openblt

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

crt0.c (4427B)


      1 /* $Id: //depot/blt/lib/crt0.c#20 $
      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 #include <blt/os.h>
     36 
     37 int main(int argc, char **argv);
     38 static void _init(void);
     39 
     40 char *__progname;
     41 
     42 void _start(int argc, char **argv)
     43 {
     44 	_init();
     45 	__progname = *argv;
     46 	os_terminate (main (argc, argv));
     47 }
     48 
     49 #define MAXINIT 8
     50 
     51 void __libc_init_memory(unsigned int top_of_binary,
     52                         unsigned int start_bss, unsigned int bss_length);
     53 
     54 static void _init(void)
     55 {
     56 	char *strtab;
     57 	int symtablen, top, i, j, p;
     58 	elf32_hdr_t *hdr;
     59 	elf32_sym_t *symtab;
     60 	elf32_sec_hdr_t *last;
     61 	init_info *inits[MAXINIT];
     62 	
     63 	hdr = (elf32_hdr_t *) 0x1000;
     64 	symtab = _elf_find_section_data (hdr, ".symtab");
     65 	strtab = _elf_find_section_data (hdr, ".strtab");
     66 	symtablen = _elf_section_size (hdr, ".symtab") / sizeof (elf32_sym_t);
     67 	last = (elf32_sec_hdr_t *) ((unsigned int) hdr + hdr->e_shoff +
     68 		hdr->e_shentsize * (hdr->e_shnum - 1));
     69 	top = (unsigned int) hdr + last->sh_offset + last->sh_size;
     70 	
     71 	/* Find any __init_... symbols and build a list of 'em
     72 	** These will all be called before main(), but after
     73 	** the .bss is zero'd
     74 	*/
     75 	for (j = 0, i = 0; i < symtablen; i++){
     76 		if (!strncmp(strtab + symtab[i].st_name, "__init_", 7) &&
     77 			(symtab[i].st_shndx != SHN_UNDEF)){
     78 			inits[j++] = (init_info *) symtab[i].st_value;
     79 			if(j == MAXINIT) break;
     80 		}
     81 	}
     82 	
     83 	__libc_init_memory((unsigned int) top, (unsigned int)
     84 		_elf_find_section_data (hdr, ".bss"), _elf_section_size (hdr, ".bss"));
     85 
     86 	for(p=0;p<5;p++){	
     87 		for(i = 0; i < j; i++){
     88 			if(inits[i]->priority == p) inits[i]->func();
     89 		}
     90 	}
     91 }
     92 
     93 elf32_sec_hdr_t *_elf_find_section_hdr (elf32_hdr_t *hdr, char *name)
     94 {
     95 	char *section_name;
     96 	int i;
     97 	elf32_sec_hdr_t *sec_hdr;
     98 
     99 	sec_hdr = (elf32_sec_hdr_t *) ((unsigned int) hdr + hdr->e_shoff +
    100 	    hdr->e_shstrndx * hdr->e_shentsize);
    101 	section_name = (char *) ((unsigned int) hdr + sec_hdr->sh_offset);
    102 	sec_hdr = (elf32_sec_hdr_t *) ((unsigned int) hdr + hdr->e_shoff);
    103 	for (i = 0; i < hdr->e_shnum; i++, sec_hdr = (elf32_sec_hdr_t *)
    104 	        ((unsigned int) sec_hdr + hdr->e_shentsize))
    105 	    if (!strcmp (section_name + sec_hdr->sh_name, name))
    106 	        return sec_hdr;
    107 	return NULL;
    108 }
    109 
    110 void *_elf_find_section_data (elf32_hdr_t *hdr, char *name)
    111 {
    112 	elf32_sec_hdr_t *sec_hdr;
    113 
    114 	sec_hdr = _elf_find_section_hdr (hdr, name);
    115 	return (sec_hdr == NULL) ? NULL : (void *) ((unsigned int) hdr +
    116 	    sec_hdr->sh_offset);
    117 }
    118 
    119 int _elf_section_size (elf32_hdr_t *hdr, char *name)
    120 {
    121 	elf32_sec_hdr_t *sec_hdr;
    122 
    123 	sec_hdr = _elf_find_section_hdr (hdr, name);
    124 	return (sec_hdr == NULL) ? 0 : sec_hdr->sh_size;
    125 }
    126 
    127 /****** this crap is to make ld happy when we build shared executables ******/
    128 
    129 int ___brk_addr;
    130 int __environ;
    131 
    132 void __attribute__ ((noreturn)) abort ()
    133 {
    134 	for (;;) ;
    135 }
    136 
    137 void atexit ()
    138 {
    139 }
    140 
    141 /********************************* end crap *********************************/
    142