A /Kids array listing one widget many times, or shared by several fields,
built a Widget for every listing, so a small file expanded into fields times
listings widgets. A widget now belongs to the first field that lists it, and a
page widget already owned is not adopted again.
The tests each branch appends to the audit, edit and organize test files are
kept side by side; prune.rs merges cleanly, with the form memo on top of the
budgeted page content.
The JPEG decoder re-sorts and rescans every pending Extended XMP chunk after
each marker, so a file of many small chunks cost time quadratic in their
number before any pixel limit applied. Turning a photo upright now counts
the chunks first and leaves a JPEG with more than 1024 as it is.
A one-pixel GIF on a huge logical screen decodes to a canvas that size,
which the conversion then copied before splitting it into colour and alpha,
so a few bytes could hold over a gigabyte. Screens past 16 Mpx are refused
before decoding, and the decoded canvas is converted without a copy.
A TIFF's pages were each capped at 2 GiB but all kept in memory until
embedded, so many small directories sharing one compressed strip could ask
for many times that; embedding one image also decoded every page. The pages
of one TIFF are now refused past 4 GiB together, and image_xobject reads
only the first page.
The redaction audit read each page's text through text_lines, which walked
the whole page tree again for every page (quadratic in the page count) and
let /ActualText replace the glyphs, so an empty or substitute ActualText hid
covered text from the audit. Edit gains glyph_text_lines, which reads the
page dictionary it is given and ignores ActualText; the audit uses it.
Text extraction copies a ToUnicode destination for every glyph showing its
code, and the page's total text was not bounded, so a small page could expand
into gigabytes. One page's extraction (its forms included) stops with an error
past 16 MiB of text.
Past the marked-content depth budget the number of open sequences is unknown,
and the mark on top was appended with none of them closed, so the page's own
optional-content scopes (possibly hidden) could hide a redaction box, a
header or a watermark. Placing on top of such a page is now refused before
anything changes; behind it is still possible.
Removing flattened widgets from the field tree recursed into every /Kids
entry with only a depth limit, so a node listing its child twice per level
(or itself) made the walk exponential. Each node's answer is now remembered;
a node met again while it is still being visited survives, as it did when
the depth limit stopped a cycle.
Writing an added text item re-wrapped the whole text inside the loop over its
lines to learn the line count, so multiline text cost time and temporary
memory quadratic in its length. The wrapped lines are computed once.
Each candidate attribute match searched the whole packet before it for the
last < and >, so a long text node repeating the attribute name cost time
quadratic in the packet size (up to the 16 MiB decode cap). The scan now
keeps the last < and > as it moves forward.
The pruner decoded and walked a form XObject again on every Do that drew
it, so a form drawing itself a few times per level was analysed
exponentially often within the depth limit. Forms are now remembered with
the resources owner they were drawn against, and a repeat records nothing
new.
Looking up a named destination and listing attachments in a source's name
trees followed every /Kids entry with only a depth limit, so a node listing
the same child twice per level made the walk (and the attachment list)
exponential in the depth. Both walks now skip a node already read.
Fixing up copied annotations cloned the whole source-to-destination map for
every non-GoTo action and dropped the copies it made, so many annotations
cost quadratic memory and time and an object shared by their actions was
copied once per action. The copier now lends its map to the action copy and
takes it back with the new entries.
Renaming a colliding field tried Name-1, Name-2, ... from 1 every time, so
many fields of one name cost a quadratic number of attempts during import,
combine and their conflict previews. Taken names only grow, so the search
now resumes after the last suffix handed out for that name; the result is
still the first free variant.
Each imported top-level field was checked against every field already in
/AcroForm /Fields before it was appended, so a page with many distinct
widget fields cost time quadratic in their number. Membership is now kept
in a set beside the list.
Adds a test-only work counter to the crate, so tests can bound the work a
hostile document causes without timing it.
Redaction reads page content and form XObjects strictly (upstream) and
within one page's decode budget (this branch): both now go through
DecodeBudget::decode_strict.
Filtered inline image data has no length, so its end is an EI chosen
among candidates, and the content parser chose by a different rule
than the renderer's tokenizer (hayro-syntax): the renderer also takes an
EI with no whitespace before it, and checks a candidate by reading what
follows as operators. With image data such as "7FEI 1 0 0 1 200 0 cm",
the renderer ran a cm that redaction read as image data, so text was
drawn 200 pt from where removal and its verify pass looked.
The parser now takes each inline image's end from the renderer's
tokenizer (already in the tree through pdfcraft-cos), so both read the
same operators after the image; a test runs both on the same fixtures.
Only where that tokenizer reads no image (no EI it accepts, or
parameters it can't read) does the parser fall back to its own rules,
counting the image in Parsed::ambiguous_images, and applying redactions
refuses such a page as unreadable.
