/*  Copyright (c) 2021 David Anderson
    This test code is hereby placed in the public domain
    for anyone to use in any way.  */

/*! @file jitreader.c
    @defgroup jitreader Demonstrating reading DWARF without a file.
    @brief How to read DWARF2 and later from memory. JIT.

    @code

    The C source is src/bin/dwarfexample/jitreader.c

*/

#include <config.h>

#include <stddef.h> /* NULL */
#include <stdio.h>  /* printf() */
#include <stdlib.h> /* exit() */
#include <string.h> /* strcmp() */

#include "dwarf.h"
#include "libdwarf.h"
#include "libdwarf_private.h"

/*
    This demonstates processing DWARF
    from in_memory data.  For simplicity
    in this example we are using static arrays.
    The C source is src/bin/dwarfexample/jitreader.c

    The motivation is from JIT compiling, where
    at runtime of some application, it generates
    code on the file and DWARF information for it too.

    This gives an example of enabling all of libdwarf's
    functions without actually having the DWARF information
    in a file.  (If you have a file in some odd format
    you can use this approach to have libdwarf access
    the format for DWARF data and work normally without
    ever exposing the format to libdwarf.)

    None of the structures defined here in this source
    (or any source using this feature)
    are ever known to libdwarf. They are totally
    private to your code.
    The code you write (like this example) you compile
    separate from libdwarf. Never place your code
    into libdwarf, just link your compiled code into
    your application and link in libdwarf as usual.

*/

/* Some valid DWARF2 data */
static Dwarf_Small abbrevbytes[] = {
0x01, 0x11, 0x01, 0x25, 0x0e, 0x13, 0x0b, 0x03, 0x08, 0x1b,
0x0e, 0x11, 0x01, 0x12, 0x01, 0x10, 0x06, 0x00, 0x00, 0x02,
0x2e, 0x01, 0x3f, 0x0c, 0x03, 0x08, 0x3a, 0x0b, 0x3b, 0x0b,
0x39, 0x0b, 0x27, 0x0c, 0x11, 0x01, 0x12, 0x01, 0x40, 0x06,
0x97, 0x42, 0x0c, 0x01, 0x13, 0x00, 0x00, 0x03, 0x34, 0x00,
0x03, 0x08, 0x3a, 0x0b, 0x3b, 0x0b, 0x39, 0x0b, 0x49, 0x13,
0x02, 0x0a, 0x00, 0x00, 0x04, 0x24, 0x00, 0x0b, 0x0b, 0x3e,
0x0b, 0x03, 0x08, 0x00, 0x00, 0x00, };
static Dwarf_Small infobytes[] = {
0x60, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00,
0x08, 0x01, 0x00, 0x00, 0x00, 0x00, 0x0c, 0x74, 0x2e, 0x63,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x01, 0x66, 0x00, 0x01,
0x02, 0x06, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x01, 0x5c, 0x00, 0x00, 0x00, 0x03, 0x69,
0x00, 0x01, 0x03, 0x08, 0x5c, 0x00, 0x00, 0x00, 0x02, 0x91,
0x6c, 0x00, 0x04, 0x04, 0x05, 0x69, 0x6e, 0x74, 0x00, 0x00, };
static Dwarf_Small strbytes[] = {
0x47, 0x4e, 0x55, 0x20, 0x43, 0x31, 0x37, 0x20, 0x39, 0x2e,
0x33, 0x2e, 0x30, 0x20, 0x2d, 0x6d, 0x74, 0x75, 0x6e, 0x65,
0x3d, 0x67, 0x65, 0x6e, 0x65, 0x72, 0x69, 0x63, 0x20, 0x2d,
0x6d, 0x61, 0x72, 0x63, 0x68, 0x3d, 0x78, 0x38, 0x36, 0x2d,
0x36, 0x34, 0x20, 0x2d, 0x67, 0x64, 0x77, 0x61, 0x72, 0x66,
0x2d, 0x32, 0x20, 0x2d, 0x4f, 0x30, 0x20, 0x2d, 0x66, 0x61,
0x73, 0x79, 0x6e, 0x63, 0x68, 0x72, 0x6f, 0x6e, 0x6f, 0x75,
0x73, 0x2d, 0x75, 0x6e, 0x77, 0x69, 0x6e, 0x64, 0x2d, 0x74,
0x61, 0x62, 0x6c, 0x65, 0x73, 0x20, 0x2d, 0x66, 0x73, 0x74,
0x61, 0x63, 0x6b, 0x2d, 0x70, 0x72, 0x6f, 0x74, 0x65, 0x63,
0x74, 0x6f, 0x72, 0x2d, 0x73, 0x74, 0x72, 0x6f, 0x6e, 0x67,
0x20, 0x2d, 0x66, 0x73, 0x74, 0x61, 0x63, 0x6b, 0x2d, 0x63,
0x6c, 0x61, 0x73, 0x68, 0x2d, 0x70, 0x72, 0x6f, 0x74, 0x65,
0x63, 0x74, 0x69, 0x6f, 0x6e, 0x20, 0x2d, 0x66, 0x63, 0x66,
0x2d, 0x70, 0x72, 0x6f, 0x74, 0x65, 0x63, 0x74, 0x69, 0x6f,
0x6e, 0x00, 0x2f, 0x76, 0x61, 0x72, 0x2f, 0x74, 0x6d, 0x70,
0x2f, 0x74, 0x69, 0x6e, 0x79, 0x64, 0x77, 0x61, 0x72, 0x66,
0x00, };

