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/*
  Copyright (c) 2009, David Anderson.
  All rights reserved.
 
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
  * Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
  * Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
  * Neither the name of the example nor the
    names of its contributors may be used to endorse or promote products
    derived from this software without specific prior written permission.
 
  THIS SOFTWARE IS PROVIDED BY David Anderson ''AS IS'' AND ANY
  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL David Anderson BE LIABLE FOR ANY
  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
*/
/* simplereader.c
   This is an example of code reading dwarf .debug_info.
   It is kept as simple as possible to expose essential features.
   It does not do all possible error reporting or error handling.

   To use, try
       make
       ./simplereader simplereader
*/
#include <sys/types.h> /* For open() */
#include <sys/stat.h>  /* For open() */
#include <fcntl.h>     /* For open() */
#include <stdlib.h>     /* For exit() */
#include <unistd.h>     /* For close() */
#include <stdio.h>
#include <errno.h>
#include "dwarf.h"
#include "libdwarf.h"


static void read_cu_list(Dwarf_Debug dbg);
static void print_die_data(Dwarf_Debug dbg, Dwarf_Die print_me,int level);
static void get_die_and_siblings(Dwarf_Debug dbg, Dwarf_Die in_die,int in_level);

int 
main(int argc, char **argv)
{

    Dwarf_Debug dbg = 0;
    int fd = -1;
    const char *filepath = "<stdin>";
    int res = DW_DLV_ERROR;
    Dwarf_Error error;
    Dwarf_Handler errhand = 0;
    Dwarf_Ptr errarg = 0;

    if(argc < 2) {
        fd = 0; /* stdin */
    } else {
        filepath = argv[1];
        fd = open(filepath,O_RDONLY);
    }
    if(fd < 0) {
        printf("Failure attempting to open %s\n",filepath);
    }
    res = dwarf_init(fd,DW_DLC_READ,errhand,errarg, &dbg,&error);
    if(res != DW_DLV_OK) {
        printf("Giving up, cannot do DWARF processing\n");
        exit(1);
    }

    read_cu_list(dbg);
    res = dwarf_finish(dbg,&error);
    if(res != DW_DLV_OK) {
        printf("dwarf_finish failed!\n");
    }
    close(fd);
    return 0;
}

static void 
read_cu_list(Dwarf_Debug dbg)
{
    Dwarf_Unsigned cu_header_length = 0;
    Dwarf_Half version_stamp = 0;
    Dwarf_Unsigned abbrev_offset = 0;
    Dwarf_Half address_size = 0;
    Dwarf_Unsigned next_cu_header = 0;
    Dwarf_Error error;
    int cu_number = 0;

    for(;;++cu_number) {
        Dwarf_Die no_die = 0;
        Dwarf_Die cu_die = 0;
        int res = DW_DLV_ERROR;
        res = dwarf_next_cu_header(dbg,&cu_header_length,
            &version_stamp, &abbrev_offset, &address_size,
            &next_cu_header, &error);
        if(res == DW_DLV_ERROR) {
            printf("Error in dwarf_next_cu_header\n");
            exit(1);
        }
        if(res == DW_DLV_NO_ENTRY) {
            /* Done. */
            return;
        }
        /* The CU will have a single sibling, a cu_die. */
        res = dwarf_siblingof(dbg,no_die,&cu_die,&error);
        if(res == DW_DLV_ERROR) {
            printf("Error in dwarf_siblingof on CU die \n");
            exit(1);
        }
        if(res == DW_DLV_NO_ENTRY) {
            /* Impossible case. */
            printf("no entry! in dwarf_siblingof on CU die \n");
            exit(1);
        }
        get_die_and_siblings(dbg,cu_die,0);
        dwarf_dealloc(dbg,cu_die,DW_DLA_DIE);
    }
}

static void
get_die_and_siblings(Dwarf_Debug dbg, Dwarf_Die in_die,int in_level)
{
    int res = DW_DLV_ERROR;
    Dwarf_Die cur_die=in_die;
    Dwarf_Die child = 0;
    Dwarf_Error error;
    print_die_data(dbg,in_die,in_level);

    for(;;) {
        Dwarf_Die sib_die = 0;
        res = dwarf_child(cur_die,&child,&error);
        if(res == DW_DLV_ERROR) {
            printf("Error in dwarf_child , level %d \n",in_level);
            exit(1);
        }
        if(res == DW_DLV_OK) {
            get_die_and_siblings(dbg,child,in_level+1);
        }
        /* res == DW_DLV_NO_ENTRY */
        res = dwarf_siblingof(dbg,cur_die,&sib_die,&error);
        if(res == DW_DLV_ERROR) {
            printf("Error in dwarf_siblingof , level %d \n",in_level);
            exit(1);
        }
        if(res == DW_DLV_NO_ENTRY) {
            /* Done at this level. */
            break;
        }
        /* res == DW_DLV_OK */
        if(cur_die != in_die) {
            dwarf_dealloc(dbg,cur_die,DW_DLA_DIE);
        }
        cur_die = sib_die;
    }
    return;
}

static void
print_die_data(Dwarf_Debug dbg, Dwarf_Die print_me,int level)
{
    char *name = 0;
    Dwarf_Error error = 0;
    Dwarf_Half tag = 0;
    const char *tagname = 0;
    int res = dwarf_diename(print_me,&name,&error);
    if(res == DW_DLV_ERROR) {
        printf("Error in dwarf_diename , level %d \n",level);
        exit(1);
    }
    if(res == DW_DLV_NO_ENTRY) {
        return;
    }
    res = dwarf_tag(print_me,&tag,&error);
    if(res != DW_DLV_OK) {
        printf("Error in dwarf_tag , level %d \n",level);
        exit(1);
    }
    res = dwarf_get_TAG_name(tag,&tagname);
    if(res != DW_DLV_OK) {
        printf("Error in dwarf_get_TAG_name , level %d \n",level);
        exit(1);
    }
    printf("<%d> tag: %d %s  name: %s\n",level,tag,tagname,name);
    dwarf_dealloc(dbg,name,DW_DLA_STRING);
}