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More unique uniqid (no BC) #19264

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34 changes: 23 additions & 11 deletions ext/standard/uniqid.c
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Original file line number Diff line number Diff line change
Expand Up @@ -53,20 +53,32 @@ PHP_FUNCTION(uniqid)
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.
/* This implementation needs current microsecond to change.
* We will manually move the time forward if needed. This is
* more stable as polling or sleeping as it will not be
* effected by time changes (like ntp) and 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);
(void)gettimeofday((struct timeval *) &tv, (struct timezone *) NULL);
if (UNEXPECTED((tv.tv_sec == prev_tv.tv_sec && tv.tv_usec <= prev_tv.tv_usec)
|| tv.tv_sec < prev_tv.tv_sec
)) {
prev_tv.tv_usec += 1;
if (UNEXPECTED(prev_tv.tv_usec > 999999)) {
prev_tv.tv_sec += prev_tv.tv_usec / 1000000;
prev_tv.tv_usec = prev_tv.tv_usec % 1000000;
}

prev_tv.tv_sec = tv.tv_sec;
prev_tv.tv_usec = tv.tv_usec;
sec = (int) prev_tv.tv_sec;
usec = (int) prev_tv.tv_usec;
} else {
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);
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.
Expand Down