How to implement Opcodes viewer using PHP Embed SAPI, sapiopcodes_PHP tutorial

How to use PHP Embed SAPI to implement Opcodes viewer, sapiopcodes

PHP provides an Embed SAPI, that is to say, PHP allows you to call PHP/ZE in C/C language provided function. This article implements a PHP opcodes viewer based on Embed SAPI.

First, download the PHP source code for compilation. I am currently using PHP5.3 alpha2

Enter the source code directory:

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

Finally, remember to copy the generated libphp5.so to the directory of the runtime library. I copied it directly to /lib/, otherwise an error will be reported when running your own embed program:

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

If you are not familiar with PHP’s SAPI, I suggest you read this article of mine: In-depth understanding of Zend SAPIs (Zend SAPI Internals)
At this time, you can embed the PHP script parser in your C code, my example:

#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;
}

Then you need to specify the include path, a simple 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)

After successful compilation and running, we can see that stdout outputs Hello World!

Based on this, we can easily implement an Opcodes dumper similar to vld:
First we define the opcode conversion function (all opcodes can be viewed in 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;

Then define the output functions of zval and znode:

 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;
 }
}

Then define the output function of op_array:

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);
  }
 }
}

Finally, there is the main function of the program:

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;
}

Compile and run the test script (sample.php):

Copy code The code is as follows:
sample.php:
echo "laruence";

Command:

Copy code The code is as follows:
./opcodes_dumper sample.php

Get the output result (if you are confused by the results below, I suggest you read my article: In-depth understanding of PHP principles: Opcodes):

Script: sample.php

opnum line opcode op1 op2 result
0 2 2 ZEND_ECHO "laruence"
1 4 1 ZEND_RETURN 1

Haha, how about it? Isn’t it fun?

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