FFI: support symbol lookup without specifying lib on Windows

This works similar to `dlsym(RTLD_DEFAULT, …)` with the caveat that
symbols on Windows may not be unique, and are usually qualified by the
module they are exported from.  That means that wrong symbols may be
fetched, potentially causing serious issues; therefore this usage is
not recommended for production purposes, but is a nice simplification
for quick experiments and the ext/ffi test suite.

Closes phpGH-16351.

Author: cmb69

UPGRADING

@@ -116,6 +116,11 @@ PHP 8.5 UPGRADE NOTES
   PHP_RELEASE_VERSION are now always numbers.  Previously, they have been
   strings for buildconf builds.
 
+* FFI:
+  . It is no longer necessary to specify the library when using FFI::cdef()
+    and FFI::load(). However, this convenience feature should not be used in
+    production.
+
 ========================================
 13. Other Changes
 ========================================

ext/ffi/ffi.c

@@ -2974,6 +2974,40 @@ static zend_always_inline bool zend_ffi_validate_api_restriction(zend_execute_da
 		} \
 	} while (0)
 
+#ifdef PHP_WIN32
+# ifndef DWORD_MAX
+#  define DWORD_MAX ULONG_MAX
+# endif
+# define NUM_MODULES 1024
+/* A rough approximation of dlysm(RTLD_DEFAULT) */
+static void *dlsym_loaded(char *symbol)
+{
+	HMODULE modules_static[NUM_MODULES], *modules = modules_static;
+	DWORD num = NUM_MODULES, i;
+	void * addr;
+	if (!EnumProcessModules(GetCurrentProcess(), modules, num * sizeof(HMODULE), &num)) {
+		return NULL;
+	}
+	if (num >= NUM_MODULES && num <= DWORD_MAX / sizeof(HMODULE)) {
+		modules = emalloc(num *sizeof(HMODULE));
+		if (!EnumProcessModules(GetCurrentProcess(), modules, num * sizeof(HMODULE), &num)) {
+			efree(modules);
+			return NULL;
+		}
+	}
+	for (i = 0; i < num; i++) {
+		addr = GetProcAddress(modules[i], symbol);
+		if (addr != NULL) break;
+	}
+	if (modules != modules_static) {
+		efree(modules);
+	}
+	return addr;
+}
+# undef DL_FETCH_SYMBOL
+# define DL_FETCH_SYMBOL(h, s) (h == NULL ? dlsym_loaded(s) : GetProcAddress(h, s))
+#endif
+
 ZEND_METHOD(FFI, cdef) /* {{{ */
 {
 	zend_string *code = NULL;

ext/ffi/tests/100.phpt

@@ -3,10 +3,9 @@ FFI 100: PHP symbols
 --EXTENSIONS--
 ffi
 --SKIPIF--
-<?php require_once('utils.inc'); ?>
 <?php
 try {
-    ffi_cdef("extern void *zend_printf;", ffi_get_php_dll_name());
+    FFI::cdef("extern void *zend_printf;");
 } catch (Throwable $e) {
     die('skip PHP symbols not available');
 }
@@ -17,7 +16,7 @@ ffi.enable=1
 <?php
 require_once('utils.inc');
 $fastcall = ffi_get_fastcall_specifier();
-$zend = ffi_cdef("
+$zend = FFI::cdef("
     const char *get_zend_version(void);
     //char *get_zend_version(void);
     extern size_t (*zend_printf)(const char *format, ...);
@@ -26,7 +25,7 @@ $zend = ffi_cdef("
 
     void $fastcall zend_str_tolower(char *str, size_t length);
 
-", ffi_get_php_dll_name());
+");
 var_dump(trim(explode("\n",$zend->get_zend_version())[0]));
 //var_dump(trim(FFI::string($zend->get_zend_version())));
 var_dump($zend->zend_printf);

ext/ffi/tests/101.phpt

@@ -3,10 +3,9 @@ FFI 101: PHP symbols (function address)
 --EXTENSIONS--
 ffi
 --SKIPIF--
-<?php require_once('utils.inc'); ?>
 <?php
 try {
-    ffi_cdef("extern void *zend_printf;", ffi_get_php_dll_name());
+    FFI::cdef("extern void *zend_printf;");
 } catch (Throwable $e) {
     die('skip PHP symbols not available');
 }
@@ -17,7 +16,7 @@ ffi.enable=1
 <?php
 require_once('utils.inc');
 $fastcall = ffi_get_fastcall_specifier();
-$zend = ffi_cdef("
+$zend = FFI::cdef("
     const char *get_zend_version(void);
     //char *get_zend_version(void);
     extern size_t (*zend_printf)(const char *format, ...);
@@ -26,7 +25,7 @@ $zend = ffi_cdef("
 
     void $fastcall zend_str_tolower(char *str, size_t length);
 
-", ffi_get_php_dll_name());
+");
 $f = $zend->get_zend_version;
 var_dump(trim(explode("\n",$f())[0]));
 //var_dump(trim(FFI::string($zend->get_zend_version())));

ext/ffi/tests/200.phpt

@@ -6,7 +6,7 @@ ffi
 <?php require_once('utils.inc'); ?>
 <?php
 try {
-    FFI::cdef("void* zend_write;", ffi_get_php_dll_name());
+    FFI::cdef("void* zend_write;");
 } catch (Throwable $e) {
     die('skip PHP symbols not available');
 }
@@ -20,7 +20,7 @@ require_once('utils.inc');
 $zend = FFI::cdef("
     typedef size_t (*zend_write_func_t)(const char *str, size_t str_length);
     extern zend_write_func_t zend_write;
-", ffi_get_php_dll_name());
+");
 
 echo "Hello World!\n";
 

ext/ffi/tests/300-win32.h.in

@@ -2,8 +2,6 @@
 FFI 301: FFI loading
 --EXTENSIONS--
 ffi
---SKIPIF--
-<?php if (substr(PHP_OS, 0, 3) == 'WIN') die('skip not for Windows'); ?>
 --INI--
 ffi.enable=1
 --FILE--

ext/ffi/tests/301-win32.phpt

@@ -4,9 +4,8 @@ Bug #77632 (FFI function pointers with variadics)
 ffi
 --SKIPIF--
 <?php
-require_once('utils.inc');
 try {
-    FFI::cdef("extern void *zend_printf;", ffi_get_php_dll_name());
+    FFI::cdef("extern void *zend_printf;");
 } catch (Throwable $_) {
     die('skip PHP symbols not available');
 }
@@ -15,8 +14,7 @@ try {
 ffi.enable=1
 --FILE--
 <?php
-require_once('utils.inc');
-$libc = FFI::cdef("extern size_t (*zend_printf)(const char *format, ...);", ffi_get_php_dll_name());
+$libc = FFI::cdef("extern size_t (*zend_printf)(const char *format, ...);");
 $args = ["test from zend_printf\n"];
 ($libc->zend_printf)(...$args);
 $args2 = ["Hello, %s from zend_printf\n", "world"];

ext/ffi/tests/301.phpt

@@ -6,9 +6,8 @@ ffi
 ffi.enable=1
 --FILE--
 <?php
-require_once('utils.inc');
 $def = 'char * __cdecl get_zend_version(void);';
-$ffi = ffi_cdef($def, ffi_get_php_dll_name());
+$ffi = FFI::cdef($def);
 echo substr(FFI::string($ffi->get_zend_version()), 0, 4) . "\n";
 ?>
 --EXPECT--