Reduce footprint of :fd property.

Querying the :fd stream property is equivalent to calling the
stream-fd function. Streams have a C virtual function get_fd,
so implementing :fd in their getprop functions is redundant
functionality.  The stream-getprop function can test for
:fd and call stream-fd, so the stream implementations don't
have to deal with the :fd property.

Also, there are still places in the code base that are using
stream_getprop to get the file descriptor, instead of calling
stream_fd.

If we fix all this, then fd_k remains referenced only in
a very small number of places.

* socket.c (dgram_get_prop): Don't handle :fd any more.

* stream.c (unimpl_get_fd): Static function removed.
(fill_stream_ops): Default the get_fd function to null_get_fd
instead of unimpl_get_fd, so it doesn't throw.
Even a stdio stream don't throw; when the file is closed,
it returns nil.
(stdio_get_prop): Don't handle :fd any more.
(stream_get_prop): Handle :fd here. If the stream has a get_fd
function that isn't null_get_fd, then call it. Only if the
stream doesn't have a get_fd function, fall back on its
get_prop function.

* sysif.c (mkdir_wrap, poll_wrap, simulate_setuid_setgid):
Call stream_fd instead of stream_get_prop.

1 files changed, 3 insertions, 3 deletions

diff --git a/sysif.c b/sysif.c
index dcea7964..4b8f8b29 100644
--- a/sysif.c
+++ b/sysif.c
@@ -303,7 +303,7 @@ static val mkdir_wrap(val path, val mode)
 #if HAVE_CHMOD || HAVE_CHOWN || HAVE_SYS_STAT || HAVE_FILE_STAMP_CHANGE
 static int get_fd(val stream, val self)
 {
-  val fd_in = if3(integerp(stream), stream, stream_get_prop(stream, fd_k));
+  val fd_in = if3(integerp(stream), stream, stream_fd(stream));
 
   if (stream && !fd_in)
     uw_throwf(file_error_s,
@@ -1326,7 +1326,7 @@ static val poll_wrap(val poll_list, val timeout_in)
       break;
     case COBJ:
       if (subtypep(obj->co.cls, stream_s)) {
-        val fdval = stream_get_prop(obj, fd_k);
+        val fdval = stream_fd(obj);
         if (!fdval) {
           free(pfd);
           uw_throwf(file_error_s,
@@ -1553,7 +1553,7 @@ void simulate_setuid_setgid(val open_script)
     return;
 
   {
-    val fdv = stream_get_prop(open_script, fd_k);
+    val fdv = stream_fd(open_script);
 
     if (fdv) {
       struct stat stb;