update proto, add config update publish broadcast, add messages compacting

Makefile

@@ -11,7 +11,7 @@ LIBS_HEADERS=deps/ $(OPENSSL_INCLUDE)
 SYSTEM_INCLUDES=-isystem deps/flatcc/include/ -isystem $(PROTO_INC_DIR)/
 STATIC_LIBS=crypto
 STANDART=c23
-OPTIMIZE=-Og
+OPTIMIZE=-O3
 TARGET=main
 
 FLATCC           = deps/flatcc/bin/flatcc

flatbuffers/compacted.fbs

@@ -0,0 +1,12 @@
+namespace hmmmm;
+
+// A single serialized ServerMessage frame packed into a byte vector.
+table CompactedFrame {
+    data: [ubyte];
+}
+
+// A batch of ServerMessage frames sent as a single WebSocket frame to reduce
+// per-frame syscall overhead when message rate exceeds the batching threshold.
+table CompactedMessage {
+    frames: [CompactedFrame];
+}

flatbuffers/proto.fbs

@@ -2,6 +2,7 @@ include "auth/auth.fbs";
 include "control/control.fbs";
 include "stream/stream.fbs";
 include "mem/mem.fbs";
+include "compacted.fbs";
 
 namespace hmmmm;
 
@@ -29,6 +30,7 @@ union ServerPayload {
     hmmmm.ctrl.CtrlServerMessage,
     hmmmm.stream.StreamServerMessage,
     hmmmm.mem.MemServerMessage,
+    CompactedMessage,
 }
 
 // Every frame sent by the server is a ServerMessage.

inc/context.h

@@ -38,6 +38,9 @@ typedef struct {
     size_t interceptCtxCount;
     flatcc_builder_t stream_builder;
     uint64_t simRateLimit;
+    // Cached DeviceIdMappingNotif broadcast message (sent to newly authed clients)
+    uint8_t* deviceIdMappingMsg;
+    size_t   deviceIdMappingMsgLen;
 } EmulContext;
 
 

inc/proto/msg.h

@@ -16,6 +16,7 @@ typedef struct {
     ws_cli_conn_t clientIdx;
     uint8_t*      msg;
     size_t        msgLen;
+    uint64_t      dispatch_us; // microsecond timestamp when queued (for batching window)
 } OutgoingMessage;
 
 // Build a ServerMessage{AuthResponse} frame.  Returns a malloc'd buffer;
@@ -59,12 +60,21 @@ uint8_t* fb_build_stream_reg_confirm(
 
 // Build a ServerMessage{CtrlServerMessage{ConfigNotifMessage{DeviceIdMappingNotif}}} frame.
 // paths: array of NULL-terminated string arrays; path_lens: component count per path.
+// seg_names[i]: array of seg_counts[i] segment name strings for device i.
 uint8_t* fb_build_config_device_id_mapping(
     uint64_t nonce,
     char** paths[], size_t path_lens[],
+    char* seg_names[][64], size_t seg_counts[],
     size_t device_count, size_t* len_out);
 
 // Build a ServerMessage{CtrlServerMessage{ConfigNotifMessage{ConfigLoadError}}} frame.
 uint8_t* fb_build_config_error(uint64_t nonce, const char* message, size_t* len_out);
 
+// Build a ServerMessage{CompactedMessage{frames=[...]}} frame.
+// msgs / msg_lens: array of `count` pre-built ServerMessage byte buffers to pack.
+// The caller retains ownership of the source buffers; this function copies their bytes.
+// Nonce is set to UINT64_MAX (no-nonce / fire-and-forget).
+uint8_t* fb_build_compacted_message(
+    uint8_t* const* msgs, const size_t* msg_lens, size_t count, size_t* len_out);
+
 #endif // __PROTO_MSG_H__

src/main.c

@@ -164,6 +164,74 @@ void my_sleep(int microseconds) {
 
 
 
