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lookup_elf32.c revision 1.3.6.2 
      1 /* $NetBSD: lookup_elf32.c,v 1.3.6.2 2010/04/30 14:44:15 uebayasi Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2010 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Martin Husemann.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 /* If not included by lookup_elf64.c, ELFSIZE won't be defined. */
     33 #ifndef ELFSIZE
     34 #define	ELFSIZE	32
     35 #endif
     36 
     37 #include <lib/libkern/libkern.h>
     38 #include <sys/param.h>
     39 #include <sys/exec_elf.h>
     40 
     41 #if ((ELFSIZE == 32) && defined(BOOT_ELF32)) || \
     42     ((ELFSIZE == 64) && defined(BOOT_ELF64))
     43 
     44 void * ELFNAMEEND(lookup_symbol)(const char *, void *, void *);
     45 
     46 void *
     47 ELFNAMEEND(lookup_symbol)(const char *symname, void *sstab, void *estab)
     48 {
     49 	Elf_Ehdr *elf;
     50 	Elf_Shdr *shp;
     51 	Elf_Sym *symtab_start, *symtab_end, *sp;
     52 	char *strtab_start, *strtab_end;
     53 	int i, j;
     54 
     55 	elf = sstab;
     56 	if (elf->e_shoff == 0)
     57 		return NULL;
     58 
     59 	switch (elf->e_machine) {
     60 	ELFDEFNNAME(MACHDEP_ID_CASES)
     61 	default:
     62 		return NULL;
     63 	}
     64 
     65 	symtab_start = symtab_end = NULL;
     66 	strtab_start = strtab_end = NULL;
     67 
     68 	shp = (Elf_Shdr *)((char *)sstab + elf->e_shoff);
     69 	for (i = 0; i < elf->e_shnum; i++) {
     70 		if (shp[i].sh_type != SHT_SYMTAB)
     71 			continue;
     72 		if (shp[i].sh_offset == 0)
     73 			continue;
     74 		symtab_start = (Elf_Sym*)((char*)sstab + shp[i].sh_offset);
     75 		symtab_end = (Elf_Sym*)((char*)sstab + shp[i].sh_offset
     76 			+ shp[i].sh_size);
     77 		j = shp[i].sh_link;
     78 		if (shp[j].sh_offset == 0)
     79 			continue;
     80 		strtab_start = (char*)sstab + shp[j].sh_offset;
     81 		strtab_end = (char*)sstab + shp[j].sh_offset + shp[j].sh_size;
     82 		break;
     83 	}
     84 
     85 	if (!symtab_start || !strtab_start)
     86 		return NULL;
     87 
     88 	for (sp = symtab_start; sp < symtab_end; sp++)
     89 		if (sp->st_name != 0 &&
     90 		    strcmp(strtab_start + sp->st_name, symname) == 0)
     91 			return (void*)(uintptr_t)sp->st_value;
     92 
     93 	return NULL;
     94 }
     95 
     96 #endif /* (ELFSIZE == 32 && BOOT_ELF32) || (ELFSIZE == 64 && BOOT_ELF64) */
     97