Implement php_url_encode_to_smart_str() and use it in http_build_query()

This avoids temporary allocations and some copies.

For this benchmark:
```php
for ($i=0;$i<2000000;$i++) {
  http_build_query([999999 => 'foo', 'aaab' => 'def', 'aaaaa'=>1, 'aaaaaaaa' => 'a']);
}
```

On an i7-4790:
```
Benchmark 1: ./sapi/cli/php ../buildquery.php
  Time (mean ± σ):     298.9 ms ±   7.3 ms    [User: 295.6 ms, System: 2.3 ms]
  Range (min … max):   293.6 ms … 314.0 ms    10 runs

Benchmark 2: ./sapi/cli/php_old ../buildquery.php
  Time (mean ± σ):     594.8 ms ±   8.6 ms    [User: 590.8 ms, System: 2.4 ms]
  Range (min … max):   586.3 ms … 616.1 ms    10 runs

Summary
  ./sapi/cli/php ../buildquery.php ran
    1.99 ± 0.06 times faster than ./sapi/cli/php_old ../buildquery.php
```

For this benchmark:
```php
for ($i=0;$i<2000000;$i++) {
  http_build_query(['test' => 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa']);
}
```

On an i7-4790:
```
Benchmark 1: ./sapi/cli/php ../buildquery.php
  Time (mean ± σ):     188.4 ms ±   6.7 ms    [User: 184.6 ms, System: 2.9 ms]
  Range (min … max):   182.0 ms … 205.4 ms    14 runs

Benchmark 2: ./sapi/cli/php_old ../buildquery.php
  Time (mean ± σ):     323.9 ms ±   8.7 ms    [User: 319.8 ms, System: 2.7 ms]
  Range (min … max):   318.0 ms … 341.2 ms    10 runs

Summary
  ./sapi/cli/php ../buildquery.php ran
    1.72 ± 0.08 times faster than ./sapi/cli/php_old ../buildquery.php
```

Author: nielsdos

UPGRADING.INTERNALS

@@ -68,6 +68,7 @@ PHP 8.5 INTERNALS UPGRADE NOTES
 - ext/standard
   . Added php_url_decode_ex() and php_raw_url_decode_ex() that unlike their
     non-ex counterparts do not work in-place.
+  . Added php_url_encode_to_smart_str() to encode a URL to a smart_str buffer.
 
 ========================
 4. OpCode changes

ext/standard/http.c

@@ -37,14 +37,7 @@ static void php_url_encode_scalar(zval *scalar, smart_str *form_str,
 		smart_str_append(form_str, key_prefix);
 	}
 	if (index_string) {
-		zend_string *encoded_key;
-		if (encoding_type == PHP_QUERY_RFC3986) {
-			encoded_key = php_raw_url_encode(index_string, index_string_len);
-		} else {
-			encoded_key = php_url_encode(index_string, index_string_len);
-		}
-		smart_str_append(form_str, encoded_key);
-		zend_string_free(encoded_key);
+		php_url_encode_to_smart_str(form_str, index_string, index_string_len, encoding_type == PHP_QUERY_RFC3986);
 	} else {
 		/* Numeric key */
 		if (num_prefix) {
@@ -59,31 +52,16 @@ static void php_url_encode_scalar(zval *scalar, smart_str *form_str,
 
 try_again:
 	switch (Z_TYPE_P(scalar)) {
-		case IS_STRING: {
-			zend_string *encoded_data;
-			if (encoding_type == PHP_QUERY_RFC3986) {
-				encoded_data = php_raw_url_encode(Z_STRVAL_P(scalar), Z_STRLEN_P(scalar));
-			} else {
-				encoded_data = php_url_encode(Z_STRVAL_P(scalar), Z_STRLEN_P(scalar));
-			}
-			smart_str_append(form_str, encoded_data);
-			zend_string_free(encoded_data);
+		case IS_STRING:
+			php_url_encode_to_smart_str(form_str, Z_STRVAL_P(scalar), Z_STRLEN_P(scalar), encoding_type == PHP_QUERY_RFC3986);
 			break;
-		}
 		case IS_LONG:
 			smart_str_append_long(form_str, Z_LVAL_P(scalar));
 			break;
 		case IS_DOUBLE: {
-			zend_string *encoded_data;
 			zend_string *tmp = zend_double_to_str(Z_DVAL_P(scalar));
-			if (encoding_type == PHP_QUERY_RFC3986) {
-				encoded_data = php_raw_url_encode(ZSTR_VAL(tmp), ZSTR_LEN(tmp));
-			} else {
-				encoded_data = php_url_encode(ZSTR_VAL(tmp), ZSTR_LEN(tmp));
-			}
-			smart_str_append(form_str, encoded_data);
+			php_url_encode_to_smart_str(form_str, ZSTR_VAL(tmp), ZSTR_LEN(tmp), encoding_type == PHP_QUERY_RFC3986);
 			zend_string_free(tmp);
-			zend_string_free(encoded_data);
 			break;
 		}
 		case IS_FALSE:

ext/standard/url.c

@@ -27,6 +27,7 @@
 
 #include "url.h"
 #include "file.h"
+#include "Zend/zend_smart_str.h"
 
 /* {{{ free_url */
 PHPAPI void php_url_free(php_url *theurl)
@@ -449,16 +450,13 @@ static int php_htoi(const char *s)
 
 static const unsigned char hexchars[] = "0123456789ABCDEF";
 
-static zend_always_inline zend_string *php_url_encode_impl(const char *s, size_t len, bool raw) /* {{{ */ {
+static zend_always_inline size_t php_url_encode_impl(unsigned char *to, const char *s, size_t len, bool raw) /* {{{ */ {
 	unsigned char c;
-	unsigned char *to;
 	unsigned char const *from, *end;
-	zend_string *start;
+	const unsigned char *to_init = to;
 
 	from = (unsigned char *)s;
 	end = (unsigned char *)s + len;
-	start = zend_string_safe_alloc(3, len, 0, 0);
-	to = (unsigned char*)ZSTR_VAL(start);
 
 #ifdef __SSE2__
 	while (from + 16 < end) {
@@ -537,19 +535,24 @@ static zend_always_inline zend_string *php_url_encode_impl(const char *s, size_t
 			*to++ = c;
 		}
 	}
-	*to = '\0';
 
-	ZEND_ASSERT(!ZSTR_IS_INTERNED(start) && GC_REFCOUNT(start) == 1);
-	start = zend_string_truncate(start, to - (unsigned char*)ZSTR_VAL(start), 0);
-
-	return start;
+	return to - to_init;
 }
 /* }}} */
 
+static zend_always_inline zend_string *php_url_encode_helper(char const *s, size_t len, bool raw)
+{
+	zend_string *result = zend_string_safe_alloc(3, len, 0, false);
+	size_t length = php_url_encode_impl((unsigned char *) ZSTR_VAL(result), s, len, raw);
+	ZSTR_VAL(result)[length] = '\0';
+	ZEND_ASSERT(!ZSTR_IS_INTERNED(result) && GC_REFCOUNT(result) == 1);
+	return zend_string_truncate(result, length, false);
+}
+
 /* {{{ php_url_encode */
 PHPAPI zend_string *php_url_encode(char const *s, size_t len)
 {
-	return php_url_encode_impl(s, len, 0);
+	return php_url_encode_helper(s, len, false);
 }
 /* }}} */
 
@@ -616,10 +619,19 @@ PHPAPI size_t php_url_decode(char *str, size_t len)
 /* {{{ php_raw_url_encode */
 PHPAPI zend_string *php_raw_url_encode(char const *s, size_t len)
 {
-	return php_url_encode_impl(s, len, 1);
+	return php_url_encode_helper(s, len, true);
 }
 /* }}} */
 
+PHPAPI void php_url_encode_to_smart_str(smart_str *buf, char const *s, size_t len, bool raw)
+{
+	size_t start_length = smart_str_get_len(buf);
+	size_t extend = zend_safe_address_guarded(3, len, 0);
+	char *dest = smart_str_extend(buf, extend);
+	size_t length = php_url_encode_impl((unsigned char *) dest, s, len, raw);
+	ZSTR_LEN(buf->s) = start_length + length;
+}
+
 /* {{{ URL-encodes string */
 PHP_FUNCTION(rawurlencode)
 {

ext/standard/url.h

@@ -38,6 +38,7 @@ PHPAPI size_t php_raw_url_decode(char *str, size_t len); /* return value: length
 PHPAPI size_t php_raw_url_decode_ex(char *dest, const char *src, size_t src_len);
 PHPAPI zend_string *php_url_encode(char const *s, size_t len);
 PHPAPI zend_string *php_raw_url_encode(char const *s, size_t len);
+PHPAPI void php_url_encode_to_smart_str(smart_str *buf, char const *s, size_t len, bool raw);
 
 #define PHP_URL_SCHEME 0
 #define PHP_URL_HOST 1