the other day i typoed something and fed a directory to `got patch'
instead of a file; that made got segfault.  (in this case it's pledge
that doesn't allow to send directory fds.)

in theory 'got patch' should work (sometimes) when fed with a fifo:
got-read-patch needs to do some seeking, but often the buffering of
FILEs has us covered.  i guess it's not that important thought.

diff /home/op/w/got
commit - 10a16316a03005a07c45b2bbf1b5644b64e846fb
path + /home/op/w/got
blob - 426fe05030db9048691647f7a8580d916d95ab60
file + got/got.c
--- got/got.c
+++ got/got.c
@@ -7941,6 +7941,7 @@ cmd_patch(int argc, char *argv[])
 	const struct got_error *error = NULL, *close_error = NULL;
 	struct got_worktree *worktree = NULL;
 	struct got_repository *repo = NULL;
+	struct stat sb;
 	const char *errstr;
 	char *cwd = NULL;
 	int ch, nop = 0, strip = -1, reverse = 0;
@@ -7980,6 +7981,14 @@ cmd_patch(int argc, char *argv[])
 			error = got_error_from_errno2("open", argv[0]);
 			return error;
 		}
+		if (fstat(patchfd, &sb) == -1) {
+			error = got_error_from_errno2("fstat", argv[0]);
+			goto done;
+		}
+		if (!S_ISREG(sb.st_mode)) {
+			error = got_error_path(argv[0], GOT_ERR_BAD_FILETYPE);
+			goto done;
+		}
 	} else
 		usage_patch();