Fix issue found via asan

Don't try to use more bytes then there are in the string.

2 files changed, 15 insertions, 2 deletions

diff --git a/Foundation/GTMRegex.m b/Foundation/GTMRegex.m
index 38077be..3d6f96f 100644
--- a/Foundation/GTMRegex.m
+++ b/Foundation/GTMRegex.m
@@ -652,11 +652,15 @@ static NSString *const kReplacementPattern =
 }
 
 - (NSString *)description {
-  return [NSString stringWithFormat:@"%@<%p> { regex=\"%@\", allSegments=%s, string=\"%.20s...\" }",
+  // `[utf8StrBuf_ bytes]` won't be null terminated, must manually ensure we
+  // don't ask for more bytes then there are.
+  NSUInteger len = (int)[utf8StrBuf_ length];
+  return [NSString stringWithFormat:@"%@<%p> { regex=\"%@\", allSegments=%s, string=\"%.*s%s\" }",
     [self class], self,
     regex_,
     (allSegments_ ? "YES" : "NO"),
-    [utf8StrBuf_ bytes]];
+    (int)(MIN(len, 20)), [utf8StrBuf_ bytes],
+    (len > 20 ? "..." : "")];
 }
 
 @end
diff --git a/Foundation/GTMRegexTest.m b/Foundation/GTMRegexTest.m
index 75f5aad..d43b731 100644
--- a/Foundation/GTMRegexTest.m
+++ b/Foundation/GTMRegexTest.m
@@ -885,6 +885,15 @@
   XCTAssertNotNil(seg);
   XCTAssertGreaterThan([[seg description] length], (NSUInteger)10,
                        @"failed to get a reasonable description for regex string segment");
+
+  // Truncation on the input string (and handling sort lengths)
+  enumerator = [regex segmentEnumeratorForString:@"aaabbbccc"];
+  XCTAssertNotNil(enumerator);
+  XCTAssertTrue([[enumerator description] hasSuffix:@", string=\"aaabbbccc\" }"]);
+  enumerator = [regex segmentEnumeratorForString:@"aaabbbcccdddeeefffggghhh"];
+  XCTAssertNotNil(enumerator);
+  XCTAssertTrue([[enumerator description] hasSuffix:@", string=\"aaabbbcccdddeeefffgg...\" }"]);
+
   // regex w/ other options
   regex = [GTMRegex regexWithPattern:@"a+"
                              options:(kGTMRegexOptionIgnoreCase | kGTMRegexOptionSupressNewlineSupport)];