM_ARGS(), "pp", &frompath, &frompath_len, &topath, &topath_len) == FAILURE) {
 		return;
 	}
 
diff --git a/ext/standard/tests/file/windows_links/bug78862.phpt b/ext/standard/tests/file/windows_links/bug78862.phpt
new file mode 100644
index 0000000000..33b4b49293
--- /dev/null
+++ b/ext/standard/tests/file/windows_links/bug78862.phpt
@@ -0,0 +1,17 @@
+--TEST--
+Bug #78862 (link() silently truncates after a null byte on Windows)
+--FILE--
+<?php
+file_put_contents(__DIR__ . '/bug78862.target', 'foo');
+var_dump(link(__DIR__ . "/bug78862.target\0more", __DIR__ . "/bug78862.link\0more"));
+var_dump(file_exists(__DIR__ . '/bug78862.link'));
+?>
+--EXPECTF--
+Warning: link() expects parameter 1 to be a valid path, string given in %s on line %d
+NULL
+bool(false)
+--CLEAN--
+<?php
+unlink(__DIR__ . '/bug78862.target');
+unlink(__DIR__ . '/bug78862.link');
+?>
-- 
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