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fix(pdf): classify unsafe text states #123

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Merged
McanKul merged 1 commit into from
Oct 4, 2026
Merged

fix(pdf): classify unsafe text states #123

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52 changes: 49 additions & 3 deletions src-tauri/src/pdf_engine/source_content.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -173,6 +173,8 @@ struct Flags {
ambiguous: bool,
subset_font: bool,
custom_encoding: bool,
text_rise: bool,
text_render_mode: bool,
masked: bool,
shared: bool,
geometry: bool,
Expand Down Expand Up @@ -201,6 +203,8 @@ struct GState {
hscale: f64,
tc: f64,
tw: f64,
text_rise: f64,
text_render_mode: u8,
}

impl Default for GState {
Expand All @@ -218,6 +222,8 @@ impl Default for GState {
hscale: 100.0,
tc: 0.0,
tw: 0.0,
text_rise: 0.0,
text_render_mode: 0,
}
}
}
Expand All @@ -235,13 +241,15 @@ impl GState {
struct TextState {
tm: [f64; 6],
tlm: [f64; 6],
clip_pending: bool,
}

impl Default for TextState {
fn default() -> Self {
Self {
tm: IDENTITY,
tlm: IDENTITY,
clip_pending: false,
}
}
}
Expand Down Expand Up @@ -396,8 +404,14 @@ impl Walker<'_> {
"BT" => {
ts.tm = IDENTITY;
ts.tlm = IDENTITY;
ts.clip_pending = false;
}
"ET" => {
if ts.clip_pending {
gs.clip_active = true;
ts.clip_pending = false;
}
}
"ET" => {}
"Tf" => {
if let Some(name) = op.operands.first().and_then(|o| o.as_name().ok()) {
gs.font_name = Some(name.to_vec());
Expand All @@ -421,6 +435,28 @@ impl Walker<'_> {
gs.hscale = z;
}
}
"Ts" => {
gs.text_rise = match op.operands.as_slice() {
[value] => obj_f64(value).ok_or_else(|| {
malformed_content("A text-rise operator has an invalid operand.")
})?,
_ => {
return Err(malformed_content(
"A text-rise operator must have one operand.",
))
}
};
}
"Tr" => {
gs.text_render_mode = match op.operands.as_slice() {
[Object::Integer(mode)] if (0..=7).contains(mode) => *mode as u8,
_ => {
return Err(malformed_content(
"A text-rendering-mode operator must contain an integer from 0 to 7.",
))
}
};
}
"TL" => {
if let Some(l) = op.operands.first().and_then(obj_f64) {
gs.leading = l;
Expand Down Expand Up @@ -480,6 +516,9 @@ impl Walker<'_> {
nested,
geom_unsafe,
)?;
if gs.text_render_mode >= 4 && pieces.iter().any(|piece| !piece.is_empty()) {
ts.clip_pending = true;
}
}
"Do" => {
let Some(name) = op.operands.first().and_then(|o| o.as_name().ok()) else {
Expand Down Expand Up @@ -611,6 +650,7 @@ impl Walker<'_> {
let shown = inspect.width * th;
let width = (shown * sx).abs().max(0.01);
let tx = (inspect.width + spacing_advance(pieces, gs.tc, gs.tw)) * th;
let origin = apply_point(effective, 0.0, gs.text_rise);
let flags = Flags {
nested_form: nested,
type3: inspect.type3,
Expand All @@ -624,6 +664,8 @@ impl Walker<'_> {
ambiguous: inspect.ambiguous,
subset_font: inspect.subset_font,
custom_encoding: inspect.custom_encoding,
text_rise: gs.text_rise != 0.0,
text_render_mode: gs.text_render_mode != 0,
masked: gs.masked,
geometry: geom_unsafe,
..Flags::default()
Expand All @@ -632,8 +674,8 @@ impl Walker<'_> {
page_index,
kind: SourceKind::Text,
rect: SourceRect {
x: effective[4],
y: effective[5],
x: origin.0,
y: origin.1,
w: width,
h: height,
},
Expand Down Expand Up @@ -808,6 +850,10 @@ fn pick_reason(flags: &Flags) -> (SourceCapability, Option<String>) {
Some("SUBSET_FONT")
} else if flags.custom_encoding {
Some("CUSTOM_ENCODING")
} else if flags.text_rise {
Some("TEXT_RISE")
} else if flags.text_render_mode {
Some("TEXT_RENDER_MODE")
} else if flags.masked {
Some("MASKED_IMAGE")
} else if flags.shared {
Expand Down
72 changes: 72 additions & 0 deletions src-tauri/src/pdf_engine/source_content_integ.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,8 @@ const FROZEN_REASONS: &[&str] = &[
"MISSING_FONT",
"SUBSET_FONT",
"CUSTOM_ENCODING",
"TEXT_RISE",
"TEXT_RENDER_MODE",
"NO_TOUNICODE",
"AMBIGUOUS_UNICODE",
"TYPE3",
Expand Down Expand Up @@ -853,6 +855,76 @@ fn classify_named_standard_encoding_remains_supported() {
);
}