+// Compact threshold: if a client has more than this many messages in a single
+// outgoing buffer that all arrived within COMPACT_WINDOW_US, pack them into
+// a single CompactedMessage frame to reduce ws_sendframe_bin syscall overhead.
+#define COMPACT_THRESHOLD 4
+#define COMPACT_WINDOW_US 100000ULL   // 100 ms
+
+static void compact_outgoing_buffer(SizedPtr* buf)
+{
+    OutgoingMessage* msgs = (OutgoingMessage*)buf->ptr;
+    size_t n = buf->size;
+    if (n <= COMPACT_THRESHOLD) return;
+
+    // Collect unique client IDs present in the buffer (stack-allocated; n is small).
+    ws_cli_conn_t clients[n];
+    size_t client_count = 0;
+    for (size_t i = 0; i < n; i++) {
+        if (msgs[i].msg == NULL) continue;
+        ws_cli_conn_t cid = msgs[i].clientIdx;
+        uint8_t found = 0;
+        for (size_t j = 0; j < client_count; j++) {
+            if (clients[j] == cid) { found = 1; break; }
+        }
+        if (!found) clients[client_count++] = cid;
+    }
+
+    for (size_t ci = 0; ci < client_count; ci++) {
+        ws_cli_conn_t cid = clients[ci];
+
+        // Gather indices, timestamps for this client.
+        size_t idxs[n];
+        size_t cnt = 0;
+        uint64_t first_us = UINT64_MAX, last_us = 0;
+        for (size_t i = 0; i < n; i++) {
+            if (msgs[i].msg == NULL || msgs[i].clientIdx != cid) continue;
+            idxs[cnt++] = i;
+            if (msgs[i].dispatch_us < first_us) first_us = msgs[i].dispatch_us;
+            if (msgs[i].dispatch_us > last_us)  last_us  = msgs[i].dispatch_us;
+        }
+
+        // Only compact if: more than threshold AND all arrived within 100ms window.
+        if (cnt <= COMPACT_THRESHOLD) continue;
+        if (last_us - first_us > COMPACT_WINDOW_US) continue;
+
+        // Collect pointers for the builder (it copies the bytes internally).
+        uint8_t* ptrs[cnt];
+        size_t   lens[cnt];
+        for (size_t i = 0; i < cnt; i++) {
+            ptrs[i] = msgs[idxs[i]].msg;
+            lens[i] = msgs[idxs[i]].msgLen;
+        }
+
+        size_t cm_len = 0;
+        uint8_t* cm = fb_build_compacted_message(
+            (uint8_t* const*)ptrs, lens, cnt, &cm_len);
+        if (cm == NULL) continue;  // builder failed; send individually
+
+        // Replace the first slot with the compacted frame; free and null the rest.
+        free(msgs[idxs[0]].msg);
+        msgs[idxs[0]].msg    = cm;
+        msgs[idxs[0]].msgLen = cm_len;
+        for (size_t i = 1; i < cnt; i++) {
+            free(msgs[idxs[i]].msg);
+            msgs[idxs[i]].msg = NULL;  // sentinel: skip in send loop
+        }
+    }
+}
+
+
 void* outgoingMain(void* args)
 {
     OutgoingBuffers* outBufs = args;
@@ -175,19 +243,20 @@ void* outgoingMain(void* args)
     {
         if(curBuf != NULL)
         {
+            compact_outgoing_buffer(curBuf);
+
             OutgoingMessage* messages = curBuf->ptr;
             for(size_t i = 0; i < curBuf->size; i++)
             {
-                // my_sleep(100000);
                 OutgoingMessage *outMsg = &messages[i];
                 if(outMsg->msg == NULL)
                 {
-                    panic("Got double read on buf %d while writing on buf %d\n", currBufIdx, currWritingIdxPtr);
+                    // Slot was merged into a CompactedMessage; skip.
+                    continue;
                 }
                 ws_sendframe_bin(outMsg->clientIdx, (const char*)outMsg->msg, outMsg->msgLen);
                 free(outMsg->msg);
                 outMsg->msg = NULL;
-                // printf("done free on buf %d message %lu\n", currBufIdx, i);
             }
             curBuf->size = 0;
             atomic_store(&outBufs->readRequestIdx, currBufIdx);
@@ -205,7 +274,7 @@ void* outgoingMain(void* args)
             atomic_store(&outBufs->readRequestIdx, currBufIdx);
             if(curBuf == NULL)
             {
-                my_sleep(100);
+                // my_sleep(1);
             }
             else
             {
@@ -315,9 +384,41 @@ uint64_t getCurrentUsec()
     return (1000000 * (uint64_t)tv.tv_sec) + (uint64_t)tv.tv_usec;
 }
 
