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[])(void) __attribute__((weak));
17 extern void (*const __preinit_array_end[])(void) __attribute__((weak));
18
19 extern void (*const __init_array_start[])(void) __attribute__((weak));
20 extern void (*const __init_array_end[])(void) __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))
26 void _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
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