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/* |
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* Copyright (c) 2012 eMN Technologies ([email protected]) |
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* |
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* |
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* This is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* This 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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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include <stdio.h> |
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#include <elf.h> |
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#include <sys/types.h> |
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#include <unistd.h> |
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#include <fcntl.h> |
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#include <stdlib.h> |
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#include <sys/procfs.h> |
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struct layout { |
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void *next; |
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void *return_addr; |
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}; |
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int get_ebp(char *corefile, unsigned int *ebp, unsigned int *eip) |
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{ |
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Elf32_Ehdr *elfh; |
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Elf32_Shdr *elfsh; |
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Elf32_Phdr *elfphdr; |
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char *p = NULL; |
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char buf[1000], sbuf[1000]; |
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int ret, fd, i = 0, size; |
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fd = open(corefile, O_RDONLY); |
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if (fd < 0) { |
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perror("open"); |
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return 0; |
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} |
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/* Read ELF header*/ |
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ret = read(fd, buf, sizeof(*elfh)); |
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if (!ret) { |
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perror("Error Reading the ELF Header"); |
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close(fd); |
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return -1; |
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} |
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elfh = (Elf32_Ehdr *) buf; |
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/* Is it ELF*/ |
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if ((elfh->e_ident[0] != 0x7f) || (elfh->e_ident[1] != 'E') || |
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(elfh->e_ident[2] != 'L') || (elfh->e_ident[3] != 'F')) { |
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printf("\nUnrecongised File Format"); |
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close(fd); |
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return -1; |
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} |
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/* |
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* read program headers and print |
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*/ |
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size = elfh->e_phnum * elfh->e_phentsize; |
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p = malloc(size); |
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lseek(fd, elfh->e_phoff, SEEK_SET); |
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ret = read(fd, p, size); |
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if (ret != size) { |
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printf("\nCannot read Program Header"); |
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close(fd); |
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return -1; |
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} |
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elfphdr = (Elf32_Phdr *)p; |
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for (i = 0; i < elfh->e_phnum; i++) { |
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if (elfphdr->p_type == PT_NOTE) { |
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unsigned char *pdata; |
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struct note { |
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unsigned int namesz; |
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unsigned int descsz; |
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unsigned int type; |
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}; |
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struct note *not; |
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int pad = 0; |
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pdata = malloc(elfphdr->p_filesz); |
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lseek(fd, elfphdr->p_offset, SEEK_SET); |
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ret = read(fd, pdata, elfphdr->p_filesz); |
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not = (struct note *) pdata; |
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if (not->namesz % 4) |
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pad = 4 - (not->namesz % 4); |
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if (not->type == NT_PRSTATUS) { |
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struct elf_prstatus *prs; |
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prs = (struct elf_prstatus *)(pdata + sizeof(*not) + not->namesz + pad); |
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*ebp = prs->pr_reg[5]; |
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*eip = prs->pr_reg[12]; |
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} |
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} |
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elfphdr++; |
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} |
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free(p); |
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close(fd); |
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return 0; |
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} |
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int print_syms(unsigned int symaddr, char *symbolfile) |
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{ |
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FILE *fp; |
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int fd, ret, i; |
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char buf[300] = { 0 }; |
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unsigned int addr = 0, nextaddr; |
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char symbol[40], nxtsymbol[40], type; |
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fp = fopen(symbolfile, "r"); |
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if (!fp) { |
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printf("Error"); |
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return 0; |
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} |
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while (fgets(buf, 300, fp)) { |
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sscanf(buf, "%x %c %s", &addr, &type, symbol); |
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if (!addr) |
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continue; |
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if (symaddr >= addr) { |
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/* |
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* find next symbol |
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*/ |
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int foff = ftell(fp); |
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if (fgets(buf, 300, fp)) { |
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sscanf(buf, "%x %c %s", &nextaddr, &type, |
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nxtsymbol); |
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if (symaddr <= nextaddr) { |
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/* |
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* We found the range, print the symbol |
