good example of unserialization fundamentals?

9 years ago by j adams — view source

unread

I have completed a first draft of serialization functionality which is
intended to be an updated to amfext. It's on github[0] if anyone is
interested. I would now like to write all the unserialization routines and
would like some suggestions from experienced php devs. I've been reading
Sara Golemon's book, but am still a little unsure.

In particular, I want my userland function, amf_decode to accept as a
parameter a string (and possibly other args). This is not so difficult but
I must call upon another function, php_amf_decode, which needs to be able
to handle recursive calls.

Something like this:

// userland function
static PHP_FUNCTION(amf_decode) {
char *buf; // char buffer, contains serialize data string
int buf_len, buf_cursor=0; // the length of the buffer
long flags = 0;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &buf,

&buf_len, &flags) == FAILURE) {
return;
}

if (!buf_len) {
    RETURN_NULL();
}

php_amf_decode(return_value, buf, buf_len, &buf_cursor, flags

TSRMLS_CC);
}

// proposed recursive decoding function
PHP_AMF_API void php_amf_decode(zval *return_value, char *buf, int buf_len,
int *buf_cursor, long flags TSRMLS_DC)
{

// is it safe to use these macros in this recursive function?
RETVAL_BOOL(1);

// or this
RETURN_LONG(42);

}

[0] https://github.com/sneakyimp/amfext

9 years ago by Sean DuBois — view source

unread

I have completed a first draft of serialization functionality which is
intended to be an updated to amfext. It's on github[0] if anyone is
interested. I would now like to write all the unserialization routines and
would like some suggestions from experienced php devs. I've been reading
Sara Golemon's book, but am still a little unsure.

In particular, I want my userland function, amf_decode to accept as a
parameter a string (and possibly other args). This is not so difficult but
I must call upon another function, php_amf_decode, which needs to be able
to handle recursive calls.

Something like this:

// userland function
static PHP_FUNCTION(amf_decode) {
char *buf; // char buffer, contains serialize data string
int buf_len, buf_cursor=0; // the length of the buffer
long flags = 0;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &buf,
&buf_len, &flags) == FAILURE) {
return;
}
if (!buf_len) {
    RETURN_NULL();
}

php_amf_decode(return_value, buf, buf_len, &buf_cursor, flags
TSRMLS_CC);
}

// proposed recursive decoding function
PHP_AMF_API void php_amf_decode(zval *return_value, char *buf, int buf_len,
int *buf_cursor, long flags TSRMLS_DC)
{
// is it safe to use these macros in this recursive function?
RETVAL_BOOL(1);

// or this
RETURN_LONG(42);
}

[0] https://github.com/sneakyimp/amfext

Yep those are safe!

RETVAL_* expands out so you don't have to repeat the variable return_value
ZVAL_LONG(return_value, l)

RETURN_* expands out so you don't have to call return OR specify the variable return_value
ZVAL_LONG(return_value, l)
return;

Here they are in 5.6 http://lxr.php.net/xref/PHP_5_6/Zend/zend_API.h#618

A great tool to look these things up quickly is lxr, sure beats grep!
http://lxr.php.net/search?q=&defs=RETURN_LONG&refs=&path=&hist=&project=PHP_5_6

9 years ago by j adams — view source

unread

Thanks for your response. I do follow the concept of macros (and my IDE
expands them for me if I need), however, I just want to confirm that it's
OK to be using these in a recursive function? I'm aware from S. Golemon's
book that these (deeply nested) macros also have the effect of incrementing
refcounts and such. For instance, I'm sure the RETURN_* macros will break
your code if you don't have a zval *return_value defined in the current
scope. Are there other caveats or heuristic rules to avoid abusing these
macros?

OH, and perhaps I forgot to ask with my original post. Can anyone point me
to a good example of a function that takes some userland input and
recursively interprets it as possibly nested arrays or objects? I've been
looking at php_json_decode_ex[0] but it is allocating and freeing memory
for utf16/8 converters and JSON_Parser_structs and so on.

[0] http://lxr.php.net/xref/PHP_5_6/ext/json/json.c#683

I have completed a first draft of serialization functionality which is
intended to be an updated to amfext. It's on github[0] if anyone is
interested. I would now like to write all the unserialization routines
and
would like some suggestions from experienced php devs. I've been reading
Sara Golemon's book, but am still a little unsure.

In particular, I want my userland function, amf_decode to accept as a
parameter a string (and possibly other args). This is not so difficult
but
I must call upon another function, php_amf_decode, which needs to be able
to handle recursive calls.

Something like this:

// userland function
static PHP_FUNCTION(amf_decode) {
char *buf; // char buffer, contains serialize data string
int buf_len, buf_cursor=0; // the length of the buffer
long flags = 0;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &buf,
&buf_len, &flags) == FAILURE) {
return;
}
if (!buf_len) {
    RETURN_NULL();
}

php_amf_decode(return_value, buf, buf_len, &buf_cursor, flags
TSRMLS_CC);
}

// proposed recursive decoding function
PHP_AMF_API void php_amf_decode(zval *return_value, char *buf, int
buf_len,
int *buf_cursor, long flags TSRMLS_DC)
{
// is it safe to use these macros in this recursive function?
RETVAL_BOOL(1);

// or this
RETURN_LONG(42);
}

[0] https://github.com/sneakyimp/amfext
Yep those are safe!

RETVAL_* expands out so you don't have to repeat the variable
return_value
ZVAL_LONG(return_value, l)

RETURN_* expands out so you don't have to call return OR specify the
variable return_value
ZVAL_LONG(return_value, l)
return;

Here they are in 5.6 http://lxr.php.net/xref/PHP_5_6/Zend/zend_API.h#618

A great tool to look these things up quickly is lxr, sure beats grep!

http://lxr.php.net/search?q=&defs=RETURN_LONG&refs=&path=&hist=&project=PHP_5_6