{"id":7150,"date":"2020-05-28T15:42:26","date_gmt":"2020-05-28T15:42:26","guid":{"rendered":"http:\/\/www.max-sperling.bplaced.net\/?p=7150"},"modified":"2024-02-20T11:48:12","modified_gmt":"2024-02-20T11:48:12","slug":"child-process-linux-vs-windows","status":"publish","type":"post","link":"http:\/\/www.max-sperling.bplaced.net\/?p=7150","title":{"rendered":"Child process (Linux vs. Windows)"},"content":{"rendered":"

Windows<\/strong>
\nYou always have to create a totally new process via a CreateProcess(…) call.<\/p>\n

\r\n#include <iostream>\r\n\r\nint main()\r\n{\r\n  std::cout << "I'm a child" << std::endl;\r\n\r\n  return 0;\r\n}\r\n<\/pre>\n
\r\n#include <windows.h>\r\n#include <iostream>\r\n\r\nint main()\r\n{\r\n  char path[] = ".\\\\child.exe";\r\n  char args[] = "child.exe";\r\n  STARTUPINFO startupInfo = { sizeof(startupInfo) };\r\n  PROCESS_INFORMATION processInfo;\r\n\r\n  if (!CreateProcess(path, args, NULL, NULL, TRUE, 0, NULL, NULL,\r\n                     &startupInfo, &processInfo))\r\n  {\r\n    \/* Couldn't create process *\/\r\n    std::cout << "Couldn't create process" << std::endl;\r\n  }\r\n  std::cout << "I'm the parent" << std::endl;\r\n\r\n  WaitForSingleObject(processInfo.hProcess, INFINITE);\r\n\r\n  return 0;\r\n}\r\n<\/pre>\n
\n
Linux<\/strong>
\nYou can either just copy the process (1) or copy it and replace the program (2).<\/p>\n
(1) Just copy parent process<\/p>\n
\r\n#include <sys\/types.h>\r\n#include <unistd.h>\r\n#include <iostream>\r\n\r\nint main()\r\n{\r\n  pid_t pid = fork();\r\n\r\n  if (pid == -1) {\r\n    \/* Couldn't fork *\/\r\n    std::cout << "Couldn't fork" << std::endl;\r\n  } else if (pid == 0) {\r\n    \/* Child process *\/\r\n    std::cout << "I'm the child" << std::endl;\r\n  } else {\r\n    \/* Parent process *\/\r\n    std::cout << "I'm the parent" << std::endl;\r\n  }\r\n\r\n  return 0;\r\n}\r\n<\/pre>\n
(2) Copy parent process and replace program<\/p>\n
\r\n#include <sys\/types.h>\r\n#include <sys\/wait.h>\r\n#include <unistd.h>\r\n#include <iostream>\r\n\r\nint main()\r\n{\r\n  pid_t pid = fork();\r\n\r\n  if (pid == -1) {\r\n    \/* Couldn't fork *\/\r\n    std::cout << "Couldn't fork" << std::endl;\r\n  } else if (pid == 0) {\r\n    \/* Child process *\/\r\n    execlp(".\/child.out", "child.out", NULL);\r\n  } else {\r\n    \/* Parent process *\/\r\n    std::cout << "I'm the parent" << std::endl;\r\n    waitpid(pid, NULL, 0);\r\n  }\r\n\r\n  return 0;\r\n}\r\n<\/pre>\n
In the past fork() would do straight away a copy of the memory of the parent process. That makes no sence at all if you call exec(…) afterwards. These days it only starts to copy that memory as soon as it gets modified.<\/p>\n","protected":false},"excerpt":{"rendered":"
Windows You always have to create a totally new process via a CreateProcess(…) call. Linux You can either just copy<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false},"categories":[65,66],"tags":[],"_links":{"self":[{"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=\/wp\/v2\/posts\/7150"}],"collection":[{"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7150"}],"version-history":[{"count":1,"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=\/wp\/v2\/posts\/7150\/revisions"}],"predecessor-version":[{"id":16960,"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=\/wp\/v2\/posts\/7150\/revisions\/16960"}],"wp:attachment":[{"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7150"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7150"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.max-sperling.bplaced.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7150"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}