通过gdb用户定义的命令返回一个值 [英] Return a value via a gdb user-defined command

问题描述

我正在调试一个核心文件，所以我没有任何运行任何活动进程。

我使用gdb用户定义的命令检查核心文件中的一堆数据，并尝试使用用户定义的命令简化进程。

然而，我找不到一种方法来让用户定义命令返回可用于其他命令的值。

例如：

（注意return行的注释）

  define dump_linked_list 
 set $ node = global_list-> head 
 set $ count = 1 
 while $ node！= 0 
 printf％p  - >，$ node 
 set $ node = $ node-> next 
 set $ count = $ count + 1 
 end 
 return $ count ## GDB不理解此返回
结束
  

理想情况下，我的dump_linked_list命令将返回列表中找到的节点数，以便可以在另一个已定义的com中使用它mand：

  define higher_function 
 set $ total_nodes = dump_linked_list 
 printf总节点数为％d \ n，$ total_nodes 
 end 
  

gdb命令中可能会出现这种情况？

我觉得它一定是，但我一直在搜索文档，找不到任何提及它或任何示例。 b $ b

解决方案

据我所知，GDB没有这样的功能。您可以设置一个您知道的某个名称的变量，并将其用作返回值。例如，总是像下面这样设置变量 retval ：

  set $ retval =<任意值> 
  

然后，所有新定义的函数都可以将它用作以前调用函数的返回值。我知道这只是解决方法，但它相对简单，它的工作原理。

I'm debugging with a core-file, so I have no active process in which to run anything.

I'm using gdb user-defined commands to inspect a bunch of data from the core file, and attempting to simplify the process using user-defined commands.

However, I cannot find a way to make the user-defined commands return values which could be used in other commands.

For example:
(note the comment on the "return" line)

define dump_linked_list
    set $node = global_list->head
    set $count = 1
    while $node != 0
        printf "%p -->", $node
        set $node = $node->next
        set $count = $count + 1
    end
    return $count  ## GDB doesn't understand this return
end

Ideally, my dump_linked_list command would return the number of nodes found in the list, so that it could be used in another defined command:

define higher_function
    set $total_nodes = dump_linked_list
    printf "Total Nodes is %d\n", $total_nodes
end

Is such a thing possible in gdb commands?

I feel it must be, but I've been searching documentation and cannot find a mention of it, or any examples.

解决方案

As far as I know GDB does not have such a functionality. You can set a variable of some name that you know and use it as a "return" value. For example always set the variable retval like this:

set $retval = <whatever value>

Then all your newly defined functions can use it as a return value from previously called functions. I know this is only workaround, but it is relatively simple and it works.

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