update DESIGN document, put skeleton code in place

DESIGN

@@ -1,5 +1,6 @@
 [9p directory structure]
-/ctl: control file for inputing system commands
+/ctl: write only control file for inputing system commands
+  login NAME PW: authenticate with xrxs -- pw is hashed against realm pw hash
   load CART: load a cartridge
   create REALM: create a new realm (start a new game or app session)
   protect REALM: protect the realm with auth data
@@ -8,25 +9,45 @@
   save: save the current universe to the realm
   reset: reset the cartridge (attempts to leave the realm, but doesn't save)
   unload: unload the cartridge
-  shutdown: disconnect from the xrxs server
+  
+  should we check the /realms file for success or failure, or should we make ctl rw and return success or failure of the current user's last command on read?
 
-/carts/: available game/app cartridges for this server
+/users: read-only; self and others in the realm are readable from here in the form:
+  <AFID> <username>
+  one per line;
+  file is blank before login,
+  contains only self before joining a realm
 
-/realms/: open/saved realms
+/carts: available game/app cartridges for this server, read only
+  carts are listed per line upon reading the file
+  backed by files on the server (carts/<cart_name>/{<cart_name.rom>, data/}
+  
+/slot: after loading the cartridge, its ROM is read from here; read only
+
+/data/: any supporting data that comes with the cartridge will be found here; read only
+
+/realms: open/saved realms; read only
+  realms and their associated universe are backed by real files on the server so that they can be preserved across service instantiations. (realms/<realm_name>/{realm, universe})
   realms can either be solo, open, or protected;
   open or protected realms can have limited member numbers
   depending on the cartridge, these settings can be user-managed or managed by the cartridge itself
-
-/realm/REALM/index: realm data readable by the client before entering, eg:
-  1 4 1
+  realms are listed per line upon reading the file like:
+  realmx 1 4 1
   first number is number of members
   second is member limit
   third is 1 if protected, 0 if not
   0 1 1 represents a protected solo realm that is empty (saved game with password)
   0 1 0 represents an unprotected solo realm that is empty (saved game with no password)
-/realms/REALM/members: members of the realm
-realms/REALM/allowed: allowed membernames (if empty, anyone is allowed)
-realms/REALM/password: realm password
-realms/REALM/universe/: universe data synced to the realm
 
-/universe/: arbitrary game data not yet synced to the realm
+/universe: read/write: write here to update serverside state for this cart/realm; read from here to get the current state.
+  each cart will have its own format for encoding data here
+  since this changes frequently in multiplayer games, perhaps only flush to disk at regular intervals instead of after every write
+  
+[Realm format]
+
+each realm directory on the server should have the following files:
+  realm: basic data for the realm. file contents should contain only the maximum number of members, and the password hash, if any, separated by a space
+  members: members currently in the realm, in the form "<AFID> <username>", one per line
+  universe: the actual game state in for the realm, format is cartridge-specific
+  
+everything in the realm directory is synchronized to disc both when realm membership, limit, or password changes, and at regular intervals. if a member makes no writes to the universe after a certain time, consider them gone from the realm (so there should be a common SYN message all cartridges implement to keep them alive in the realm)

xrxs.c

@@ -29,20 +29,28 @@ char *ccat(char *dst, char c) { int len = slen(dst); dst[len] = c; dst[len + 1]
 
 /* clang-format on */
 int chatty9p = 1;
-static int serving = 1;
 
 static char Ebad[] = "something bad happened";
 static char Enomem[] = "no memory";
 
-enum { CTL = 1, SLOT, CART, REALM, UNIVERSE };
+typedef enum { CTL = 1, USERS, CARTS, SLOT, DATA, REALMS, UNIVERSE } FileType;
 
 typedef struct Aux Aux;
 struct Aux {
-  int type;
+  FileType type;
   char* data;
   int count;
 };
 
+Aux* create_aux(FileType t) {
+  Aux* self = (Aux*)malloc(sizeof(Aux));
+  self.type = t;
+  self.data = nil;
+  self.count = 0;
+  
+  return self;
+}
+
 void fsread(Req* r) {
   Aux* a;
   vlong offset;
@@ -102,7 +110,7 @@ void fswrite(Req* r) {
   respond(r, nil);
 }
 
