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Merged
snshn merged 1 commit into from
Oct 16, 2026
Merged

Avoid copying data when creating data URLs #539

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6 changes: 3 additions & 3 deletions src/core.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -228,9 +228,9 @@ pub fn create_monolithic_document_from_data(

match session.retrieve_asset(/*&target_url, */ &base_url, &favicon_ico_url) {
Ok((data, final_url, media_type, charset)) => {
let favicon_data_url: Url =
create_data_url(&media_type, &charset, &data, &final_url);
dom = add_favicon(&dom.document, favicon_data_url.to_string());
let favicon_data_url: String =
create_data_url(&media_type, &charset, data, &final_url, None);
dom = add_favicon(&dom.document, favicon_data_url);
}
Err(_) => {
// Failed to retrieve /favicon.ico
Expand Down
43 changes: 24 additions & 19 deletions src/css.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -272,21 +272,19 @@ pub fn process_css<'a>(
import_media_type,
import_charset,
)) => {
let mut import_data_url = create_data_url(
let import_data_url = create_data_url(
&import_media_type,
"utf-8",
embed_stylesheet(
session,
&import_final_url,
&import_contents,
&import_charset,
)
.as_bytes(),
),
&import_final_url,
import_full_url.fragment(),
);
import_data_url.set_fragment(import_full_url.fragment());
result
.push_str(format_quoted_string(import_data_url.as_ref()).as_str());
result.push_str(format_quoted_string(&import_data_url).as_str());
}
Err(_) => {
// Keep remote reference if unable to retrieve the asset
Expand Down Expand Up @@ -314,11 +312,14 @@ pub fn process_css<'a>(
match session.retrieve_asset(document_url, &resolved_url) {
Ok((data, final_url, media_type, charset)) => {
// TODO: if it's @font-face, exclude definitions of non-woff/woff-2 fonts (if woff/woff-2 are present)
let mut data_url =
create_data_url(&media_type, &charset, &data, &final_url);
data_url.set_fragment(resolved_url.fragment());
result
.push_str(format_quoted_string(data_url.as_ref()).as_str());
let data_url = create_data_url(
&media_type,
&charset,
data,
&final_url,
resolved_url.fragment(),
);
result.push_str(format_quoted_string(&data_url).as_str());
}
Err(_) => {
// Keep remote reference if unable to retrieve the asset
Expand Down Expand Up @@ -404,14 +405,14 @@ pub fn process_css<'a>(
let full_url: Url = resolve_url(document_url, value);
match session.retrieve_asset(document_url, &full_url) {
Ok((css, final_url, media_type, charset)) => {
let mut data_url = create_data_url(
let data_url = create_data_url(
&media_type,
"utf-8",
embed_stylesheet(session, &final_url, &css, &charset).as_bytes(),
embed_stylesheet(session, &final_url, &css, &charset),
&final_url,
full_url.fragment(),
);
data_url.set_fragment(full_url.fragment());
result.push_str(format_quoted_string(data_url.as_ref()).as_str());
result.push_str(format_quoted_string(&data_url).as_str());
}
Err(_) => {
// Keep remote reference if unable to retrieve the asset
Expand All @@ -428,10 +429,14 @@ pub fn process_css<'a>(
if session.options.output_format == MonolithOutputFormat::HTML {
match session.retrieve_asset(document_url, &full_url) {
Ok((data, final_url, media_type, charset)) => {
let mut data_url =
create_data_url(&media_type, &charset, &data, &final_url);
data_url.set_fragment(full_url.fragment());
result.push_str(format_quoted_string(data_url.as_ref()).as_str());
let data_url = create_data_url(
&media_type,
&charset,
data,
&final_url,
full_url.fragment(),
);
result.push_str(format_quoted_string(&data_url).as_str());
}
Err(_) => {
// Keep remote reference if unable to retrieve the asset
Expand Down
63 changes: 35 additions & 28 deletions src/html.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -159,15 +159,14 @@ pub fn embed_srcset(session: &mut Session, document_url: &Url, srcset: &str) ->
match session.retrieve_asset(document_url, &image_full_url) {
Ok((image_data, image_final_url, image_media_type, image_charset)) => {
if session.options.output_format == MonolithOutputFormat::HTML {
let mut image_data_url = create_data_url(
// Append retrieved asset as a data URL
result.push_str(&create_data_url(
&image_media_type,
&image_charset,
&image_data,
image_data,
&image_final_url,
);
// Append retrieved asset as a data URL
image_data_url.set_fragment(image_full_url.fragment());
result.push_str(image_data_url.as_ref());
image_full_url.fragment(),
));
} else {
// MHTML
result.push_str(image_full_url.as_ref());
Expand Down Expand Up @@ -808,9 +807,8 @@ pub fn retrieve_and_embed_asset(
let css: String = embed_stylesheet(session, &final_url, &data, &charset);

