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Merge pull request #3357 from NK-Nikunj/static_hpx_main_impl
Static/dynamic executable implementation
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| Original file line number | Diff line number | Diff line change |
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| // Copyright (c) 20018 Nikunj Gupta | ||
| // | ||
| // Distributed under the Boost Software License, Version 1.0. (See accompanying | ||
| // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | ||
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| // The following implementation is only possible for Linux systems. | ||
| #if defined(__linux) || defined(__linux__) || defined(linux) | ||
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| namespace hpx_start { | ||
| // include_libhpx_wrap is a weak symbol which helps to determine the course | ||
| // of function calls at runtime. It has a deafult value of `false` which | ||
| // corresponds to the program's entry point being main(). | ||
| // It is overriden in hpx/hpx_main.hpp. Thus, inclusion of the header file | ||
| // will change the program's entry point to HPX's own custom entry point | ||
| // initialize_main. Subsequent calls before entering main() are handled | ||
| // by this code. | ||
| extern bool include_libhpx_wrap; | ||
| bool include_libhpx_wrap __attribute__((weak)) = false; | ||
| } | ||
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| #include <hpx/hpx_init.hpp> | ||
| #include <hpx/hpx.hpp> | ||
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| #include<vector> | ||
| #include <iostream> | ||
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| //////////////////////////////////////////////////////////////////////////////// | ||
| // Function declarations | ||
| // | ||
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| namespace hpx_start{ | ||
| // Main entry point of HPX runtime system | ||
| extern int hpx_entry(int argc, char* argv[]); | ||
| } | ||
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| // HPX's implented program's entry point | ||
| extern int initialize_main(int argc, char** argv, char** envp); | ||
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| // Real libc function __libc_start_main. Function definition can be | ||
| // found in the glibc source in `glibc/csu/libc-start.c` | ||
| extern "C" int __real___libc_start_main ( | ||
| int (*main)(int, char**, char**), int argc, char * * ubp_av, | ||
| void (*init) (void), void (*fini) (void), | ||
| void (*rtld_fini) (void), void (* stack_end)); | ||
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| // Wrapper function for __libc_start_main | ||
| extern "C" int __wrap___libc_start_main ( | ||
| int (*main)(int, char**, char**), int argc, char * * ubp_av, | ||
| void (*init) (void), void (*fini) (void), | ||
| void (*rtld_fini) (void), void (* stack_end)); | ||
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| //////////////////////////////////////////////////////////////////////////////// | ||
| // Global pointers | ||
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| namespace hpx_start { | ||
| // actual_main is responsible to store the pointer to the main() | ||
| // function. POSIX implementation of main requires pointer to envp | ||
| // so it is stored as well. | ||
| int (*actual_main)(int, char**, char**) = nullptr; | ||
| char** __envp = nullptr; | ||
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| // main entry point of the HPX runtime system | ||
| int hpx_entry(int argc, char* argv[]) | ||
| { | ||
| // Call to the main() function | ||
| int return_value = hpx_start::actual_main(argc, argv, __envp); | ||
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| //Finalizing the HPX runtime | ||
| return hpx::finalize(return_value); | ||
| } | ||
| } | ||
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| // This is the main entry point of C runtime system. | ||
| // The HPX runtime system is initialized here, which | ||
| // is similar to initializing HPX from main() and utilising | ||
| // the hpx_main() as the entry point. | ||
| int initialize_main(int argc, char** argv, char** envp) | ||
| { | ||
| // initializing envp pointer to utilize when | ||
| // calling the actual main. | ||
| hpx_start::__envp = envp; | ||
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| // Configuring HPX system before runtime | ||
| std::vector<std::string> const cfg = { | ||
| "hpx.commandline.allow_unknown!=1", | ||
| "hpx.commandline.aliasing=0", | ||
| }; | ||
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| using hpx::util::placeholders::_1; | ||
| using hpx::util::placeholders::_2; | ||
| hpx::util::function_nonser<int(int, char**)> start_function = | ||
| hpx::util::bind(&hpx_start::hpx_entry, _1, _2); | ||
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| // Initialize the HPX runtime system | ||
| return hpx::init(start_function, argc, argv, | ||
| cfg, hpx::runtime_mode_console); | ||
| } | ||
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| //////////////////////////////////////////////////////////////////////////////// | ||
| // Wrapper for the libc function __libc_start_main | ||
| // | ||
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| // We are hooking into __libc_start_main to change the entry | ||
| // point of the C runtime system to our custom implemented | ||
| // function initialize_main | ||
| extern "C" int __wrap___libc_start_main ( | ||
| int (*main)(int, char**, char**), int argc, char * * ubp_av, | ||
| void (*init) (void), void (*fini) (void), | ||
| void (*rtld_fini) (void), void (* stack_end)) | ||
| { | ||
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| // We determine the function call stack at runtime from the | ||
| // value of include_libhpx_wrap. | ||
| if(hpx_start::include_libhpx_wrap) { | ||
| // Assigning pointer to C main to actual_main | ||
| hpx_start::actual_main = main; | ||
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| // Calling original __libc_start_main with our custom entry point. | ||
| return __real___libc_start_main(&initialize_main, argc, ubp_av, init, | ||
| fini, rtld_fini, stack_end); | ||
| } | ||
| return __real___libc_start_main(main, argc, ubp_av, init, | ||
| fini, rtld_fini, stack_end); | ||
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| } | ||
| //////////////////////////////////////////////////////////////////////////////// | ||
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| #endif |