From 764514a330cb561824aab8ccc3cac84bbd6f1e0d Mon Sep 17 00:00:00 2001
From: Spiros Eliopoulos <seliopou@gmail.com>
Date: Tue, 24 Sep 2019 20:43:25 -0400
Subject: [PATCH 1/2] input-bugfix: add test demonstrating bug

---
 lib_test/test_angstrom.ml | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/lib_test/test_angstrom.ml b/lib_test/test_angstrom.ml
index 8c5668d..d18fd83 100644
--- a/lib_test/test_angstrom.ml
+++ b/lib_test/test_angstrom.ml
@@ -370,6 +370,22 @@ let choice_commit =
       (parse_string p "@@^");
   end ]
 
+let input = 
+  [ "non-zero offset", `Quick, begin fun () ->
+    let parser = take_while (fun _ -> true) in
+    match Angstrom.Unbuffered.parse parser with
+    | Done _ | Fail _ -> assert false
+    | Partial { continue; committed } ->
+      Alcotest.(check int) "committed is zero" 0 committed;
+      let state = continue (Bigstringaf.of_string "abcd" ~off:0 ~len:4) ~off:1 ~len:2 Complete in
+      Alcotest.(check (result string string))
+        "offset and length respected"
+        (Ok "bc")
+        (Angstrom.Unbuffered.state_to_result state);
+  end ]
+;;
+
+
 
 let () =
   Alcotest.run "test suite"
@@ -383,4 +399,5 @@ let () =
     ; "incremental input"     , incremental 
     ; "count_while regression", count_while_regression
     ; "choice and commit"     , choice_commit
+    ; "input"                 , input
   ]

From 63dd1f06623308c5987fea1b34f4935dcd3d6f28 Mon Sep 17 00:00:00 2001
From: Spiros Eliopoulos <seliopou@gmail.com>
Date: Tue, 24 Sep 2019 20:47:32 -0400
Subject: [PATCH 2/2] input-bugfix: account for offset in termination condition

---
 lib/input.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/input.ml b/lib/input.ml
index 3237772..1e3d0fe 100644
--- a/lib/input.ml
+++ b/lib/input.ml
@@ -100,7 +100,7 @@ let count_while t pos ~f =
   let off    = offset_in_buffer t pos in
   let i      = ref off in
   let len    = t.len in
-  while !i < len && f (Bigstringaf.unsafe_get buffer !i) do 
+  while !i < off + len && f (Bigstringaf.unsafe_get buffer !i) do
     incr i
   done;
   !i - off