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/*
* Copyright 2018 Vincent Sanders <vince@netsurf-browser.org>
*
* This file is part of libnspdf.
*
* Licensed under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
*/
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <nspdf/errors.h>
#include "cos_parse.h"
#include "cos_object.h"
#include "pdf_doc.h"
/** indirect object */
struct xref_table_entry {
/* reference identifier */
struct cos_reference ref;
/** offset of object */
uint64_t offset;
/* indirect object if already decoded */
struct cos_object *object;
};
static struct cos_object cos_null_obj = {
.type = COS_TYPE_NULL,
};
nspdferror nspdf__xref_allocate(struct nspdf_doc *doc, int64_t size)
{
if (doc->xref_table != NULL) {
/** \todo handle freeing xref table */
return NSPDFERROR_SYNTAX;
}
doc->xref_table_size = size;
doc->xref_table = calloc(doc->xref_table_size,
sizeof(struct xref_table_entry));
if (doc->xref_table == NULL) {
return NSPDFERROR_NOMEM;
}
return NSPDFERROR_OK;
}
nspdferror nspdf__xref_parse(struct nspdf_doc *doc, uint64_t *offset_out)
{
uint64_t offset;
nspdferror res;
uint64_t objnumber; /* current object number */
uint64_t objcount;
offset = *offset_out;
/* xref object header */
if ((DOC_BYTE(doc, offset ) != 'x') &&
(DOC_BYTE(doc, offset + 1) != 'r') &&
(DOC_BYTE(doc, offset + 2) != 'e') &&
(DOC_BYTE(doc, offset + 3) != 'f')) {
return NSPDFERROR_SYNTAX;
}
offset += 4;
res = nspdf__stream_skip_ws(doc->stream, &offset);
if (res != NSPDFERROR_OK) {
return res;
}
/* subsections
* <first object number> <number of references in subsection>
*/
res = doc_read_uint(doc, &offset, &objnumber);
while (res == NSPDFERROR_OK) {
uint64_t lastobj;
res = nspdf__stream_skip_ws(doc->stream, &offset);
if (res != NSPDFERROR_OK) {
return res;
}
res = doc_read_uint(doc, &offset, &objcount);
if (res != NSPDFERROR_OK) {
return res;
}
res = nspdf__stream_skip_ws(doc->stream, &offset);
if (res != NSPDFERROR_OK) {
return res;
}
//printf("decoding subsection %lld %lld\n", objnumber, objcount);
lastobj = objnumber + objcount;
for (; objnumber < lastobj ; objnumber++) {
/* each entry is a fixed format */
uint64_t objindex;
uint64_t objgeneration;
/* object index */
res = doc_read_uint(doc, &offset, &objindex);
if (res != NSPDFERROR_OK) {
return res;
}
offset++; /* skip space */
res = doc_read_uint(doc, &offset, &objgeneration);
if (res != NSPDFERROR_OK) {
return res;
}
offset++; /* skip space */
if ((DOC_BYTE(doc, offset++) == 'n')) {
if (objnumber < doc->xref_table_size) {
struct xref_table_entry *indobj;
indobj = doc->xref_table + objnumber;
indobj->ref.id = objnumber;
indobj->ref.generation = objgeneration;
indobj->offset = objindex;
//printf("xref %lld %lld -> %lld\n", objnumber, objgeneration, objindex);
} else {
//printf("index out of bounds\n");
}
}
offset += 2; /* skip EOL */
}
res = doc_read_uint(doc, &offset, &objnumber);
}
return NSPDFERROR_OK;
}
nspdferror
nspdf__xref_get_referenced(struct nspdf_doc *doc, struct cos_object **cobj_out)
{
nspdferror res;
struct cos_object *cobj;
struct cos_object *indirect;
uint64_t offset;
struct xref_table_entry *entry;
cobj = *cobj_out;
if (cobj->type != COS_TYPE_REFERENCE) {
/* not passed a reference object so just return what was passed */
return NSPDFERROR_OK;
}
entry = doc->xref_table + cobj->u.reference->id;
/* check if referenced object is in range and exists. return null object if
* not
*/
if ((cobj->u.reference->id >= doc->xref_table_size) ||
(cobj->u.reference->id == 0) ||
(entry->ref.id == 0)) {
*cobj_out = &cos_null_obj;
return NSPDFERROR_OK;
}
if (entry->object == NULL) {
/* indirect object has never been parsed */
offset = entry->offset;
res = cos_parse_object(doc, &offset, &indirect);
if (res != NSPDFERROR_OK) {
//printf("failed to decode indirect object\n");
return res;
}
entry->object = indirect;
}
*cobj_out = entry->object;
return NSPDFERROR_OK;
}
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