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/* data.c
* This file is part of Decomp - a decompiler. In this file are
* routines for disassembling data sections from an object file.
*
* Copyright (C) 2001, Jonathan duSaint <dusaint@earthlink.net>
*
* Started around 1 December 2001.
*/
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include <ctype.h>
#include "decomp.h"
/* Whether or not to align the datum size. */
int unalign;
/* find_size
* Guess the size of the datum at OFFSET.
*/
unsigned long
find_size (hash_t symtab, char *data, unsigned long base,
unsigned long offset, unsigned long limit)
{
unsigned long seek;
/* check for a zero byte or for another symbol */
for (seek = offset + 1; data[seek]; seek++) {
if (hash_get (symtab, base + seek) != NULL) { unalign = 1; break; }
}
return seek - offset;
}
/* check_is_string
* Determine if STR, which is LEN bytes long, is a string or not, using
* a heuristic.
*/
int
check_is_string (char *str, unsigned long len)
{
unsigned long k = -1;
if (len < 2) return 0;
if (str[len - 1] != '\0' && str[len] != '\0') return 0;
while (++k < len - 1) if (!isgraph (str[k]) && !isspace (str[k])) return 0;
return 1;
}
/* escape_string
* Convert chars that need escaping into an escape. The returned string
* must be freed.
*/
char *
escape_string (char *str)
{
unsigned long k, o;
char *esc;
/* allocate a lot */
esc = xmalloc (strlen (str) * 2 + 1);
for (k = 0, o = 0; k < strlen (str); k++)
switch (str[k])
{
case '\f':
esc[o++] = '\\';
esc[o++] = 'f';
break;
case '\n':
esc[o++] = '\\';
esc[o++] = 'n';
break;
case '\r':
esc[o++] = '\\';
esc[o++] = 'r';
break;
case '\t':
esc[o++] = '\\';
esc[o++] = 't';
break;
case '\v':
esc[o++] = '\\';
esc[o++] = 'v';
break;
case '"':
esc[o++] = '\\';
esc[o++] = '"';
break;
case '\\':
esc[o++] = '\\';
esc[o++] = '\\';
break;
default:
esc[o++] = str[k];
break;
}
return esc;
}
/* print_symbol
* Print the named object at VADDR.
*/
void
print_symbol (hash_t symtab, struct symtab *sym, unsigned long load_addr,
unsigned long *offset, unsigned long limit,
unsigned long align, char *data, FILE *ofp)
{
unsigned long k, size;
char *buff;
unalign = 0;
if (sym->size == 0)
size = find_size (symtab, data, load_addr, *offset, limit);
else
size = sym->size;
/* double check the size */
if (size == 0) /* rare but possible */
size = align;
buff = xmalloc (size);
memcpy (buff, data + *offset, size);
/* fprintf (ofp, "\t.size\t%ld\n", size); */
if (check_is_string (buff, size))
{
char *esc = escape_string (buff);
fprintf (ofp, "\t.string\t\"%s\"", esc);
xfree (esc);
}
else
{
/* if we guessed the size, it's not a string and there isn't a symbol
immediately after, round up to align */
if (sym->size == 0 && !unalign) while (size % align) size++;
switch (size)
{
case 1:
fprintf (ofp, "\t.byte\t%#x", *buff);
break;
case 2:
fprintf (ofp, "\t.hword\t%#hx", *(uint16_t *)buff);
break;
case 4:
fprintf (ofp, "\t.int\t%#x", *(uint32_t *)buff);
break;
case 8:
fprintf (ofp, "\t.quad\t%#llx", *(uint64_t *)buff);
break;
default:
for (k = 0; k < size; k++)
{
if (!(k % 8)) fprintf (ofp, "\n\t.byte\t0x%02hhx", buff[k]);
else fprintf (ofp, ", 0x%02hhx", buff[k]);
}
}
}
fputc ('\n', ofp);
xfree (buff);
*offset += size;
}
/* decode_data_section
* Disassemble a data section into named and unnamed chunks of data.
*/
void
decode_data_section (struct file_info *fi, struct section_info *s,
hash_t symtab, FILE *ofp)
{
int need_to_print_header = 1;
unsigned long offset = 0;
struct symtab *sym;
char *data;
data = xmalloc (s->section_size);
fseek (fi->fp, s->section_offset, SEEK_SET);
if (fread (data, sizeof (char), s->section_size, fi->fp) < s->section_size)
error_out (ERR_READ_SECTION);
fprintf (ofp, "\n\n\t.section\t%s%s\n\t.align\t%d\n", s->section_name,
s->flags, s->align);
for (offset = 0; offset < s->section_size;)
{
sym = hash_get (symtab, s->load_address + offset);
if (sym != NULL)
{
fputc ('\n', ofp);
/* if this sym is global, mark it */
if (sym->type == GLOBAL_DATA || sym->type == GLOBAL_UNKNOWN)
fprintf (ofp, "\n\t.global\t%s", sym->name);
/* if it's data, say so */
if (sym->type == GLOBAL_DATA || sym->type == LOCAL_DATA
|| sym->type == UNKNOWN_DATA)
fprintf (ofp, "\n\t.type\t%s,@object", sym->name);
if (sym->size != 0) fprintf (ofp, "\n\t.size\t%s, %ld", sym->name,
sym->size);
fprintf (ofp, "\n%s:", sym->name);
print_symbol (symtab, sym, s->load_address, &offset, s->section_size,
s->align, data, ofp);
/* skip to next aligned address */
/* this doesn't seem to be a good idea - not sure why */
/* maybe it's because data isn't always aligned in the object file */
/* while ((s->load_address + offset) % s->align) offset++; */
need_to_print_header = 1;
}
else /* no data - just print out the section contents */
{
char byte = data[offset++];
if (!((s->load_address + offset) % 8) || need_to_print_header)
{
fprintf (ofp, "\n\t.byte\t0x%02hhx", byte);
need_to_print_header = 0;
}
else
fprintf (ofp, ", 0x%02hhx", byte);
}
}
}
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