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standard: Optimize explode() with negative limit #20417

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standard: Optimize explode() with negative limit #20417

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62 changes: 25 additions & 37 deletions ext/standard/string.c
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Original file line number Diff line number Diff line change
Expand Up @@ -829,16 +829,19 @@ PHP_FUNCTION(wordwrap)
}
/* }}} */

/* {{{ php_explode */
PHPAPI void php_explode(const zend_string *delim, zend_string *str, zval *return_value, zend_long limit)
static void php_explode_ex(const zend_string *delim, zend_string *str, zval *return_value, zend_long limit, const char *endp)
{
const char *p1 = ZSTR_VAL(str);
const char *endp = ZSTR_VAL(str) + ZSTR_LEN(str);
const char *p2 = php_memnstr(ZSTR_VAL(str), ZSTR_VAL(delim), ZSTR_LEN(delim), endp);
const char *p2 = php_memnstr(p1, ZSTR_VAL(delim), ZSTR_LEN(delim), endp);
zval tmp;

if (p2 == NULL) {
ZVAL_STR_COPY(&tmp, str);
if (endp == ZSTR_VAL(str) + ZSTR_LEN(str)) {
ZVAL_STR_COPY(&tmp, str);
} else {
ZEND_ASSERT(endp != ZSTR_VAL(str));
ZVAL_STRINGL_FAST(&tmp, ZSTR_VAL(str), endp - ZSTR_VAL(str));
}
zend_hash_next_index_insert_new(Z_ARRVAL_P(return_value), &tmp);
} else {
zend_hash_real_init_packed(Z_ARRVAL_P(return_value));
Expand All @@ -859,46 +862,31 @@ PHPAPI void php_explode(const zend_string *delim, zend_string *str, zval *return
} ZEND_HASH_FILL_END();
}
}

/* {{{ php_explode */
PHPAPI void php_explode(const zend_string *delim, zend_string *str, zval *return_value, zend_long limit)
{
php_explode_ex(delim, str, return_value, limit, ZSTR_VAL(str) + ZSTR_LEN(str));
}
/* }}} */

/* {{{ php_explode_negative_limit */
PHPAPI void php_explode_negative_limit(const zend_string *delim, zend_string *str, zval *return_value, zend_long limit)
{
#define EXPLODE_ALLOC_STEP 64
const char *p1 = ZSTR_VAL(str);
const char *p = ZSTR_VAL(str);
const char *endp = ZSTR_VAL(str) + ZSTR_LEN(str);
const char *p2 = php_memnstr(ZSTR_VAL(str), ZSTR_VAL(delim), ZSTR_LEN(delim), endp);
zval tmp;

if (p2 == NULL) {
/*
do nothing since limit <= -1, thus if only one chunk - 1 + (limit) <= 0
by doing nothing we return empty array
*/
} else {
size_t allocated = EXPLODE_ALLOC_STEP, found = 0;
zend_long i, to_return;
const char **positions = emalloc(allocated * sizeof(char *));

positions[found++] = p1;
do {
if (found >= allocated) {
allocated = found + EXPLODE_ALLOC_STEP;/* make sure we have enough memory */
positions = erealloc(ZEND_VOIDP(positions), allocated*sizeof(char *));
}
positions[found++] = p1 = p2 + ZSTR_LEN(delim);
p2 = php_memnstr(p1, ZSTR_VAL(delim), ZSTR_LEN(delim), endp);
} while (p2 != NULL);

to_return = limit + found;
/* limit is at least -1 therefore no need of bounds checking : i will be always less than found */
for (i = 0; i < to_return; i++) { /* this checks also for to_return > 0 */
ZVAL_STRINGL(&tmp, positions[i], (positions[i+1] - ZSTR_LEN(delim)) - positions[i]);
zend_hash_next_index_insert_new(Z_ARRVAL_P(return_value), &tmp);
ZEND_ASSERT(limit < 0);
do {
endp = zend_memnrstr(p, ZSTR_VAL(delim), ZSTR_LEN(delim), endp);
if (!endp) {
return;
}
efree((void *)positions);
}
#undef EXPLODE_ALLOC_STEP
--endp;
++limit;
} while (limit < 0);

php_explode_ex(delim, str, return_value, ZEND_LONG_MAX, endp + 1);
}
/* }}} */

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