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/* rdfload.c RDOFF Object File loader library
*
* The Netwide Assembler is copyright (C) 1996 Simon Tatham and
* Julian Hall. All rights reserved. The software is
* redistributable under the licence given in the file "Licence"
* distributed in the NASM archive.
*
* Permission to use this file in your own projects is granted, as int32_t
* as acknowledgement is given in an appropriate manner to its authors,
* with instructions of how to obtain a copy via ftp.
*/
/*
* TODO: this has been modified from previous version only in very
* simplistic ways. Needs to be improved drastically, especially:
* - support for more than the 2 standard segments
* - support for segment relocations (hard to do in ANSI C)
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "rdfload.h"
#include "symtab.h"
#include "collectn.h"
extern int rdf_errno;
rdfmodule *rdfload(const int8_t *filename)
{
rdfmodule *f;
int32_t bsslength = 0;
int8_t *hdr;
rdfheaderrec *r;
f = malloc(sizeof(rdfmodule));
if (f == NULL) {
rdf_errno = RDF_ERR_NOMEM;
return NULL;
}
f->symtab = symtabNew();
if (!f->symtab) {
free(f);
rdf_errno = RDF_ERR_NOMEM;
return NULL;
}
/* open the file */
if (rdfopen(&(f->f), filename)) {
free(f);
return NULL;
}
/* read in text and data segments, and header */
f->t = malloc(f->f.seg[0].length);
f->d = malloc(f->f.seg[1].length); /* BSS seg allocated later */
hdr = malloc(f->f.header_len);
if (!f->t || !f->d || !hdr) {
rdf_errno = RDF_ERR_NOMEM;
rdfclose(&f->f);
if (f->t)
free(f->t);
if (f->d)
free(f->d);
free(f);
return NULL;
}
if (rdfloadseg(&f->f, RDOFF_HEADER, hdr) ||
rdfloadseg(&f->f, RDOFF_CODE, f->t) ||
rdfloadseg(&f->f, RDOFF_DATA, f->d)) {
rdfclose(&f->f);
free(f->t);
free(f->d);
free(f);
free(hdr);
return NULL;
}
rdfclose(&f->f);
/* Allocate BSS segment; step through header and count BSS records */
while ((r = rdfgetheaderrec(&f->f))) {
if (r->type == 5)
bsslength += r->b.amount;
}
f->b = malloc(bsslength);
if (bsslength && (!f->b)) {
free(f->t);
free(f->d);
free(f);
free(hdr);
rdf_errno = RDF_ERR_NOMEM;
return NULL;
}
rdfheaderrewind(&f->f);
f->textrel = (int32_t)f->t;
f->datarel = (int32_t)f->d;
f->bssrel = (int32_t)f->b;
return f;
}
int rdf_relocate(rdfmodule * m)
{
rdfheaderrec *r;
Collection imports;
symtabEnt e;
int32_t rel;
uint8_t *seg;
rdfheaderrewind(&m->f);
collection_init(&imports);
while ((r = rdfgetheaderrec(&m->f))) {
switch (r->type) {
case 1: /* Relocation record */
/* calculate relocation factor */
if (r->r.refseg == 0)
rel = m->textrel;
else if (r->r.refseg == 1)
rel = m->datarel;
else if (r->r.refseg == 2)
rel = m->bssrel;
else
/* We currently do not support load-time linkage.
This should be added some time soon... */
return 1; /* return error code */
if ((r->r.segment & 63) == 0)
seg = m->t;
else if ((r->r.segment & 63) == 1)
seg = m->d;
else
continue; /* relocation not in a loaded segment */
/* it doesn't matter in this case that the code is non-portable,
as the entire concept of executing a module like this is
non-portable */
switch (r->r.length) {
case 1:
seg[r->r.offset] += (int8_t)rel;
break;
case 2:
*(uint16_t *) (seg + r->r.offset) += (uint16_t) rel;
break;
case 4:
*(int32_t *)(seg + r->r.offset) += rel;
break;
}
break;
case 3: /* export record - add to symtab */
e.segment = r->e.segment;
e.offset = r->e.offset + (e.segment == 0 ? m->textrel : /* 0 -> code */
e.segment == 1 ? m->datarel : /* 1 -> data */
m->bssrel); /* 2 -> bss */
e.flags = 0;
e.name = malloc(strlen(r->e.label) + 1);
if (!e.name)
return 1;
strcpy(e.name, r->e.label);
symtabInsert(m->symtab, &e);
break;
case 6: /* segment relocation */
fprintf(stderr, "%s: segment relocation not supported by this "
"loader\n", m->f.name);
return 1;
}
}
return 0;
}
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