Pass array by reference and modify inside function

[gorazdr]

I have something like this:
PHP_FUNCTION(modify) {
smart_str ss = { 0 };
zval *val;
long opts = 0;
zval *strings ;
HashTable sht;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "zla", &val, &opts, &strings) == FAILURE) return;
sht = Z_ARRVAL_P(strings) ;
cmodify(&ss, val, opts, &sht TSRML_CC) ;
RETVAL_STRINGL(ss.c, ss.len, 1);
smart_str_free(&ss);
}

cmodify expects sht to be HashTable but I would like strings(array) could replace sht

Thanks in advance.

[mkoppanen]

I am not sure I fully understand that the question. Do you want to modify the elements of "strings" array inside cmodify function?

[gorazdr]

Yes that is exactly what I want.
Basicly a would like to rewrite php-amf3 (AMF serializator) extension so that it keeps proper stringReferences.
I tried writing to strings inside modify function with add_assoc_* and that worked OK but when I try writing to sht with zend_hash_add_* I get internal error

[gorazdr]

This is original unmodified function
PHP_FUNCTION(amf3_encode) {
smart_str ss = { 0 };
zval *val;
long opts = 0;
HashTable sht, oht, tht;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z|l", &val, &opts) == FAILURE) return;
zend_hash_init(&sht, 0, NULL, NULL, 0);
zend_hash_init(&oht, 0, NULL, NULL, 0);
zend_hash_init(&tht, 0, NULL, NULL, 0);
encodeValue(&ss, val, opts, &sht, &oht, &tht TSRMLS_CC);
zend_hash_destroy(&sht);
zend_hash_destroy(&oht);
zend_hash_destroy(&tht);
RETVAL_STRINGL(ss.c, ss.len, 1);
smart_str_free(&ss);
}
I would like sht, oht and tht to be passed in by reference

[mkoppanen]

Essentially what you need to do is to mark the argument as a reference in arg info, see first parameter in: http://lxr.php.net/xref/PHP_5_5/Zend/zend_API.h#101

Also, note that Z_ARRVAL_P gives a pointer to the HashTable so if the cmodify expects HashTable * you need to pass "sht" rather than "&sht".

[gorazdr]

So change to:
ZEND_BEGIN_ARG_INFO_EX(arginfo_amf3_encode, 0, 0, 1)
ZEND_ARG_INFO(0, value)
ZEND_ARG_INFO(1, sht)
ZEND_ARG_INFO(1, oht)
ZEND_ARG_INFO(1, tht)
ZEND_ARG_INFO(0, options)
ZEND_END_ARG_INFO()

and

PHP_FUNCTION(amf3_encode) {
smart_str ss = { 0 };
zval *val, *sht, *oht, *tht;
long opts = 0;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "zaaa|l", &val, &sht, &oht, &tht, &opts) == FAILURE) return;

encodeValue(&ss, val, opts, HASH_OF(sht), HASH_OF(oht), HASH_OF(tht) TSRMLS_CC);

RETVAL_STRINGL(ss.c, ss.len, 1);
smart_str_free(&ss);

}

Is that correct?

[mkoppanen]

The last argument to ZEND_BEGIN_ARG_INFO_EX should be 4 as there are four mandatory arguments for the function. Other than that it looks ok.

[gorazdr]

Changed ZEND_BEGIN_ARG_INFO_EX to 4 and it compiled without problems. When I test it I get in kern.log
php5-fpm[6403]: segfault at 10 ip 00000000006db764 sp 00007fff75b5cd90 error 4 in php5-fpm[400000+7fd000]

php version:
php 5.5.3

[gorazdr]

if I comment out
//encodeValue(&ss, val, opts, HASH_OF(sht), HASH_OF(oht), HASH_OF(tht) TSRMLS_CC);
There is no segfault but of course it does nothing

[gorazdr]

Definition of encodeValue

static void encodeValue(smart_str *ss, zval *val, int opts, HashTable *sht, HashTable *oht, HashTable *tht TSRMLS_DC) {

[mkoppanen]

What are the contents of encodeValue? Have you tried debugging with gdb?

