Fixed StringIndexOutOfBoundsException in the lexer

--
MOS_MIGRATED_REVID=138387292

2 files changed, 12 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java b/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
index 71a3fd1b41..0ace1f2bcf 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Lexer.java
@@ -489,6 +489,12 @@ public final class Lexer {
       }
     }
 
+    // If the current position is beyond the end of the file, need to move it backwards
+    // Possible if the file ends with `r"\` (unterminated raw string literal with a backslash)
+    if (pos > buffer.length) {
+      pos = buffer.length;
+    }
+
     error("unterminated string literal at eof", oldPos, pos);
     return new Token(TokenKind.STRING, oldPos, pos,
                      bufferSlice(oldPos + 1, pos));
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/LexerTest.java b/src/test/java/com/google/devtools/build/lib/syntax/LexerTest.java
index db49b4ed2a..311922e429 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/LexerTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/LexerTest.java
@@ -483,4 +483,10 @@ public class LexerTest {
     assertEquals(s.length(), lastErrorLocation.getEndOffset());
     assertEquals("STRING(unterminated) NEWLINE EOF", values(tokens(s)));
   }
+
+  @Test
+  public void testUnterminatedRawStringWithEscapingError() throws Exception {
+    assertEquals("STRING NEWLINE EOF", names(tokens("r'\\")));
+    assertEquals("/some/path.txt:1: unterminated string literal at eof", lastError);
+  }
 }