Re: [PATCH] gettimeofday: do not use LoadLibrary when built for Windows Store apps

[Bruno Haible]

Hi,

Steve Lhomme wrote:
> LoadLibrary is forbidden in such apps (can only load DLLs from within the app
> package).
> The API entries are available to all apps linking with the Windows API as 
> found
> here:
> https://docs.microsoft.com/en-us/uwp/win32-and-com/win32-apis

Thanks for these infos.

> +#if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) && _WIN32_WINNT >= 
> 0x0A00 /* _WIN32_WINNT_WIN10 */

The GetSystemTimePreciseAsFileTime function is available starting with Windows 
8,
therefore
  - the condition with WINAPI_FAMILY_PARTITION is not necessary,
  - the condition _WIN32_WINNT >= 0x0A00 is overly restrictive;
    _WIN32_WINNT >= _WIN32_WINNT_WIN8 will work just as well.

I have added a page about the native Windows APIs at
https://gitlab.com/ghwiki/gnow-how/-/wikis/Platforms/Native_Windows

Then here is a patch to avoid LoadLibrary when possible.


2020-05-28  Bruno Haible  <bruno@clisp.org>

        Avoid dynamic loading of Windows API functions when possible.
        Reported by Steve Lhomme <robux4@ycbcr.xyz> in
        <https://lists.gnu.org/archive/html/bug-gnulib/2020-05/msg00182.html>.
        * lib/gettimeofday.c (GetProcAddress,
        GetSystemTimePreciseAsFileTimeFuncType,
        GetSystemTimePreciseAsFileTimeFunc, initialized, initialize): Don't
        define in a build for Windows 8 or higher.
        * lib/isatty.c (GetProcAddress, GetNamedPipeClientProcessIdFuncType,
        GetNamedPipeClientProcessIdFunc, QueryFullProcessImageNameFuncType,
        QueryFullProcessImageNameFunc, initialized, initialize): Don't define
        in a build for Windows Vista or higher.
        * lib/stat-w32.c (GetProcAddress, GetFileInformationByHandleExFuncType,
        GetFileInformationByHandleExFunc, GetFinalPathNameByHandleFuncType,
        GetFinalPathNameByHandleFunc, initialized, initialize): Likewise.

diff --git a/lib/gettimeofday.c b/lib/gettimeofday.c
index 1980479..3d53115 100644
--- a/lib/gettimeofday.c
+++ b/lib/gettimeofday.c
@@ -33,9 +33,11 @@
 
 #ifdef WINDOWS_NATIVE
 
+# if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8)
+
 /* Avoid warnings from gcc -Wcast-function-type.  */
-# define GetProcAddress \
-   (void *) GetProcAddress
+#  define GetProcAddress \
+    (void *) GetProcAddress
 
 /* GetSystemTimePreciseAsFileTime was introduced only in Windows 8.  */
 typedef void (WINAPI * GetSystemTimePreciseAsFileTimeFuncType) (FILETIME 
*lpTime);
@@ -54,6 +56,8 @@ initialize (void)
   initialized = TRUE;
 }
 
+# endif
+
 #endif
 
 /* This is a wrapper for gettimeofday.  It is used only on systems
@@ -84,8 +88,10 @@ gettimeofday (struct timeval *restrict tv, void *restrict tz)
      <http://www.windowstimestamp.com/description>.  */
   FILETIME current_time;
 
+# if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8)
   if (!initialized)
     initialize ();
+# endif
   if (GetSystemTimePreciseAsFileTimeFunc != NULL)
     GetSystemTimePreciseAsFileTimeFunc (&current_time);
   else
diff --git a/lib/isatty.c b/lib/isatty.c
index 6cdc0fb..fc771d1 100644
--- a/lib/isatty.c
+++ b/lib/isatty.c
@@ -39,9 +39,11 @@
 # include <io.h>
 #endif
 
