Pad TOC entries when closing the trace.

Author: Rot127

contrib/plugins/bap-tracing/frame_buffer.c

@@ -164,17 +164,25 @@ bool frame_buffer_is_empty(const FrameBuffer *buf) {
 }
 
 /// @brief Dumps the file buffer as TOC entry into the file.
-uint64_t frame_buffer_flush_to_file(FrameBuffer *buf, WLOCKED FILE *file) {
+uint64_t frame_buffer_flush_to_file(FrameBuffer *buf, WLOCKED FILE *file, bool add_padding) {
   uint64_t n = 0;
-  for (size_t i = 0; i <= buf->idx && i < frames_per_toc_entry; ++i) {
-    Frame *frame = buf->fbuf[i];
-    size_t msg_size = frame__get_packed_size(frame);
-    uint8_t *packed_buffer = g_alloca(msg_size);
-    uint64_t packed_size = frame__pack(frame, packed_buffer);
-    WRITE(packed_size);
-    WRITE_BUF(packed_buffer, packed_size);
-    frame_free(frame);
-    n++;
+  for (size_t i = 0; i < frames_per_toc_entry; ++i) {
+    if (i <= buf->idx) {
+      Frame *frame = buf->fbuf[i];
+      size_t msg_size = frame__get_packed_size(frame);
+      uint8_t *packed_buffer = g_alloca(msg_size);
+      uint64_t packed_size = frame__pack(frame, packed_buffer);
+      WRITE(packed_size);
+      WRITE_BUF(packed_buffer, packed_size);
+      frame_free(frame);
+      n++;
+    } else if (add_padding) {
+      uint64_t pad = 0;
+      WRITE(pad);
+      n++;
+    } else {
+      break;
+    }
   }
   memset(buf->fbuf, 0, sizeof(buf->fbuf));
   buf->idx = 0;

contrib/plugins/bap-tracing/frame_buffer.h

@@ -28,7 +28,7 @@ typedef struct {
  */
 FrameBuffer *frame_buffer_new(void);
 
-uint64_t frame_buffer_flush_to_file(FrameBuffer *buf, WLOCKED FILE *file);
+uint64_t frame_buffer_flush_to_file(FrameBuffer *buf, WLOCKED FILE *file, bool add_padding);
 bool frame_buffer_is_full(const FrameBuffer *buf);
 bool frame_buffer_is_empty(const FrameBuffer *buf);
 void frame_buffer_close_frame(FrameBuffer *buf);

contrib/plugins/bap-tracing/tracing.c

@@ -100,12 +100,12 @@ static GPtrArray *registers_init(void) {
   return registers->len ? g_steal_pointer(&registers) : NULL;
 }
 
-static void write_toc_entry(FrameBuffer *fbuf) {
+static void write_toc_entry(FrameBuffer *fbuf, bool add_padding) {
   g_rw_lock_writer_lock(&state.file_lock);
   g_rw_lock_writer_lock(&state.toc_entries_offsets_lock);
   g_rw_lock_writer_lock(&state.total_num_frames_lock);
 
-  state.total_num_frames += frame_buffer_flush_to_file(fbuf, state.file);
+  state.total_num_frames += frame_buffer_flush_to_file(fbuf, state.file, add_padding);
   uint64_t next_toc_entry = ftell(state.file);
   g_array_append_val(state.toc_entries_offsets, next_toc_entry);
 
@@ -130,7 +130,7 @@ static void log_insn_reg_access(unsigned int vcpu_index, void *udata) {
   }
 
   if (frame_buffer_is_full(fbuf)) {
-    write_toc_entry(fbuf);
+    write_toc_entry(fbuf, false);
   }
 
   // Open new one.
@@ -202,7 +202,7 @@ static void plugin_exit(qemu_plugin_id_t id, void *udata) {
   // Dump the rest of the frames.
   for (size_t i = 0; i < state.vcpus->len; ++i) {
     FrameBuffer *fbuf = g_ptr_array_index(state.frame_buffer, i);
-    write_toc_entry(fbuf);
+    write_toc_entry(fbuf, true);
   }
   g_rw_lock_writer_unlock(&state.frame_buffer_lock);