neatdbg/coredump.c

   1 /*
   2  * a simple elf core file backtrace viewer
   3  *
   4  * Copyright (C) 2010-2013 Ali Gholami Rudi
   5  *
   6  * This program is released under the Modified BSD license.
   7  */
   8 #include <elf.h>
   9 #include <fcntl.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <sys/mman.h>
  13 #include <sys/stat.h>
  14 #include <unistd.h>
  15 #include "elfcore.h"
  16
  17 /* simplified elf struct and macro names */
  18 #ifdef __x86_64__
  19 #  define Elf_Phdr      Elf64_Phdr
  20 #  define Elf_Ehdr      Elf64_Ehdr
  21 #else
  22 #  define Elf_Phdr      Elf32_Phdr
  23 #  define Elf_Ehdr      Elf32_Ehdr
  24 #endif
  25
  26 #define ALIGN(x,a)              __ALIGN_MASK(x,(typeof(x))(a)-1)
  27 #define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
  28
  29 static long readlong(char *mem, unsigned long addr)
  30 {
  31         Elf_Ehdr *ehdr = (void *) mem;
  32         Elf_Phdr *phdr = (void *) (mem + ehdr->e_phoff);
  33         int i;
  34         for (i = 0; i < ehdr->e_phnum; i++) {
  35                 unsigned long beg = phdr[i].p_vaddr;
  36                 if (addr >= beg && addr < beg + phdr[i].p_filesz) {
  37                         unsigned long diff = addr - beg;
  38                         return *(long *) (mem + phdr[i].p_offset + diff);
  39                 }
  40         }
  41         return 0;
  42 }
  43
  44 static void dump_prstatus(char *mem, struct elf_prstatus *prs)
  45 {
  46         struct user_regs_struct *regs = (void *) &prs->pr_reg;
  47         unsigned long bp = regs->bp;
  48         printf("ip=%lx, sp=%lx, bp=%lx\n\n", regs->ip, regs->sp, regs->bp);
  49         printf("\t%lx: %lx\n", regs->ip, regs->bp);
  50         while (bp) {
  51                 printf("\t%lx: %lx\n",
  52                         readlong(mem, bp + sizeof(long)), readlong(mem, bp));
  53                 bp = readlong(mem, bp);
  54         }
  55         printf("\n");
  56 }
  57
  58 struct elfnote {
  59         int namesz;
  60         int descsz;
  61         int type;
  62 };
  63
  64 static void dumpnote(char *mem, char *note, int len)
  65 {
  66         struct elfnote *elfnote;
  67         char *end = note + len;
  68         while (note < end) {
  69                 elfnote = (void *) note;
  70                 note += sizeof(*elfnote);
  71                 note += ALIGN(elfnote->namesz, 4);
  72                 if (elfnote->type == NT_PRSTATUS)
  73                         dump_prstatus(mem, (void *) note);
  74                 note += ALIGN(elfnote->descsz, 4);
  75         }
  76 }
  77
  78 static void dumpelf(char *mem)
  79 {
  80         Elf_Ehdr *ehdr = (void *) mem;
  81         Elf_Phdr *phdr = (void *) (mem + ehdr->e_phoff);
  82         if (ehdr->e_type == ET_CORE && phdr[0].p_type == PT_NOTE)
  83                 dumpnote(mem, mem + phdr[0].p_offset, phdr[0].p_filesz);
  84 }
  85
  86 static void die(char *msg)
  87 {
  88         perror(msg);
  89         exit(1);
  90 }
  91
  92 static long filesize(int fd)
  93 {
  94         struct stat stat;
  95         fstat(fd, &stat);
  96         return stat.st_size;
  97 }
  98
  99 int main(int argc, char **argv)
 100 {
 101         int fd;
 102         long size;
 103         void *mem;
 104         if (argc < 2) {
 105                 printf("Usage: %s path\n", argv[0]);
 106                 return 0;
 107         }
 108         fd = open(argv[1], O_RDONLY);
 109         if (fd == -1)
 110                 die("open");
 111         size = filesize(fd);
 112         mem = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
 113         if (!mem)
 114                 die("mmap");
 115         dumpelf(mem);
 116         munmap(mem, size);
 117         close(fd);
 118         return 0;
 119 }