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 #include "compiler.h"
11
12 char **environ __attribute__((weak));
13 const unsigned long *_auxv __attribute__((weak));
14
15 void _start(void);
16 static void __stack_chk_init(void);
17 static void exit(int);
18
19 extern void (*const __preinit_array_start[])(int, char **, char**) __attribute__((weak));
20 extern void (*const __preinit_array_end[])(int, char **, char**) __attribute__((weak));
21
22 extern void (*const __init_array_start[])(int, char **, char**) __attribute__((weak));
23 extern void (*const __init_array_end[])(int, char **, char**) __attribute__((weak));
24
25 extern void (*const __fini_array_start[])(void) __attribute__((weak));
26 extern void (*const __fini_array_end[])(void) __attribute__((weak));
27
28 void _start_c(long *sp);
29 __attribute__((weak,used))
30 #if __nolibc_has_feature(undefined_behavior_sanitizer)
31 __attribute__((no_sanitize("function")))
32 #endif
_start_c(long * sp)33 void _start_c(long *sp)
34 {
35 long argc;
36 char **argv;
37 char **envp;
38 int exitcode;
39 void (* const *ctor_func)(int, char **, char **);
40 void (* const *dtor_func)(void);
41 const unsigned long *auxv;
42 /* silence potential warning: conflicting types for 'main' */
43 int _nolibc_main(int, char **, char **) __asm__ ("main");
44
45 /* initialize stack protector */
46 __stack_chk_init();
47
48 /*
49 * sp : argc <-- argument count, required by main()
50 * argv: argv[0] <-- argument vector, required by main()
51 * argv[1]
52 * ...
53 * argv[argc-1]
54 * null
55 * environ: environ[0] <-- environment variables, required by main() and getenv()
56 * environ[1]
57 * ...
58 * null
59 * _auxv: _auxv[0] <-- auxiliary vector, required by getauxval()
60 * _auxv[1]
61 * ...
62 * null
63 */
64
65 /* assign argc and argv */
66 argc = *sp;
67 argv = (void *)(sp + 1);
68
69 /* find environ */
70 environ = envp = argv + argc + 1;
71
72 /* find _auxv */
73 for (auxv = (void *)envp; *auxv++;)
74 ;
75 _auxv = auxv;
76
77 for (ctor_func = __preinit_array_start; ctor_func < __preinit_array_end; ctor_func++)
78 (*ctor_func)(argc, argv, envp);
79 for (ctor_func = __init_array_start; ctor_func < __init_array_end; ctor_func++)
80 (*ctor_func)(argc, argv, envp);
81
82 /* go to application */
83 exitcode = _nolibc_main(argc, argv, envp);
84
85 for (dtor_func = __fini_array_end; dtor_func > __fini_array_start;)
86 (*--dtor_func)();
87
88 exit(exitcode);
89 }
90
91 #endif /* _NOLIBC_CRT_H */
92