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*/ |
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printf("\n0x%x %s+0x%x", symaddr, |
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symbol, symaddr - addr); |
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break; |
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} |
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} |
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fseek(fp, foff, SEEK_SET); |
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} |
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} |
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fclose(fp); |
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} |
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void btrace(char *symfile, int depth, int withsyms, unsigned eip, unsigned int ebp, void *data) |
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{ |
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struct layout *lay; |
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int i; |
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unsigned int nextebp = ebp; |
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lay = (struct layout *) data; |
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if (eip) { // print current instruction |
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if (withsyms) |
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print_syms((unsigned int)eip, symfile); |
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else |
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printf("%x\n", eip); |
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} |
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for (i = 0; i < depth; i++) { |
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ebp = nextebp; |
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if (withsyms) |
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print_syms((unsigned int)lay->return_addr, symfile); |
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else |
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printf("%p\n", lay->return_addr); |
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nextebp = (unsigned int) lay->next; |
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lay = (struct layout *) (data + (nextebp - ebp)); |
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} |
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printf("\n"); |
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} |
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int main (int argc, char **arg) |
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{ |
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Elf32_Ehdr *elfh; |
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Elf32_Shdr *elfsh; |
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Elf32_Phdr *elfphdr; |
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unsigned int ebp, eip; |
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char *p = NULL; |
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char buf[1000], sbuf[1000]; |
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int ret, fd, i = 0, size; |
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char *symfile = NULL; |
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int depth = 2; //default depth |
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if (argc < 2) { |
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printf("\nUsage: coretrace <core> [symbolfile]\n"); |
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return 0; |
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} |
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ret = get_ebp(arg[1], &ebp, &eip); |
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if (ret < 0) { |
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printf("\nCannot read EBP value\n"); |
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return 0; |
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} |
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fd = open(arg[1], O_RDONLY); |
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if (fd < 0) { |
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perror("open"); |
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return 0; |
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} |
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/* Read ELF header*/ |
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ret = read(fd, buf, sizeof(*elfh)); |
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if (!ret) { |
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perror("Error Reading the ELF Header"); |
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goto cl; |
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} |
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elfh = (Elf32_Ehdr *) buf; |
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/* Is it ELF*/ |
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if ((elfh->e_ident[0] != 0x7f) || (elfh->e_ident[1] != 'E') || |
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(elfh->e_ident[2] != 'L') || (elfh->e_ident[3] != 'F')) { |
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printf("\nUnrecongised File Format"); |
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goto cl; |
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} |
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/* |
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* read program headers and print |
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*/ |
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size = elfh->e_phnum * elfh->e_phentsize; |
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p = malloc(size); |
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lseek(fd, elfh->e_phoff, SEEK_SET); |
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ret = read(fd, p, size); |
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if (ret != size) { |
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printf("\nCannot read Program Header"); |
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goto cl; |
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} |
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elfphdr = (Elf32_Phdr *)p; |
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for (i = 0; i < elfh->e_phnum; i++) { |
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if (elfphdr->p_type == PT_LOAD) { |
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unsigned char *pdata, *temp; |
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unsigned int addr, endaddr; |
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int j; |
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pdata = malloc(elfphdr->p_filesz); |
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lseek(fd, elfphdr->p_offset, SEEK_SET); |
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ret = read(fd, pdata, elfphdr->p_filesz); |
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addr = elfphdr->p_vaddr; |
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endaddr = elfphdr->p_vaddr + elfphdr->p_filesz; |
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if ((ebp > addr) && (ebp < endaddr)) { // we have got stack segment |
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temp = pdata + (ebp - addr); |
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if (arg[2]) // we have symbol file given*/ |
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btrace(arg[2], depth, 1, eip, ebp, temp); |
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else |
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btrace(NULL, depth, 0, eip, ebp, temp); |
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free(pdata); |
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break; // we are done |
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} |
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free(pdata); |
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} |
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elfphdr++; |
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} |
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free(p); |
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cl: |
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close(fd); |
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return 0; |
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} |
It is indeed usefull to get stack trace easily,
When tried to increase depth, backtrace is not working until main function, with same core file it is working in GDB.
how can I achieve this?