msvcrt: Reimplement rand() and srand() to use per-thread data for the

random seed.

dlls/msvcrt/misc.c

@@ -38,12 +38,26 @@ void _beep( unsigned int freq, unsigned int duration)
     Beep(freq, duration);
 }
 
+/*********************************************************************
+ *		srand (MSVCRT.@)
+ */
+void MSVCRT_srand( unsigned int seed )
+{
+    thread_data_t *data = msvcrt_get_thread_data();
+    data->random_seed = seed;
+}
+
 /*********************************************************************
  *		rand (MSVCRT.@)
  */
 int MSVCRT_rand(void)
 {
-  return (rand() & 0x7fff);
+    thread_data_t *data = msvcrt_get_thread_data();
+
+    /* this is the algorithm used by MSVC, according to
+     * http://en.wikipedia.org/wiki/List_of_pseudorandom_number_generators */
+    data->random_seed = data->random_seed * 214013 + 2531011;
+    return (data->random_seed >> 16) & MSVCRT_RAND_MAX;
 }
 
 /*********************************************************************

dlls/msvcrt/msvcrt.h

@@ -93,6 +93,7 @@ extern DWORD msvcrt_tls_index;
 struct __thread_data {
     int                             thread_errno;
     unsigned long                   thread_doserrno;
+    unsigned int                    random_seed;        /* seed for rand() */
     char                           *strtok_next;        /* next ptr for strtok() */
     unsigned char                  *mbstok_next;        /* next ptr for mbstok() */
     MSVCRT_wchar_t                 *wcstok_next;        /* next ptr for wcstok() */
@@ -375,6 +376,7 @@ struct MSVCRT__stati64 {
 #define MSVCRT_WEOF (MSVCRT_wint_t)(0xFFFF)
 #define MSVCRT_EOF       (-1)
 #define MSVCRT_TMP_MAX   0x7fff
+#define MSVCRT_RAND_MAX  0x7fff
 #define MSVCRT_BUFSIZ    512
 
 #define MSVCRT_STDIN_FILENO  0

dlls/msvcrt/msvcrt.spec

@@ -695,7 +695,7 @@
 @ cdecl sinh(double)
 @ varargs sprintf(ptr str) MSVCRT_sprintf
 @ cdecl sqrt(double)
-@ cdecl srand(long)
+@ cdecl srand(long) MSVCRT_srand
 @ varargs sscanf(str str) MSVCRT_sscanf
 @ cdecl strcat(str str)
 @ cdecl strchr(str long)

dlls/msvcrt/tests/headers.c

@@ -303,6 +303,7 @@ static void test_defines(void)
     CHECK_DEF(WEOF);
     CHECK_DEF(EOF);
     CHECK_DEF(TMP_MAX);
+    CHECK_DEF(RAND_MAX);
     CHECK_DEF(BUFSIZ);
     CHECK_DEF(STDIN_FILENO);
     CHECK_DEF(STDOUT_FILENO);

dlls/msvcrt/thread.c

@@ -44,6 +44,7 @@ thread_data_t *msvcrt_get_thread_data(void)
         if (!(ptr = HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*ptr) )))
             _amsg_exit( _RT_THREAD );
         if (!TlsSetValue( msvcrt_tls_index, ptr )) _amsg_exit( _RT_THREAD );
+        ptr->random_seed = 1;
     }
     SetLastError( err );
     return ptr;