Re: [PATCH] Cygwin: Make native clipboard layout same for 32- and 64-bit

[Ken Brown <kbrown@cornell.edu>]

On 10/8/2021 5:52 AM, Takashi Yano wrote:
> How about simply just:
> 
> diff --git a/winsup/cygwin/fhandler_clipboard.cc b/winsup/cygwin/fhandler_clipboard.cc
> index ccdb295f3..d822f4fc4 100644
> --- a/winsup/cygwin/fhandler_clipboard.cc
> +++ b/winsup/cygwin/fhandler_clipboard.cc
> @@ -28,9 +28,10 @@ static const WCHAR *CYGWIN_NATIVE = L"CYGWIN_NATIVE_CLIPBOARD";
>   
>   typedef struct
>   {
> -  timestruc_t	timestamp;
> -  size_t	len;
> -  char		data[1];
> +  uint64_t tv_sec;
> +  uint64_t tv_nsec;
> +  uint64_t len;
> +  char data[1];
>   } cygcb_t;

The only problem with this is that it might leave readers scratching their heads 
unless they look at the commit that introduced this.  What about something like 
the following, in which the code speaks for itself:

diff --git a/winsup/cygwin/fhandler_clipboard.cc 
b/winsup/cygwin/fhandler_clipboard.cc
index ccdb295f3..028c00f1e 100644
--- a/winsup/cygwin/fhandler_clipboard.cc
+++ b/winsup/cygwin/fhandler_clipboard.cc
@@ -26,12 +26,26 @@ details. */

  static const WCHAR *CYGWIN_NATIVE = L"CYGWIN_NATIVE_CLIPBOARD";

+#ifdef __x86_64__
  typedef struct
  {
    timestruc_t  timestamp;
    size_t       len;
    char         data[1];
  } cygcb_t;
+#else
+/* Use same layout. */
+typedef struct
+{
+  struct
+  {
+    int64_t tv_sec;
+    int64_t tv_nsec;
+  }            timestamp;
+  uint64_t     len;
+  char         data[1];
+} cygcb_t;
+#endif

  fhandler_dev_clipboard::fhandler_dev_clipboard ()
    : fhandler_base (), pos (0), membuffer (NULL), msize (0)
@@ -74,7 +88,14 @@ fhandler_dev_clipboard::set_clipboard (const void *buf, 
size_t len)
         }
        clipbuf = (cygcb_t *) GlobalLock (hmem);

+#ifdef __x86_64__
        clock_gettime (CLOCK_REALTIME, &clipbuf->timestamp);
+#else
+      timestruc_t ts;
+      clock_gettime (CLOCK_REALTIME, &ts);
+      clipbuf->timestamp->tv_sec = ts.tv_sec;
+      clipbuf->timestamp->tv_nsec = ts.tv_nsec;
+#endif
        clipbuf->len = len;
        memcpy (clipbuf->data, buf, len);

@@ -179,7 +200,14 @@ fhandler_dev_clipboard::fstat (struct stat *buf)
           && (hglb = GetClipboardData (format))
           && (clipbuf = (cygcb_t *) GlobalLock (hglb)))
         {
+#ifdef __x86_64__
           buf->st_atim = buf->st_mtim = clipbuf->timestamp;
+#else
+         timestruc_t ts;
+         ts.tv_sec = clipbuf->timestamp->tv_sec;
+         ts.tv_nsec = clipbuf->timestamp->tv_nsec;
+         buf->st_atim = buf->st_mtim = ts;
+#endif
           buf->st_size = clipbuf->len;
           GlobalUnlock (hglb);
         }

Ken