fixup! Instead of creating Cygwin symlinks, use deep copy by default

Factor out deepcopy symlink to its own worker function, like wsl,
native, and nfs.  Move it up into the beginning switch with them, so the
fallback behavior is more obvious.  See also msys2#113/msys2#114.

Author: jeremyd2019

winsup/cygwin/path.cc

@@ -2156,6 +2156,77 @@ symlink_wsl (const char *oldpath, path_conv &win32_newpath)
   return 0;
 }
 
+int
+symlink_deepcopy (const char *oldpath, path_conv &win32_newpath)
+{
+  path_conv win32_oldpath;
+  /* The symlink target is relative to the directory in which the
+     symlink gets created, not relative to the cwd.  Therefore we
+     have to mangle the path quite a bit before calling path_conv.*/
+  mangle_symlink_target (oldpath, win32_newpath, win32_oldpath);
+  if (win32_oldpath.error)
+    {
+      set_errno (win32_oldpath.error);
+      return -1;
+    }
+  if (win32_oldpath.isspecial ())
+    return -2;
+
+  /* MSYS copy file instead make symlink */
+  /* As a MSYS limitation, the source path must exist. */
+  if (!win32_oldpath.exists ())
+    {
+      set_errno (ENOENT);
+      return -1;
+    }
+
+  PUNICODE_STRING w_oldpath = win32_oldpath.get_nt_native_path ();
+  PUNICODE_STRING w_newpath = win32_newpath.get_nt_native_path ();
+  if (w_oldpath->Buffer[1] == L'?')
+    w_oldpath->Buffer[1] = L'\\';
+  if (w_newpath->Buffer[1] == L'?')
+    w_newpath->Buffer[1] = L'\\';
+  if (win32_oldpath.isdir ())
+    {
+      /* we need a larger UNICODE_STRING MaximumLength than
+	 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);
+      return recursiveCopy (&u_oldpath, &u_newpath,
+			    u_oldpath.Length, u_newpath.Length);
+    }
+  else
+    {
+      bool isdirlink = false;
+      if (win32_oldpath.issymlink () &&
+	  win32_oldpath.is_known_reparse_point ())
+	{
+	  /* Is there a better way to know this? */
+	  DWORD attr = getfileattr (win32_oldpath.get_win32 (),
+				    !!win32_oldpath.objcaseinsensitive ());
+	  if (attr == INVALID_FILE_ATTRIBUTES)
+	    {
+	      __seterrno ();
+	      return -1;
+	    }
+	  isdirlink = attr & FILE_ATTRIBUTE_DIRECTORY;
+	}
+      if (!CopyFileExW (w_oldpath->Buffer, w_newpath->Buffer,
+			NULL, NULL, NULL,
+			COPY_FILE_COPY_SYMLINK|
+			(isdirlink ? COPY_FILE_DIRECTORY : 0)))
+	{
+	  __seterrno ();
+	  return -1;
+	}
+      else
+	{
+	  return 0;
+	}
+    }
+}
+
 int
 symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 {
@@ -2223,6 +2294,13 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 	case WSYM_nfs:
 	  res = symlink_nfs (oldpath, win32_newpath);
 	  __leave;
+	case WSYM_deepcopy:
+	  res = symlink_deepcopy (oldpath, win32_newpath);
+	  if (!res || res == -1)
+	    __leave;
+	  /* fall back to default symlink type */
+	  wsym_type = WSYM_default;
+	  goto handle_default;
 	case WSYM_native:
 	case WSYM_nativestrict:
 	  res = symlink_native (oldpath, win32_newpath);
@@ -2239,6 +2317,7 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 	  wsym_type = WSYM_default;
 	  fallthrough;
 	case WSYM_default:
+ handle_default:
 	  if (win32_newpath.fs_flags () & FILE_SUPPORTS_REPARSE_POINTS)
 	    {
 	      res = symlink_wsl (oldpath, win32_newpath);
@@ -2375,79 +2454,8 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice)
 		  * sizeof (WCHAR);
 	  cp += *plen;
 	}
-      else
+      else /* wsym_type == WSYM_sysfile */
 	{
-	  if (wsym_type == WSYM_deepcopy)
-	    {
-	      path_conv win32_oldpath;
-	      /* The symlink target is relative to the directory in which the
-		 symlink gets created, not relative to the cwd.  Therefore we
-		 have to mangle the path quite a bit before calling path_conv.*/
-	      mangle_symlink_target (oldpath, win32_newpath, win32_oldpath);
-	      if (win32_oldpath.error)
-		{
-		  set_errno (win32_oldpath.error);
-		  __leave;
-		}
-	      if (!win32_oldpath.isspecial ())
-		{
-		  /* MSYS copy file instead make symlink */
-		  /* As a MSYS limitation, the source path must exist. */
-		  if (!win32_oldpath.exists ())
-		    {
-		      set_errno (ENOENT);
-		      __leave;
-		    }
-
-		  PUNICODE_STRING w_oldpath = win32_oldpath.get_nt_native_path ();
-		  PUNICODE_STRING w_newpath = win32_newpath.get_nt_native_path ();
-		  if (w_oldpath->Buffer[1] == L'?')
-		    w_oldpath->Buffer[1] = L'\\';
-		  if (w_newpath->Buffer[1] == L'?')
-		    w_newpath->Buffer[1] = L'\\';
-		  if (win32_oldpath.isdir ())
-		    {
-		      /* we need a larger UNICODE_STRING MaximumLength than
-			 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);
-		      res = recursiveCopy (&u_oldpath, &u_newpath,
-					   u_oldpath.Length, u_newpath.Length);
-		    }
-		  else
-		    {
-		      bool isdirlink = false;
-		      if (win32_oldpath.issymlink () &&
-			  win32_oldpath.is_known_reparse_point ())
-		        {
-			  /* Is there a better way to know this? */
-			  DWORD attr = getfileattr (win32_oldpath.get_win32 (),
-					!!win32_oldpath.objcaseinsensitive ());
-			  if (attr == INVALID_FILE_ATTRIBUTES)
-			    {
-			      __seterrno ();
-			      __leave;
-			    }
-			  isdirlink = attr & FILE_ATTRIBUTE_DIRECTORY;
-			}
-		      if (!CopyFileExW (w_oldpath->Buffer, w_newpath->Buffer,
-					NULL, NULL, NULL,
-					COPY_FILE_COPY_SYMLINK|
-					(isdirlink ? COPY_FILE_DIRECTORY : 0)))
-			{
-			  __seterrno ();
-			}
-		      else
-			{
-			  res = 0;
-			}
-		    }
-		  __leave;
-		}
-	    }
-
-	  /* wsym_type == WSYM_sysfile */
 	  /* Default technique creating a symlink. */
 	  buf = tp.t_get ();
 	  cp = stpcpy (buf, SYMLINK_COOKIE);