/*  An internals_t , data used elsewhere but
    not directly visible elsewhere. One needs to have one
    of these but  maybe the content here too little
    or useless, this is just an example of sorts.  */
#define SECCOUNT 4
struct sectiondata_s {
    unsigned int   sd_addr;
    unsigned int   sd_objoffsetlen;
    unsigned int   sd_objpointersize;
    Dwarf_Unsigned sd_sectionsize;
    const char   * sd_secname;
    Dwarf_Small  * sd_content;
};

/*  The secname must not be 0 , pass "" if
    there is no name. */
static struct sectiondata_s sectiondata[SECCOUNT] = {
{0,0,0,0,"",0},
{0,32,32,sizeof(abbrevbytes),".debug_abbrev",abbrevbytes},
{0,32,32,sizeof(infobytes),".debug_info",infobytes},
{0,32,32,sizeof(strbytes),".debug_str",strbytes}
};

typedef struct special_filedata_s {
    int            f_is_64bit;
    Dwarf_Small    f_object_endian;
    unsigned       f_pointersize;
    unsigned       f_offsetsize;
    Dwarf_Unsigned f_filesize;
    Dwarf_Unsigned f_sectioncount;
    struct sectiondata_s * f_sectarray;
} special_filedata_internals_t;

/*  Use DW_END_little.
    Libdwarf finally sets the file-format-specific
    f_object_endianness field to a DW_END_little or
    DW_END_big (see dwarf.h).
    Here we must do that ourselves. */
static special_filedata_internals_t base_internals =
{ FALSE,DW_END_little,32,32,200,SECCOUNT, sectiondata };

static
int gsinfo(void* obj,
    Dwarf_Unsigned section_index,
    Dwarf_Obj_Access_Section_a* return_section,
    int* error )
{
    special_filedata_internals_t *internals =
        (special_filedata_internals_t *)(obj);
    struct sectiondata_s *finfo = 0;

    *error = 0; /* No error. Avoids unused arg */
    if (section_index >= SECCOUNT) {
        return DW_DLV_NO_ENTRY;
    }
    finfo = internals->f_sectarray + section_index;
    return_section->as_name   = finfo->sd_secname;
    return_section->as_type   = 0;
    return_section->as_flags  = 0;
    return_section->as_addr   = finfo->sd_addr;
    return_section->as_offset = 0;
    return_section->as_size   = finfo->sd_sectionsize;
    return_section->as_link   = 0;
    return_section->as_info   = 0;
    return_section->as_addralign = 0;
    return_section->as_entrysize = 1;
    return DW_DLV_OK;
}
static Dwarf_Small
gborder(void * obj)
{
    special_filedata_internals_t *internals =
        (special_filedata_internals_t *)(obj);
    return internals->f_object_endian;
}
static
Dwarf_Small glensize(void * obj)
{
    /* offset size */
    special_filedata_internals_t *internals =
        (special_filedata_internals_t *)(obj);
    return internals->f_offsetsize/8;
}
static
Dwarf_Small gptrsize(void * obj)
{
    special_filedata_internals_t *internals =
        (special_filedata_internals_t *)(obj);
    return internals->f_pointersize/8;
}
static
Dwarf_Unsigned gfilesize(void * obj)
{
    special_filedata_internals_t *internals =
        (special_filedata_internals_t *)(obj);
    return internals->f_filesize;
}
static
Dwarf_Unsigned gseccount(void* obj)
{
    special_filedata_internals_t *internals =
        (special_filedata_internals_t *)(obj);
    return internals->f_sectioncount;
}
static
int gloadsec(void * obj,
    Dwarf_Unsigned secindex,
    Dwarf_Small**rdata,
    int *error)
{
    special_filedata_internals_t *internals =
        (special_filedata_internals_t *)(obj);
    struct sectiondata_s *secp = 0;

