From 4a06b57d270f6972d4f910a73a624a701a707d5c Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sat, 25 Apr 2020 10:43:42 -0700
Subject: 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.
---
 socket.c |  3 ---
 stream.c | 13 +++++--------
 sysif.c  |  6 +++---
 3 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/socket.c b/socket.c
index cda85e7e..9b213e4f 100644
--- a/socket.c
+++ b/socket.c
@@ -552,9 +552,6 @@ static val dgram_get_prop(val stream, val ind)
 {
   struct dgram_stream *d = coerce(struct dgram_stream *, stream->co.handle);
 
-  if (ind == fd_k)
-    return num(d->fd);
-
   if (ind == name_k) {
     if (d->fd == -1)
       return lit("closed");
diff --git a/stream.c b/stream.c
index 2f42ac3f..23dfc30e 100644
--- a/stream.c
+++ b/stream.c
@@ -217,11 +217,6 @@ static noreturn val unimpl_truncate(val stream, val len)
   unimpl(stream, lit("truncate-stream"));
 }
 
-static noreturn val unimpl_get_fd(val stream)
-{
-  unimpl(stream, lit("fileno"));
-}
-
 static noreturn val unimpl_get_sock_family(val stream)
 {
   unimpl(stream, lit("sock-family"));
@@ -421,7 +416,7 @@ void fill_stream_ops(struct strm_ops *ops)
   if (!ops->clear_error)
     ops->clear_error = null_clear_error;
   if (!ops->get_fd)
-    ops->get_fd = unimpl_get_fd;
+    ops->get_fd = null_get_fd;
   if (!ops->get_sock_family)
     ops->get_sock_family = unimpl_get_sock_family;
   if (!ops->get_sock_type)
@@ -726,8 +721,6 @@ static val stdio_get_prop(val stream, val ind)
     return h->is_real_time ? t : nil;
   } else if (ind == name_k) {
     return h->descr;
-  } else if (ind == fd_k) {
-    return h->f ? num(fileno(h->f)) : nil;
   } else if (ind == byte_oriented_k) {
     return h->is_byte_oriented ? t : nil;
   }
@@ -2896,6 +2889,10 @@ val stream_get_prop(val stream, val ind)
   val self = lit("stream-get-prop");
   struct strm_ops *ops = coerce(struct strm_ops *,
                                 cobj_ops(self, stream, stream_s));
+
+  if (ind == fd_k && ops->get_fd != null_get_fd)
+    return ops->get_fd(stream);
+
   return ops->get_prop(stream, ind);
 }
 
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;
-- 
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