Fix #79423: copy command is limited to size of file it can copy

Passing `NULL` as `lpFileSizeHigh` to `GetFileSize()` gives wrong
results for files larger than 0xFFFFFFFF bytes.  We fix this by using
`GetFileSizeEx()`, and proceed with `MIN(file_size, SIZE_MAX)`.

Author: cmb69

ext/standard/tests/streams/bug79423.phpt

@@ -0,0 +1,31 @@
+--TEST--
+Bug #79423 (copy command is limited to size of file it can copy)
+--SKIPIF--
+<?php
+if (getenv('SKIP_SLOW_TESTS')) die('skip slow test');
+?>
+--FILE--
+<?php
+$orig = __DIR__ . '/bug79423_orig.txt';
+$copy = __DIR__ . '/bug79423_copy.txt';
+
+// create file of 0xFFFFFFFF bytes (SIZE_MAX on 32bit systems)
+$text = str_repeat('*', 1024 * 1024);
+$stream = fopen($orig, 'w');
+for ($i = 0; $i < 4095; $i++) {
+    fwrite($stream, $text);
+}
+fwrite($stream, $text, strlen($text) - 1);
+fclose($stream);
+
+var_dump(copy($orig, $copy));
+var_dump(filesize($orig) === filesize($copy));
+?>
+--CLEAN--
+<?php
+unlink(__DIR__ . '/bug79423_orig.txt');
+unlink(__DIR__ . '/bug79423_copy.txt');
+?>
+--EXPECT--
+bool(true)
+bool(true)

main/streams/plain_wrapper.c

@@ -749,6 +749,7 @@ static int php_stdiop_set_option(php_stream *stream, int option, int value, void
 				php_stream_mmap_range *range = (php_stream_mmap_range*)ptrparam;
 				HANDLE hfile = (HANDLE)_get_osfhandle(fd);
 				DWORD prot, acc, loffs = 0, delta = 0;
+				LARGE_INTEGER file_size;
 
 				switch (value) {
 					case PHP_STREAM_MMAP_SUPPORTED:
@@ -785,7 +786,19 @@ static int php_stdiop_set_option(php_stream *stream, int option, int value, void
 							return PHP_STREAM_OPTION_RETURN_ERR;
 						}
 
-						size = GetFileSize(hfile, NULL);
+						if (!GetFileSizeEx(hfile, &file_size)) {
+							return PHP_STREAM_OPTION_RETURN_ERR;
+						}
+# if defined(_WIN64)
+						size = file_size.QuadPart;
+# else
+						if (file_size.HighPart) {
+							/* file is too large; process as much as possible */
+							size = SIZE_MAX;
+						} else {
+							size = file_size.LowPart;
+						}
+# endif
 						if (range->offset > size) {
 							range->offset = size;
 						}