1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */ 2 /* 3 * C Run Time support for NOLIBC 4 * Copyright (C) 2023 Zhangjin Wu <falcon@tinylab.org> 5 */ 6 7 #ifndef _NOLIBC_CRT_H 8 #define _NOLIBC_CRT_H 9 10 char **environ __attribute__((weak)); 11 const unsigned long *_auxv __attribute__((weak)); 12 13 static void __stack_chk_init(void); 14 static void exit(int); 15 16 void _start_c(long *sp) 17 { 18 long argc; 19 char **argv; 20 char **envp; 21 const unsigned long *auxv; 22 /* silence potential warning: conflicting types for 'main' */ 23 int _nolibc_main(int, char **, char **) __asm__ ("main"); 24 25 /* initialize stack protector */ 26 __stack_chk_init(); 27 28 /* 29 * sp : argc <-- argument count, required by main() 30 * argv: argv[0] <-- argument vector, required by main() 31 * argv[1] 32 * ... 33 * argv[argc-1] 34 * null 35 * environ: environ[0] <-- environment variables, required by main() and getenv() 36 * environ[1] 37 * ... 38 * null 39 * _auxv: _auxv[0] <-- auxiliary vector, required by getauxval() 40 * _auxv[1] 41 * ... 42 * null 43 */ 44 45 /* assign argc and argv */ 46 argc = *sp; 47 argv = (void *)(sp + 1); 48 49 /* find environ */ 50 environ = envp = argv + argc + 1; 51 52 /* find _auxv */ 53 for (auxv = (void *)envp; *auxv++;) 54 ; 55 _auxv = auxv; 56 57 /* go to application */ 58 exit(_nolibc_main(argc, argv, envp)); 59 } 60 61 #endif /* _NOLIBC_CRT_H */ 62