    *error = 0; /* No Error, avoids compiler warning */
    if (secindex >= internals->f_sectioncount) {
        return DW_DLV_NO_ENTRY;
    }
    secp = secindex +internals->f_sectarray;
    *rdata = secp->sd_content;
    return DW_DLV_OK;
}

const Dwarf_Obj_Access_Methods_a methods = {
    gsinfo,
    gborder,
    glensize,
    gptrsize,
    gfilesize,
    gseccount,
    gloadsec,
    0 /* no relocating anything */,
    0 /* no file with DWARF here, so mmap impossible */,
    0 /* no destructor appropriate */
    };

struct Dwarf_Obj_Access_Interface_a_s dw_interface =
{ &base_internals,&methods };

static const Dwarf_Sig8 zerosignature;
static int
isformstring(Dwarf_Half form)
{
    /*  Not handling every form string, just the
        ones used in simple cases. */
    switch(form) {
    case DW_FORM_string:        return TRUE;
    case DW_FORM_GNU_strp_alt:  return TRUE;
    case DW_FORM_GNU_str_index: return TRUE;
    case DW_FORM_strx:          return TRUE;
    case DW_FORM_strx1:         return TRUE;
    case DW_FORM_strx2:         return TRUE;
    case DW_FORM_strx3:         return TRUE;
    case DW_FORM_strx4:         return TRUE;
    case DW_FORM_strp:          return TRUE;
    default: break;
    };
    return FALSE;
}

static int
print_attr(Dwarf_Attribute atr,
    Dwarf_Signed anumber, Dwarf_Error *error)
{
    int res = 0;
    char *str = 0;
    const char *attrname = 0;
    const char *formname = 0;
    Dwarf_Half form = 0;
    Dwarf_Half attrnum = 0;
    res = dwarf_whatform(atr,&form,error);
    if (res != DW_DLV_OK) {
        printf("dwarf_whatform failed! res %d\n",res);
        return res;
    }
    res = dwarf_whatattr(atr,&attrnum,error);
    if (res != DW_DLV_OK) {
        printf("dwarf_whatattr failed! res %d\n",res);
        return res;
    }
    res = dwarf_get_AT_name(attrnum,&attrname);
    if (res == DW_DLV_NO_ENTRY) {
        printf("Bogus attrnum 0x%x\n",attrnum);
        attrname = "<internal error ?>";
    }
    res = dwarf_get_FORM_name(form,&formname);
    if (res == DW_DLV_NO_ENTRY) {
        printf("Bogus form 0x%x\n",attrnum);
        attrname = "<internal error ?>";
    }
    if (!isformstring(form)) {
        printf("  [%2d] Attr: %-15s  Form: %-15s\n",
            (int)anumber,attrname,formname);
        return DW_DLV_OK;
    }
    res = dwarf_formstring(atr,&str,error);
    if (res != DW_DLV_OK) {
        printf("dwarf_formstring failed! res %d\n",res);
        return res;
    }
    printf("  [%2d] Attr: %-15s  Form: %-15s %s\n",
        (int)anumber,attrname,formname,str);
    return DW_DLV_OK;
}

static void
dealloc_list(Dwarf_Debug dbg,
    Dwarf_Attribute *attrbuf,
    Dwarf_Signed attrcount,
    Dwarf_Signed i)
{
    for ( ; i < attrcount; ++i) {
        dwarf_dealloc_attribute(attrbuf[i]);
    }
    dwarf_dealloc(dbg,attrbuf,DW_DLA_LIST);
}

static int
print_one_die(Dwarf_Debug dbg,Dwarf_Die in_die,int level,
    Dwarf_Error *error)
{
    Dwarf_Attribute *attrbuf = 0;
    Dwarf_Signed  attrcount = 0;
    Dwarf_Half tag = 0;
    const char * tagname = 0;
    int res = 0;
    Dwarf_Signed i = 0;

    res = dwarf_tag(in_die,&tag,error);
    if (res != DW_DLV_OK) {
        printf("dwarf_tag failed! res %d\n",res);
        return res;
    }
    res = dwarf_get_TAG_name(tag,&tagname);
    if (res != DW_DLV_OK) {
        tagname = "<bogus tag>";
    }
    printf("%3d:  Die: %s\n",level,tagname);
    res = dwarf_attrlist(in_die,&attrbuf,&attrcount,error);
    if (res != DW_DLV_OK) {
        printf("dwarf_attrlist failed! res %d\n",res);
        return res;
    }
    for (i = 0; i <attrcount;++i) {
        res  =print_attr(attrbuf[i],i,error);
        if (res != DW_DLV_OK) {
            dealloc_list(dbg,attrbuf,attrcount,0);
            printf("dwarf_attr print failed! res %d\n",res);
            return res;
        }
    }
    dealloc_list(dbg,attrbuf,attrcount,0);
    return DW_DLV_OK;
}

