Merge pull request #1594 from emekoi/master

added dynamic library loading for windows

std/dynamic_library.zig

@@ -1,10 +1,23 @@
+const builtin = @import("builtin");
+const Os = builtin.Os;
+
 const std = @import("index.zig");
 const mem = std.mem;
-const elf = std.elf;
 const cstr = std.cstr;
-const linux = std.os.linux;
+const os = std.os;
+const assert = std.debug.assert;
+const elf = std.elf;
+const linux = os.linux;
+const windows = os.windows;
+const win_util = @import("os/windows/util.zig");
 
-pub const DynLib = struct {
+pub const DynLib = switch (builtin.os) {
+    Os.linux => LinuxDynLib,
+    Os.windows => WindowsDynLib,
+    else => void,
+};
+
+pub const LinuxDynLib = struct {
     allocator: *mem.Allocator,
     elf_lib: ElfLib,
     fd: i32,
@@ -107,7 +120,7 @@ pub const ElfLib = struct {
             }
         }
 
-        return ElfLib{
+        return ElfLib {
             .base = base,
             .strings = maybe_strings orelse return error.ElfStringSectionNotFound,
             .syms = maybe_syms orelse return error.ElfSymSectionNotFound,
@@ -154,3 +167,48 @@ fn checkver(def_arg: *elf.Verdef, vsym_arg: i32, vername: []const u8, strings: [
     const aux = @intToPtr(*elf.Verdaux, @ptrToInt(def) + def.vd_aux);
     return mem.eql(u8, vername, cstr.toSliceConst(strings + aux.vda_name));
 }
+
+pub const WindowsDynLib = struct {
+    allocator: *mem.Allocator,
+    dll: windows.HMODULE,
+
+    pub fn open(allocator: *mem.Allocator, path: []const u8) !WindowsDynLib {
+        const wpath = try win_util.sliceToPrefixedFileW(path);
+        
+        return WindowsDynLib {
+            .allocator = allocator,
+            .dll = windows.LoadLibraryW(&wpath) orelse {
+                const err = windows.GetLastError();
+                switch (err) {
+                    windows.ERROR.FILE_NOT_FOUND => return error.FileNotFound,
+                    windows.ERROR.PATH_NOT_FOUND => return error.FileNotFound,
+                    windows.ERROR.MOD_NOT_FOUND => return error.FileNotFound,
+                    else => return os.unexpectedErrorWindows(err),
+                }
+            },
+        };
+    }
+
+    pub fn close(self: *WindowsDynLib) void {
+        assert(windows.FreeLibrary(self.dll) != 0);
+        self.* = undefined;
+    }
+
+    pub fn lookup(self: *WindowsDynLib, name: []const u8) ?usize {
+        return @ptrToInt(windows.GetProcAddress(self.dll, name.ptr));
+    }
+};
+
+test "dynamic_library" {
+    const libname = switch (builtin.os) {
+        Os.linux => "invalid_so.so",
+        Os.windows => "invalid_dll.dll",
+        else => return;,
+    };
+
+    const dynlib = DynLib.open(std.debug.global_allocator, libname) catch |err| {
+        assert(err == error.FileNotFound);
+        return;
+    };
+    @panic("Expected error from function");
+}

std/os/index.zig

@@ -58,8 +58,6 @@ pub const windowsWrite = windows_util.windowsWrite;
 pub const windowsIsCygwinPty = windows_util.windowsIsCygwinPty;
 pub const windowsOpen = windows_util.windowsOpen;
 pub const windowsOpenW = windows_util.windowsOpenW;
-pub const windowsLoadDll = windows_util.windowsLoadDll;
-pub const windowsUnloadDll = windows_util.windowsUnloadDll;
 pub const createWindowsEnvBlock = windows_util.createWindowsEnvBlock;
 
 pub const WindowsCreateIoCompletionPortError = windows_util.WindowsCreateIoCompletionPortError;

std/os/windows/index.zig

@@ -24,6 +24,7 @@ pub const HANDLE = *c_void;
 pub const HCRYPTPROV = ULONG_PTR;
 pub const HINSTANCE = *@OpaqueType();
 pub const HMODULE = *@OpaqueType();
+pub const FARPROC = *@OpaqueType();
 pub const INT = c_int;
 pub const LPBYTE = *BYTE;
 pub const LPCH = *CHAR;

std/os/windows/kernel32.zig

@@ -178,6 +178,8 @@ pub extern "kernel32" stdcallcc fn WriteFileEx(hFile: HANDLE, lpBuffer: [*]const
 
 pub extern "kernel32" stdcallcc fn LoadLibraryW(lpLibFileName: [*]const u16) ?HMODULE;
 
+pub extern "kernel32" stdcallcc fn GetProcAddress(hModule: HMODULE, lpProcName: [*]const u8) ?FARPROC;
+
 pub extern "kernel32" stdcallcc fn FreeLibrary(hModule: HMODULE) BOOL;
 
 pub const FILE_NOTIFY_INFORMATION = extern struct {

std/os/windows/util.zig

@@ -188,37 +188,6 @@ pub fn createWindowsEnvBlock(allocator: *mem.Allocator, env_map: *const BufMap)
     return allocator.shrink(u16, result, i);
 }
 
-pub fn windowsLoadDllW(dll_path_w: [*]const u16) !windows.HMODULE {
-    return windows.LoadLibraryW(dll_path_w) orelse {
-        const err = windows.GetLastError();
-        switch (err) {
-            windows.ERROR.FILE_NOT_FOUND => return error.FileNotFound,
-            windows.ERROR.PATH_NOT_FOUND => return error.FileNotFound,
-            windows.ERROR.MOD_NOT_FOUND => return error.FileNotFound,
-            else => return os.unexpectedErrorWindows(err),
-        }
-    };
-}
-
-pub fn windowsLoadDll(dll_path: []const u8) !windows.HMODULE {
-    const dll_path_w = try sliceToPrefixedFileW(dll_path);
-    return windowsLoadDllW(&dll_path_w);
-}
-
-pub fn windowsUnloadDll(hModule: windows.HMODULE) void {
-    assert(windows.FreeLibrary(hModule) != 0);
-}
-
-test "InvalidDll" {
-    if (builtin.os != builtin.Os.windows) return error.SkipZigTest;
-
-    const handle = os.windowsLoadDll("asdf.dll") catch |err| {
-        assert(err == error.FileNotFound);
-        return;
-    };
-    @panic("Expected error from function");
-}
-
 pub fn windowsFindFirstFile(
     dir_path: []const u8,
     find_file_data: *windows.WIN32_FIND_DATAW,