Improve random number generation

[wimlib] / src / win32_replacements.c

diff --git a/src/win32_replacements.c b/src/win32_replacements.c
index 26f4b4b7969398ea7c6b81adb696d803703cbcd5..2a16500da67964bd8e87b3e293a46023a439263b 100644 (file)
--- a/src/win32_replacements.c
+++ b/src/win32_replacements.c
@@ -439,7 +439,7 @@ win32_rename_replacement(const wchar_t *srcpath, const wchar_t *dstpath)
                p = tmpname;
                p = wmempcpy(p, dstpath, dstlen);
                p = wmempcpy(p, orig_suffix, ARRAY_LEN(orig_suffix));
-               randomize_char_array_with_alnum(p, num_rand_chars);
+               get_random_alnum_chars(p, num_rand_chars);
                p += num_rand_chars;
                *p = L'\0';
        }
@@ -748,4 +748,30 @@ win32_open_logfile(const wchar_t *path)
        return fp;
 }
 
+#define RtlGenRandom SystemFunction036
+BOOLEAN WINAPI RtlGenRandom(PVOID RandomBuffer, ULONG RandomBufferLength);
+
+/*
+ * Generate @n cryptographically secure random bytes (thread-safe)
+ *
+ * This is the Windows version.  It uses RtlGenRandom() (actually called
+ * SystemFunction036) from advapi32.dll.
+ */
+void
+get_random_bytes(void *p, size_t n)
+{
+       while (n != 0) {
+               u32 count = min(n, UINT32_MAX);
+
+               if (!RtlGenRandom(p, count)) {
+                       win32_error(GetLastError(),
+                                   L"RtlGenRandom() failed (count=%u)", count);
+                       wimlib_assert(0);
+                       count = 0;
+               }
+               p += count;
+               n -= count;
+       }
+}
+
 #endif /* __WIN32__ */