From 150c9823e71a161e97003849cf8b2f55b21520bd Mon Sep 17 00:00:00 2001
From: Tim Redfern <tim@eclectronics.org>
Date: Mon, 26 Aug 2013 15:10:18 +0100
Subject: adding ffmpeg specific version

---
 ffmpeg1/libavutil/random_seed.c | 151 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 151 insertions(+)
 create mode 100644 ffmpeg1/libavutil/random_seed.c

(limited to 'ffmpeg1/libavutil/random_seed.c')

diff --git a/ffmpeg1/libavutil/random_seed.c b/ffmpeg1/libavutil/random_seed.c
new file mode 100644
index 0000000..c674704
--- /dev/null
+++ b/ffmpeg1/libavutil/random_seed.c
@@ -0,0 +1,151 @@
+/*
+ * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "config.h"
+
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#if HAVE_CRYPTGENRANDOM
+#include <windows.h>
+#include <wincrypt.h>
+#endif
+#include <fcntl.h>
+#include <math.h>
+#include <time.h>
+#include <string.h>
+#include "avassert.h"
+#include "timer.h"
+#include "random_seed.h"
+#include "sha.h"
+#include "intreadwrite.h"
+
+#ifndef TEST
+#define TEST 0
+#endif
+
+static int read_random(uint32_t *dst, const char *file)
+{
+#if HAVE_UNISTD_H
+    int fd = open(file, O_RDONLY);
+    int err = -1;
+
+    if (fd == -1)
+        return -1;
+    err = read(fd, dst, sizeof(*dst));
+    close(fd);
+
+    return err;
+#else
+    return -1;
+#endif
+}
+
+static uint32_t get_generic_seed(void)
+{
+    uint8_t tmp[120];
+    struct AVSHA *sha = (void*)tmp;
+    clock_t last_t  = 0;
+    static uint64_t i = 0;
+    static uint32_t buffer[512] = {0};
+    unsigned char digest[20];
+    uint64_t last_i = i;
+
+    av_assert0(sizeof(tmp) >= av_sha_size);
+
+    if(TEST){
+        memset(buffer, 0, sizeof(buffer));
+        last_i = i = 0;
+    }else{
+#ifdef AV_READ_TIME
+        buffer[13] ^= AV_READ_TIME();
+        buffer[41] ^= AV_READ_TIME()>>32;
+#endif
+    }
+
+    for (;;) {
+        clock_t t = clock();
+
+        if(last_t == t){
+            buffer[i&511]++;
+        }else{
+            buffer[++i&511]+= (t-last_t) % 3294638521U;
+            if(last_i && i-last_i > 4 || i-last_i > 64 || TEST && i-last_i > 8)
+                break;
+        }
+        last_t = t;
+    }
+
+    if(TEST)
+        buffer[0] = buffer[1] = 0;
+
+    av_sha_init(sha, 160);
+    av_sha_update(sha, (uint8_t*)buffer, sizeof(buffer));
+    av_sha_final(sha, digest);
+    return AV_RB32(digest) + AV_RB32(digest+16);
+}
+
+uint32_t av_get_random_seed(void)
+{
+    uint32_t seed;
+
+#if HAVE_CRYPTGENRANDOM
+    HCRYPTPROV provider;
+    if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
+                            CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
+        BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed);
+        CryptReleaseContext(provider, 0);
+        if (ret)
+            return seed;
+    }
+#endif
+
+    if (read_random(&seed, "/dev/urandom") == sizeof(seed))
+        return seed;
+    if (read_random(&seed, "/dev/random")  == sizeof(seed))
+        return seed;
+    return get_generic_seed();
+}
+
+#if TEST
+#undef printf
+#define N 256
+#include <stdio.h>
+
+int main(void)
+{
+    int i, j, retry;
+    uint32_t seeds[N];
+
+    for (retry=0; retry<3; retry++){
+        for (i=0; i<N; i++){
+            seeds[i] = av_get_random_seed();
+            for (j=0; j<i; j++)
+                if (seeds[j] == seeds[i])
+                    goto retry;
+        }
+        printf("seeds OK\n");
+        return 0;
+        retry:;
+    }
+    printf("FAIL at %d with %X\n", j, seeds[j]);
+    return 1;
+}
+#endif
-- 
cgit v1.2.3