-void handlectl(Req* r) {
+void write_ctl(Req* r) {
   char cmd[16];
   char* c = r->ifcall.data;
   int i;
@@ -114,33 +122,61 @@ void handlectl(Req* r) {
   unsigned long long const cmd_hashv = hash(cmd);
 
   switch (cmd_hashv) {
-    case SHUTDOWN_HASHV:
-      printf("what");
-      break;
     default:
       break;
   }
   r->ofcall.count = r->ifcall.count;
   r->fid->file->dir.length = r->ifcall.count;
+  respond(r, nil);
 }
 
-void xrxswrite(Req* r) {
+void xrxs_write(Req* r) {
   Aux* a = r->fid->file->aux;
   switch (a->type) {
     case CTL:
-      handlectl(r);
+      write_ctl(r);
+      break;
+    case UNIVERSE:
+      //write_universe(r);
       break;
     default:
+      respond(r, nil);
+      break;
+  }
+}
+
+void xrxs_read(Req* r) {
+  Aux* a = r->fid->file->aux;
+  switch (a->type) {
+    case USERS:
+      //read_users(r);
+      break;
+    case CARTS:
+      //read_carts(r);
+      break;
+    case SLOT:
+      //read_slot(r);
+      break;
+    case DATA:
+      //read_data(r);
+      break;
+    case REALMS:
+      //read_realms(r);
+      break;
+    case UNIVERSE:
+      //read_universe(r);
+      break;
+    default:
+      respond(r, nil);
       break;
   }
-  respond(r, nil);
 }
 
 void fsopen(Req* r) { respond(r, nil); }
 
 void wstat(Req* r) { respond(r, nil); }
 
-void fsdestroyfile(File* f) {
+void fs_destroy_file(File* f) {
   Aux* a = f->aux;
   if (a && a->data) {
     free(a->data);
@@ -177,8 +213,8 @@ String** listdir(char* path) {
 
 Srv fs = {
   .open = fsopen,
-  .read = fsread,
-  .write = xrxswrite,
+  .read = xrs_read,
+  .write = xrxs_write,
   .create = fsopen,
   .wstat = wstat};
 
@@ -190,10 +226,6 @@ void threadmain(int argc, char* argv[]) {
   char* usocket = nil;
   int i;
   String** cart;
-  Aux* ctlfile = malloc(sizeof(Aux));
-  ctlfile->type = CTL;
-  ctlfile->data = malloc(256 * sizeof(char));
-  ctlfile->count = 0;
 
   /* if -m PATH is supplied, mount on PATH */
   /* if -s NAME is supplied, create a socket for the namespace */
@@ -212,19 +244,18 @@ void threadmain(int argc, char* argv[]) {
   }
 
   fs.foreground = 1;
-  fs.tree = alloctree(nil, nil, DMDIR | 0777, fsdestroyfile);
+  fs.tree = alloctree(nil, nil, DMDIR | 0777, fs_destroy_file);
   tree = fs.tree;
-  closefile(createfile(tree->root, "carts", nil, DMDIR | 0555, nil));
-  closefile(createfile(tree->root, "ctl", nil, DMAPPEND | 0300, ctlfile));
+  closefile(createfile(tree->root, "carts", nil, 0444, create_aux(CARTS)));
+  closefile(createfile(tree->root, "ctl", nil, DMAPPEND | 0300, create_aux(CTL)));
   String** carts = listdir("carts/");
   cart = carts;
+  
   while (*cart) {
-    closefile(
-      createfile(walkfile(tree->root, "carts"), (*cart)->base, nil, 0444, nil));
-    cart++;
+    // just concatenate the carts into a multiline string, and put it in CARTS.data
   }
 
-  while (serving) {
+
     if (argc >= 3) {
       if (mtpt != nil && access(mtpt, AEXIST) < 0 && access(mtpt, AEXIST) < 0)
         sysfatal("mountpoint %s does not exist", mtpt);
@@ -234,5 +265,4 @@ void threadmain(int argc, char* argv[]) {
     } else {
       srv(&fs);
     }
-  }
 }