uniqid.c

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/*
   +----------------------------------------------------------------------+
   | Copyright (c) The PHP Group                                          |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | https://www.php.net/license/3_01.txt                                 |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Author: Stig Sæther Bakken <ssb@php.net>                             |
   +----------------------------------------------------------------------+
 */
 
#include "php.h"
 
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
 
#include <string.h>
#include <errno.h>
 
#include <stdio.h>
#ifdef PHP_WIN32
#include "win32/time.h"
#else
#include <sys/time.h>
#endif
 
#include "ext/random/php_random.h"
#include "ext/random/php_random_csprng.h"
 
#ifdef HAVE_GETTIMEOFDAY
ZEND_TLS struct timeval prev_tv = { 0, 0 };
 
/* {{{ Generates a unique ID */
PHP_FUNCTION(uniqid)
{
    char *prefix = "";
    bool more_entropy = 0;
    zend_string *uniqid;
    int sec, usec;
    size_t prefix_len = 0;
    struct timeval tv;
 
    ZEND_PARSE_PARAMETERS_START(0, 2)
        Z_PARAM_OPTIONAL
        Z_PARAM_STRING(prefix, prefix_len)
        Z_PARAM_BOOL(more_entropy)
    ZEND_PARSE_PARAMETERS_END();
 
    /* This implementation needs current microsecond to change,
     * hence we poll time until it does. This is much faster than
     * calling usleep(1) which may cause the kernel to schedule
     * another process, causing a pause of around 10ms.
     */
    do {
        (void)gettimeofday((struct timeval *) &tv, (struct timezone *) NULL);
    } while (tv.tv_sec == prev_tv.tv_sec && tv.tv_usec == prev_tv.tv_usec);
 
    prev_tv.tv_sec = tv.tv_sec;
    prev_tv.tv_usec = tv.tv_usec;
 
    sec = (int) tv.tv_sec;
    usec = (int) (tv.tv_usec % 0x100000);
 
    /* The max value usec can have is 0xF423F, so we use only five hex
     * digits for usecs.
     */
    if (more_entropy) {
        uint32_t bytes;
        double seed;
        if (php_random_bytes_silent(&bytes, sizeof(uint32_t)) == FAILURE) {
            bytes = php_random_generate_fallback_seed();
        }
        seed = ((double) bytes / UINT32_MAX) * 10.0;
        uniqid = strpprintf(0, "%s%08x%05x%.8F", prefix, sec, usec, seed);
    } else {
        uniqid = strpprintf(0, "%s%08x%05x", prefix, sec, usec);
    }
 
    RETURN_STR(uniqid);
}
#endif
/* }}} */