New parameter parsing functions

===============================

It should be easier to parse input parameters to an extension function.

Hence, borrowing from Python's example, there are now a set of functions

that given the string of type specifiers, can parse the input parameters

and store the results in the user specified variables. This avoids most

of the IS_* checks and convert_to_* conversions. The functions also

check for the appropriate number of parameters, and try to output

meaningful error messages.

Prototypes

----------

/* Implemented. */

int zend_parse_parameters(int num_args TSRMLS_DC, char *type_spec, ...);

int zend_parse_parameters_ex(int flags, int num_args TSRMLS_DC, char *type_spec, ...);

The zend_parse_parameters() function takes the number of parameters

passed to the extension function, the type specifier string, and the

list of pointers to variables to store the results in. The _ex() version

also takes 'flags' argument -- current only ZEND_PARSE_PARAMS_QUIET can

be used as 'flags' to specify that the function should operate quietly

and not output any error messages.

Both functions return SUCCESS or FAILURE depending on the result.

The auto-conversions are performed as necessary. Arrays, objects, and

resources cannot be auto-converted.

PHP 5.5 includes a new function:

int zend_parse_parameter(int flags, int arg_num TSRMLS_DC, zval **arg, const char *spec, ...);

This function behaves like zend_parse_parameters_ex() except that instead of

reading the arguments from the stack, it receives a single zval to convert

(passed with double indirection). The passed zval may be changed in place as

part of the conversion process.

See also https://wiki.php.net/rfc/zpp_improv#expose_zend_parse_arg_as_zend_parse_parameter

Type specifiers

---------------

The following list shows the type specifier, its meaning and the parameter

types that need to be passed by address. All passed parameters are set

if the PHP parameter is non optional and untouched if optional and the

parameter is not present. The only exception is O where the zend_class_entry*

has to be provided on input and is used to verify the PHP parameter is an

instance of that class.

a - array (zval*)

A - array or object (zval *)

b - boolean (zend_bool)

C - class (zend_class_entry*)

d - double (double)

f - function or array containing php method call info (returned as

zend_fcall_info and zend_fcall_info_cache)

h - array (returned as HashTable*)

H - array or HASH_OF(object) (returned as HashTable*)

l - long (long)

L - long, limits out-of-range numbers to LONG_MAX/LONG_MIN (long)

o - object of any type (zval*)

O - object of specific type given by class entry (zval*, zend_class_entry)

p - valid path (string without null bytes in the middle) and its length (char*, int)

r - resource (zval*)

s - string (with possible null bytes) and its length (char*, int)

z - the actual zval (zval*)

Z - the actual zval (zval**)

* - variable arguments list (0 or more)

+ - variable arguments list (1 or more)

The following characters also have a meaning in the specifier string:

| - indicates that the remaining parameters are optional, they

should be initialized to default values by the extension since they

will not be touched by the parsing function if they are not

passed to it.

/ - use SEPARATE_ZVAL_IF_NOT_REF() on the parameter it follows

! - the parameter it follows can be of specified type or NULL. If NULL is

passed and the output for such type is a pointer, then the output

pointer is set to a native NULL pointer.

For 'b', 'l' and 'd', an extra argument of type zend_bool* must be

passed after the corresponding bool*, long* or double* arguments,

respectively. A non-zero value will be written to the zend_bool iif a

PHP NULL is passed.

Note on 64bit compatibility

---------------------------

Please do not forget that int and long are two different things on 64bit

OSes (int is 4 bytes and long is 8 bytes), so make sure you pass longs to "l"

and ints to strings length (i.e. for "s" you need to pass char * and int),

not the other way round!

Remember: "l" is the only case when you need to pass long (and that's why

it's "l", not "i" btw).

Both mistakes cause memory corruptions and segfaults on 64bit OSes:

1)

char *str;

long str_len; /* XXX THIS IS WRONG!! Use int instead. */

zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &str, &str_len)

2)

int num; /* XXX THIS IS WRONG!! Use long instead. */

zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", &num)

If you're in doubt, use check_parameters.php script to the parameters

and their types (it can be found in ./scripts/dev/ directory of PHP sources):

# php ./scripts/dev/check_parameters.php /path/to/your/sources/

Examples

--------

/* Gets a long, a string and its length, and a zval */

long l;

char *s;

int s_len;

zval *param;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "lsz",

&l, &s, &s_len, &param) == FAILURE) {

return;

}

/* Gets an object of class specified by my_ce, and an optional double. */

zval *obj;

double d = 0.5;

zend_class_entry *my_ce;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "O|d",

&obj, my_ce, &d) == FAILURE) {

return;

}

/* Gets an object or null, and an array.

If null is passed for object, obj will be set to NULL. */

zval *obj;

zval *arr;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "o!a",

&obj, &arr) == FAILURE) {

return;

}

/* Gets a separated array which can also be null. */

zval *arr;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "a/!",

&arr) == FAILURE) {

return;

}

/* Get either a set of 3 longs or a string. */

long l1, l2, l3;

char *s;

/*

* The function expects a pointer to a integer in this case, not a long

* or any other type. If you specify a type which is larger

* than a 'int', the upper bits might not be initialized

* properly, leading to random crashes on platforms like

* Tru64 or Linux/Alpha.

*/

int length;

if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC,

"lll", &l1, &l2, &l3) == SUCCESS) {

/* manipulate longs */

} else if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC,

"s", &s, &length) == SUCCESS) {

/* manipulate string */

} else {

/* output error */

return;

}

/* Function that accepts only varargs (0 or more) */

int i, num_varargs;

zval ***varargs = NULL;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "*", &varargs, &num_varargs) == FAILURE) {

return;

}

for (i = 0; i < num_varargs; i++) {

/* do something with varargs[i] */

}

if (varargs) {

efree(varargs);

}

/* Function that accepts a string, followed by varargs (1 or more) */

char *str;

int str_len;

int i, num_varargs;

zval ***varargs = NULL;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s+", &str, &str_len, &varargs, &num_varargs) == FAILURE) {

return;

}

for (i = 0; i < num_varargs; i++) {

/* do something with varargs[i] */

}

if (varargs) {

efree(varargs);

}

/* Function that takes an array, followed by varargs, and ending with a long */

long num;

zval *array;

int i, num_varargs;

zval ***varargs = NULL;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "a*l", &array, &varargs, &num_varargs, &num) == FAILURE) {

return;

}

for (i = 0; i < num_varargs; i++) {

/* do something with varargs[i] */

}

if (varargs) {

efree(varargs);

}