+#if !(_WIN32_WINNT >= _WIN32_WINNT_VISTA)
+
 /* Avoid warnings from gcc -Wcast-function-type.  */
-#define GetProcAddress \
-  (void *) GetProcAddress
+# define GetProcAddress \
+   (void *) GetProcAddress
 
 /* GetNamedPipeClientProcessId was introduced only in Windows Vista.  */
 typedef BOOL (WINAPI * GetNamedPipeClientProcessIdFuncType) (HANDLE hPipe,
@@ -69,6 +71,8 @@ initialize (void)
   initialized = TRUE;
 }
 
+#endif
+
 static BOOL IsConsoleHandle (HANDLE h)
 {
   DWORD mode;
@@ -84,8 +88,10 @@ static BOOL IsCygwinConsoleHandle (HANDLE h)
   BOOL result = FALSE;
   ULONG processId;
 
+#if !(_WIN32_WINNT >= _WIN32_WINNT_VISTA)
   if (!initialized)
     initialize ();
+#endif
 
   /* GetNamedPipeClientProcessId
      
<https://docs.microsoft.com/en-us/windows/desktop/api/winbase/nf-winbase-getnamedpipeclientprocessid>
diff --git a/lib/stat-w32.c b/lib/stat-w32.c
index b9163f5..02ad9ab 100644
--- a/lib/stat-w32.c
+++ b/lib/stat-w32.c
@@ -40,18 +40,20 @@
 #include "pathmax.h"
 #include "verify.h"
 
+#if !(_WIN32_WINNT >= _WIN32_WINNT_VISTA)
+
 /* Avoid warnings from gcc -Wcast-function-type.  */
-#define GetProcAddress \
-  (void *) GetProcAddress
+# define GetProcAddress \
+   (void *) GetProcAddress
 
-#if _GL_WINDOWS_STAT_INODES == 2
+# if _GL_WINDOWS_STAT_INODES == 2
 /* GetFileInformationByHandleEx was introduced only in Windows Vista.  */
 typedef DWORD (WINAPI * GetFileInformationByHandleExFuncType) (HANDLE hFile,
                                                                
FILE_INFO_BY_HANDLE_CLASS fiClass,
                                                                LPVOID lpBuffer,
                                                                DWORD 
dwBufferSize);
 static GetFileInformationByHandleExFuncType GetFileInformationByHandleExFunc = 
NULL;
-#endif
+# endif
 /* GetFinalPathNameByHandle was introduced only in Windows Vista.  */
 typedef DWORD (WINAPI * GetFinalPathNameByHandleFuncType) (HANDLE hFile,
                                                            LPSTR lpFilePath,
@@ -66,16 +68,18 @@ initialize (void)
   HMODULE kernel32 = LoadLibrary ("kernel32.dll");
   if (kernel32 != NULL)
     {
-#if _GL_WINDOWS_STAT_INODES == 2
+# if _GL_WINDOWS_STAT_INODES == 2
       GetFileInformationByHandleExFunc =
         (GetFileInformationByHandleExFuncType) GetProcAddress (kernel32, 
"GetFileInformationByHandleEx");
-#endif
+# endif
       GetFinalPathNameByHandleFunc =
         (GetFinalPathNameByHandleFuncType) GetProcAddress (kernel32, 
"GetFinalPathNameByHandleA");
     }
   initialized = TRUE;
 }
 
+#endif
+
 /* Converts a FILETIME to GMT time since 1970-01-01 00:00:00.  */
 #if _GL_WINDOWS_STAT_TIMESPEC
 struct timespec
@@ -134,8 +138,10 @@ _gl_fstat_by_handle (HANDLE h, const char *path, struct 
stat *buf)
   DWORD type = GetFileType (h);
   if (type == FILE_TYPE_DISK)
     {
+#if !(_WIN32_WINNT >= _WIN32_WINNT_VISTA)
       if (!initialized)
         initialize ();
+#endif
 
       /* st_mode can be determined through
          GetFileAttributesEx