replace VLA formatting buffer with dprintf

libc/bionic/bionic_systrace.cpp

@@ -26,8 +26,6 @@
 
 #include <cutils/trace.h> // For ATRACE_TAG_BIONIC.
 
-#define WRITE_OFFSET   32
-
 static Lock g_lock;
 static CachedProperty g_debug_atrace_tags_enableflags("debug.atrace.tags.enableflags");
 static uint64_t g_tags;
@@ -61,15 +59,9 @@ void bionic_trace_begin(const char* message) {
     return;
   }
 
-  // If bionic tracing has been enabled, then write the message to the
-  // kernel trace_marker.
-  int length = strlen(message);
-  char buf[length + WRITE_OFFSET];
-  size_t len = snprintf(buf, length + WRITE_OFFSET, "B|%d|%s", getpid(), message);
-
   // Tracing may stop just after checking property and before writing the message.
   // So the write is acceptable to fail. See b/20666100.
-  TEMP_FAILURE_RETRY(write(trace_marker_fd, buf, len));
+  dprintf(trace_marker_fd, "B|%d|%s", getpid(), message);
 }
 
 void bionic_trace_end() {