extmod/re1.5: Check and report byte overflow errors in _compilecode.

The generated regex code is limited in the range of jumps and counts, and
this commit checks all cases which can overflow given the right kind of
input regex, and returns an error in such a case.

This change assumes that the results that overflow an int8_t do not
overflow a platform int.

Closes: #7078

Signed-off-by: Jeff Epler <jepler@gmail.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/tests/extmod/ure_limit.py b/tests/extmod/ure_limit.py
new file mode 100644
index 000000000..99c6a818e
--- /dev/null
+++ b/tests/extmod/ure_limit.py
@@ -0,0 +1,34 @@
+# Test overflow in ure.compile output code.
+
+try:
+    import ure as re
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+def test_re(r):
+    try:
+        re.compile(r)
+    except:
+        print("Error")
+
+
+# too many chars in []
+test_re("[" + "a" * 256 + "]")
+
+# too many groups
+test_re("(a)" * 256)
+
+# jump too big for ?
+test_re("(" + "a" * 62 + ")?")
+
+# jump too big for *
+test_re("(" + "a" * 60 + ".)*")
+test_re("(" + "a" * 60 + "..)*")
+
+# jump too big for +
+test_re("(" + "a" * 62 + ")+")
+
+# jump too big for |
+test_re("b" * 63 + "|a")