openblt

a hobby OS from the late 90s
git clone http://frotz.net/git/openblt.git
Log | Files | Refs | LICENSE

c++rt0.c (4408B)


      1 /* $Id: //depot/blt/lib/c++rt0.c#5 $
      2 **
      3 ** Copyright 1998 Brian J. Swetland
      4 ** All rights reserved.
      5 ** Copyright 1998-1999 Sidney Cammeresi
      6 ** All rights reserved.
      7 **
      8 ** Redistribution and use in source and binary forms, with or without
      9 ** modification, are permitted provided that the following conditions
     10 ** are met:
     11 ** 1. Redistributions of source code must retain the above copyright
     12 **    notice, this list of conditions, and the following disclaimer.
     13 ** 2. Redistributions in binary form must reproduce the above copyright
     14 **    notice, this list of conditions, and the following disclaimer in the
     15 **    documentation and/or other materials provided with the distribution.
     16 ** 3. The name of the author may not be used to endorse or promote products
     17 **    derived from this software without specific prior written permission.
     18 **
     19 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     20 ** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     21 ** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     22 ** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     23 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     24 ** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25 ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26 ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27 ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     28 ** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29 */
     30 
     31 #include <string.h>
     32 #include <elf.h>
     33 #include <blt/syscall.h>
     34 #include <blt/libsyms.h>
     35 
     36 int main(int argc, char **argv);
     37 static void _init(void);
     38 
     39 char *__progname;
     40 
     41 void _start(int argc, char **argv)
     42 {
     43 	_init();
     44 	__progname = *argv;
     45 	os_terminate (main (argc, argv));
     46 }
     47 
     48 #define MAXINIT 8
     49 
     50 void __libc_init_memory(unsigned int top_of_binary,
     51                         unsigned int start_bss, unsigned int bss_length);
     52 
     53 static void _init(void)
     54 {
     55 	char *strtab;
     56 	int symtablen, top, i, j, p;
     57 	elf32_hdr_t *hdr;
     58 	elf32_sym_t *symtab;
     59 	elf32_sec_hdr_t *last;
     60 	init_info *inits[MAXINIT];
     61 	
     62 	hdr = (elf32_hdr_t *) 0x1000;
     63 	symtab = _elf_find_section_data (hdr, ".symtab");
     64 	strtab = _elf_find_section_data (hdr, ".strtab");
     65 	symtablen = _elf_section_size (hdr, ".symtab") / sizeof (elf32_sym_t);
     66 	last = (elf32_sec_hdr_t *) ((unsigned int) hdr + hdr->e_shoff +
     67 		hdr->e_shentsize * (hdr->e_shnum - 1));
     68 	top = (unsigned int) hdr + last->sh_offset + last->sh_size;
     69 	
     70 	/* Find any __init_... symbols and build a list of 'em
     71 	** These will all be called before main(), but after
     72 	** the .bss is zero'd
     73 	*/
     74 	for (j = 0, i = 0; i < symtablen; i++){
     75 		if (!strncmp(strtab + symtab[i].st_name, "__init_", 7) &&
     76 			(symtab[i].st_shndx != SHN_UNDEF)){
     77 			inits[j++] = (init_info *) symtab[i].st_value;
     78 			if(j == MAXINIT) break;
     79 		}
     80 	}
     81 	
     82 	__libc_init_memory((unsigned int) top, (unsigned int)
     83 		_elf_find_section_data (hdr, ".bss"), _elf_section_size (hdr, ".bss"));
     84 
     85 	for(p=0;p<5;p++){	
     86 		for(i = 0; i < j; i++){
     87 			if(inits[i]->priority == p) inits[i]->func();
     88 		}
     89 	}
     90 }
     91 
     92 elf32_sec_hdr_t *_elf_find_section_hdr (elf32_hdr_t *hdr, char *name)
     93 {
     94 	char *section_name;
     95 	int i;
     96 	elf32_sec_hdr_t *sec_hdr;
     97 
     98 	sec_hdr = (elf32_sec_hdr_t *) ((unsigned int) hdr + hdr->e_shoff +
     99 	    hdr->e_shstrndx * hdr->e_shentsize);
    100 	section_name = (char *) ((unsigned int) hdr + sec_hdr->sh_offset);
    101 	sec_hdr = (elf32_sec_hdr_t *) ((unsigned int) hdr + hdr->e_shoff);
    102 	for (i = 0; i < hdr->e_shnum; i++, sec_hdr = (elf32_sec_hdr_t *)
    103 	        ((unsigned int) sec_hdr + hdr->e_shentsize))
    104 	    if (!strcmp (section_name + sec_hdr->sh_name, name))
    105 	        return sec_hdr;
    106 	return NULL;
    107 }
    108 
    109 void *_elf_find_section_data (elf32_hdr_t *hdr, char *name)
    110 {
    111 	elf32_sec_hdr_t *sec_hdr;
    112 
    113 	sec_hdr = _elf_find_section_hdr (hdr, name);
    114 	return (sec_hdr == NULL) ? NULL : (void *) ((unsigned int) hdr +
    115 	    sec_hdr->sh_offset);
    116 }
    117 
    118 int _elf_section_size (elf32_hdr_t *hdr, char *name)
    119 {
    120 	elf32_sec_hdr_t *sec_hdr;
    121 
    122 	sec_hdr = _elf_find_section_hdr (hdr, name);
    123 	return (sec_hdr == NULL) ? 0 : sec_hdr->sh_size;
    124 }
    125 
    126 /****** this crap is to make ld happy when we build shared executables ******/
    127 
    128 int ___brk_addr;
    129 int __environ;
    130 
    131 void __attribute__ ((noreturn)) abort ()
    132 {
    133 	for (;;) ;
    134 }
    135 
    136 void atexit ()
    137 {
    138 }
    139 
    140 /********************************* end crap *********************************/
    141