potential fix for windows static linking with thread creation in dll's

include/mimalloc-internal.h

@@ -60,6 +60,8 @@ void       _mi_error_message(int err, const char* fmt, ...);
 
 // random.c
 void       _mi_random_init(mi_random_ctx_t* ctx);
+void       _mi_random_init_weak(mi_random_ctx_t* ctx);
+void       _mi_random_reinit_if_weak(mi_random_ctx_t * ctx);
 void       _mi_random_split(mi_random_ctx_t* ctx, mi_random_ctx_t* new_ctx);
 uintptr_t  _mi_random_next(mi_random_ctx_t* ctx);
 uintptr_t  _mi_heap_random_next(mi_heap_t* heap);

include/mimalloc-types.h

@@ -357,6 +357,7 @@ typedef struct mi_random_cxt_s {
   uint32_t input[16];
   uint32_t output[16];
   int      output_available;
+  bool     weak;
 } mi_random_ctx_t;
 
 

src/init.c

@@ -142,8 +142,13 @@ mi_stats_t _mi_stats_main = { MI_STATS_NULL };
 static void mi_heap_main_init(void) {
   if (_mi_heap_main.cookie == 0) {
     _mi_heap_main.thread_id = _mi_thread_id();
-    _mi_heap_main.cookie = _mi_os_random_weak((uintptr_t)&mi_heap_main_init);
+    _mi_heap_main.cookie = 1;
-    _mi_random_init(&_mi_heap_main.random);
+    #if defined(_WIN32) && !defined(MI_SHARED_LIB)
+      _mi_random_init_weak(&_mi_heap_main.random);    // prevent allocation failure during bcrypt dll initialization with static linking
+    #else
+      _mi_random_init(&_mi_heap_main.random);
+    #endif
+    _mi_heap_main.cookie  = _mi_heap_random_next(&_mi_heap_main);
     _mi_heap_main.keys[0] = _mi_heap_random_next(&_mi_heap_main);
     _mi_heap_main.keys[1] = _mi_heap_random_next(&_mi_heap_main);
   }
@@ -502,12 +507,13 @@ static void mi_process_load(void) {
   MI_UNUSED(dummy);
   #endif
   os_preloading = false;
+  mi_assert_internal(_mi_is_main_thread());
   #if !(defined(_WIN32) && defined(MI_SHARED_LIB))  // use Dll process detach (see below) instead of atexit (issue #521)
   atexit(&mi_process_done);  
   #endif
   _mi_options_init();
-  mi_process_init();
+  mi_process_setup_auto_thread_done();
-  //mi_stats_reset();-
+  mi_process_init();  
   if (mi_redirected) _mi_verbose_message("malloc is redirected.\n");
 
   // show message from the redirector (if present)
@@ -516,6 +522,9 @@ static void mi_process_load(void) {
   if (msg != NULL && (mi_option_is_enabled(mi_option_verbose) || mi_option_is_enabled(mi_option_show_errors))) {
     _mi_fputs(NULL,NULL,NULL,msg);
   }
+
+  // reseed random
+  _mi_random_reinit_if_weak(&_mi_heap_main.random);
 }
 
 #if defined(_WIN32) && (defined(_M_IX86) || defined(_M_X64))
@@ -542,7 +551,6 @@ void mi_process_init(void) mi_attr_noexcept {
   _mi_process_is_initialized = true;
   mi_process_setup_auto_thread_done();
 
-  
   mi_detect_cpu_features();
   _mi_os_init();
   mi_heap_main_init();

src/random.c

@@ -168,7 +168,7 @@ If we cannot get good randomness, we fall back to weak randomness based on a tim
 
 #if defined(_WIN32)
 
-#if defined(MI_USE_RTLGENRANDOM) || defined(__cplusplus)
+#if defined(MI_USE_RTLGENRANDOM) // || defined(__cplusplus)
 // We prefer to use BCryptGenRandom instead of (the unofficial) RtlGenRandom but when using 
 // dynamic overriding, we observed it can raise an exception when compiled with C++, and 
 // sometimes deadlocks when also running under the VS debugger.
@@ -303,23 +303,41 @@ uintptr_t _mi_os_random_weak(uintptr_t extra_seed) {
   return x;
 }
 
-void _mi_random_init(mi_random_ctx_t* ctx) {
+static void mi_random_init_ex(mi_random_ctx_t* ctx, bool use_weak) {
   uint8_t key[32];
-  if (!os_random_buf(key, sizeof(key))) {
+  if (use_weak || !os_random_buf(key, sizeof(key))) {
     // if we fail to get random data from the OS, we fall back to a
     // weak random source based on the current time
     #if !defined(__wasi__)
-    _mi_warning_message("unable to use secure randomness\n");
+    if (!use_weak) { _mi_warning_message("unable to use secure randomness\n"); }
     #endif
     uintptr_t x = _mi_os_random_weak(0);
     for (size_t i = 0; i < 8; i++) {  // key is eight 32-bit words.
       x = _mi_random_shuffle(x);
       ((uint32_t*)key)[i] = (uint32_t)x;
     }
+    ctx->weak = true;
+  }
+  else {
+    ctx->weak = false;
   }
   chacha_init(ctx, key, (uintptr_t)ctx /*nonce*/ );
 }
 
+void _mi_random_init(mi_random_ctx_t* ctx) {
+  mi_random_init_ex(ctx, false);  
+}
+
+void _mi_random_init_weak(mi_random_ctx_t * ctx) {
+  mi_random_init_ex(ctx, true);
+}
+
+void _mi_random_reinit_if_weak(mi_random_ctx_t * ctx) {
+  if (ctx->weak) {
+    _mi_random_init(ctx);
+  }
+}
+
 /* --------------------------------------------------------
 test vectors from <https://tools.ietf.org/html/rfc8439>
 ----------------------------------------------------------- */