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Optimize var_export #23189

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77451c4
Optimize var_export() to avoid spprintf
kamil-tekiela Aug 9, 2026
b588316
Replace php_addcslashes() in var_export() with a dedicated function
kamil-tekiela Aug 9, 2026
dc5f795
Add UPGRADING entry
kamil-tekiela Aug 9, 2026
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1 change: 1 addition & 0 deletions UPGRADING
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Original file line number Diff line number Diff line change
Expand Up @@ -746,6 +746,7 @@ PHP 8.6 UPGRADE NOTES
. Improved performance of array_walk().
. Improved performance of intval('+0b...', 2) and intval('0b...', 2).
. Improved performance of str_split().
. Improved performance of var_export().

- URI:
. Improved performance of Uri\WhatWg\Url::parse() when collecting
Expand Down
82 changes: 47 additions & 35 deletions ext/standard/var.c
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Original file line number Diff line number Diff line change
Expand Up @@ -467,14 +467,49 @@ PHP_FUNCTION(debug_zval_dump)
}
/* }}} */

#define buffer_append_spaces(buf, num_spaces) \
do { \
char *tmp_spaces; \
size_t tmp_spaces_len; \
tmp_spaces_len = spprintf(&tmp_spaces, 0,"%*c", num_spaces, ' '); \
smart_str_appendl(buf, tmp_spaces, tmp_spaces_len); \
efree(tmp_spaces); \
} while(0);
static void buffer_append_spaces(smart_str *buf, int num_spaces)
{
char *target = smart_str_extend(buf, (size_t) num_spaces);
memset(target, ' ', num_spaces);
}

static size_t php_var_export_compute_escaped_string_len(const char *str, size_t len, bool escape_nul)
{
size_t i, escaped_len = len;
for (i = 0; i < len; ++i) {
char c = str[i];
if (c == '\'' || c == '\\') {
escaped_len += 1;
} else if (escape_nul && c == '\0') {
escaped_len += 11;
}
}
return escaped_len;
}

static void php_var_export_append_escaped(smart_str *buf, const char *str, size_t len, bool escape_nul)
{
size_t escaped_len = php_var_export_compute_escaped_string_len(str, len, escape_nul);

smart_str_appendc(buf, '\'');
if (escaped_len == len) {
smart_str_appendl(buf, str, len);
} else {
char *target = smart_str_extend(buf, escaped_len);
for (size_t i = 0; i < len; i++) {
char c = str[i];
if (c == '\'' || c == '\\') {
*target++ = '\\';
*target++ = c;
} else if (escape_nul && c == '\0') {
target = zend_mempcpy(target, "' . \"\\0\" . '", 12);
} else {
*target++ = c;
}
}
}
smart_str_appendc(buf, '\'');
}

static zend_result php_array_element_export(zval *zv, zend_ulong index, zend_string *key, int level, smart_str *buf) /* {{{ */
{
Expand All @@ -484,18 +519,10 @@ static zend_result php_array_element_export(zval *zv, zend_ulong index, zend_str
smart_str_appendl(buf, " => ", 4);

} else { /* string key */
zend_string *tmp_str;
zend_string *ckey = php_addcslashes(key, "'\\", 2);
tmp_str = php_str_to_str(ZSTR_VAL(ckey), ZSTR_LEN(ckey), "\0", 1, "' . \"\\0\" . '", 12);

buffer_append_spaces(buf, level + 1);

smart_str_appendc(buf, '\'');
smart_str_append(buf, tmp_str);
smart_str_appendl(buf, "' => ", 5);

zend_string_free(ckey);
zend_string_free(tmp_str);
php_var_export_append_escaped(buf, ZSTR_VAL(key), ZSTR_LEN(key), /* escape_nul */ true);
smart_str_appendl(buf, " => ", 4);
}
zend_result result = php_var_export_ex(zv, level + 2, buf);

Expand All @@ -512,15 +539,9 @@ static zend_result php_object_element_export(zval *zv, zend_ulong index, zend_st
if (key != NULL) {
const char *class_name, *prop_name;
size_t prop_name_len;
zend_string *pname_esc;

zend_unmangle_property_name_ex(key, &class_name, &prop_name, &prop_name_len);
pname_esc = php_addcslashes_str(prop_name, prop_name_len, "'\\", 2);

smart_str_appendc(buf, '\'');
smart_str_append(buf, pname_esc);
smart_str_appendc(buf, '\'');
zend_string_release_ex(pname_esc, 0);
php_var_export_append_escaped(buf, prop_name, prop_name_len, /* escape_nul */ false);
} else {
smart_str_append_long(buf, (zend_long) index);
}
Expand All @@ -536,7 +557,6 @@ static zend_result php_object_element_export(zval *zv, zend_ulong index, zend_st
PHPAPI zend_result php_var_export_ex(zval *struc, int level, smart_str *buf) /* {{{ */
{
HashTable *myht;
zend_string *ztmp, *ztmp2;
zend_ulong index;
zend_string *key;
zval *val;
Expand Down Expand Up @@ -567,15 +587,7 @@ PHPAPI zend_result php_var_export_ex(zval *struc, int level, smart_str *buf) /*
buf, Z_DVAL_P(struc), (int) PG(serialize_precision), /* zero_fraction */ true);
break;
case IS_STRING:
ztmp = php_addcslashes(Z_STR_P(struc), "'\\", 2);
ztmp2 = php_str_to_str(ZSTR_VAL(ztmp), ZSTR_LEN(ztmp), "\0", 1, "' . \"\\0\" . '", 12);

smart_str_appendc(buf, '\'');
smart_str_append(buf, ztmp2);
smart_str_appendc(buf, '\'');

zend_string_free(ztmp);
zend_string_free(ztmp2);
php_var_export_append_escaped(buf, Z_STRVAL_P(struc), Z_STRLEN_P(struc), /* escape_nul */ true);
break;
case IS_ARRAY:
myht = Z_ARRVAL_P(struc);
Expand Down
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