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  1. #include <cstdlib>
  2.  
  3. #include <vector>
  4. #include <unordered_map>
  5. #include <string>
  6. #include <algorithm>
  7. #include <iostream>
  8.  
  9.  
  10. int main (void)
  11. {
  12. 	/* Even if a std::string was used, a string literal would not work, because
  13. 	the fake packet contains '\0'. */
  14. 	//const std::vector<char> msg{"add@/sys/devices\0SUBSYSTEM=block\0DEVTYPE=partition"};
  15. 	const std::vector<char> msg{
  16. 		'a','d','d','@','/','s','y','s','/','d','e','v','i','c','e','s','\0',
  17. 		'S','U','B','S','Y','S','T','E','M','=','b','l','o','c','k','\0','D',
  18. 		'E','V','T','Y','P','E','=','p','a','r','t','i','t','i','o','n','\0'
  19. 	};
  20.  
  21. 	std::unordered_map<std::string , std::string> hotplug_event_variables;
  22.  
  23. 	auto it1 = std::find( msg.begin() , msg.end() , '@' );
  24. 	if ( it1 != msg.end() )
  25. 	{
  26. 		/* As per the kernel documentation, the piece before the '@' token is
  27. 		the implicit "ACTION" event variable. */
  28. 		hotplug_event_variables.emplace( std::piecewise_construct , std::forward_as_tuple("ACTION") , std::forward_as_tuple(msg.begin(),it1) );
  29.  
  30. 		/* It points to the '@'; increment it. */
  31. 		++it1;
  32.  
  33. 		auto it2 = std::find( it1 , msg.end() , '\0' );
  34. 		if ( it2 != msg.end() )
  35. 		{
  36. 			/* As with the previous event variable, DEVPATH is implicit. */
  37. 			hotplug_event_variables.emplace( std::piecewise_construct , std::forward_as_tuple("DEVPATH") , std::forward_as_tuple(it1,it2) );
  38.  
  39. 			/* It points to the '\0'; increment it. */
  40. 			++it2;
  41.  
  42. 			/*
  43. 			 * An example packet:
  44. 			 *
  45. 			 * Pass of the loop
  46. 			 *                   |$ACTION@$DEVPATH0·····=·····0······=······0|
  47. 			 *                           ^^       ^^    ^     ^^     ^      ^
  48. 			 *                          it1      it2    |     ||     |      |
  49. 			 * #1                                it2   it3   it4     |      |
  50. 			 * #2                                             it2   it3    it4
  51. 			*/
  52. 			for ( auto it3 = std::find( it2 , msg.end() , '=' ) , it4 = std::find( it3+1 , msg.end() , '\0') ; it2 != msg.end() , it3 != msg.end() , it4 != msg.end() ; it2 = it4+1 , it3 = std::find( it2 , msg.end() , '=' ) , it4 = std::find( it3 , msg.end() , '\0' ) )
  53. 			{
  54. 				/* While playing with the fake packet, I found that empty pairs
  55. 				could made it into the map. */
  56. 				if ( std::distance(it2,it3) > 0 && std::distance(it3+1,it4) > 0 )
  57. 				{
  58. 					hotplug_event_variables.emplace( std::piecewise_construct , std::forward_as_tuple(it2,it3) , std::forward_as_tuple(it3+1,it4) );
  59. 				}
  60. 			}
  61.  
  62. 			/*
  63. 			 * Expected output:
  64. 			 *
  65. 			 * "ACTION"    = "add"
  66. 			 * "DEVPATH"   = "/sys/devices"
  67. 			 * "SUBSYSTEM" = "block"
  68. 			 * "DEVTYPE"   = "partition"
  69. 			*/
  70. 			for ( const auto & x : hotplug_event_variables )
  71. 			{
  72. 				std::cout << '"' << x.first << "\" = \"" << x.second << "\"\n";
  73. 			}
  74. 		}
  75. 	}
  76.  
  77. 	return EXIT_SUCCESS;
  78. }
Success #stdin #stdout 0.01s 3484KB
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stdin
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Standard input is empty
stdout
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"DEVTYPE" = "partition"
"SUBSYSTEM" = "block"
"DEVPATH" = "/sys/devices"
"ACTION" = "add"
https://ideone.com/mLu8Sb
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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