From 08a2f39108d879c289d45ffd983451e7fc689407 Mon Sep 17 00:00:00 2001
From: Wilson Lin <code@wilsonl.in>
Date: Thu, 30 Jul 2020 00:28:57 +1000
Subject: [PATCH] Fix debug repr line boundaries check; reduce debug repr
 output by stopping at read position; provide expected and actual tag names
 for closing tag mismatch error

---
 cli/Cargo.toml  |  2 +-
 src/err.rs      | 20 +++++++++++++-------
 src/unit/tag.rs |  5 ++++-
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/cli/Cargo.toml b/cli/Cargo.toml
index 963d58d..56d2c52 100644
--- a/cli/Cargo.toml
+++ b/cli/Cargo.toml
@@ -7,4 +7,4 @@ edition = "2018"
 
 [dependencies]
 minify-html = { path = "..", features = ["js-esbuild"] }
-structopt = "0.3.5"
+structopt = "0.3"
diff --git a/src/err.rs b/src/err.rs
index ef07e8f..0976a81 100644
--- a/src/err.rs
+++ b/src/err.rs
@@ -1,7 +1,7 @@
 // Implement debug to allow .unwrap().
 #[derive(Debug)]
 pub enum ErrorType {
-    ClosingTagMismatch,
+    ClosingTagMismatch { expected: String, got: String },
     NotFound(&'static str),
     UnexpectedEnd,
 }
@@ -9,8 +9,8 @@ pub enum ErrorType {
 impl ErrorType {
     pub fn message(self) -> String {
         match self {
-            ErrorType::ClosingTagMismatch => {
-                format!("Closing tag name does not match opening tag.")
+            ErrorType::ClosingTagMismatch { expected, got } => {
+                format!("Closing tag name does not match opening tag (expected \"{}\", got \"{}\").", expected, got)
             }
             ErrorType::NotFound(exp) => {
                 format!("Expected {}.", exp)
@@ -38,15 +38,18 @@ pub struct FriendlyError {
 pub type ProcessingResult<T> = Result<T, ErrorType>;
 
 #[inline(always)]
-fn maybe_mark_indicator(line: &mut Vec<u8>, marker: u8, maybe_pos: isize, lower: usize, upper: usize) -> () {
+fn maybe_mark_indicator(line: &mut Vec<u8>, marker: u8, maybe_pos: isize, lower: usize, upper: usize) -> bool {
     let pos = maybe_pos as usize;
-    if maybe_pos > -1 && pos < upper {
+    if maybe_pos > -1 && pos >= lower && pos < upper {
         let pos_in_line = pos - lower;
         while line.len() <= pos_in_line {
             line.push(b' ');
         };
         line.insert(pos_in_line, if line[pos_in_line] != b' ' { b'B' } else { marker });
-    };
+        true
+    } else {
+        false
+    }
 }
 
 // Pass -1 for read_pos or write_pos to prevent them from being represented.
@@ -62,12 +65,15 @@ pub fn debug_repr(code: &[u8], read_pos: isize, write_pos: isize) -> String {
 
         // Rust does lazy allocation by default, so this is not wasteful.
         let mut indicator_line = Vec::new();
-        maybe_mark_indicator(&mut indicator_line, b'R', read_pos, cur_pos, new_pos);
         maybe_mark_indicator(&mut indicator_line, b'W', write_pos, cur_pos, new_pos);
+        let marked_read = maybe_mark_indicator(&mut indicator_line, b'R', read_pos, cur_pos, new_pos);
         if !indicator_line.is_empty() {
             lines.push((-1, unsafe { String::from_utf8_unchecked(indicator_line) }));
         };
         cur_pos = new_pos;
+        if marked_read {
+            break;
+        };
     };
 
     let line_no_col_width = lines.len().to_string().len();
diff --git a/src/unit/tag.rs b/src/unit/tag.rs
index 730b63c..c3e83eb 100644
--- a/src/unit/tag.rs
+++ b/src/unit/tag.rs
@@ -221,7 +221,10 @@ pub fn process_tag(proc: &mut Processor, cfg: &Cfg, ns: Namespace, mut prev_sibl
     let closing_tag = proc.m(WhileInLookup(TAG_NAME_CHAR), Discard).require("closing tag name")?;
     // We need to check closing tag matches as otherwise when we later write closing tag, it might be longer than source closing tag and cause source to be overwritten.
     if !proc[closing_tag].eq(&proc[tag_name]) {
-        return Err(ErrorType::ClosingTagMismatch);
+        return Err(ErrorType::ClosingTagMismatch {
+            expected: unsafe { String::from_utf8_unchecked(proc[tag_name].to_vec()) },
+            got: unsafe { String::from_utf8_unchecked(proc[closing_tag].to_vec()) },
+        });
     };
     proc.m(WhileInLookup(WHITESPACE), Discard);
     proc.m(IsChar(b'>'), Discard).require("closing tag end")?;