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如何使用PHP Embed SAPI实现Opcodes查看器

发布时间：2023-04-04 09:14:28 来源：好代码

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秋天的人们是勤劳的。人们忙着摘果实、收稻谷，脸上挂满了丰收的喜悦。

PHP提供了一个Embed SAPI，也就是说，PHP容许你在C/C++语言中调用PHP/ZE提供的函数。本文就通过基于Embed SAPI实现一个PHP的opcodes查看器。

首先，下载PHP源码以供编译，我现在使用的是PHP5.3 alpha2

进入源码目录：

./configure --enable-embed --with-config-file-scan-dir=/etc/php.d --with-mysql --with-config-file-path=/etc/
./make
./make install

最后，记得要将生成的libphp5.so复制到运行时库的目录，我直接拷贝到了/lib/, 否则会在运行你自己的embed程序的时候报错：

./embed: error while loading shared libraries: libphp5.so: cannot open shared object file: No such file or directory

如果你对PHP的SAPI还不熟悉的话，我建议你看看我的这篇文章：深入理解Zend SAPIs(Zend SAPI Internals)
这个时候，你就可以在你的C代码中，嵌入PHP脚本解析器了，我的例子：

#include "sapi/embed/php_embed.h"
int main(int argc, char * argv[]){
 PHP_EMBED_START_BLOCK(argc,argv);
 char * script = " print 'Hello World!';";
 zend_eval_string(script, NULL,
          "Simple Hello World App" TSRMLS_CC);
 PHP_EMBED_END_BLOCK();
 return 0;
}

然后就是要指明include path了，一个简单的Makefile

CC = gcc
CFLAGS = -I/usr/local/include/php/ \
   -I/usr/local/include/php/main \
   -I/usr/local/include/php/Zend \
   -I/usr/local/include/php/TSRM \
   -Wall -g
LDFLAGS = -lstdc++ -L/usr/local/lib -lphp5
ALL:
 $(CC) -o embed embed.cpp $(CFLAGS) $(LDFLAGS)

编译成功以后，运行，我们可以看到， stdout输出 Hello World！

基于这个，我们就可以很容易的实现一个类似于vld的Opcodes dumper：
首先我们定义opcode的转换函数（全部的opcodes可以查看Zend/zend_vm_opcodes.h）；

char *opname(zend_uchar opcode){
 switch(opcode) {
  case ZEND_NOP: return "ZEND_NOP"; break;
  case ZEND_ADD: return "ZEND_ADD"; break;
  case ZEND_SUB: return "ZEND_SUB"; break;
  case ZEND_MUL: return "ZEND_MUL"; break;
  case ZEND_DIV: return "ZEND_DIV"; break;
  case ZEND_MOD: return "ZEND_MOD"; break;
  case ZEND_SL: return "ZEND_SL"; break;
  case ZEND_SR: return "ZEND_SR"; break;
  case ZEND_CONCAT: return "ZEND_CONCAT"; break;
  case ZEND_BW_OR: return "ZEND_BW_OR"; break;
  case ZEND_BW_AND: return "ZEND_BW_AND"; break;
  case ZEND_BW_XOR: return "ZEND_BW_XOR"; break;
  case ZEND_BW_NOT: return "ZEND_BW_NOT"; break;
  /*...省略 ....*/
  default : return "UNKNOW"; break;

然后定义zval和znode的输出函数：

 char *format_zval(zval *z)
{
 static char buffer[BUFFER_LEN];
 int len;
 switch(z->type) {
  case IS_NULL:
   return "NULL";
  case IS_LONG:
  case IS_BOOL:
   snprintf(buffer, BUFFER_LEN, "%d", z->value.lval);
   return buffer;
  case IS_DOUBLE:
   snprintf(buffer, BUFFER_LEN, "%f", z->value.dval);
   return buffer;
  case IS_STRING:
   snprintf(buffer, BUFFER_LEN, "\"%s\"", z->value.str.val);
   return buffer;
  case IS_ARRAY:
  case IS_OBJECT:
  case IS_RESOURCE:
  case IS_CONSTANT:
  case IS_CONSTANT_ARRAY:
   return "";
  default:
   return "unknown";
 }
}
char * format_znode(znode *n){
 static char buffer[BUFFER_LEN];
 switch (n->op_type) {
  case IS_CONST:
   return format_zval(&n->u.constant);
   break;
  case IS_VAR:
   snprintf(buffer, BUFFER_LEN, "$%d", n->u.var/sizeof(temp_variable));
   return buffer;
   break;
  case IS_TMP_VAR:
   snprintf(buffer, BUFFER_LEN, "~%d", n->u.var/sizeof(temp_variable));
   return buffer;
   break;
  default:
   return "";
   break;
 }
}

然后定义op_array的输出函数：

void dump_op(zend_op *op, int num){
 printf("%5d %5d %30s %040s %040s %040s\n", num, op->lineno,
   opname(op->opcode),
   format_znode(&op->op1),
   format_znode(&op->op2),
   format_znode(&op->result)) ;
}
void dump_op_array(zend_op_array *op_array){
 if(op_array) {
  int i;
  printf("%5s %5s %30s %040s %040s %040s\n", "opnum", "line", "opcode", "op1", "op2", "result");
  for(i = 0; i < op_array->last; i++) {
   dump_op(&op_array->opcodes[i], i);
  }
 }
}

最后，就是程序的主函数了：

int main(int argc, char **argv){
 zend_op_array *op_array;
 zend_file_handle file_handle;
 if(argc != 2) {
  printf("usage: op_dumper <script>\n");
  return 1;
 }
 PHP_EMBED_START_BLOCK(argc,argv);
 printf("Script: %s\n", argv[1]);
 file_handle.filename = argv[1];
 file_handle.free_filename = 0;
 file_handle.type = ZEND_HANDLE_FILENAME;
 file_handle.opened_path = NULL;
 op_array = zend_compile_file(&file_handle, ZEND_INCLUDE TSRMLS_CC);
 if(!op_array) {
  printf("Error parsing script: %s\n", file_handle.filename);
  return 1;
 }
 dump_op_array(op_array);
 PHP_EMBED_END_BLOCK();
 return 0;
}

编译，运行测试脚本(sample.php):