From 9695d6a990477b7a61472d31741c786fc9b94efb Mon Sep 17 00:00:00 2001
From: Wilson Lin <code@wilsonl.in>
Date: Sat, 4 Jan 2020 17:50:39 +1100
Subject: [PATCH] Fix empty attribute processing

---
 fuzz/src/main.rs       | 4 ++--
 src/unit/attr/value.rs | 8 ++++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fuzz/src/main.rs b/fuzz/src/main.rs
index 67bc6eb..90b2819 100644
--- a/fuzz/src/main.rs
+++ b/fuzz/src/main.rs
@@ -1,9 +1,9 @@
 use afl::fuzz;
-use hyperbuild::{hyperbuild, ErrorType};
+use hyperbuild::hyperbuild;
 
 fn main() {
     fuzz!(|data: &[u8]| {
         let mut mut_data: Vec<u8> = data.iter().map(|x| *x).collect();
-        hyperbuild(&mut mut_data);
+        let _ = hyperbuild(&mut mut_data);
     });
 }
diff --git a/src/unit/attr/value.rs b/src/unit/attr/value.rs
index a300c51..dafb044 100644
--- a/src/unit/attr/value.rs
+++ b/src/unit/attr/value.rs
@@ -236,6 +236,14 @@ pub fn process_attr_value(proc: &mut Processor, should_collapse_and_trim_ws: boo
     };
     // Ending delimiter quote (if any) has already been discarded at this point.
     let minimum_value = proc.written_range(src_start);
+    // If minimum value is empty, return now before trying to read out of range later.
+    // (Reading starts at one character before end of minimum value.)
+    if minimum_value.empty() {
+        return Ok(ProcessedAttrValue {
+            delimiter: DelimiterType::Unquoted,
+            value: None,
+        });
+    };
 
     // Stage 2: optimally minify attribute value using metrics.
     let (optimal_delimiter, optimal_len) = metrics.get_optimal_delimiter_type(minimum_value.len());