[socket|doc] Fixed links and stuff

Corrected linking references (links) to functions.
Also added links from getopt/setopt functions to
the users guide.

Also added some comments to the socket module regarding
open with (ready made) descriptor (which is not yet
supported).

OTP-14831

4 files changed, 26 insertions, 5 deletions

diff --git a/erts/doc/src/socket.xml b/erts/doc/src/socket.xml
index 56737b1a8f..8a68ee3e90 100644
--- a/erts/doc/src/socket.xml
+++ b/erts/doc/src/socket.xml
@@ -4,7 +4,7 @@
 <erlref>
   <header>
     <copyright>
-      <year>2018</year><year>2018</year>
+      <year>2018</year><year>2019</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -55,7 +55,7 @@
     <datatype>
       <name>socket()</name>
       <desc><p>As returned by
-        <seealso marker="#open/1"><c>open/2,3,4</c></seealso> and
+        <seealso marker="#open/2"><c>open/2,3,4</c></seealso> and
         <seealso marker="#accept/1"><c>accept/1,2</c></seealso>.</p>
       </desc>
     </datatype>
@@ -305,6 +305,10 @@
 	on what kind of socket it is (<c>domain</c>, <c>type</c> and
 	<c>protocol</c>).</p>
 
+	See the
+	<seealso marker="socket_usage#socket_options">socket options</seealso>
+	chapter of the users guide for more info.
+
 	<note><p>Not all options are valid on all platforms. That is,
 	even if "we" support an option, that does not mean that the
 	underlying OS does.</p></note>
@@ -324,6 +328,10 @@
 	using "native mode", it is *currently* up to the caller to
 	know how to interpret the result.</p>
 
+	See the
+	<seealso marker="socket_usage#socket_options">socket options</seealso>
+	chapter of the users guide for more info.
+
 	<note><p>Not all options are valid on all platforms. That is,
 	even if "we" support an option, that does not mean that the
 	underlying OS does.</p></note>
@@ -398,7 +406,8 @@
 	how much we want to read, it returns when we get a message.</p>
         <p>The <c>BufSz</c> argument basically defines the size of the
 	receive buffer. By setting the value to zero (0), the configured
-	size (setopt with <c>Level</c> = <c>otp</c>) is used.</p>
+	size (setopt with <c>Level</c> = <c>otp</c> and <c>Key</c> = <c>rcvbuf</c>)
+	is used.</p>
         <p>It may be impossible to know what (buffer) size is appropriate
 	"in advance", and in those cases it may be convenient to use the
 	(recv) 'peek' flag. When this flag is provided, the message is *not*
@@ -427,7 +436,8 @@
 	
         <p>The <c>BufSz</c> argument basically defines the size of the
 	receive buffer. By setting the value to zero (0), the configured
-	size (setopt with <c>Level</c> = <c>otp</c>) is used.</p>
+	size (setopt with <c>Level</c> = <c>otp</c> and <c>Key</c> = <c>rcvbuf</c>)
+	is used.</p>
 
         <p>The <c>CtrlSz</c> argument basically defines the size of the
 	receive buffer for the control messages.
@@ -503,6 +513,10 @@
 	what kind of socket it is (<c>domain</c>, <c>type</c> and
 	<c>protocol</c>).</p>
 
+	See the
+	<seealso marker="socket_usage#socket_options">socket options</seealso>
+	chapter of the users guide for more info.
+
 	<note><p>Not all options are valid on all platforms. That is,
 	even if "we" support an option, that does not mean that the
 	underlying OS does.</p></note>
@@ -522,6 +536,10 @@
 	what kind of socket it is (<c>domain</c>, <c>type</c> and
 	<c>protocol</c>).</p>
 
+	See the
+	<seealso marker="socket_usage#socket_options">socket options</seealso>
+	chapter of the users guide for more info.
+
 	<note><p>Not all options are valid on all platforms. That is,
 	even if "we" support an option, that does not mean that the
 	underlying OS does.</p></note>
diff --git a/erts/doc/src/socket_usage.xml b/erts/doc/src/socket_usage.xml
index 4ec31b5296..e0f006e618 100644
--- a/erts/doc/src/socket_usage.xml
+++ b/erts/doc/src/socket_usage.xml
@@ -42,6 +42,7 @@
   </section>
 
   <section>
+    <marker id="socket_options"></marker>
     <title>Socket Options</title>
 
     <p>Options for level <c>otp</c>: </p>
diff --git a/erts/preloaded/ebin/socket.beam b/erts/preloaded/ebin/socket.beam
index 360ac195f1..7f6fa76ece 100644
--- a/erts/preloaded/ebin/socket.beam
+++ b/erts/preloaded/ebin/socket.beam
diff --git a/erts/preloaded/src/socket.erl b/erts/preloaded/src/socket.erl
index f889c6e37b..f04f9701d3 100644
--- a/erts/preloaded/src/socket.erl
+++ b/erts/preloaded/src/socket.erl
@@ -949,10 +949,12 @@ supports(_Key1, _Key2, _Key3) ->
 %%
 %% <KOLLA>
 %%
-%% How do we handle the case when an fd has beem created (somehow)
+%% How do we handle the case when an fd has been created (somehow)
 %% and we shall create a socket "from it".
 %% Can we figure out Domain, Type and Protocol from fd?
 %% Yes we can: SO_DOMAIN, SO_PROTOCOL, SO_TYPE
+%% But does that work on all platforms? Or shall we require that the 
+%% caller provide this explicitly?
 %%
 %% </KOLLA>
 %%