// Create and embed data URL (decoded stylesheets are always stored as UTF-8)
let css_data_url =
create_data_url(&media_type, "utf-8", css.as_bytes(), &final_url);
set_node_attr(node, attr_name, Some(css_data_url.to_string()));
let css_data_url = create_data_url(&media_type, "utf-8", css, &final_url, None);
set_node_attr(node, attr_name, Some(css_data_url));
} else if node_name == "frame" || node_name == "iframe" {
// (I)FRAMEs are also quite different from conventional resources
let mut frame_dom = html_to_dom(&data, charset.clone());
Expand Down Expand Up @@ -841,10 +839,14 @@ pub fn retrieve_and_embed_asset(
serialize(&mut frame_data, &serializable, SerializeOpts::default()).unwrap();

// Create and embed data URL (serialized frames are always UTF-8)
let mut frame_data_url =
create_data_url(&media_type, "utf-8", &frame_data, &final_url);
frame_data_url.set_fragment(resolved_url.fragment());
set_node_attr(node, attr_name, Some(frame_data_url.to_string()));
let frame_data_url = create_data_url(
&media_type,
"utf-8",
frame_data,
&final_url,
resolved_url.fragment(),
);
set_node_attr(node, attr_name, Some(frame_data_url));
} else {
// Every other type of element gets processed here

Expand Down Expand Up @@ -894,17 +896,25 @@ pub fn retrieve_and_embed_asset(
}
} else {
// Create and embed data URL
let mut data_url =
create_data_url(&script_media_type, &charset, &data, &final_url);
data_url.set_fragment(resolved_url.fragment());
set_node_attr(node, attr_name, Some(data_url.to_string()));
let data_url = create_data_url(
&script_media_type,
&charset,
data,
&final_url,
resolved_url.fragment(),
);
set_node_attr(node, attr_name, Some(data_url));
}
} else {
// Create and embed data URL
let mut data_url =
create_data_url(&media_type, &charset, &data, &final_url);
data_url.set_fragment(resolved_url.fragment());
set_node_attr(node, attr_name, Some(data_url.to_string()));
let data_url = create_data_url(
&media_type,
&charset,
data,
&final_url,
resolved_url.fragment(),
);
set_node_attr(node, attr_name, Some(data_url));
}
}
}
Expand Down Expand Up @@ -1230,17 +1240,14 @@ pub fn walk(session: &mut Session, document_url: &Url, node: &Handle) {
}
} else {
// It's likely a raster image; embed it as data URL
let image_asset_data: Url = create_data_url(
let image_asset_data: String = create_data_url(
&media_type,
&charset,
&data,
data,
&final_url,
None,
);
set_node_attr(
node,
attr_name,
Some(image_asset_data.to_string()),
);
set_node_attr(node, attr_name, Some(image_asset_data));
}
}
Err(_) => {
Expand Down
22 changes: 19 additions & 3 deletions src/url.rs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
use std::fmt::Write;

use dataurl::{DataEncoding, DataUrl};
pub use url::Url;

Expand All @@ -15,17 +17,28 @@ pub fn clean_url(url: Url) -> Url {
url
}

pub fn create_data_url(media_type: &str, charset: &str, data: &[u8], final_asset_url: &Url) -> Url {
/// Creates a data URL for an asset, with an optional fragment (already percent-encoded, as Url::fragment() returns it).
/// Passing data as a Vec<u8> moves it in without copying.
pub fn create_data_url(
media_type: &str,
charset: &str,
data: impl Into<Vec<u8>>,
final_asset_url: &Url,
fragment: Option<&str>,
) -> String {
let data: Vec<u8> = data.into();

// TODO: move this block out of this function
let media_type: String = if media_type.is_empty() {
detect_media_type(data, final_asset_url)
detect_media_type(&data, final_asset_url)
} else {
media_type.to_string()
};

let mut data_url = DataUrl::new();
data_url.set_data_encoding(DataEncoding::Base64);
data_url.set_data(data);
data_url.set_fragment(fragment);

// Invalid media types get omitted, which makes browsers treat the data as text/plain, same as they would anyway
if !media_type.is_empty() {
Expand All @@ -39,7 +52,10 @@ pub fn create_data_url(media_type: &str, charset: &str, data: &[u8], final_asset
let _ = data_url.set_parameter("charset", Some(charset));
}

Url::parse(&data_url.to_string()).unwrap()
// Allocating the exact size upfront avoids reallocations (and copies) while the string grows
let mut result = String::with_capacity(data_url.encoded_len());
write!(result, "{data_url}").unwrap();
result
}

pub fn domain_is_within_domain(domain: &str, domain_to_match_against: &str) -> bool {
Expand Down
14 changes: 11 additions & 3 deletions tests/css/embed_css.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@ mod passing {
("", "p::before{content:'café'}".as_bytes()),
("", b"p::before{content:'caf\xe9'}".as_slice()),
] {
let asset = monolith::url::create_data_url("text/css", charset, bytes, &url);
let asset = monolith::url::create_data_url("text/css", charset, bytes, &url, None);

