操纵

5个静态包装器操作中的4个用来处理不是基于I/O的流资源操作. 你已经看到过它们并了解它们的原型; 现在我们看看varstream包装器框架中它们的实现:

在你的wrapper_ops结构体中增加下面的函数, 它可以让unlink()通过varstream包装器, 拥有和unset()一样的行为:

  1. static int php_varstream_unlink(php_stream_wrapper *wrapper,
  2.                         char *filename, int options,
  3.                         php_stream_context *context
  4.                         TSRMLS_DC)
  5. {               
  6.     php_url *url;   
  8.     url = php_url_parse(filename);
  9.     if (!url) {         
  10.         php_stream_wrapper_log_error(wrapper, options
  11.             TSRMLS_CC, "Unexpected error parsing URL");
  12.         return -1;   
  13.     }       
  14.     if (!url->host || (url->host[0] == 0) ||
  15.         strcasecmp("var", url->scheme) != 0) {
  16.         /* URL不合法 */
  17.         php_stream_wrapper_log_error(wrapper, options
  18.             TSRMLS_CC, "Invalid URL, must be in the form: "
  19.                      "var://variablename");
  20.         php_url_free(url);
  21.         return -1;
  22.     }
  24.     /* 从符号表删除变量 */
  25.     //zend_hash_del(&EG(symbol_table), url->host, strlen(url->host) + 1);
  26.     zend_delete_global_variable(url->host, strlen(url->host) + 1 TSRMLS_CC);
  28.     php_url_free(url);                                      
  29.     return 0;
  30. }

这个函数的编码量和php_varstream_opener差不多. 唯一的不同在于这里你需要传递变量名给zend_hash_del()去删除变量.

译注: 译者的php-5.4.10环境中, 使用unlink()删除变量后, 在用户空间再次读取该变量名的值会导致core dump. 因此上面代码中译者进行了修正, 删除变量时使用了zend_delete_global_variable(), 请读者参考阅读zend_delete_global_variable()函数源代码, 考虑为什么直接用zend_hash_del()删除, 会导致core dump. 下面是译者测试用的用户空间代码:

  1. <?php
  2. $fp = fopen('var://hello', 'r');
  3. fwrite($fp, 'world');
  4. var_dump($hello);
  5. unlink('var://hello');
  6. $a  = $hello;

这个函数的代码量应该和php_varstream_opener差不多. 唯一的不同是这里是传递变量名给zend_hash_del()去删除变量.

rename, mkdir, rmdir

为了一致性, 下面给出rename, mkdir, rmdir函数的实现:

  1. static int php_varstream_rename(php_stream_wrapper *wrapper,
  2.         char *url_from, char *url_to, int options,
  3.         php_stream_context *context TSRMLS_DC)
  4. {
  5.     php_url *from, *to;
  6.     zval **var;
  8.     /* 来源URL解析 */
  9.     from = php_url_parse(url_from);
  10.     if (!from) {
  11.         php_stream_wrapper_log_error(wrapper, options
  12.             TSRMLS_CC, "Unexpected error parsing source");
  13.         return -1;
  14.     }
  15.     /* 查找变量 */
  16.     if (zend_hash_find(&EG(symbol_table), from->host,
  17.                 strlen(from->host) + 1,
  18.                 (void**)&var) == FAILURE) {
  19.         php_stream_wrapper_log_error(wrapper, options
  20.             TSRMLS_CC, "$%s does not exist", from->host);
  21.         php_url_free(from);
  22.         return -1;
  23.     }
  24.     /* 目标URL解析 */
  25.     to = php_url_parse(url_to);
  26.     if (!to) {
  27.         php_stream_wrapper_log_error(wrapper, options
  28.             TSRMLS_CC, "Unexpected error parsing dest");
  29.         php_url_free(from);
  30.         return -1;
  31.     }
  32.     /* 变量的改名 */
  33.     Z_SET_REFCOUNT_PP(var, Z_REFCOUNT_PP(var) + 1);
  34.     zend_hash_update(&EG(symbol_table), to->host,
  35.                 strlen(to->host) + 1, (void*)var,
  36.                 sizeof(zval*), NULL);
  37.     zend_hash_del(&EG(symbol_table), from->host,
  38.                 strlen(from->host) + 1);
  39.     php_url_free(from);
  40.     php_url_free(to);
  41.     return 0;
  42. }
  44. static int php_varstream_mkdir(php_stream_wrapper *wrapper,
  45.                 char *url_from, int mode, int options,
  46.                 php_stream_context *context TSRMLS_DC)
  47. {
  48.     php_url *url;
  50.     /* URL解析 */
  51.     url = php_url_parse(url_from);
  52.     if (!url) {
  53.        php_stream_wrapper_log_error(wrapper, options
  54.            TSRMLS_CC, "Unexpected error parsing URL");
  55.        return -1;
  56.     }
  58.     /* 检查变量是否存在 */
  59.     if (zend_hash_exists(&EG(symbol_table), url->host,
  60.                     strlen(url->host) + 1)) {
  61.         php_stream_wrapper_log_error(wrapper, options
  62.             TSRMLS_CC, "$%s already exists", url->host);
  63.         php_url_free(url);
  64.         return -1;
  65.     }
  66.     /* EG(uninitialized_zval_ptr)通常是IS_NULL的zval *, 引用计数无限大 */
  67.     zend_hash_add(&EG(symbol_table), url->host,
  68.             strlen(url->host) + 1,
  69.             (void*)&EG(uninitialized_zval_ptr),
  70.             sizeof(zval*), NULL);
  71.     php_url_free(url);
  72.     return 0;
  73. }
  75. static int php_varstream_rmdir(php_stream_wrapper *wrapper,
  76.                 char *url, int options,
  77.                 php_stream_context *context TSRMLS_DC)
  78. {
  79.     /* 行为等价于unlink() */
  80.     wrapper->wops->unlink(wrapper, url, options,
  81.                                 context TSRMLS_CC);
  82. }