#include "Python.h"
#ifdef MS_WINDOWS
#include 
#else
#include 
#if defined(HAVE_SYS_RANDOM_H) && (defined(HAVE_GETRANDOM) || defined(HAVE_GETENTROPY))
#include 
#endif
#endif

#ifdef Py_DEBUG
int _Py_HashSecret_Initialized = 0;
#else
static int _Py_HashSecret_Initialized = 0;
#endif

#ifdef MS_WINDOWS
typedef BOOL (WINAPI *CRYPTACQUIRECONTEXTA)(HCRYPTPROV *phProv,\
              LPCSTR pszContainer, LPCSTR pszProvider, DWORD dwProvType,\
              DWORD dwFlags );
typedef BOOL (WINAPI *CRYPTGENRANDOM)(HCRYPTPROV hProv, DWORD dwLen,\
              BYTE *pbBuffer );

static CRYPTGENRANDOM pCryptGenRandom = NULL;
/* This handle is never explicitly released. Instead, the operating
   system will release it when the process terminates. */
static HCRYPTPROV hCryptProv = 0;

static int
win32_urandom_init(int raise)
{
    HINSTANCE hAdvAPI32 = NULL;
    CRYPTACQUIRECONTEXTA pCryptAcquireContext = NULL;

    /* Obtain handle to the DLL containing CryptoAPI. This should not fail. */
    hAdvAPI32 = GetModuleHandle("advapi32.dll");
    if(hAdvAPI32 == NULL)
        goto error;

    /* Obtain pointers to the CryptoAPI functions. This will fail on some early
       versions of Win95. */
    pCryptAcquireContext = (CRYPTACQUIRECONTEXTA)GetProcAddress(
                               hAdvAPI32, "CryptAcquireContextA");
    if (pCryptAcquireContext == NULL)
        goto error;

    pCryptGenRandom = (CRYPTGENRANDOM)GetProcAddress(hAdvAPI32,
                                                     "CryptGenRandom");
    if (pCryptGenRandom == NULL)
        goto error;

    /* Acquire context */
    if (! pCryptAcquireContext(&hCryptProv, NULL, NULL,
                               PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
        goto error;

    return 0;

error:
    if (raise)
        PyErr_SetFromWindowsErr(0);
    else
        Py_FatalError("Failed to initialize Windows random API (CryptoGen)");
    return -1;
}

/* Fill buffer with size pseudo-random bytes generated by the Windows CryptoGen
   API. Return 0 on success, or -1 on error. */
static int
win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise)
{
    Py_ssize_t chunk;

    if (hCryptProv == 0)
    {
        if (win32_urandom_init(raise) == -1)
            return -1;
    }

    while (size > 0)
    {
        chunk = size > INT_MAX ? INT_MAX : size;
        if (!pCryptGenRandom(hCryptProv, chunk, buffer))
        {
            /* CryptGenRandom() failed */
            if (raise)
                PyErr_SetFromWindowsErr(0);
            else
                Py_FatalError("Failed to initialized the randomized hash "
                        "secret using CryptoGen)");
            return -1;
        }
        buffer += chunk;
        size -= chunk;
    }
    return 0;
}

/* Issue #25003: Don't use getentropy() on Solaris (available since
   Solaris 11.3), it is blocking whereas os.urandom() should not block.

   Issue #29188: Don't use getentropy() on Linux since the glibc 2.24
   implements it with the getrandom() syscall which can fail with ENOSYS,
   and this error is not supported in py_getentropy() and getrandom() is called
   with flags=0 which blocks until system urandom is initialized, which is not
   the desired behaviour to seed the Python hash secret nor for os.urandom():
   see the PEP 524 which was only implemented in Python 3.6. */
#elif defined(HAVE_GETENTROPY) && !defined(sun) && !defined(linux)
#define PY_GETENTROPY 1

/* Fill buffer with size pseudo-random bytes generated by getentropy().
   Return 0 on success, or raise an exception and return -1 on error.
   If fatal is nonzero, call Py_FatalError() instead of raising an exception
   on error. */
static int
py_getentropy(unsigned char *buffer, Py_ssize_t size, int fatal)
{
    while (size > 0) {
        Py_ssize_t len = size < 256 ? size : 256;
        int res;

        if (!fatal) {
            Py_BEGIN_ALLOW_THREADS
            res = getentropy(buffer, len);
            Py_END_ALLOW_THREADS

            if (res < 0) {
                PyErr_SetFromErrno(PyExc_OSError);
                return -1;
            }
        }
        else {
            res = getentropy(buffer, len);
            if (res < 0)
                Py_FatalError("getentropy() failed");
        }

        buffer += len;
        size -= len;
    }
    return 0;
}
#endif

#ifdef __VMS
/* Use openssl random routine */
#include 
static int
vms_urandom(unsigned char *buffer, Py_ssize_t size, int raise)
{
    if (RAND_pseudo_bytes(buffer, size) < 0) {
        if (raise) {
            PyErr_Format(PyExc_ValueError,
                         "RAND_pseudo_bytes");
        } else {
            Py_FatalError("Failed to initialize the randomized hash "
                          "secret using RAND_pseudo_bytes");
        }
        return -1;
    }
    return 0;
}
#endif /* __VMS */


#if !defined(MS_WINDOWS) && !defined(__VMS)

static struct {
    int fd;
    dev_t st_dev;
    ino_t st_ino;
} urandom_cache = { -1 };

/* Read size bytes from /dev/urandom into buffer.
   Call Py_FatalError() on error. */
static void
dev_urandom_noraise(unsigned char *buffer, Py_ssize_t size)
{
    int fd;
    Py_ssize_t n;

    assert (0 < size);

    fd = open("/dev/urandom", O_RDONLY);
    if (fd < 0)
        Py_FatalError("Failed to open /dev/urandom");

    while (0 < size)
    {
        do {
            n = read(fd, buffer, (size_t)size);
        } while (n < 0 && errno == EINTR);
        if (n