PHP strstr函数原型源码分析

目录strstr函数原型源码分析 版本PHP5.3.291、ext/standard/php_string.h2、ext/standard/string.czval *needle1、char *haystack2、zend_parse_parameters3、if (Z_TYPE_P(needle) == IS_STRING)4、if (!Z_STRLEN_P(needle)) {5、php_memnstr(haystack, Z_STRVAL_P(needle), Z_STRLEN_P(needle), haystack + haystack_len);核心函数zend_memnstr 代码分析strstr函数原型

源码分析 版本PHP5.3.291、ext/standard/php_string.hPHP_FUNCTION(strstr);2、ext/standard/string.cPHP_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;}zval *needle

文件位置 Zend/zend.h

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;};

needle是一个变量结构体，对应php strstr 函数参数 mixed $needle

1、char *haystack

char *haystack s是一个字符指针，对应 php strstr函数参数 string $haystack

2、zend_parse_parameters

文件位置 Zend/zend_API.c

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;}

最简单的获取函数调用者传递过来的参数便是使用zend_parse_parameters()函数。

zend_parse_parameters() 函数的前几个参数我们直接用内核里宏来生成便可以了，形式为：ZEND_NUM_ARGS() TSRMLS_CC，注意两者之间有个空格，但是没有逗号。从名字可以看出，ZEND_NUM_ARGS()代表着参数的个数。

紧接着需要传递给zend_parse_parameters()函数的参数是一个用于格式化的字符串，就像printf的第一个参数一样。下面表示了最常用的几个符号。

type_spec是格式化字符串，其常见的含义如下：参数 代表着的类型b Booleanl Integer 整型d Floating point 浮点型s String 字符串r Resource 资源a Array 数组o Object instance 对象O Object instance of a specified type 特定类型的对象z Non-specific zval 任意类型～Z zval**类型f 表示函数、方法名称，PHP5.1里貌似木有... ...

3、if (Z_TYPE_P(needle) == IS_STRING)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).type4、if (!Z_STRLEN_P(needle)) {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.len5、php_memnstr(haystack, Z_STRVAL_P(needle), Z_STRLEN_P(needle), haystack + haystack_len);文件位置：main/php.h#define php_memnstr zend_memnstr文件位置：Zend/zend_operators.hstatic 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;}核心函数memchr memcmp

zend_memnstr 代码分析

举例：

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) 尾部指针char *p = haystack 字符首元素地址char ne = needle[needle_len-1] needle 尾部单个字符 dend -= needle_len // 初始：4231185 减后：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] == dif (!memcmp(needle, p, needle_len-1)) //world == worldreturn p

引用

https://www.runoob.com/cprogramming/c-function-memcmp.html

https://www.jb51.net/article/77667.htm

https://www.jb51.net/article/210253.htm

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