Import code from previous AssetBuilder version

thirdparty/libtomcrypt/prngs/rng_get_bytes.c

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+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+#include "tomcrypt.h"
+
+#ifdef LTC_RNG_GET_BYTES
+/**
+   @file rng_get_bytes.c
+   portable way to get secure random bits to feed a PRNG (Tom St Denis)
+*/
+
+#if defined(LTC_DEVRANDOM) && !defined(_WIN32)
+/* on *NIX read /dev/random */
+static unsigned long _rng_nix(unsigned char *buf, unsigned long len,
+                             void (*callback)(void))
+{
+#ifdef LTC_NO_FILE
+    LTC_UNUSED_PARAM(callback);
+    LTC_UNUSED_PARAM(buf);
+    LTC_UNUSED_PARAM(len);
+    return 0;
+#else
+    FILE *f;
+    unsigned long x;
+    LTC_UNUSED_PARAM(callback);
+#ifdef LTC_TRY_URANDOM_FIRST
+    f = fopen("/dev/urandom", "rb");
+    if (f == NULL)
+#endif /* LTC_TRY_URANDOM_FIRST */
+       f = fopen("/dev/random", "rb");
+
+    if (f == NULL) {
+       return 0;
+    }
+
+    /* disable buffering */
+    if (setvbuf(f, NULL, _IONBF, 0) != 0) {
+       fclose(f);
+       return 0;
+    }
+
+    x = (unsigned long)fread(buf, 1, (size_t)len, f);
+    fclose(f);
+    return x;
+#endif /* LTC_NO_FILE */
+}
+
+#endif /* LTC_DEVRANDOM */
+
+#if !defined(_WIN32_WCE)
+
+#define ANSI_RNG
+
+static unsigned long _rng_ansic(unsigned char *buf, unsigned long len,
+                               void (*callback)(void))
+{
+   clock_t t1;
+   int l, acc, bits, a, b;
+
+   l = len;
+   bits = 8;
+   acc  = a = b = 0;
+   while (len--) {
+       if (callback != NULL) callback();
+       while (bits--) {
+          do {
+             t1 = XCLOCK(); while (t1 == XCLOCK()) a ^= 1;
+             t1 = XCLOCK(); while (t1 == XCLOCK()) b ^= 1;
+          } while (a == b);
+          acc = (acc << 1) | a;
+       }
+       *buf++ = acc;
+       acc  = 0;
+       bits = 8;
+   }
+   return l;
+}
+
+#endif
+
+/* Try the Microsoft CSP */
+#if defined(_WIN32) || defined(_WIN32_WCE)
+#ifndef _WIN32_WINNT
+  #define _WIN32_WINNT 0x0400
+#endif
+#ifdef _WIN32_WCE
+   #define UNDER_CE
+   #define ARM
+#endif
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <wincrypt.h>
+
+static unsigned long _rng_win32(unsigned char *buf, unsigned long len,
+                               void (*callback)(void))
+{
+   HCRYPTPROV hProv = 0;
+   LTC_UNUSED_PARAM(callback);
+   if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
+                            (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) &&
+       !CryptAcquireContext (&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL,
+                            CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET))
+      return 0;
+
+   if (CryptGenRandom(hProv, len, buf) == TRUE) {
+      CryptReleaseContext(hProv, 0);
+      return len;
+   } else {
+      CryptReleaseContext(hProv, 0);
+      return 0;
+   }
+}
+
+#endif /* WIN32 */
+
+/**
+  Read the system RNG
+  @param out       Destination
+  @param outlen    Length desired (octets)
+  @param callback  Pointer to void function to act as "callback" when RNG is slow.  This can be NULL
+  @return Number of octets read
+*/
+unsigned long rng_get_bytes(unsigned char *out, unsigned long outlen,
+                            void (*callback)(void))
+{
+   unsigned long x;
+
+   LTC_ARGCHK(out != NULL);
+
+#ifdef LTC_PRNG_ENABLE_LTC_RNG
+   if (ltc_rng) {
+      x = ltc_rng(out, outlen, callback);
+      if (x != 0) {
+         return x;
+      }
+   }
+#endif
+
+#if defined(_WIN32) || defined(_WIN32_WCE)
+   x = _rng_win32(out, outlen, callback); if (x != 0) { return x; }
+#elif defined(LTC_DEVRANDOM)
+   x = _rng_nix(out, outlen, callback);   if (x != 0) { return x; }
+#endif
+#ifdef ANSI_RNG
+   x = _rng_ansic(out, outlen, callback); if (x != 0) { return x; }
+#endif
+   return 0;
+}
+#endif /* #ifdef LTC_RNG_GET_BYTES */
+
+/* ref:         HEAD -> master, tag: v1.18.2 */
+/* git commit:  7e7eb695d581782f04b24dc444cbfde86af59853 */
+/* commit time: 2018-07-01 22:49:01 +0200 */