for source in [
format!("@import \"{}\";", asset),
Expand Down Expand Up @@ -68,6 +68,7 @@ mod passing {
"",
b"@charset \"windows-1252\";p::before{content:'caf\xe9'}",
&url,
None,
);
let mut session = Session::new(None, None, MonolithOptions::default());
let result = embed_css(&mut session, &url, &format!("@import \"{}\";", asset));
Expand All @@ -89,6 +90,7 @@ mod passing {
"",
b"p{font-family:'\x83\x81\x83\x43\x83\x8a\x83\x49'}",
&url,
None,
);
let mut session = Session::new(None, None, MonolithOptions::default());
session.environment_encoding = Some(encoding_rs::SHIFT_JIS);
Expand All @@ -109,13 +111,19 @@ mod passing {
fn nested_import_inherits_importing_stylesheet_encoding() {
let url = Url::parse("https://example.com/").unwrap();
// EUC-JP "両", which also happens to be valid UTF-8 ("ξ")
let inner =
monolith::url::create_data_url("text/css", "", b"p::before{content:'\xce\xbe'}", &url);
let inner = monolith::url::create_data_url(
"text/css",
"",
b"p::before{content:'\xce\xbe'}",
&url,
None,
);
let outer = monolith::url::create_data_url(
"text/css",
"",
format!("@charset \"EUC-JP\";@import \"{}\";", inner).as_bytes(),
&url,
None,
);
let mut session = Session::new(None, None, MonolithOptions::default());
session.environment_encoding = Some(encoding_rs::SHIFT_JIS);
Expand Down
8 changes: 4 additions & 4 deletions tests/html/walk.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ mod passing {
"@charset \"UTF-8\";p::before{content:\"café\"}",
),
] {
let asset = monolith::url::create_data_url("text/css", charset, bytes, &url);
let asset = monolith::url::create_data_url("text/css", charset, bytes, &url, None);
let source = format!("<link rel=\"stylesheet\" href=\"{}\">", asset);
let dom = html::html_to_dom(&source.into_bytes(), "utf-8".to_string());
let mut session = Session::new(None, None, MonolithOptions::default());
Expand Down Expand Up @@ -80,7 +80,7 @@ mod passing {
#[test]
fn linked_stylesheet_environment_encoding() {
let url = Url::parse("https://example.com/").unwrap();
let asset = monolith::url::create_data_url("text/css", "", SHIFT_JIS_CSS, &url);
let asset = monolith::url::create_data_url("text/css", "", SHIFT_JIS_CSS, &url, None);
let source = format!("<link rel=\"stylesheet\" href=\"{}\">", asset);
let dom = html::html_to_dom(&source.into_bytes(), "utf-8".to_string());
let mut session = Session::new(None, None, MonolithOptions::default());
Expand All @@ -102,14 +102,14 @@ mod passing {
#[test]
fn frame_encoding() {
let url = Url::parse("https://example.com/").unwrap();
let css = monolith::url::create_data_url("text/css", "", SHIFT_JIS_CSS, &url);
let css = monolith::url::create_data_url("text/css", "", SHIFT_JIS_CSS, &url, None);
let mut frame_html: Vec<u8> = format!(
"<html><head><meta charset=\"Shift_JIS\"><link rel=\"stylesheet\" href=\"{}\"></head><body>",
css
)
.into_bytes();
frame_html.extend_from_slice(b"\x83\x81\x83\x43\x83\x8a\x83\x49</body></html>");
let frame = monolith::url::create_data_url("text/html", "", &frame_html, &url);
let frame = monolith::url::create_data_url("text/html", "", frame_html, &url, None);
let source = format!("<iframe src=\"{}\"></iframe>", frame);
let dom = html::html_to_dom(&source.into_bytes(), "utf-8".to_string());
let mut session = Session::new(None, None, MonolithOptions::default());
Expand Down
8 changes: 4 additions & 4 deletions tests/session/retrieve_asset.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,8 +32,8 @@ mod passing {
assert_eq!(&media_type, "text/html");
assert_eq!(&charset, "");
assert_eq!(
url::create_data_url(&media_type, &charset, &data, &final_url),
Url::parse("data:text/html;base64,dGFyZ2V0").unwrap(),
url::create_data_url(&media_type, &charset, data, &final_url, None),
"data:text/html;base64,dGFyZ2V0",
);
assert_eq!(
final_url,
Expand Down Expand Up @@ -72,8 +72,8 @@ mod passing {
assert_eq!(&charset, "");
let data_url = "data:text/javascript;base64,ZG9jdW1lbnQuYm9keS5zdHlsZS5iYWNrZ3JvdW5kQ29sb3IgPSAiZ3JlZW4iOwpkb2N1bWVudC5ib2R5LnN0eWxlLmNvbG9yID0gInJlZCI7Cg==";
assert_eq!(
url::create_data_url(&media_type, &charset, &data, &final_url),
Url::parse(data_url).unwrap()
url::create_data_url(&media_type, &charset, data, &final_url, None),
data_url
);
assert_eq!(
final_url,
Expand Down
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