IPC: Difference between revisions

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 | Same as above except for read-only buffer. Prior(?) to the kernel version which implemented memory-permission checking for PXI buffers, this was unused and hence triggered a kernelpanic.
 |}
+== SVCs ==
+=== svcReplyAndReceive ===
+'''Signature:'''
+ Result ReplyAndReceive(s32* index, Handle* handles, s32 handleCount, Handle replyTarget)
+In a single operation, sends a IPC reply and waits for a new request. <code>handles</code> should be a pointer to an array of <code>handleCount</code> handles.<sup>TODO: Are only port/session handles supported?</sup>
+<code>replyTarget</code> should contain a handle to the session to send the reply to. (This us usually the session from which we received the previous request.)
+If <code>replyTarget</code> is 0, no reply and the call will simply wait for an incoming event.<sup>TODO: It doesn't seem like the 0xFFFF0000 command id mentioned in the above sections is necessary, but needs confirmation.</sup>
+Upon returning, <code>index</code> will contain an index into <code>handles</code> specifying which object changed state.
+If it's a server port endpoint, it means that there is a new incoming connection on that port which should be accepted using svcAcceptSession.
+If it's a server session endpoint it means that we received a request from that session and should process and then reply to it by calling svcReplyAndReceive again with <code>replyTarget</code> set to that session's handle.
+An example of a server svcReplyAndReceive loop is:
+ #define MAX_CLIENTS 4
+ Handle server_port = ...;
+ s32 requesting_index;
+ Handle handles[1 + MAX_CLIENTS] = { server_port };
+ s32 connected_clients = 0;
+ Handle reply_target = 0;
+ while (true) {
+     Result res = svcReplyAndReceive(&requesting_index, &handles, 1 + connected_clients, reply_target);
+     if (res == 0xC920181A) {
+         // Session was closed by remote
+         // TODO: Handle disconnects
+         reply_target = 0;
+         continue;
+     }
+     if (requesting_index == 0) {
+         // New connection in server_port
+         ASSERT(connected_client < MAX_CLIENTS);
+         svcAcceptSession(&handles[1 + connected_clients++], server_port);
+         reply_target = 0;
+         continue;
+     }
+     reply_target = handles[requesting_index];
+     // Handle command here and write reply to command buffer
+ }