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
10char **environ __attribute__((weak));
11const unsigned long *_auxv __attribute__((weak));
12
13static void __stack_chk_init(void);
14static void exit(int);
15
16extern void (*const __preinit_array_start[])(void) __attribute__((weak));
17extern void (*const __preinit_array_end[])(void) __attribute__((weak));
18
19extern void (*const __init_array_start[])(void) __attribute__((weak));
20extern void (*const __init_array_end[])(void) __attribute__((weak));
21
22extern void (*const __fini_array_start[])(void) __attribute__((weak));
23extern void (*const __fini_array_end[])(void) __attribute__((weak));
24
25__attribute__((weak))
26void _start_c(long *sp)
27{
28	long argc;
29	char **argv;
30	char **envp;
31	int exitcode;
32	void (* const *func)(void);
33	const unsigned long *auxv;
34	/* silence potential warning: conflicting types for 'main' */
35	int _nolibc_main(int, char **, char **) __asm__ ("main");
36
37	/* initialize stack protector */
38	__stack_chk_init();
39
40	/*
41	 * sp  :    argc          <-- argument count, required by main()
42	 * argv:    argv[0]       <-- argument vector, required by main()
43	 *          argv[1]
44	 *          ...
45	 *          argv[argc-1]
46	 *          null
47	 * environ: environ[0]    <-- environment variables, required by main() and getenv()
48	 *          environ[1]
49	 *          ...
50	 *          null
51	 * _auxv:   _auxv[0]      <-- auxiliary vector, required by getauxval()
52	 *          _auxv[1]
53	 *          ...
54	 *          null
55	 */
56
57	/* assign argc and argv */
58	argc = *sp;
59	argv = (void *)(sp + 1);
60
61	/* find environ */
62	environ = envp = argv + argc + 1;
63
64	/* find _auxv */
65	for (auxv = (void *)envp; *auxv++;)
66		;
67	_auxv = auxv;
68
69	for (func = __preinit_array_start; func < __preinit_array_end; func++)
70		(*func)();
71	for (func = __init_array_start; func < __init_array_end; func++)
72		(*func)();
73
74	/* go to application */
75	exitcode = _nolibc_main(argc, argv, envp);
76
77	for (func = __fini_array_end; func > __fini_array_start;)
78		(*--func)();
79
80	exit(exitcode);
81}
82
83#endif /* _NOLIBC_CRT_H */
84