win32_common.c: Refactor dll loading
authorEric Biggers <ebiggers3@gmail.com>
Tue, 13 May 2014 19:52:23 +0000 (14:52 -0500)
committerEric Biggers <ebiggers3@gmail.com>
Tue, 13 May 2014 19:55:03 +0000 (14:55 -0500)
include/wimlib/win32_common.h
src/win32_apply.c
src/win32_common.c

index 5e108ec..dfc98e6 100644 (file)
@@ -32,19 +32,9 @@ extern HANDLE
 win32_open_existing_file(const wchar_t *path, DWORD dwDesiredAccess);
 
 /* Vista and later */
-extern HANDLE (WINAPI *win32func_FindFirstStreamW)(LPCWSTR lpFileName,
-                                                  STREAM_INFO_LEVELS InfoLevel,
-                                                  LPVOID lpFindStreamData,
-                                                  DWORD dwFlags);
-
-/* Vista and later */
-extern BOOL (WINAPI *win32func_FindNextStreamW)(HANDLE hFindStream,
-                                               LPVOID lpFindStreamData);
-
-/* Vista and later */
-extern BOOL (WINAPI *win32func_CreateSymbolicLinkW)(const wchar_t *lpSymlinkFileName,
-                                                   const wchar_t *lpTargetFileName,
-                                                   DWORD dwFlags);
+extern BOOL (WINAPI *func_CreateSymbolicLinkW)(const wchar_t *lpSymlinkFileName,
+                                              const wchar_t *lpTargetFileName,
+                                              DWORD dwFlags);
 
 /* ntdll functions  */
 
index ac0bed0..b357dd8 100644 (file)
@@ -193,7 +193,7 @@ win32_start_extract(const wchar_t *path, struct apply_ctx *ctx)
 
        if (vol_flags & FILE_SUPPORTS_REPARSE_POINTS) {
                ctx->supported_features.reparse_points = 1;
-               if (win32func_CreateSymbolicLinkW)
+               if (func_CreateSymbolicLinkW)
                        ctx->supported_features.symlink_reparse_points = 1;
        }
 
@@ -348,12 +348,12 @@ static int
 win32_create_symlink(const wchar_t *oldpath, const wchar_t *newpath,
                     struct apply_ctx *ctx)
 {
-       if (!(*win32func_CreateSymbolicLinkW)(newpath, oldpath, 0)) {
+       if (!(*func_CreateSymbolicLinkW)(newpath, oldpath, 0)) {
                if (GetLastError() != ERROR_ALREADY_EXISTS)
                        goto error;
                if (!win32_delete_file_wrapper(newpath))
                        goto error;
-               if (!(*win32func_CreateSymbolicLinkW)(newpath, oldpath, 0))
+               if (!(*func_CreateSymbolicLinkW)(newpath, oldpath, 0))
                        goto error;
        }
        return 0;
index d6f6888..fa890c1 100644 (file)
@@ -511,9 +511,9 @@ win32_open_existing_file(const wchar_t *path, DWORD dwDesiredAccess)
 /* Pointers to dynamically loaded functions  */
 
 /* kernel32.dll:  Vista and later */
-BOOL (WINAPI *win32func_CreateSymbolicLinkW)(const wchar_t *lpSymlinkFileName,
-                                            const wchar_t *lpTargetFileName,
-                                            DWORD dwFlags);
+BOOL (WINAPI *func_CreateSymbolicLinkW)(const wchar_t *lpSymlinkFileName,
+                                       const wchar_t *lpTargetFileName,
+                                       DWORD dwFlags);
 
 /* ntdll.dll  */
 
@@ -554,10 +554,6 @@ static OSVERSIONINFO windows_version_info = {
        .dwOSVersionInfoSize = sizeof(OSVERSIONINFO),
 };
 
-static HMODULE hKernel32 = NULL;
-
-static HMODULE hNtdll = NULL;
-
 static bool acquired_privileges = false;
 
 bool
@@ -568,32 +564,102 @@ windows_version_is_at_least(unsigned major, unsigned minor)
                 windows_version_info.dwMinorVersion >= minor);
 }
 
