1 /* rdfload.c RDOFF Object File loader library
3 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
4 * Julian Hall. All rights reserved. The software is
5 * redistributable under the licence given in the file "Licence"
6 * distributed in the NASM archive.
8 * Permission to use this file in your own projects is granted, as int32_t
9 * as acknowledgement is given in an appropriate manner to its authors,
10 * with instructions of how to obtain a copy via ftp.
14 * TODO: this has been modified from previous version only in very
15 * simplistic ways. Needs to be improved drastically, especially:
16 * - support for more than the 2 standard segments
17 * - support for segment relocations (hard to do in ANSI C)
30 rdfmodule *rdfload(const int8_t *filename)
33 int32_t bsslength = 0;
37 f = malloc(sizeof(rdfmodule));
39 rdf_errno = RDF_ERR_NOMEM;
43 f->symtab = symtabNew();
46 rdf_errno = RDF_ERR_NOMEM;
51 if (rdfopen(&(f->f), filename)) {
56 /* read in text and data segments, and header */
58 f->t = malloc(f->f.seg[0].length);
59 f->d = malloc(f->f.seg[1].length); /* BSS seg allocated later */
60 hdr = malloc(f->f.header_len);
62 if (!f->t || !f->d || !hdr) {
63 rdf_errno = RDF_ERR_NOMEM;
73 if (rdfloadseg(&f->f, RDOFF_HEADER, hdr) ||
74 rdfloadseg(&f->f, RDOFF_CODE, f->t) ||
75 rdfloadseg(&f->f, RDOFF_DATA, f->d)) {
86 /* Allocate BSS segment; step through header and count BSS records */
88 while ((r = rdfgetheaderrec(&f->f))) {
90 bsslength += r->b.amount;
93 f->b = malloc(bsslength);
94 if (bsslength && (!f->b)) {
99 rdf_errno = RDF_ERR_NOMEM;
103 rdfheaderrewind(&f->f);
105 f->textrel = (int32_t)f->t;
106 f->datarel = (int32_t)f->d;
107 f->bssrel = (int32_t)f->b;
112 int rdf_relocate(rdfmodule * m)
120 rdfheaderrewind(&m->f);
121 collection_init(&imports);
123 while ((r = rdfgetheaderrec(&m->f))) {
125 case 1: /* Relocation record */
127 /* calculate relocation factor */
129 if (r->r.refseg == 0)
131 else if (r->r.refseg == 1)
133 else if (r->r.refseg == 2)
136 /* We currently do not support load-time linkage.
137 This should be added some time soon... */
139 return 1; /* return error code */
141 if ((r->r.segment & 63) == 0)
143 else if ((r->r.segment & 63) == 1)
146 continue; /* relocation not in a loaded segment */
148 /* it doesn't matter in this case that the code is non-portable,
149 as the entire concept of executing a module like this is
151 switch (r->r.length) {
153 seg[r->r.offset] += (int8_t)rel;
156 *(uint16_t *) (seg + r->r.offset) += (uint16_t) rel;
159 *(int32_t *)(seg + r->r.offset) += rel;
164 case 3: /* export record - add to symtab */
165 e.segment = r->e.segment;
166 e.offset = r->e.offset + (e.segment == 0 ? m->textrel : /* 0 -> code */
167 e.segment == 1 ? m->datarel : /* 1 -> data */
168 m->bssrel); /* 2 -> bss */
170 e.name = malloc(strlen(r->e.label) + 1);
174 strcpy(e.name, r->e.label);
175 symtabInsert(m->symtab, &e);
178 case 6: /* segment relocation */
179 fprintf(stderr, "%s: segment relocation not supported by this "
180 "loader\n", m->f.name);