From 53426c0a3e190a3329a28f5cd645389992d5bfea Mon Sep 17 00:00:00 2001
From: Phil Hagelberg <phil@hagelb.org>
Date: Sun, 19 Oct 2025 13:28:44 -0700
Subject: [PATCH] Don't loop endlessly on EOF in server mode.

---
 src/fennel-ls/json-rpc.fnl | 19 +++++++++----------
 test/cli.fnl               |  2 +-
 test/json-rpc.fnl          |  2 +-
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/src/fennel-ls/json-rpc.fnl b/src/fennel-ls/json-rpc.fnl
index 086c1b7..5bd7cfc 100644
--- a/src/fennel-ls/json-rpc.fnl
+++ b/src/fennel-ls/json-rpc.fnl
@@ -19,16 +19,15 @@ on the empty table to tell dkjson to serialize as {}."
 
 (λ read-header [in ?header]
   "Reads the header of a JSON-RPC message"
-  (let [header (or ?header {})]
-    (case (in:read)
-      nil nil ;; I've hit end of stream, return nil instead of a header
-      line (case (line:match "^(.-)\r?$") ;; strip trailing \r
-             "" header ;; base case. empty line marks end of header
-             line (let [(k v) (line:match "^(.-): (.-)$")]
-                    (if (not (and k v))
-                      (error (.. "fennel-ls encountered a malformed json-rpc header: \"" line "\"")))
-                    (tset header k v)
-                    (read-header in header))))))
+  (let [header (or ?header {})
+        line (assert (in:read) "EOF")]
+    (case (line:match "^(.-)\r?$") ;; strip trailing \r
+      "" header ;; base case. empty line marks end of header
+      line (let [(k v) (line:match "^(.-): (.-)$")]
+             (if (not (and k v))
+                 (error (.. "fennel-ls encountered a malformed json-rpc header: \"" line "\"")))
+             (tset header k v)
+             (read-header in header)))))
 
 (λ read-n [in len ?buffer]
   "read a string of exactly `len` characters from the `in` stream.
diff --git a/test/cli.fnl b/test/cli.fnl
index b70911d..f60ee80 100644
--- a/test/cli.fnl
+++ b/test/cli.fnl
@@ -26,7 +26,7 @@
   (with-temp-form [f [(let [(a b) (values 1 (+ 2))] (+ a b))
                       [(do (print "done doing all the fun things we did!"))]]
                    out "./fennel-ls --fix --yes"]
-    (faith.= "[(let [[a b] [(values 1 2)]] (+ a b))
+    (faith.= "[(let [(a b) (values 1 2)] (+ a b))
  [(print \"done doing all the fun things we did!\")]]"
              (with-open [file (assert (io.open f))]
                (file:read :*a)) out)))
diff --git a/test/json-rpc.fnl b/test/json-rpc.fnl
index a9fa596..cc26c5f 100644
--- a/test/json-rpc.fnl
+++ b/test/json-rpc.fnl
@@ -9,7 +9,7 @@
   (let [out (stringio.open "Content-Length: 29\r\n\r\n{\"my json content\":\"is cool\"}Content-Length: 29\r\n\r\n{\"my json content\":\"is neat\"}")]
     (faith.= {"my json content" "is cool"} (json-rpc.read out))
     (faith.= {"my json content" "is neat"} (json-rpc.read out))
-    (faith.= nil (json-rpc.read out)))
+    (faith.error "EOF" #(json-rpc.read out)))
 
   (let [out (stringio.open "Content-Length: 9\r\n\r\n{{{{{}}}}")]
     (faith.= :string (type (json-rpc.read out)) "json-rpc returns a table on successful read, and a string on unsuccessful read. It's jank and should probably be replaced with an ok, err system")))