Elf file reader.
Reads the symbols of all sections and provides addresses to functions and data objects. git-svn-id: https://www4.informatik.uni-erlangen.de/i4svn/danceos/trunk/devel/fail@1592 8c4709b5-6ec9-48aa-a5cd-a96041d1645a
This commit is contained in:
hoffmann
343
src/core/util/elfinfo/elfinfo.cc
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343
src/core/util/elfinfo/elfinfo.cc
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/* DISCLAIMER :This is a FREE SOFTWARE You can Use it at your own RISK
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that is if you are screwed by using this software, then
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accept the fact that you screwed yourself.
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## THIS HAS BEEN DEVELOPED AND TESTED UNDER FEDORA-9 HOPEFULLY IT WILL
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## WORK ON OTHER SYSTEMS
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======================================================================
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elfinfo.c - Copyright (C)2008 Ashok Shankar Das ashok.s.das@gmail.com
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This code is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This code is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <string.h>
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#include <elf.h>
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void read_ELF_file_header(FILE* fp,Elf32_Ehdr *filehdr)
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{
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//rewind(fp);
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fread(filehdr,sizeof(Elf32_Ehdr),1,fp);
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}
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int is_ELF(Elf32_Ehdr *hdr)
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{
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if(strncmp(reinterpret_cast<const char*>(hdr->e_ident),"\177ELF",4)==0)
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return 1;
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else
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return -1;
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}
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int read_ELF_section_header(int sect_num,Elf32_Shdr *sect_hdr,FILE *fp)
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{
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int numsect;
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Elf32_Ehdr elfhdr;
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off_t sect_hdr_off;
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fseek(fp,(off_t)0,SEEK_SET);
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read_ELF_file_header(fp,&elfhdr);
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numsect=elfhdr.e_shnum;
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if ((numsect<sect_num)||(sect_num<0))
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return -1;
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sect_hdr_off=elfhdr.e_shoff;
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//rewind(fp);
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sect_hdr_off+=elfhdr.e_shentsize*sect_num;
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fseek(fp,(off_t)sect_hdr_off,SEEK_SET);
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fread(sect_hdr,sizeof(Elf32_Shdr),1,fp);
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return 1;
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}
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void process_sect_hdr(Elf32_Shdr *sect_hdr,char *sect_name_buff)
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{
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int idx;
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idx=sect_hdr->sh_name;
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printf(" %-20s ",sect_name_buff+idx);
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if(sect_hdr->sh_entsize)
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printf(" %c ",'*');
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else
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printf(" %c ",' ');
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switch(sect_hdr->sh_type)
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{
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case 0: printf("NULL \t");
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break;
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case 1: printf("PROGBITS \t");
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break;
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case 2: printf("SYMTAB \t");
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break;
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case 3: printf("STRTAB \t");
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break;
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case 4: printf("RELOC ADN \t");
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break;
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case 5: printf("HASH \t");
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break;
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case 6: printf("SYMTAB \t");
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break;
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case 7: printf("NOTE \t");
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break;
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case 8: printf("NOBIT \t");
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break;
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case 9: printf("RELOC \t");
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break;
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case 10: printf("*reserved* \t");
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break;
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case 11: printf("DYNSYM \t");
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break;
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case 14: printf("INITARR \t");
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break;
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case 15: printf("FINIARR \t");
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break;
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case 16: printf("PREINIT \t");
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break;
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case 17: printf("SECTGRP \t");
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break;
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case 18: printf("EXT-SHNDX \t");
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break;
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case 19: printf("NUM-DEF-TYP \t");
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break;
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case 0x60000000: printf("OS SPECIFIC \t");
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break;
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case 0x6ffffff5: printf("GNU_ATTR \t");
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break;
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case 0x6ffffff6: printf("GNU_HASH \t");
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break;
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case 0x6ffffff7: printf("PRELNKLIBLST \t");
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break;
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case 0x6ffffff8: printf("CKSUM \t");
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break;
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case 0x6ffffffa: printf("SUN SPECIFIC \t");
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break;
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case 0x6ffffffb: printf("SUNCOMDAT \t");
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break;
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case 0x6ffffffc: printf("SUNSYMINFO \t");
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break;
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case 0x6ffffffd: printf("GNUVERDEF \t");
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break;
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case 0x6ffffffe: printf("GNUVERNEED \t");
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break;
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case 0x6fffffff: printf("GNUVERSYM \t");
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break;
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case 0x70000000: printf("LOPROC \t");
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break;
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case 0x7fffffff: printf("HIPROC \t");
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break;
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case 0x80000000: printf("APP beg \t");
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break;
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case 0x8fffffff: printf("APP end \t");
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break;
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}
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printf("linked to %3d sect\n",sect_hdr->sh_link);
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}
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void display_sections(FILE *fp)
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{
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Elf32_Ehdr ehdr;
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Elf32_Shdr sec_hdr;
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int num_hdrs,i;
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char *buff=NULL;
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fseek(fp,(off_t)0,SEEK_SET);
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read_ELF_file_header(fp, &ehdr);
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if(is_ELF(&ehdr)==-1)
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{
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printf("Not an ELF file\n");
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exit(0);
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}
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num_hdrs=ehdr.e_shnum;
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if(read_ELF_section_header(ehdr.e_shstrndx,&sec_hdr,fp)==-1)
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{
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printf("Error: reading section string table sect_num= %d\n",ehdr.e_shstrndx);
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exit(0);
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}
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//we read the shstrtab
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// read content from the file
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buff=(char*)malloc(sec_hdr.sh_size);
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if (!buff)
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{
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printf("Malloc failed to allocate buffer for shstrtab\n");
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exit(0);
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}
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//seek to the offset in the file,
