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Rollup merge of rust-lang#61908 - matklad:overflow, r=petrochenkov
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don't ICE on large files

This is an extremely marginal error, so the cost of properly threading
`Handler` everywhere just not seemed justified. However, it's useful
to panic when we create a file, and not when we slice strings with
overflown indexes somewhere in the guts of the compiler.

For this reason, while we provide safe `try_new_source_file`, we don't
change the existing public interface and just panic more or less
cleanly.

closes rust-lang#61904

r? @petrochenkov
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Centril authored Jun 17, 2019
2 parents 04d6539 + ccb2dfb commit 6fe2653
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Showing 2 changed files with 25 additions and 6 deletions.
19 changes: 16 additions & 3 deletions src/libsyntax/source_map.rs
Original file line number Diff line number Diff line change
Expand Up @@ -191,6 +191,18 @@ impl SourceMap {
/// If a file already exists in the source_map with the same id, that file is returned
/// unmodified
pub fn new_source_file(&self, filename: FileName, src: String) -> Lrc<SourceFile> {
self.try_new_source_file(filename, src)
.unwrap_or_else(|OffsetOverflowError| {
eprintln!("fatal error: rustc does not support files larger than 4GB");
errors::FatalError.raise()
})
}

fn try_new_source_file(
&self,
filename: FileName,
src: String
) -> Result<Lrc<SourceFile>, OffsetOverflowError> {
let start_pos = self.next_start_pos();

// The path is used to determine the directory for loading submodules and
Expand All @@ -212,7 +224,7 @@ impl SourceMap {
was_remapped,
Some(&unmapped_path));

return match self.source_file_by_stable_id(file_id) {
let lrc_sf = match self.source_file_by_stable_id(file_id) {
Some(lrc_sf) => lrc_sf,
None => {
let source_file = Lrc::new(SourceFile::new(
Expand All @@ -221,7 +233,7 @@ impl SourceMap {
unmapped_path,
src,
Pos::from_usize(start_pos),
));
)?);

let mut files = self.files.borrow_mut();

Expand All @@ -230,7 +242,8 @@ impl SourceMap {

source_file
}
}
};
Ok(lrc_sf)
}

/// Allocates a new SourceFile representing a source file from an external
Expand Down
12 changes: 9 additions & 3 deletions src/libsyntax_pos/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -859,6 +859,9 @@ impl ExternalSource {
}
}

#[derive(Debug)]
pub struct OffsetOverflowError;

/// A single source in the `SourceMap`.
#[derive(Clone)]
pub struct SourceFile {
Expand Down Expand Up @@ -1040,7 +1043,7 @@ impl SourceFile {
name_was_remapped: bool,
unmapped_path: FileName,
mut src: String,
start_pos: BytePos) -> SourceFile {
start_pos: BytePos) -> Result<SourceFile, OffsetOverflowError> {
remove_bom(&mut src);

let src_hash = {
Expand All @@ -1054,11 +1057,14 @@ impl SourceFile {
hasher.finish()
};
let end_pos = start_pos.to_usize() + src.len();
if end_pos > u32::max_value() as usize {
return Err(OffsetOverflowError);
}

let (lines, multibyte_chars, non_narrow_chars) =
analyze_source_file::analyze_source_file(&src[..], start_pos);

SourceFile {
Ok(SourceFile {
name,
name_was_remapped,
unmapped_path: Some(unmapped_path),
Expand All @@ -1072,7 +1078,7 @@ impl SourceFile {
multibyte_chars,
non_narrow_chars,
name_hash,
}
})
}

/// Returns the `BytePos` of the beginning of the current line.
Expand Down

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