static int
print_object_info(Dwarf_Debug dbg,Dwarf_Error *error)
{
    Dwarf_Bool is_info = TRUE; /* our data is not DWARF4
        .debug_types. */
    Dwarf_Unsigned cu_header_length = 0;
    Dwarf_Half     version_stamp = 0;
    Dwarf_Off      abbrev_offset = 0;
    Dwarf_Half     address_size  = 0;
    Dwarf_Half     length_size   = 0;
    Dwarf_Half     extension_size = 0;
    Dwarf_Sig8     type_signature;
    Dwarf_Unsigned typeoffset     = 0;
    Dwarf_Unsigned next_cu_header_offset = 0;
    Dwarf_Half     header_cu_type = 0;
    int res = 0;
    Dwarf_Die cu_die = 0;
    int level = 0;

    type_signature = zerosignature;
    res = dwarf_next_cu_header_d(dbg,
        is_info,
        &cu_header_length,
        &version_stamp,
        &abbrev_offset,
        &address_size,
        &length_size,
        &extension_size,
        &type_signature,
        &typeoffset,
        &next_cu_header_offset,
        &header_cu_type,
        error);
    if (res != DW_DLV_OK) {
        printf("Next cu header  result %d. "
            "Something is wrong FAIL, line %d\n",res,__LINE__);
        if (res == DW_DLV_ERROR) {
            printf("Error is: %s\n",dwarf_errmsg(*error));
        }
        exit(EXIT_FAILURE);
    }
    printf("CU header length..........0x%lx\n",
        (unsigned long)cu_header_length);
    printf("Version stamp.............%d\n",version_stamp);
    printf("Address size .............%d\n",address_size);
    printf("Offset size...............%d\n",length_size);
    printf("Next cu header offset.....0x%lx\n",
        (unsigned long)next_cu_header_offset);

    res = dwarf_siblingof_b(dbg, NULL,is_info, &cu_die, error);
    if (res != DW_DLV_OK) {
        /* There is no CU die, which should be impossible. */
        if (res == DW_DLV_ERROR) {
            printf("ERROR: dwarf_siblingof_b failed, no CU die\n");
            printf("Error is: %s\n",dwarf_errmsg(*error));
            return res;
        } else {
            printf("ERROR: dwarf_siblingof_b got NO_ENTRY, "
                "no CU die\n");
            return res;
        }
    }
    res = print_one_die(dbg,cu_die,level,error);
    if (res != DW_DLV_OK) {
        dwarf_dealloc_die(cu_die);
        printf("print_one_die failed! %d\n",res);
        return res;
    }
    dwarf_dealloc_die(cu_die);
    return DW_DLV_OK;
}

/*  testing interfaces useful for embedding
    libdwarf inside another program or library. */
int main(int argc, char **argv)
{
    int res = 0;
    Dwarf_Debug dbg = 0;
    Dwarf_Error error = 0;
    int fail = FALSE;
    int i = 1;

    if (i >= argc) {
        /* OK */
    } else {
        if (!strcmp(argv[i],"--suppress-de-alloc-tree")) {
            /* Do nothing, ignore the argument */
            ++i;
        }
    }
    /*  Fill in interface before this call.
        We are using a static area, see above. */
    res = dwarf_object_init_b(&dw_interface,
        0,0,DW_GROUPNUMBER_ANY,&dbg,
        &error);
    if (res == DW_DLV_NO_ENTRY) {
        printf("FAIL Cannot dwarf_object_init_b() NO ENTRY. \n");
        exit(EXIT_FAILURE);
    } else if (res == DW_DLV_ERROR){
        printf("FAIL Cannot dwarf_object_init_b(). \n");
        printf("msg: %s\n",dwarf_errmsg(error));
        dwarf_dealloc_error(dbg,error);
        exit(EXIT_FAILURE);
    }
    res = print_object_info(dbg,&error);
    if (res != DW_DLV_OK) {
        if (res == DW_DLV_ERROR) {
            dwarf_dealloc_error(dbg,error);
        }
        printf("FAIL printing, res %d line %d\n",res,__LINE__);
        exit(EXIT_FAILURE);
    }
    dwarf_object_finish(dbg);
    if (fail) {
        printf("FAIL objectaccess.c\n");
        exit(EXIT_FAILURE);
    }
    return 0;
}
/*! @endcode */