+static void print_usage(const char* progname)
+{
+    fprintf(stderr, "Usage: %s [--port PORT] [--token TOKEN] [--host HOST]\n", progname);
+    fprintf(stderr, "  --port PORT    WebSocket listen port (default: 8181)\n");
+    fprintf(stderr, "  --token TOKEN  Access token for client auth\n");
+    fprintf(stderr, "  --host HOST    Listen host (default: localhost)\n");
+}
+
 int main(int argc, char** argv)
 {
-    (void)argc; (void)argv;
+    uint16_t cli_port = 8181;
+    const char* cli_host = "localhost";
+    const char* cli_token = NULL;
+
+    for (int i = 1; i < argc; i++) {
+        if (strcmp(argv[i], "--port") == 0 && i + 1 < argc) {
+            long p = strtol(argv[++i], NULL, 10);
+            if (p <= 0 || p > 65535) {
+                fprintf(stderr, "Invalid port: %s\n", argv[i]);
+                return 1;
+            }
+            cli_port = (uint16_t)p;
+        } else if (strcmp(argv[i], "--token") == 0 && i + 1 < argc) {
+            cli_token = argv[++i];
+        } else if (strcmp(argv[i], "--host") == 0 && i + 1 < argc) {
+            cli_host = argv[++i];
+        } else if (strcmp(argv[i], "--help") == 0 || strcmp(argv[i], "-h") == 0) {
+            print_usage(argv[0]);
+            return 0;
+        } else {
+            fprintf(stderr, "Unknown argument: %s\n", argv[i]);
+            print_usage(argv[0]);
+            return 1;
+        }
+    }
     char errbuf[1024];
     pthread_mutex_t mtx;
     pthread_mutex_init(&mtx, NULL);
@@ -380,20 +481,35 @@ int main(int argc, char** argv)
         deviceHandlesArr,
         NULL, /* interceptCtxs */
         0,    /* interceptCtxCount */
-        {0},   /* stream_builder — initialized below */
+        {0},  /* stream_builder — initialized below */
-        0,
+        0,    /* simRateLimit */
+        NULL, /* deviceIdMappingMsg */
+        0,    /* deviceIdMappingMsgLen */
     };
     if (flatcc_builder_init(&emulContext.stream_builder)) {
         panic("flatcc_builder_init failed\n");
     }
 
 
-    uint8_t access_token[] = "jtd3dhBWG2p73mkRCyaZ63KLmOjl5OgItIDAPa8HcyGQI2SOFA6hsJVr1NiG2Y96AvwyYSShr4GAL3sjJEo1wsmCo2vuhiqRhj8HVRrOVocD2e1jtuMwMsCmizYakT63";
+    static uint8_t default_token[] = "jtd3dhBWG2p73mkRCyaZ63KLmOjl5OgItIDAPa8HcyGQI2SOFA6hsJVr1NiG2Y96AvwyYSShr4GAL3sjJEo1wsmCo2vuhiqRhj8HVRrOVocD2e1jtuMwMsCmizYakT63";
+    uint8_t* access_token = default_token;
+    /* If --token was given, copy it into a mutable buffer */
+    uint8_t* cli_token_buf = NULL;
+    if (cli_token != NULL) {
+        size_t tlen = strlen(cli_token) + 1;
+        cli_token_buf = malloc(tlen);
+        if (cli_token_buf == NULL) {
+            fprintf(stderr, "Failed to allocate token buffer\n");
+            return 1;
+        }
+        memcpy(cli_token_buf, cli_token, tlen);
+        access_token = cli_token_buf;
+    }
 
     ServerContext ctx = {
         mtx,
         regQ,
-        (uint8_t*)&access_token,
+        access_token,
         &emulContext,
     };
 
@@ -406,8 +522,8 @@ int main(int argc, char** argv)
 
 
     ws_socket(&(struct ws_server){
-        .host = "localhost",
+        .host = cli_host,
-        .port = 8181,
+        .port = cli_port,
         .thread_loop   = 1,
         .timeout_ms    = 1000,
         .context       = &ctx,
@@ -418,7 +534,7 @@ int main(int argc, char** argv)
 
     ptQueueElem* regQueueTail = regQ->tail;
 