Structure cleanup cleared alternate text, actual text and expansions
only on the element that directly owned changed marked content, and an
element that lost an annotation reference kept its descriptions unless
it lost every kid. An ancestor's /ActualText covering a redacted span,
or a link element's /Alt repeating the address of a removed link, stayed
in the saved file. Elements that lose an annotation now always lose
their descriptions, and every ancestor of an affected element (found
through both /P and the tree's /K, which may disagree) loses its own.
An element written in place above one with a description to clear
refuses the operation, as other in-place cases already do.
Finding which marked content a redaction changed copied every operator
into the buffer of each MCID enclosing it, so content nested n deep was
held n times: a modest stream of nested BDCs could exhaust memory.
Each operator inside marked content is now serialized once, and each
MCID keeps the ranges its sequences span. The bytes compared are capped;
MCIDs past the cap count as changed, so their descriptions are cleared
rather than kept.
Clearing the pixels of a partly covered image decoded its stream with
the global 1 GiB allowance and only then cut it to the raster length its
Width, Height and bit depth declare. A small Flate stream could make
every such image allocate and inflate far more than it can use. Decoding
now stops at twice the raster plus a byte per row (filter-chain and
predictor overhead) and a little slack; an image past that is removed
whole, as an undecodable one already is.
After applying redactions, removed images and forms were unlinked from
page-tree resource dictionaries but not from the resources of forms the
page still draws. A form sharing the page's original resource dictionary
(a common producer layout) kept the removed image reachable, so a full
save wrote it. The walk over surviving forms now drops XObject entries
for removed objects that the form's own content does not draw, and fails
closed when that cannot be determined.
The redaction interpreter started every form XObject with an empty text
state (no font, size 0, no spacing) although a form inherits its caller's
graphics state, and it ignored the /Font entry of an ExtGState set by gs.
Text shown that way was placed at the wrong positions, so removal and
the verify pass could both miss glyphs under a mark. Forms now start
from the caller's state, and gs sets the font and size as Tf does.
The engine's renderer cross-check test used the gs case as its example
of interpreter/renderer disagreement; it now runs the check directly on
an unredacted page, which also covers an input stream labelled as a
redaction overlay.
Both checks for text left under applied redaction marks (redaction's own
verify pass and the engine's renderer cross-check) skipped any page
content stream whose dictionary said /PCMark /Redaction, so that the
overlay's label would not count. An input file could put that label on
its own content stream and keep it out of both checks. Applying
redactions now records the overlay streams it adds (stamp returns the
new stream), and only those are skipped.
Deleting a field took it off its pages and out of the field tree but left
its entry in the form's /CO array. That reference kept the field
dictionary, its value and its widgets reachable, so a full save after
applying redactions over the field still wrote the redacted value.
A run of images that is not one picture was searched again from each of
its groups, collecting the rest of the run every time, so many images drawn
over one another made a page quadratic. The search reads at most 16 groups
per content operator (at least 65 536) and leaves the rest of the page as
it is once that is spent.
The pixel reader capped the image size the dictionary gives, then decoded
the JPEG at the size its header gives and compared afterwards, so a small
image dictionary over a huge JPEG allocated the huge one first. The reader
takes the size from the JPEG header and refuses a mismatch before decoding.
The body-size tally and the RTF colour table searched every slot seen so
far for each block, and the RTF writer searched the colour table again for
every paragraph and cell, so a document with many distinct sizes or colours
made export quadratic. Both keep their first-seen order and look slots up
in a hash map.
Line wrapping built and measured the whole candidate line for every word,
so a long field value or annotation text at a tiny font size, with many
words on one line, took quadratic time and copying. The wrapper keeps the
line's width as it goes and measures each word, space and broken
character once.
Code-to-CID and /W range lookups scanned every record in declaration
order, once per glyph and once per explicit ToUnicode entry while a font
was read, so a few thousand records multiplied by as many codes took
billions of steps. Both tables are indexed once into stretches whose
first-declared covering record wins, the precedence the scan had, and the
/W ranges stop at the CMap entry limit.
A sequential bfrange stores one destination and builds every covered
glyph's text from all of it, so one huge destination and many repeats of
its codes made text extraction copy megabytes per glyph. Destinations keep
at most 256 UTF-16 units (the format's 512 bytes), and marked-text
extraction stops asking for a glyph's text once its id has all the text it
keeps.
Figure listing decoded and parsed a page's content once per figure on it,
so many small Figure elements pointing at one page multiplied the work.
The figures are grouped by page and one pass gathers the bounds of every
marked-content id they own; what a sequence draws also counts for the
sequences around it, as before.
Marked-text extraction and figure bounds searched the whole marked-content
stack before every operator, so deeply nested unmarked BMC blocks made a page
quadratic. The text stack now holds each level's effective id (its own, else
the enclosing one's), and the bounds pass counts the open sequences that
match.
The name-tree count cloned each node's /Kids array and skipped repeated
references without charging the budget, so a node listing the same kid
many times cost work proportional to every entry while the budget saw one
step. The walk now borrows the array, charges every entry it does not
descend into, and stops once the budget is spent.
aiongg