[socket-nif] Add support for socket (level otp) buffer options

Add support for otp level socket options rcvbuf, rcvctrlbuf and
sndctrlbuf. These options define default sizes for these
buffers.
The 'rcvbuf' is used when receiving messages when calling
the recv, recvfrom and recvmsg functions.
The 'rcvctrlbuf' is used for the control message header info
when calling the recvmsg function.
The 'sndctrlbuf' is used for the control message header info
when calling the sendmsg function.

OTP-14831

1 files changed, 29 insertions, 0 deletions

diff --git a/erts/emulator/nifs/common/socket_util.c b/erts/emulator/nifs/common/socket_util.c
index 8bb725fb5b..ff50fd2384 100644
--- a/erts/emulator/nifs/common/socket_util.c
+++ b/erts/emulator/nifs/common/socket_util.c
@@ -1261,6 +1261,35 @@ char* esock_decode_protocol(ErlNifEnv*   env,
 
 
 
+/* +++ esock_decode_bufsz +++
+ *
+ * Decode an buffer size. The size of a buffer is: 
+ * 
+ *    Sz > 0 => Use provided value
+ *    Sz     => Use provided default
+ *
+ */
+extern
+char* esock_decode_bufsz(ErlNifEnv*   env,
+                         ERL_NIF_TERM eVal,
+                         size_t       defSz,
+                         size_t*      sz)
+{
+    int val;
+
+    if (!GET_INT(env, eVal, &val))
+        return ESOCK_STR_EINVAL;
+
+    if (val > 0)
+        *sz = (size_t) val;
+    else
+        *sz = defSz;
+
+    return NULL;
+}
+
+
+
 /* *** esock_decode_string ***
  *
  * Decode a string value. A successful decode results in an