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fseek(fp,(off_t)sec_hdr.sh_offset,SEEK_SET);
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fread(buff,sec_hdr.sh_size,1,fp);
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printf("There are [%d] sections\n",num_hdrs);
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for(i=0;i<num_hdrs;i++)
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{
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if(read_ELF_section_header(i,&sec_hdr,fp)==-1)
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{
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printf("Wrong Section to read\n");
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}
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else
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{
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printf("[section %3d] ",i);
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process_sect_hdr(&sec_hdr,buff);
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}
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}
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if(buff)
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free(buff);
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}
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int process_symtab(int sect_num,FILE *fp)
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{
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Elf32_Shdr sect_hdr;
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Elf32_Sym mysym;
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char *name_buf=NULL;
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int num_sym,link,i,idx;
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off_t sym_data_offset;
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int sym_data_size;
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if(read_ELF_section_header(sect_num,§_hdr,fp)==-1)
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{
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return -1;
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}
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//we have to check to which strtab it is linked
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link=sect_hdr.sh_link;
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sym_data_offset=sect_hdr.sh_offset;
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sym_data_size=sect_hdr.sh_size;
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num_sym=sym_data_size/sizeof(Elf32_Sym);
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//read the coresponding strtab
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if(read_ELF_section_header(link,§_hdr,fp)==-1)
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{
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return -1;
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}
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//get the size of strtab in file and allocate a buffer
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name_buf=(char*)malloc(sect_hdr.sh_size);
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if(!name_buf)
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return -1;
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//get the offset of strtab in file and seek to it
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fseek(fp,sect_hdr.sh_offset,SEEK_SET);
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//read all data from the section to the buffer.
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fread(name_buf,sect_hdr.sh_size,1,fp);
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//so we have the namebuf now seek to symtab data
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fseek(fp,sym_data_offset,SEEK_SET);
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printf("[%d] symbols\n",num_sym);
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for(i=0;i<num_sym;i++)
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{
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//memcpy((char *)&mysym,(char *)sym_buf,sizeof(Elf32_Sym));
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fread(&mysym,sizeof(Elf32_Sym),1,fp);
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//dump_sym(&mysym);
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idx=mysym.st_name;
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//printf("symbol %d index in strtab %d\n",i,idx);
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printf("[%3d] %s ",i,name_buf+idx);
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switch(ELF32_ST_BIND(mysym.st_info))
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{
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case 0: printf(" LOCAL ");
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break;
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case 1: printf(" GLOBAL ");
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break;
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case 2: printf(" WEAK ");
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break;
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case 3: printf(" NUM ");
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break;
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case 10: printf(" OS-specific-start ");
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break;
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case 12: printf(" OS-specific-end ");
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break;
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case 13: printf(" CPU-specific-start ");
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break;
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case 15: printf("CPU-specific-end ");
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break;
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}
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switch(ELF32_ST_TYPE(mysym.st_info))
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{
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case 0: printf(" NOTYPE ");
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break;
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case 1: printf(" OBJECT ");
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break;
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case 2: printf(" FUNC ");
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break;
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case 3: printf(" SECTION ");
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break;
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case 4: printf(" FILE ");
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break;
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case 5: printf(" COMMON ");
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break;
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case 6: printf(" TLS ");
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break;
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case 7: printf(" NUM ");
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break;
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case 10: printf(" OS-specific-start ");
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break;
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break;
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case 12: printf(" OS-specific-end ");
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break;
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case 13: printf(" CPU-specific-start ");
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break;
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break;
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case 15: printf(" CPU-specific-end ");
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break;
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}
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switch(mysym.st_shndx)
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{
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case SHN_UNDEF: printf(" UNDEF ");
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break;
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case SHN_LOPROC: printf(" CPU-specific-start ");
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break;
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case SHN_HIPROC: printf(" CPU-specific-end ");
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break;
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case SHN_LOOS: printf(" OS-specific-start ");
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break;
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case SHN_HIOS: printf(" OS-specific-end ");
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break;
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case SHN_ABS: printf(" ABSOLUTE ");
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break;
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case SHN_COMMON: printf(" COMMON ");
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break;
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case SHN_XINDEX: printf(" XINDEX ");
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break;
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}
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printf("\n");
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}
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if(name_buf)
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free(name_buf);
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return 0;
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}
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void dump_symbols(FILE *fp)
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{
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Elf32_Ehdr ehdr;
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Elf32_Shdr sec_hdr;
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int num_hdrs,i;
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fseek(fp,(off_t)0,SEEK_SET);
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read_ELF_file_header(fp, &ehdr);
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num_hdrs=ehdr.e_shnum;
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for(i=0;i<num_hdrs;i++)
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{
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if(read_ELF_section_header(i,&sec_hdr,fp)==-1)
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{
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printf("Wrong Section to read\n");
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}
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else
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{
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if((sec_hdr.sh_type==SHT_SYMTAB)||(sec_hdr.sh_type==SHT_DYNSYM))
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{
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printf("\n[section %3d] contains ",i);
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process_symtab(i,fp);
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}
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else
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continue;
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}
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}
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}
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