Try to detect and remove stale sockets when dtach -A is used. Be

paranoid about this, and only remove the specified file if connect says
the connection was refused and stat says the file is a socket.

Also dtach -A now only tries to create the socket if the connection was
refused or the socket did not exist, instead of on any random error as
before.

1 files changed, 12 insertions, 0 deletions

diff --git a/attach.c b/attach.c
index ece56db..9db3882 100644
--- a/attach.c
+++ b/attach.c
@@ -60,6 +60,18 @@ connect_socket(char *name)
 	if (connect(s, (struct sockaddr*)&sockun, sizeof(sockun)) < 0)
 	{
 		close(s);
+
+		/* ECONNREFUSED is also returned for regular files, so make
+		** sure we are trying to connect to a socket. */
+		if (errno == ECONNREFUSED)
+		{
+			struct stat st;
+
+			if (stat(name, &st) < 0)
+				return -1;
+			else if (!S_ISSOCK(st.st_mode) || S_ISREG(st.st_mode))
+				errno = ENOTSOCK;
+		}
 		return -1;
 	}
 	return s;