-    uint8_t clients_try_timer = 100;
+    uint8_t clients_try_timer = 1;
 
     uint64_t lastTickAt = getCurrentUsec();
 
@@ -437,7 +553,7 @@ int main(int argc, char** argv)
         if (clients_try_timer == 0) 
         {
             handleAllClients(&emulContext);
-            clients_try_timer = 100;
+            clients_try_timer = 1;
         }
         else 
         {
@@ -465,8 +581,11 @@ int main(int argc, char** argv)
         }
 
         uint64_t now = emulContext.simRateLimit > 0? getCurrentUsec() : 0;
-
+        if(emulState == EMUL_STATE_STOP) 
-        if(emulState == EMUL_STATE_EXEC && emulContext.devicesCount > 0 && (emulContext.simRateLimit == 0 || now - lastTickAt >= 1000000 / emulContext.simRateLimit))
+        {
+            clockCounter = 0;
+        }
+        else if(emulState == EMUL_STATE_EXEC && emulContext.devicesCount > 0 && (emulContext.simRateLimit == 0 || now - lastTickAt >= 1000000 / emulContext.simRateLimit))
         {
             for (size_t di = 0; di < emulContext.devicesCount; di++)
             {

src/proto/dial.c

@@ -1,11 +1,19 @@
 #include "proto/dial.h"
 
 #include <string.h>
+#include <sys/time.h>
 
 #include "context.h"
 #include "panic.h"
 #include "proto/msg.h"
 
+static uint64_t dial_now_us(void)
+{
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return (uint64_t)tv.tv_sec * 1000000ULL + (uint64_t)tv.tv_usec;
+}
+
 
 void broadcastClients(EmulContext* emulContext, uint8_t* msg, size_t msgLen)
 {
@@ -42,5 +50,6 @@ void dispatchOutgoingMessage(OutgoingBuffers* outBufs, ws_cli_conn_t clientIdx,
     outmsg->msg = msg;
     outmsg->msgLen = msgLen;
     outmsg->clientIdx = clientIdx;
+    outmsg->dispatch_us = dial_now_us();
     p->size++;
 }

src/proto/handlers/auth.c

@@ -1,6 +1,7 @@
 #include "proto/handlers/auth.h"
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <openssl/sha.h>
@@ -141,4 +142,15 @@ void handleOnClientAuthDone(ClientContext* cctx, EmulContext* emulContext)
     uint8_t* stateMsg = fb_build_exec_notify(
         UINT64_MAX, *emulContext->clockCounter, *emulContext->emulState, &len);
     dispatchOutgoingMessage(emulContext->outBufs, cctx->clientId, stateMsg, len);
+
+    // Send cached DeviceIdMappingNotif if a config has been loaded
+    if (emulContext->deviceIdMappingMsg && emulContext->deviceIdMappingMsgLen > 0) {
+        uint8_t* mappingCopy = malloc(emulContext->deviceIdMappingMsgLen);
+        if (mappingCopy) {
+            memcpy(mappingCopy, emulContext->deviceIdMappingMsg, emulContext->deviceIdMappingMsgLen);
+            dispatchOutgoingMessage(
+                emulContext->outBufs, cctx->clientId,
+                mappingCopy, emulContext->deviceIdMappingMsgLen);
+        }
+    }
 }

src/proto/handlers/config.c

@@ -15,8 +15,9 @@
 #include "device_reader.h"
 #include "mem_config_reader.h"
 
-#define MAX_DEVICES 64
+#define MAX_DEVICES   64
-#define MAX_DEPTH   16
+#define MAX_DEPTH     16
+#define MAX_SEGMENTS  64
 
 
 // Converts a FlatBuffer BaseDeviceConfig into a heap-allocated conf_dev_t
@@ -75,10 +76,10 @@ typedef struct {
     const char*      path_stack[MAX_DEPTH]; // current path components
     size_t           depth;
     // For building the DeviceIdMappingNotif response:
-    // store copies of hierarchical path per device
+    char**           paths[MAX_DEVICES];            // hierarchical path per device (heap-alloc'd)
-    char**           paths[MAX_DEVICES];   // each is a NULL-terminated string array
+    size_t           path_lens[MAX_DEVICES];         // number of path components per device
-    size_t           path_lens[MAX_DEVICES]; // number of components per path
+    size_t           seg_counts[MAX_DEVICES];        // number of memory segments per device
-    size_t           seg_counts[MAX_DEVICES]; // number of memory segments per device
+    char*            seg_names[MAX_DEVICES][MAX_SEGMENTS]; // segment names (heap-alloc'd)
     size_t           count;
 } LoadState;
 
