#include "pplib.h" #define PPXREF_MAP_INIT 16 // number of xref sections ppxref * ppxref_create (ppdoc *pdf, size_t initsize, size_t xrefoffset) { ppxref *xref; if (initsize == 0) // unknown initsize = PPXREF_MAP_INIT; xref = (ppxref *)ppstruct_take(&pdf->heap, sizeof(ppxref)); xref->sects = (ppxsec *)ppstruct_take(&pdf->heap, initsize * sizeof(ppxsec)); xref->size = 0; xref->space = initsize; xref->count = 0; xref->trailer.type = PPNONE; xref->trailer.dict = NULL; xref->prev = NULL; xref->pdf = pdf; xref->offset = xrefoffset; return xref; } ppxsec * ppxref_push_section (ppxref *xref, ppheap *heap) { ppxsec *sects; if (xref->size < xref->space) return &xref->sects[xref->size++]; xref->space <<= 1; sects = xref->sects; xref->sects = (ppxsec *)ppstruct_take(heap, xref->space * sizeof(ppxsec)); // waste but rare memcpy(xref->sects, sects, xref->size * sizeof(ppxsec)); return &xref->sects[xref->size++]; } /* When loading xref table, we don't know how many sections is there. We assume 16, which is more than usual (waste). But if there is more, we double the size, wasting again. This could be made better with a dedicated allocator for xref sections (heap or generic malloc). Or an ephemeric malloced c-array stored in heap once ready (analogical to stack used for dicts/arrays). For xref streams we have explicit num of sections. */ /* void ppxref_done_sections (ppxref *xref, ppheap *heap) { // if xref->sects was initialized with mallocted array we could do ppxsec *sects; size_t size; sects = xref->sects; size = xref->size * sizeof(ppxsec); xref->sects = (ppxsec *)ppstruct_take(heap, size); memcpy(xref->sects, sects, size); pp_free(sects); xref->space = xref->size; } */ static void ppxref_sort_sects (ppxsec *left, ppxsec *right) { ppxsec *l, *r, *m, t; ppuint first, last; l = left, r = right, m = l + ((r - l) / 2); first = m->first, last = m->last; do { // don't take first/last from pointer while (l->first < first) ++l; while (r->first > last) --r; if (l <= r) { t = *l; *l = *r; *r = t; ++l, --r; } } while (l <= r); if (l < right) ppxref_sort_sects(l, right); if (r > left) ppxref_sort_sects(left, r); } int ppxref_sort (ppxref *xref) { if (xref->size == 0) return 0; ppxref_sort_sects(xref->sects, xref->sects + xref->size - 1); return 1; } ppref * ppxref_find_local (ppxref *xref, ppuint refnumber) { ppxsec *left, *right, *mid; //if (xref->size == 0) // we don't allow that // return NULL; left = xref->sects; right = xref->sects + xref->size - 1; do { mid = left + ((right - left) / 2); if (refnumber > mid->last) left = mid + 1; else if (refnumber < mid->first) right = mid - 1; else return &mid->refs[refnumber - mid->first]; } while (left <= right); return NULL; } /* PJ 20180910 So far we were resolving references in the context of the current xref: - if a given object is found in this xref, than this is the object - otherwise older xrefs are queried in order - only in linearized documents older body may refer to object from newer xref Hans sent a document where an incremental update (newer body) has only an updated page object (plus /Metadata and /Info), but /Root (catalog) and /Pages dict refs are defined only in the older body. If we resolve references using the approach so far, we actually drop the update; newer objects are parsed and linked to the newest xref, but never linked to objects tree. Assuming we will never need to interpret older versions, makes sense to assume, that the newest object version is always the correct version. */ #if 0 ppref * ppxref_find (ppxref *xref, ppuint refnumber) { ppref *ref; ppxref *other; if ((ref = ppxref_find_local(xref, refnumber)) != NULL) return ref; if (xref->pdf->flags & PPDOC_LINEARIZED) { for (other = xref->pdf->xref; other != NULL; other = other->prev) if (other != xref && (ref = ppxref_find_local(other, refnumber)) != NULL) return ref; } else { for (other = xref->prev; other != NULL; other = other->prev) if ((ref = ppxref_find_local(other, refnumber)) != NULL) return ref; /* This shouldn't happen, but I've met documents that have no linearized dict, but their xrefs are prepared as for linearized; with "older" xrefs referring to "newer". */ for (other = xref->pdf->xref; other != NULL && other != xref; other = other->prev) if ((ref = ppxref_find_local(other, refnumber)) != NULL) return ref; } return NULL; } #else ppref * ppxref_find (ppxref *xref, ppuint refnumber) { ppref *ref; ppxref *other; for (other = xref->pdf->xref; other != NULL; other = other->prev) if ((ref = ppxref_find_local(other, refnumber)) != NULL) return ref; return NULL; } #endif ppdict * ppxref_trailer (ppxref *xref) { switch (xref->trailer.type) { case PPDICT: return xref->trailer.dict; case PPSTREAM: return xref->trailer.stream->dict; default: break; } return NULL; } ppxref * ppdoc_xref (ppdoc *pdf) { return pdf->xref; } ppxref * ppxref_prev (ppxref *xref) { return xref->prev; } ppdict * ppxref_catalog (ppxref *xref) { ppdict *trailer; return (trailer = ppxref_trailer(xref)) != NULL ? ppdict_rget_dict(trailer, "Root") : NULL; } ppdict * ppxref_info (ppxref *xref) { ppdict *trailer; return (trailer = ppxref_trailer(xref)) != NULL ? ppdict_rget_dict(trailer, "Info") : NULL; } ppref * ppxref_pages (ppxref *xref) { ppdict *dict; ppref *ref; if ((dict = ppxref_catalog(xref)) == NULL || (ref = ppdict_get_ref(dict, "Pages")) == NULL) return NULL; return ref->object.type == PPDICT ? ref : NULL; }