#[test]
fn classify_text_rise_moves_bounds_and_resets_to_supported() {
let scratch = Scratch::new("review-text-rise");
let path = scratch.file("text-rise.pdf");
write_helvetica_page(
&path,
b"BT /F1 12 Tf 72 700 Td 20 Ts (Hi) Tj 0 Ts (Lo) Tj ET",
);
let hits = classify(&path, "REVIEW-TEXT-RISE");
let texts: Vec<&SourceOccurrence> = hits.iter().filter(|hit| kind_token(hit) == "text").collect();
assert_eq!(texts.len(), 2);
assert_unsupported(texts[0], "text", "TEXT_RISE", "REVIEW-TEXT-RISE");
assert!((texts[0].rect.y - 720.0).abs() <= 1.0);
assert_supported_text_or_image(texts[1], "text", "REVIEW-TEXT-RISE-RESET");
assert!((texts[1].rect.y - 700.0).abs() <= 1.0);
}

#[test]
fn classify_text_render_mode_applies_clip_only_after_text_object() {
let scratch = Scratch::new("review-text-render-mode");
let path = scratch.file("text-render-mode.pdf");
write_helvetica_page(
&path,
concat!(
"BT /F1 12 Tf 72 700 Td 7 Tr (A) Tj 0 Tr (B) Tj ET ",
"BT /F1 12 Tf 72 650 Td (C) Tj ET"
)
.as_bytes(),
);
let hits = classify(&path, "REVIEW-TEXT-RENDER-MODE");
let texts: Vec<&SourceOccurrence> = hits.iter().filter(|hit| kind_token(hit) == "text").collect();
assert_eq!(texts.len(), 3);
assert_unsupported(
texts[0],
"text",
"TEXT_RENDER_MODE",
"REVIEW-TEXT-RENDER-MODE",
);
assert_supported_text_or_image(texts[1], "text", "REVIEW-TEXT-RENDER-MODE-RESET");
assert_unsupported(
texts[2],
"text",
"CLIPPED",
"REVIEW-TEXT-RENDER-MODE-CLIP",
);
}

#[test]
fn classify_malformed_text_state_operators_fail_closed() {
let scratch = Scratch::new("review-malformed-text-state");
for (name, content) in [
("missing-rise.pdf", &b"BT /F1 12 Tf Ts (Hi) Tj ET"[..]),
(
"invalid-render-mode.pdf",
&b"BT /F1 12 Tf 1.5 Tr (Hi) Tj ET"[..],
),
(
"out-of-range-render-mode.pdf",
&b"BT /F1 12 Tf 8 Tr (Hi) Tj ET"[..],
),
] {
let path = scratch.file(name);
write_helvetica_page(&path, content);
assert_eq!(
classify_source_content(&path).unwrap_err().code,
"MALFORMED_CONTENT"
);
}
}

#[test]
fn classify_repeated_form_occurrences_have_unique_locators() {
let scratch = Scratch::new("review-repeated-form");
Expand Down
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