@@ -155,11 +156,18 @@ static int load_devices_recursive(
             size_t idx = st->count;
             st->handles[idx] = dev;
 
-            // Store segment count from FlatBuffer config
+            // Store segment count and names from FlatBuffer config
             hmmmm_config_MemSegment_vec_t dev_segs =
                 hmmmm_config_BaseDeviceConfig_mem_segments(base);
-            st->seg_counts[idx] = dev_segs
+            size_t nseg = dev_segs ? hmmmm_config_MemSegment_vec_len(dev_segs) : 0;
-                ? hmmmm_config_MemSegment_vec_len(dev_segs) : 0;
+            if (nseg > MAX_SEGMENTS) nseg = MAX_SEGMENTS;
+            st->seg_counts[idx] = nseg;
+            for (size_t si = 0; si < nseg; si++) {
+                hmmmm_config_MemSegment_table_t seg =
+                    hmmmm_config_MemSegment_vec_at(dev_segs, si);
+                flatbuffers_string_t sname = hmmmm_config_MemSegment_name(seg);
+                st->seg_names[idx][si] = strdup(sname ? sname : "");
+            }
 
             // Copy path
             st->path_lens[idx] = st->depth;
@@ -203,6 +211,9 @@ static void free_load_state_paths(LoadState* st)
             }
             free(st->paths[i]);
         }
+        for (size_t si = 0; si < st->seg_counts[i]; si++) {
+            free(st->seg_names[i][si]);
+        }
     }
 }
 
@@ -489,6 +500,12 @@ static void free_old_config(EmulContext* emulContext)
     emulContext->deviceStreamRegs = NULL;
     emulContext->devicesCount = 0;
     emulContext->simRateLimit = 0;
+
+    if (emulContext->deviceIdMappingMsg) {
+        free(emulContext->deviceIdMappingMsg);
+        emulContext->deviceIdMappingMsg = NULL;
+        emulContext->deviceIdMappingMsgLen = 0;
+    }
 }
 
 
@@ -502,9 +519,9 @@ void handleConfigCtrlMessage(
 
     char errbuf[1024];
 
-    // Must be in STILL state
+    // Block config load only while actively executing (ticking)
-    if (*emulContext->emulState != EMUL_STATE_STILL) {
+    if (*emulContext->emulState == EMUL_STATE_EXEC) {
-        snprintf(errbuf, 1024, "config load requires STILL state");
+        snprintf(errbuf, 1024, "stop or pause the emulator before loading config");
         printf("[CTRL/CONFIG] error: %s\n", errbuf);
 
         size_t msg_len;
@@ -674,12 +691,31 @@ void handleConfigCtrlMessage(
         emulContext->deviceStreamRegs[i] = dsr;
     }
 
-    // Build DeviceIdMappingNotif response
+    // Reset emulation state to STILL and notify all clients
+    if (*emulContext->emulState != EMUL_STATE_STILL) {
+        *emulContext->emulState = EMUL_STATE_STILL;
+        size_t notify_len;
+        uint8_t* notify = fb_build_exec_notify(0, *emulContext->clockCounter, EMUL_STATE_STILL, &notify_len);
+        broadcastClients(emulContext, notify, notify_len);
+    }
+
+    // Build DeviceIdMappingNotif and broadcast to all connected clients
     size_t msg_len;
     uint8_t* out = fb_build_config_device_id_mapping(
-        nonce, st.paths, st.path_lens, dc, &msg_len);
+        nonce, st.paths, st.path_lens, st.seg_names, st.seg_counts, dc, &msg_len);
 
     free_load_state_paths(&st);
 
