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ext/random: Optimized getBytes loop processing #14891

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c3a4623
Optimized getBytes loop processing
SakiTakamachi Jul 9, 2024
6a17d32
version 2
SakiTakamachi Jul 10, 2024
4d9b51c
restore it once
SakiTakamachi Jul 11, 2024
6b7400f
Optimized bit shifting
SakiTakamachi Jul 11, 2024
0cacff8
Changed to use memcpy when possible
SakiTakamachi Jul 11, 2024
7873e60
Loop optimization
SakiTakamachi Jul 11, 2024
c78d5a7
Changed RANDOM_BSWAP64 to ZEND_BYTES_SWAP64
SakiTakamachi Jul 22, 2024
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28 changes: 21 additions & 7 deletions ext/random/randomizer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@

#include "Zend/zend_enum.h"
#include "Zend/zend_exceptions.h"
#include "zend_portability.h"

static inline void randomizer_common_init(php_random_randomizer *randomizer, zend_object *engine_object) {
if (engine_object->ce->type == ZEND_INTERNAL_CLASS) {
Expand Down Expand Up @@ -278,7 +279,6 @@ PHP_METHOD(Random_Randomizer, getBytes)

zend_string *retval;
zend_long user_length;
size_t total_size = 0;

ZEND_PARSE_PARAMETERS_START(1, 1)
Z_PARAM_LONG(user_length)
Expand All @@ -291,22 +291,36 @@ PHP_METHOD(Random_Randomizer, getBytes)

size_t length = (size_t)user_length;
retval = zend_string_alloc(length, 0);
char *rptr = ZSTR_VAL(retval);

while (total_size < length) {
size_t to_read = length;
while (to_read > 0) {
php_random_result result = engine.algo->generate(engine.state);
if (EG(exception)) {
zend_string_free(retval);
RETURN_THROWS();
}
for (size_t i = 0; i < result.size; i++) {
ZSTR_VAL(retval)[total_size++] = (result.result >> (i * 8)) & 0xff;
if (total_size >= length) {
break;
uint64_t tmp_ret = result.result;
if (to_read >= sizeof(uint64_t) && result.size == sizeof(uint64_t)) {
#ifdef WORDS_BIGENDIAN
tmp_ret = ZEND_BYTES_SWAP64(tmp_ret);
#endif
memcpy(rptr, &tmp_ret, sizeof(uint64_t));
to_read -= sizeof(uint64_t);
rptr += sizeof(uint64_t);
} else {
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Is there a possibility that this else will be executed?

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Yes. It can happen with userland engines that return single bytes:

final class MyEngine implements \Random\Engine {
  public function generate(): string { return 'x'; }
}

$r = new \Random\Randomizer(new MyEngine());

var_dump($r->getBytes(10));

for (size_t i = 0; i < result.size; i++) {
*rptr++ = tmp_ret & 0xff;
tmp_ret >>= 8;
to_read--;
if (to_read == 0) {
break;
}
}
}
}

ZSTR_VAL(retval)[length] = '\0';
*rptr = '\0';
RETURN_STR(retval);
}
/* }}} */
Expand Down