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 extern void (*const __preinit_array_start[])(int, char **, char**) __attribute__((weak));
17 extern void (*const __preinit_array_end[])(int, char **, char**) __attribute__((weak));
18
19 extern void (*const __init_array_start[])(int, char **, char**) __attribute__((weak));
20 extern void (*const __init_array_end[])(int, char **, char**) __attribute__((weak));
21
22 extern void (*const __fini_array_start[])(void) __attribute__((weak));
23 extern void (*const __fini_array_end[])(void) __attribute__((weak));
24
25 __attribute__((weak,used))
_start_c(long * sp)26 void _start_c(long *sp)
27 {
28 long argc;
29 char **argv;
30 char **envp;
31 int exitcode;
32 void (* const *ctor_func)(int, char **, char **);
33 void (* const *dtor_func)(void);
34 const unsigned long *auxv;
35 /* silence potential warning: conflicting types for 'main' */
36 int _nolibc_main(int, char **, char **) __asm__ ("main");
37
38 /* initialize stack protector */
39 __stack_chk_init();
40
41 /*
42 * sp : argc <-- argument count, required by main()
43 * argv: argv[0] <-- argument vector, required by main()
44 * argv[1]
45 * ...
46 * argv[argc-1]
47 * null
48 * environ: environ[0] <-- environment variables, required by main() and getenv()
49 * environ[1]
50 * ...
51 * null
52 * _auxv: _auxv[0] <-- auxiliary vector, required by getauxval()
53 * _auxv[1]
54 * ...
55 * null
56 */
57
58 /* assign argc and argv */
59 argc = *sp;
60 argv = (void *)(sp + 1);
61
62 /* find environ */
63 environ = envp = argv + argc + 1;
64
65 /* find _auxv */
66 for (auxv = (void *)envp; *auxv++;)
67 ;
68 _auxv = auxv;
69
70 for (ctor_func = __preinit_array_start; ctor_func < __preinit_array_end; ctor_func++)
71 (*ctor_func)(argc, argv, envp);
72 for (ctor_func = __init_array_start; ctor_func < __init_array_end; ctor_func++)
73 (*ctor_func)(argc, argv, envp);
74
75 /* go to application */
76 exitcode = _nolibc_main(argc, argv, envp);
77
78 for (dtor_func = __fini_array_end; dtor_func > __fini_array_start;)
79 (*--dtor_func)();
80
81 exit(exitcode);
82 }
83
84 #endif /* _NOLIBC_CRT_H */
85