-    dispatchOutgoingMessage(emulContext->outBufs, ctx->clientId, out, msg_len);
+    // Cache a copy for newly connecting clients
+    if (emulContext->deviceIdMappingMsg) {
+        free(emulContext->deviceIdMappingMsg);
+    }
+    emulContext->deviceIdMappingMsg = malloc(msg_len);
+    if (emulContext->deviceIdMappingMsg) {
+        memcpy(emulContext->deviceIdMappingMsg, out, msg_len);
+        emulContext->deviceIdMappingMsgLen = msg_len;
+    }
+
+    // Broadcast to all clients (broadcastClients takes ownership of out)
+    broadcastClients(emulContext, out, msg_len);
 }

src/proto/msg.c

@@ -8,6 +8,7 @@
 #include "auth_builder.h"
 #include "stream_builder.h"
 #include "stream_data_builder.h"
+#include "compacted_builder.h"
 
 
 uint8_t* fb_build_auth_response(uint64_t nonce, uint64_t seat_id, size_t* len_out)
@@ -253,6 +254,7 @@ uint8_t* fb_build_stream_reg_confirm(
 uint8_t* fb_build_config_device_id_mapping(
     uint64_t nonce,
     char** paths[], size_t path_lens[],
+    char* seg_names[][64], size_t seg_counts[],
     size_t device_count, size_t* len_out)
 {
     flatcc_builder_t B;
@@ -272,8 +274,20 @@ uint8_t* fb_build_config_device_id_mapping(
         }
         flatbuffers_string_vec_ref_t path_vec = flatbuffers_string_vec_end(&B);
 
-        // Empty seg_ids vector
+        // Build SegIdEntry refs for this device's segments
+        size_t nseg = seg_counts[i];
+        hmmmm_ctrl_config_notif_SegIdEntry_ref_t seg_refs[nseg];
+        for (size_t si = 0; si < nseg; si++) {
+            flatbuffers_string_ref_t name_ref =
+                flatbuffers_string_create_str(&B, seg_names[i][si] ? seg_names[i][si] : "");
+            seg_refs[si] = hmmmm_ctrl_config_notif_SegIdEntry_create(
+                &B, name_ref, (uint32_t)si);
+        }
+
         hmmmm_ctrl_config_notif_SegIdEntry_vec_start(&B);
+        for (size_t si = 0; si < nseg; si++) {
+            hmmmm_ctrl_config_notif_SegIdEntry_vec_push(&B, seg_refs[si]);
+        }
         hmmmm_ctrl_config_notif_SegIdEntry_vec_ref_t seg_ids_vec =
             hmmmm_ctrl_config_notif_SegIdEntry_vec_end(&B);
 
@@ -350,3 +364,41 @@ uint8_t* fb_build_config_error(uint64_t nonce, const char* message, size_t* len_
     NULL_GUARD(buf);
     return buf;
 }
+
+
+uint8_t* fb_build_compacted_message(
+    uint8_t* const* msgs, const size_t* msg_lens, size_t count, size_t* len_out)
+{
+    flatcc_builder_t B;
+    if (flatcc_builder_init(&B)) {
+        panic("flatcc_builder_init failed\n");
+    }
+
+    // Build CompactedFrame refs bottom-up (FlatBuffers requires nested objects
+    // to be created before the table that references them).
+    hmmmm_CompactedFrame_ref_t frame_refs[count];
+    for (size_t i = 0; i < count; i++) {
+        flatbuffers_uint8_vec_ref_t data_vec =
+            flatbuffers_uint8_vec_create(&B, msgs[i], msg_lens[i]);
+        frame_refs[i] = hmmmm_CompactedFrame_create(&B, data_vec);
+    }
+
+    hmmmm_CompactedFrame_vec_start(&B);
+    for (size_t i = 0; i < count; i++) {
+        hmmmm_CompactedFrame_vec_push(&B, frame_refs[i]);
+    }
+    hmmmm_CompactedFrame_vec_ref_t frames_vec = hmmmm_CompactedFrame_vec_end(&B);
+
+    hmmmm_CompactedMessage_ref_t cm = hmmmm_CompactedMessage_create(&B, frames_vec);
+
+    hmmmm_ServerPayload_union_ref_t payload =
+        hmmmm_ServerPayload_as_CompactedMessage(cm);
+
+    // UINT64_MAX = no-nonce (fire-and-forget batch frame)
+    hmmmm_ServerMessage_create_as_root(&B, UINT64_MAX, payload);
+
+    uint8_t* buf = flatcc_builder_finalize_buffer(&B, len_out);
+    flatcc_builder_clear(&B);
+    NULL_GUARD(buf);
+    return buf;
+}