Merge pull request #168 from jow-/fix-binary-string-compare

types: improve comparison reliability of binary strings

2 files changed, 38 insertions, 1 deletions

diff --git a/tests/custom/99_bugs/42_types_binary_string_comparison b/tests/custom/99_bugs/42_types_binary_string_comparison
new file mode 100644
index 0000000..bc566c6
--- /dev/null
+++ b/tests/custom/99_bugs/42_types_binary_string_comparison
@@ -0,0 +1,28 @@
+When comparing strings with embedded null bytes, ensure that the comparison
+takes the entire string length into account.
+
+-- Testcase --
+printf("%.J\n", [
+	"" == "\u0000",
+	"" < "\u0000",
+	"" > "\u0000",
+	"foo\u0000bar" == "foo\u0000baz",
+	"foo\u0000bar" < "foo\u0000baz",
+	"foo\u0000bar" > "foo\u0000baz",
+]);
+-- End --
+
+-- Args --
+-R
+-- End --
+
+-- Expect stdout --
+[
+	false,
+	true,
+	false,
+	false,
+	true,
+	false
+]
+-- End --
diff --git a/types.c b/types.c
index 226c874..c9472f7 100644
--- a/types.c
+++ b/types.c
@@ -2006,7 +2006,16 @@ ucv_compare(int how, uc_value_t *v1, uc_value_t *v2, int *deltap)
 
 	/* ... otherwise if both operands are strings, compare bytewise ... */
 	else if (t1 == UC_STRING && t2 == UC_STRING) {
-		delta = strcmp(ucv_string_get(v1), ucv_string_get(v2));
+		u1 = ucv_string_length(v1);
+		u2 = ucv_string_length(v2);
+
+		delta = memcmp(ucv_string_get(v1), ucv_string_get(v2),
+			(u1 < u2) ? u1 : u2);
+
+		if (delta == 0 && u1 < u2)
+			delta = -1;
+		else if (delta == 0 && u1 > u2)
+			delta = 1;
 	}
 
 	/* handle non-string cases... */