[gorazdr]

Full:
static void encodeValue(smart_str ss, zval *val, int opts, HashTable *sht, HashTable *oht, HashTable *tht TSRMLS_DC) {
switch (Z_TYPE_P(val)) {
default:
smart_str_appendc(ss, AMF3_UNDEFINED);
break;
case IS_NULL:
smart_str_appendc(ss, AMF3_NULL);
break;
case IS_BOOL:
smart_str_appendc(ss, Z_LVAL_P(val) ? AMF3_TRUE : AMF3_FALSE);
break;
case IS_LONG: {
int i = Z_LVAL_P(val);
if ((i >= AMF3_MIN_INT) && (i <= AMF3_MAX_INT)) {
smart_str_appendc(ss, AMF3_INTEGER);
encodeU29(ss, i);
} else {
smart_str_appendc(ss, AMF3_DOUBLE);
encodeDouble(ss, i);
}
break;
}
case IS_DOUBLE:
smart_str_appendc(ss, AMF3_DOUBLE);
encodeDouble(ss, Z_DVAL_P(val));
break;
case IS_STRING:
smart_str_appendc(ss, AMF3_STRING);
encodeStr(ss, Z_STRVAL_P(val), Z_STRLEN_P(val), sht TSRMLS_CC);
break;
case IS_ARRAY:
if (!(opts & AMF3_FORCE_OBJECT) || (getHashLen(Z_ARRVAL_P(val)) >= 0)) {
smart_str_appendc(ss, AMF3_ARRAY);
encodeArray(ss, val, opts, sht, oht, tht TSRMLS_CC);
break;
} / fall through; encode array as object */
case IS_OBJECT:
smart_str_appendc(ss, AMF3_OBJECT);
encodeObject(ss, val, opts, sht, oht, tht TSRMLS_CC);
break;
}
}

I did not use GDB.

Whole extension works without problems if not changed.

[gorazdr]

One function that changes sht value
static void encodeStr(smart_str ss, const char *str, int len, HashTable *ht TSRMLS_DC) {
if (len > AMF3_MAX_INT) len = AMF3_MAX_INT;
if (len) { / empty string is never sent by reference /
int *oidx, nidx;
if (zend_hash_find(ht, str, len, (void *)&oidx) == SUCCESS) {
encodeU29(ss, *oidx << 1);
return;
}
nidx = zend_hash_num_elements(ht);
if (nidx <= AMF3_MAX_INT) zend_hash_add(ht, str, len, &nidx, sizeof(nidx), NULL);
}
encodeU29(ss, (len << 1) | 1);
smart_str_appendl(ss, str, len);
}

[gorazdr]

GDB
[New Thread 0x7ffff101e700 (LWP 11493)]
[Thread 0x7ffff101e700 (LWP 11493) exited]
string(12) " �� ��� test"

Program received signal SIGSEGV, Segmentation fault.
_zval_ptr_dtor (zval_ptr=0x7ffff7fcc330) at /build/buildd/php5-5.5.3+dfsg/Zend/zend_execute_API.c:426
426 /build/buildd/php5-5.5.3+dfsg/Zend/zend_execute_API.c: No such file or directory.

[mkoppanen]

It's going to be a lot easier if you compile a debug version of php:

./configure --prefix=/opt/php-debug --disable-all
make
make install

and then compile the extension against the debug version

./configure --with-php-config=/opt/php-debug/bin/php-config
make

And then run the code under GDB from the extension directory:

gdb --args /opt/php-debug/bin/php -d extension_dir=modules/ -d extension=<extnamehere>.so yourscript.php

That way you will get symbols in the backtrace and can see where the crash happens.

[gorazdr]

now I get

Program received signal SIGSEGV, Segmentation fault.
_zval_ptr_dtor (zval_ptr=0x7ffff7fcfd00) at /home/gorazd/Prejemi/php-5.5.5/Zend/zend_execute_API.c:426
426 i_zval_ptr_dtor(*zval_ptr ZEND_FILE_LINE_RELAY_CC);