From ab670b4e9f9cc7628f27eede802eeb32495ea933 Mon Sep 17 00:00:00 2001
From: Jihyun Yu <yjh0502@gmail.com>
Date: Sat, 29 Sep 2018 15:39:58 +0900
Subject: [PATCH] fix bug on error position

---
 src/read.rs   |  9 ++++++---
 tests/test.rs | 28 ++++++++++++++++++++++++----
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/src/read.rs b/src/read.rs
index f9fea9d..2e5b4a8 100644
--- a/src/read.rs
+++ b/src/read.rs
@@ -455,10 +455,10 @@ impl<'a> SliceRead<'a> {
                     start = self.index;
                 }
                 _ => {
+                    self.index += 1;
                     if validate {
                         return error(self, ErrorCode::ControlCharacterWhileParsingString);
                     }
-                    self.index += 1;
                 }
             }
         }
@@ -548,17 +548,20 @@ impl<'a> Read<'a> for SliceRead<'a> {
 
     fn decode_hex_escape(&mut self) -> Result<u16> {
         if self.index + 4 > self.slice.len() {
+            self.index = self.slice.len();
             return error(self, ErrorCode::EofWhileParsingString);
         }
+
         let mut n = 0;
         for _ in 0..4 {
-            match decode_hex_val(self.slice[self.index]) {
+            let ch = decode_hex_val(self.slice[self.index]);
+            self.index += 1;
+            match ch {
                 None => return error(self, ErrorCode::InvalidEscape),
                 Some(val) => {
                     n = (n << 4) + val;
                 }
             }
-            self.index += 1;
         }
         Ok(n)
     }
diff --git a/tests/test.rs b/tests/test.rs
index ec2de42..954ac90 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -995,11 +995,11 @@ fn test_parse_string() {
         ),
         (
             "\"\n\"",
-            "control character (\\u0000-\\u001F) found while parsing a string at line 1 column 1",
+            "control character (\\u0000-\\u001F) found while parsing a string at line 2 column 0",
         ),
         (
             "\"\x1F\"",
-            "control character (\\u0000-\\u001F) found while parsing a string at line 1 column 1",
+            "control character (\\u0000-\\u001F) found while parsing a string at line 1 column 2",
         ),
     ]);
 
@@ -1012,13 +1012,33 @@ fn test_parse_string() {
             &[b'"', b'\\', b'n', 159, 146, 150, b'"'],
             "invalid unicode code point at line 1 column 7",
         ),
+        (
+            &[b'"', b'\\', b'u', 48, 48, 51],
+            "EOF while parsing a string at line 1 column 6",
+        ),
+        (
+            &[b'"', b'\\', b'u', 250, 48, 51, 48, b'"'],
+            "invalid escape at line 1 column 4",
+        ),
+        (
+            &[b'"', b'\\', b'u', 48, 250, 51, 48, b'"'],
+            "invalid escape at line 1 column 5",
+        ),
+        (
+            &[b'"', b'\\', b'u', 48, 48, 250, 48, b'"'],
+            "invalid escape at line 1 column 6",
+        ),
+        (
+            &[b'"', b'\\', b'u', 48, 48, 51, 250, b'"'],
+            "invalid escape at line 1 column 7",
+        ),
         (
             &[b'"', b'\n', b'"'],
-            "control character (\\u0000-\\u001F) found while parsing a string at line 1 column 1",
+            "control character (\\u0000-\\u001F) found while parsing a string at line 2 column 0",
         ),
         (
             &[b'"', b'\x1F', b'"'],
-            "control character (\\u0000-\\u001F) found while parsing a string at line 1 column 1",
+            "control character (\\u0000-\\u001F) found while parsing a string at line 1 column 2",
         ),
     ]);