PHP_FUNCTION(strstr);

PHP_FUNCTION(strstr)
{
    zval *needle;
    char *haystack;
    int haystack_len;
    char *found = NULL;
    char needle_char[2];
    long found_offset;
    zend_bool part = 0;
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "sz|b", &haystack, &haystack_len, &needle, &part) == FAILURE) {
        return;
    }
    if (Z_TYPE_P(needle) == IS_STRING) {
        if (!Z_STRLEN_P(needle)) {
            php_error_docref(NULL TSRMLS_CC, E_WARNING, "Empty delimiter");
            RETURN_FALSE;
        }
        found = php_memnstr(haystack, Z_STRVAL_P(needle), Z_STRLEN_P(needle), haystack + haystack_len);
    } else {
        if (php_needle_char(needle, needle_char TSRMLS_CC) != SUCCESS) {
            RETURN_FALSE;
        }
        needle_char[1] = 0;
        found = php_memnstr(haystack, needle_char,    1, haystack + haystack_len);
    }
    if (found) {
        found_offset = found - haystack;
        if (part) {
            RETURN_STRINGL(haystack, found_offset, 1);
        } else {
            RETURN_STRINGL(found, haystack_len - found_offset, 1);
        }
    }
    RETURN_FALSE;
}

typedef struct _zval_struct zval;
struct _zval_struct {
    /* Variable information */
    zvalue_value value;        /* value */
    zend_uint refcount__gc;
    zend_uchar type;    /* active type */
    zend_uchar is_ref__gc;
};

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, ...);
ZEND_API int zend_parse_parameters(int num_args TSRMLS_DC, char *type_spec, ...) /* {{{ */
{
    va_list va;
    int retval;
    RETURN_IF_ZERO_ARGS(num_args, type_spec, 0);
    va_start(va, type_spec);
    retval = zend_parse_va_args(num_args, type_spec, &va, 0 TSRMLS_CC);
    va_end(va);
    return retval;
}
/* }}} */
ZEND_API int zend_parse_method_parameters(int num_args TSRMLS_DC, zval *this_ptr, char *type_spec, ...) /* {{{ */
{
    va_list va;
    int retval;
    char *p = type_spec;
    zval **object;
    zend_class_entry *ce;
    if (!this_ptr) {
        RETURN_IF_ZERO_ARGS(num_args, p, 0);
        va_start(va, type_spec);
        retval = zend_parse_va_args(num_args, type_spec, &va, 0 TSRMLS_CC);
        va_end(va);
    } else {
        p++;
        RETURN_IF_ZERO_ARGS(num_args, p, 0);
        va_start(va, type_spec);
        object = va_arg(va, zval **);
        ce = va_arg(va, zend_class_entry *);
        *object = this_ptr;
        if (ce && !instanceof_function(Z_OBJCE_P(this_ptr), ce TSRMLS_CC)) {
            zend_error(E_CORE_ERROR, "%s::%s() must be derived from %s::%s",
                ce->name, get_active_function_name(TSRMLS_C), Z_OBJCE_P(this_ptr)->name, get_active_function_name(TSRMLS_C));
        }
        retval = zend_parse_va_args(num_args, p, &va, 0 TSRMLS_CC);
        va_end(va);
    }
    return retval;
}

Z_TYPE_P
文件位置：Zend/zend_operators.h
#define Z_TYPE_P(zval_p)    Z_TYPE(*zval_p)
#define Z_TYPE(zval)        (zval).type

Z_STRLEN_P
文件位置：Zend/zend_operators.h
#define Z_STRLEN_P(zval_p)        Z_STRLEN(*zval_p)
#define Z_STRLEN(zval)            (zval).value.str.len

文件位置：main/php.h
#define php_memnstr zend_memnstr
文件位置：Zend/zend_operators.h
static inline char *
zend_memnstr(char *haystack, char *needle, int needle_len, char *end)
{
    char *p = haystack;
    char ne = needle[needle_len-1];
    if (needle_len == 1) {
        return (char *)memchr(p, *needle, (end-p));
    }
    if (needle_len > end-haystack) {
        return NULL;
    }
    end -= needle_len;
    while (p <= end) {
        if ((p = (char *)memchr(p, *needle, (end-p+1))) && ne == p[needle_len-1]) {
            if (!memcmp(needle, p, needle_len-1)) {
                return p;
            }
        }
        if (p == NULL) {
            return NULL;
        }
        p++;
    }
    return NULL;
}

memchr memcmp

strstr('hello word!','world');

zend_memnstr(char *haystack, char *needle, int needle_len, char *end)
char *haystack = "hello word!";
char *needle = "world";
int needle_len = strlen(needle);
char *end = haystack + strlen(haystack) 尾部指針
char *p = haystack 字符首元素地址
char ne = needle[needle_len-1] needle 尾部單個(gè)字符 d
end -= needle_len  // 初始：4231185 減后：4231180
(p = (char *)memchr(p, *needle, (end-p+1))) && ne == p[needle_len-1]
p = (char *)memchr(p, *needle, (end-p+1) // char *p = "world!";
ne == p[needle_len-1] // p[needle_len-1] == d
if (!memcmp(needle, p, needle_len-1)) //world == world
return p