首页 \ 问答 \ 当epoll_wait返回EPOLLERR时如何获得errno？(How to get errno when epoll_wait returns EPOLLERR?)

当epoll_wait返回EPOLLERR时如何获得errno？(How to get errno when epoll_wait returns EPOLLERR?)

 有什么方法可以在EPOLLERR为特定的fd返回EPOLLERR时找出errno ？  
 是否有关于错误性质的更多信息？  
 编辑：  
 添加更多信息以避免歧义  
 epoll_wait等待多个文件描述符。 当你调用epoll_wait你会传递一个epoll_event结构数组：  
struct epoll_event {
           uint32_t     events;    /* Epoll events */
           epoll_data_t data;      /* User data variable */
       };
 
 epoll_data_t结构具有与用于epoll_ctl向epoll添加文件描述符一样的细节：  
typedef union epoll_data {
           void    *ptr;
           int      fd;
           uint32_t u32;
           uint64_t u64;
       } epoll_data_t;
 
 我正在寻找的是当epoll正在等待的某个文件描述符出现错误时发生的情况。  
 即： epoll_event.events & EPOLLERR == 1 - 是否有办法找到文件描述符上的错误的更多细节？ 

Is there a way to find out the errno when epoll_wait returns EPOLLERR for a particular fd? 
Is there any further information about the nature of the error? 
Edit: 
Adding more information to prevent ambiguity 
epoll_wait waits on a number of file descriptors. When you call epoll_wait you pass it an array of epoll_event structures: 
struct epoll_event {
           uint32_t     events;    /* Epoll events */
           epoll_data_t data;      /* User data variable */
       };
 
The epoll_data_t structure has the same details as the one you used with epoll_ctl to add a file descriptor to epoll: 
typedef union epoll_data {
           void    *ptr;
           int      fd;
           uint32_t u32;
           uint64_t u64;
       } epoll_data_t;
 
What I'm looking for is what happens when there is an error on one of the file descriptors that epoll is waiting on. 
ie: (epoll_event.events & EPOLLERR) == 1 - is there a way to find out more details of the error on the file descriptor?

原文：https://stackoverflow.com/questions/13150377

更新时间：2023-08-15 08:08

最满意答案

 词汇Schema.org（尚未）提供用于表示餐馆菜单或单个菜单项的类型。  
 他们的menu属性需要文本或URL作为值。 如果应该有菜单类型，它将成为另一个预期值。  
 问题扩展提案：FoodProducts的FoodProduct和餐厅菜单。 问这个。 它已关闭，引用更广泛的问题创建一个新的食物类型（进一步帮助foodWarning和recipeIngredient） 。 它仍在讨论中。  
 如果您现在需要某些东西，可以使用引用OfferCatalog类型的hasOfferCatalog属性 （表示菜单或菜单的分组部分）和Offer类型 （表示单个菜单项，带有价格）。  
 例如：  
<div vocab="http://schema.org/" typeof="Restaurant">
  <section property="hasOfferCatalog" typeof="OfferCatalog">
    <h1 property="name">Menu</h1>
    <ul>

      <li property="itemListElement" typeof="Offer">
        <b property="name">Bread</b> – 
        <span property="price">1.50</span>
        <meta property="priceCurrency" content="EUR" />
      </li>

      <li property="itemListElement" typeof="Offer">
        <b property="name">Water</b> – 
        <span property="price">1.00</span>
        <meta property="priceCurrency" content="EUR" />
      </li>

    </ul>
  </section>
</div>
 
 如果您也想使用menu属性，可以添加一个包含OfferCatalog的div 。 menu的值将是文本内容。  
<div vocab="http://schema.org/" typeof="Restaurant">
  <div property="menu">
    <section property="hasOfferCatalog" typeof="OfferCatalog">
      <!-- … -->
    </section>
  </div>
</div>

The vocabulary Schema.org does not (yet) offer a type for representing restaurant menus or single menu items. 
Their menu property expects text or URL as value. If there should ever be a type for menus, it would become another expected value. 
The issue Extension Proposal: FoodProduct and Restaurant Menu with FoodProducts. asked for this. It got closed, referencing the broader issue Create a new Food type (help further with foodWarning and recipeIngredient). It’s still under discussion. 
If you need something now, you could use the hasOfferCatalog property that references an OfferCatalog type (representing the menu, or grouped parts of the menu) and the Offer type (representing a single menu item, with a price). 
For example: 
<div vocab="http://schema.org/" typeof="Restaurant">
  <section property="hasOfferCatalog" typeof="OfferCatalog">
    <h1 property="name">Menu</h1>
    <ul>

      <li property="itemListElement" typeof="Offer">
        <b property="name">Bread</b> – 
        <span property="price">1.50</span>
        <meta property="priceCurrency" content="EUR" />
      </li>

      <li property="itemListElement" typeof="Offer">
        <b property="name">Water</b> – 
        <span property="price">1.00</span>
        <meta property="priceCurrency" content="EUR" />
      </li>

    </ul>
  </section>
</div>
 
If you want to use the menu property, too, you could add a div that encloses the OfferCatalog. The value for menu would then be the textual content. 
<div vocab="http://schema.org/" typeof="Restaurant">
  <div property="menu">
    <section property="hasOfferCatalog" typeof="OfferCatalog">
      <!-- … -->
    </section>
  </div>
</div>

当epoll_wait返回EPOLLERR时如何获得errno？(How to get errno when epoll_wait returns EPOLLERR?)

最满意答案

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