From aa8b89fe84ac7693cfb488b739ef086a37ca9e68 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Madeleine=20Sydney=20=C5=9Alaga?= <msyds@deertopia.net>
Date: Tue, 24 Feb 2026 09:43:47 -0700
Subject: [PATCH]

---
 doerg/src/net/deertopia/doerg/common.clj | 65 ++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 3 deletions(-)

diff --git a/doerg/src/net/deertopia/doerg/common.clj b/doerg/src/net/deertopia/doerg/common.clj
index 9a73d5c..ed5ed93 100644
--- a/doerg/src/net/deertopia/doerg/common.clj
+++ b/doerg/src/net/deertopia/doerg/common.clj
@@ -5,7 +5,7 @@
             [clojure.java.io :as io])
   (:import (java.io FilterInputStream StringWriter InputStream
                     OutputStream PrintStream ByteArrayOutputStream
-                    ByteArrayInputStream)
+                    ByteArrayInputStream FilterOutputStream)
            (java.nio.charset StandardCharsets)))
 
 (defn deref-with-timeout [process ms]
@@ -23,7 +23,10 @@
                        :timed-out-after-milliseconds ms}))
       @p)))
 
-(defn tee-input-stream [sink input-stream]
+(defn tee-input-stream
+  "Return a wrapped `InputStream` that writes all bytes read from
+  input-stream to sink, à la the UNIX command tee(1)."
+  [input-stream sink]
   (proxy [FilterInputStream] [input-stream]
     (read
       ([]
@@ -45,16 +48,72 @@
       (try (proxy-super close)
            (finally (.close sink))))))
 
+(defn tee-output-stream
+  "Return a wrapped `OutputStream` that writes all bytes written to
+  output-stream to sink, à la the UNIX command tee(1)."
+  [output-stream sink]
+  (proxy [FilterOutputStream] [output-stream]
+    (write
+      ([bs-or-b]
+       (proxy-super write bs-or-b)
+       (.write sink bs-or-b))
+      ([^bytes bs off len]
+       (proxy-super write bs off len)
+       (.write sink bs off len)))
+    (close []
+      (try (proxy-super close)
+           (finally (.close sink))))))
+
+#_
+(defn hook-input-stream [input-stream hook]
+  (proxy [FilterInputStream] [input-stream]
+    (read
+      ([]
+       (let [c (proxy-super read)]
+         (when (not= c -1)
+           (hook (byte-array [c])))
+         c))
+      ([^bytes bs]
+       (let [n (proxy-super read bs)]
+         (when (not= n -1)
+           (let [bs* (byte-array n 0)]
+             (System/arraycopy bs 0 bs* 0 n)
+             (hook bs*)))
+         n))
+      ([^bytes bs off len]
+       (let [n (proxy-super read bs off len)]
+         (when (not= n -1)
+           (.write sink bs off n))
+         n)))
+    (close []
+      (try (proxy-super close)
+           (finally (.close sink))))))
+
 (comment
   (with-open [sink (ByteArrayOutputStream.)
               out (ByteArrayOutputStream.)
               in (ByteArrayInputStream. (.getBytes "hello worms"))]
-    (io/copy (tee-input-stream sink in) out)
+    (io/copy (tee-input-stream in sink) out)
+    (def the-out out)
+    (def the-sink sink)
+    {:out out
+     :sink sink})
+  (with-open [sink (l/log-stream :info "blah")
+              out (ByteArrayOutputStream.)
+              in (ByteArrayInputStream. (.getBytes "hello worms"))]
+    (io/copy (tee-input-stream in sink) out)
     (def the-out out)
     (def the-sink sink)
     {:out out
      :sink sink}))
 
+(comment
+  (let [out (ByteArrayOutputStream.)]
+    (p/shell {:out (tee-output-stream
+                    out
+                    (l/log-stream :info "blah"))}
+             "echo" "hello" "worms")))
+
 (defn invoke [opts & cmd]
   (l/info (str/join " " (cons "$" cmd)))
   (let [r (apply p/shell