From 3de55006728b87f8cae7364fc08f539579b18414 Mon Sep 17 00:00:00 2001
From: Jeremy Drake <github@jdrake.com>
Date: Thu, 30 Jan 2025 14:39:18 -0800
Subject: [PATCH] fixup! Instead of creating Cygwin symlinks, use deep copy by
 default

Don't attempt to recurse into directory symlinks, but instead copy them
as symlinks.

The COPY_FILE_DIRECTORY flag is documented as only supported on Windows
10 build 19041 and later, but without it copying a directory symlink
fails anyway.
---
 winsup/cygwin/path.cc | 58 +++++++++++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 21 deletions(-)

diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index 23e02fb565..7722ad86f2 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -1735,6 +1735,7 @@ recursiveCopy (PUNICODE_STRING src, PUNICODE_STRING dst, PCWSTR origpath)
   findfiles = FindNextFileW (dH, &dHfile);
   while (findfiles)
     {
+      bool isdirlink = false;
       /* Append the directory item filename to both source and destination */
       debug_printf ("dHfile(3): %W", dHfile.cFileName);
       src->Length = srcpos + sizeof (WCHAR);
@@ -1742,25 +1743,34 @@ recursiveCopy (PUNICODE_STRING src, PUNICODE_STRING dst, PCWSTR origpath)
       RtlAppendUnicodeToString (src, dHfile.cFileName);
       RtlAppendUnicodeToString (dst, dHfile.cFileName);
       debug_printf ("%S -> %S", src, dst);
-      if (dHfile.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
-        {
-          /* Recurse into the child directory */
-          debug_printf ("%S <-> %W", src, origpath);
+      if ((dHfile.dwFileAttributes &
+	    (FILE_ATTRIBUTE_DIRECTORY|FILE_ATTRIBUTE_REPARSE_POINT)) ==
+	  (FILE_ATTRIBUTE_DIRECTORY|FILE_ATTRIBUTE_REPARSE_POINT))
+	{
+	  /* this sucks hard */
+	  path_conv pc (src, PC_SYM_NOFOLLOW|PC_SYM_NOFOLLOW_REP);
+	  isdirlink = pc.issymlink ();
+	}
+      if ((dHfile.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) && !isdirlink)
+	{
+	  /* Recurse into the child directory */
+	  debug_printf ("%S <-> %W", src, origpath);
 	  // avoids endless recursion
-          if (wcsncmp (src->Buffer, origpath, src->Length / sizeof (WCHAR)))
-            if (recursiveCopy (src, dst, origpath))
-              goto done;
-        }
+	  if (wcsncmp (src->Buffer, origpath, src->Length / sizeof (WCHAR)))
+	    if (recursiveCopy (src, dst, origpath))
+	      goto done;
+	}
       else
-        {
-          /* Just copy the file */
-          if (!CopyFileExW (src->Buffer, dst->Buffer, NULL, NULL, NULL,
-			    COPY_FILE_COPY_SYMLINK))
-            {
-              __seterrno ();
-              goto done;
-            }
-        }
+	{
+	  /* Just copy the file */
+	  if (!CopyFileExW (src->Buffer, dst->Buffer, NULL, NULL, NULL,
+			    COPY_FILE_COPY_SYMLINK|
+			    (isdirlink ? COPY_FILE_DIRECTORY : 0)))
+	    {
+	      __seterrno ();
+	      goto done;
+	    }
+	}
       findfiles = FindNextFileW (dH, &dHfile);
     }
   if (GetLastError() != ERROR_NO_MORE_FILES)
@@ -2314,7 +2324,7 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 	}
       else /* wsym_type == WSYM_sysfile */
 	{
-          if (wsym_type == WSYM_deepcopy)
+	  if (wsym_type == WSYM_deepcopy)
 	    {
 	      path_conv win32_oldpath;
 	      /* The symlink target is relative to the directory in which the
@@ -2341,7 +2351,7 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 		  __leave;
 		}
 	      if (!win32_oldpath.isspecial ())
-	        {
+		{
 		  /* MSYS copy file instead make symlink */
 		  /* As a MSYS limitation, the source path must exist. */
 		  if (!win32_oldpath.exists ())
@@ -2361,7 +2371,7 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 		      PWCHAR origpath =
 			win32_oldpath.get_wide_win32_path (tp.w_get ());
 		      /* we need a larger UNICODE_STRING MaximumLength than
-		         get_nt_native_path allocates for the recursive copy */
+			 get_nt_native_path allocates for the recursive copy */
 		      UNICODE_STRING u_oldpath, u_newpath;
 		      RtlCopyUnicodeString (tp.u_get (&u_oldpath), w_oldpath);
 		      RtlCopyUnicodeString (tp.u_get (&u_newpath), w_newpath);
@@ -2369,9 +2379,15 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 		    }
 		  else
 		    {
+		      /* I don't know if there's a better way to know this */
+		      DWORD attr = getfileattr (win32_oldpath.get_win32 (),
+					  win32_oldpath.obcaseinsensitive ());
+		      bool isdirlink = attr != INVALID_FILE_ATTRIBUTES &&
+					(attr & FILE_ATTRIBUTE_DIRECTORY);
 		      if (!CopyFileExW (w_oldpath->Buffer, w_newpath->Buffer,
 					NULL, NULL, NULL,
-					COPY_FILE_COPY_SYMLINK))
+					COPY_FILE_COPY_SYMLINK|
+					(isdirlink ? COPY_FILE_DIRECTORY : 0)))
 			{
 			  __seterrno ();
 			}