-#define NTDLL_SYM(name) { (void **)&func_##name, #name }
-static const struct ntdll_sym {
+struct dll_sym {
        void **func_ptr;
        const char *name;
-} ntdll_syms[] = {
-       NTDLL_SYM(RtlNtStatusToDosError),
-       NTDLL_SYM(NtQueryInformationFile),
-       NTDLL_SYM(NtQuerySecurityObject),
-       NTDLL_SYM(NtQueryDirectoryFile),
-       NTDLL_SYM(NtSetSecurityObject),
-       {NULL, NULL},
+       bool required;
+};
+
+#define DLL_SYM(name, required) { (void **)&func_##name, #name, required }
+
+#define for_each_sym(sym, spec) \
+       for ((sym) = (spec)->syms; (sym)->name; (sym)++)
+
+struct dll_spec {
+       const wchar_t *name;
+       HMODULE handle;
+       const struct dll_sym syms[];
 };
-#undef NTDLL_SYM
+
+struct dll_spec ntdll_spec = {
+       .name = L"ntdll.dll",
+       .syms = {
+               DLL_SYM(RtlNtStatusToDosError, true),
+               DLL_SYM(NtQueryInformationFile, true),
+               DLL_SYM(NtQuerySecurityObject, true),
+               DLL_SYM(NtQueryDirectoryFile, true),
+               DLL_SYM(NtSetSecurityObject, true),
+               DLL_SYM(RtlCreateSystemVolumeInformationFolder, false),
+               {NULL, NULL},
+       },
+};
+
+struct dll_spec kernel32_spec = {
+       .name = L"kernel32.dll",
+       .syms = {
+               DLL_SYM(CreateSymbolicLinkW, false),
+               {NULL, NULL},
+       },
+};
+
+static int
+init_dll(struct dll_spec *spec)
+{
+       const struct dll_sym *sym;
+       void *addr;
+
+       if (!spec->handle)
+               spec->handle = LoadLibrary(spec->name);
+       if (!spec->handle) {
+               for_each_sym(sym, spec) {
+                       if (sym->required) {
+                               ERROR("%ls could not be loaded!", spec->name);
+                               return WIMLIB_ERR_UNSUPPORTED;
+                       }
+               }
+               return 0;
+       }
+       for_each_sym(sym, spec) {
+               addr = (void *)GetProcAddress(spec->handle, sym->name);
+               if (addr) {
+                       *(sym->func_ptr) = addr;
+               } else if (sym->required) {
+                       ERROR("Can't find %s in %ls", sym->name, spec->name);
+                       return WIMLIB_ERR_UNSUPPORTED;
+               }
+       }
+       return 0;
+}
+
+static void
+cleanup_dll(struct dll_spec *spec)
+{
+       const struct dll_sym *sym;
+
+       if (spec->handle) {
+               FreeLibrary(spec->handle);
+               spec->handle = NULL;
+
+               for_each_sym(sym, spec)
+                       *(sym->func_ptr) = NULL;
+       }
+}
 
 /* One-time initialization for Windows capture/apply code.  */
 int
 win32_global_init(int init_flags)
 {
+       int ret;
+
        /* Try to acquire useful privileges.  */
        if (!(init_flags & WIMLIB_INIT_FLAG_DONT_ACQUIRE_PRIVILEGES)) {
+               ret = WIMLIB_ERR_INSUFFICIENT_PRIVILEGES;
                if (!win32_modify_capture_privileges(true))
                        if (init_flags & WIMLIB_INIT_FLAG_STRICT_CAPTURE_PRIVILEGES)
-                               goto insufficient_privileges;
+                               goto out_drop_privs;
                if (!win32_modify_apply_privileges(true))
                        if (init_flags & WIMLIB_INIT_FLAG_STRICT_APPLY_PRIVILEGES)
-                               goto insufficient_privileges;
+                               goto out_drop_privs;
                acquired_privileges = true;
        }
 
@@ -601,38 +667,21 @@ win32_global_init(int init_flags)
        GetVersionEx(&windows_version_info);
 
        /* Try to dynamically load some functions.  */
-       if (hKernel32 == NULL)
-               hKernel32 = LoadLibrary(L"Kernel32.dll");
+       ret = init_dll(&kernel32_spec);
+       if (ret)
+               goto out_drop_privs;
 
-       if (hKernel32) {
-               win32func_CreateSymbolicLinkW =
-                       (void *)GetProcAddress(hKernel32, "CreateSymbolicLinkW");
-       }
+       ret = init_dll(&ntdll_spec);
+       if (ret)
+               goto out_cleanup_kernel32;
 
-       if (hNtdll == NULL)
-               hNtdll = LoadLibrary(L"ntdll.dll");
-
-       if (!hNtdll) {
-               ERROR("ntdll.dll could not be loaded!");
-               return WIMLIB_ERR_UNSUPPORTED;
-       }
-
-       for (const struct ntdll_sym *sym = ntdll_syms; sym->name; sym++) {
-               void *addr = (void *)GetProcAddress(hNtdll, sym->name);
-               if (!addr) {
-                       ERROR("Can't find %s() in ntdll.dll", sym->name);
-                       return WIMLIB_ERR_UNSUPPORTED;
-               }
-               *(sym->func_ptr) = addr;
-       }
-
-       func_RtlCreateSystemVolumeInformationFolder =
-               (void *)GetProcAddress(hNtdll, "RtlCreateSystemVolumeInformationFolder");
        return 0;
 
-insufficient_privileges:
+out_cleanup_kernel32:
+       cleanup_dll(&kernel32_spec);
+out_drop_privs:
        win32_release_capture_and_apply_privileges();
-       return WIMLIB_ERR_INSUFFICIENT_PRIVILEGES;
+       return ret;
 }
 
 void
@@ -640,18 +689,9 @@ win32_global_cleanup(void)
 {
        if (acquired_privileges)
                win32_release_capture_and_apply_privileges();
-       if (hKernel32 != NULL) {
-               FreeLibrary(hKernel32);
-               win32func_CreateSymbolicLinkW = NULL;
-               hKernel32 = NULL;
-       }
-       if (hNtdll != NULL) {
-               FreeLibrary(hNtdll);
-               for (const struct ntdll_sym *sym = ntdll_syms; sym->name; sym++)
-                       *(sym->func_ptr) = NULL;
-               func_RtlCreateSystemVolumeInformationFolder = NULL;
-               hNtdll = NULL;
-       }
+
+       cleanup_dll(&kernel32_spec);
+       cleanup_dll(&ntdll_spec);
 }
 
 #endif /* __WIN32__ */