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 void _start(void);
14 static void __stack_chk_init(void);
15 static void exit(int);
16
17 extern void (*const __preinit_array_start[])(int, char **, char**) __attribute__((weak));
18 extern void (*const __preinit_array_end[])(int, char **, char**) __attribute__((weak));
19
20 extern void (*const __init_array_start[])(int, char **, char**) __attribute__((weak));
21 extern void (*const __init_array_end[])(int, char **, char**) __attribute__((weak));
22
23 extern void (*const __fini_array_start[])(void) __attribute__((weak));
24 extern void (*const __fini_array_end[])(void) __attribute__((weak));
25
26 void _start_c(long *sp);
27 __attribute__((weak,used))
_start_c(long * sp)28 void _start_c(long *sp)
29 {
30 long argc;
31 char **argv;
32 char **envp;
33 int exitcode;
34 void (* const *ctor_func)(int, char **, char **);
35 void (* const *dtor_func)(void);
36 const unsigned long *auxv;
37 /* silence potential warning: conflicting types for 'main' */
38 int _nolibc_main(int, char **, char **) __asm__ ("main");
39
40 /* initialize stack protector */
41 __stack_chk_init();
42
43 /*
44 * sp : argc <-- argument count, required by main()
45 * argv: argv[0] <-- argument vector, required by main()
46 * argv[1]
47 * ...
48 * argv[argc-1]
49 * null
50 * environ: environ[0] <-- environment variables, required by main() and getenv()
51 * environ[1]
52 * ...
53 * null
54 * _auxv: _auxv[0] <-- auxiliary vector, required by getauxval()
55 * _auxv[1]
56 * ...
57 * null
58 */
59
60 /* assign argc and argv */
61 argc = *sp;
62 argv = (void *)(sp + 1);
63
64 /* find environ */
65 environ = envp = argv + argc + 1;
66
67 /* find _auxv */
68 for (auxv = (void *)envp; *auxv++;)
69 ;
70 _auxv = auxv;
71
72 for (ctor_func = __preinit_array_start; ctor_func < __preinit_array_end; ctor_func++)
73 (*ctor_func)(argc, argv, envp);
74 for (ctor_func = __init_array_start; ctor_func < __init_array_end; ctor_func++)
75 (*ctor_func)(argc, argv, envp);
76
77 /* go to application */
78 exitcode = _nolibc_main(argc, argv, envp);
79
80 for (dtor_func = __fini_array_end; dtor_func > __fini_array_start;)
81 (*--dtor_func)();
82
83 exit(exitcode);
84 }
85
86 #endif /* _NOLIBC_CRT_H */
87