From aa6327c3f630c9b7b7ceef8d07f3a57ca03cccf1 Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom@tomsmeding.com>
Date: Tue, 14 Jun 2022 19:12:53 +0200
Subject: Early-catch large show output with -interactive-print

---
 bwrap-files/entry.sh             | 6 ------
 bwrap-files/start.sh             | 6 +++---
 bwrap-files/workdir/Yahb2Defs.hs | 8 ++++++++
 bwrap-files/workdir/entry.sh     | 6 ++++++
 src/Ghci.hs                      | 3 +++
 5 files changed, 20 insertions(+), 9 deletions(-)
 delete mode 100755 bwrap-files/entry.sh
 create mode 100644 bwrap-files/workdir/Yahb2Defs.hs
 create mode 100755 bwrap-files/workdir/entry.sh

diff --git a/bwrap-files/entry.sh b/bwrap-files/entry.sh
deleted file mode 100755
index f9c4ad3..0000000
--- a/bwrap-files/entry.sh
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/bin/bash
-set -euo pipefail
-
-cd "$(dirname "$0")"
-
-ghcup --offline run -- ghci 2>&1
diff --git a/bwrap-files/start.sh b/bwrap-files/start.sh
index 03bf77e..f0d0fa1 100755
--- a/bwrap-files/start.sh
+++ b/bwrap-files/start.sh
@@ -20,6 +20,7 @@ args=(
   --ro-bind "${ghcup_base}/bin"   "${ghcup_base}/bin"
   --ro-bind "${ghcup_base}/ghc"   "${ghcup_base}/ghc"
   --ro-bind "${ghcup_base}/cache" "${ghcup_base}/cache"
+  --ro-bind "${filesdir}/workdir" /workdir
   --setenv PATH "/bin:/usr/bin:${ghcup_base}/bin"
   --setenv GHCUP_INSTALL_BASE_PREFIX "$(dirname ${ghcup_base})"
   --proc /proc
@@ -27,8 +28,7 @@ args=(
   --new-session
   --unshare-all
   --die-with-parent
-  --file 4 "/tmp/entry.sh"
-  /bin/bash "/tmp/entry.sh"
+  /bin/bash "/workdir/entry.sh"
 )
 
 # Turn off core files
@@ -40,4 +40,4 @@ ulimit -u 10000
 # Limit memory to 500 MiB.
 ulimit -d $(( 500 * 1024 ))
 
-exec bwrap "${args[@]}" 4<"${filesdir}/entry.sh"
+exec bwrap "${args[@]}"
diff --git a/bwrap-files/workdir/Yahb2Defs.hs b/bwrap-files/workdir/Yahb2Defs.hs
new file mode 100644
index 0000000..c0dfbfd
--- /dev/null
+++ b/bwrap-files/workdir/Yahb2Defs.hs
@@ -0,0 +1,8 @@
+module Yahb2Defs where
+
+
+limitedPrint :: Show a => a -> IO ()
+limitedPrint x =
+  case splitAt 200 (show x) of
+    (s, "") -> putStrLn s
+    (s, _) -> putStrLn (take 197 s ++ "...")
diff --git a/bwrap-files/workdir/entry.sh b/bwrap-files/workdir/entry.sh
new file mode 100755
index 0000000..1a466da
--- /dev/null
+++ b/bwrap-files/workdir/entry.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+set -euo pipefail
+
+cd "$(dirname "$0")"
+
+ghcup --offline run -- ghci Yahb2Defs.hs 2>&1
diff --git a/src/Ghci.hs b/src/Ghci.hs
index 13eb4ca..649403f 100644
--- a/src/Ghci.hs
+++ b/src/Ghci.hs
@@ -47,6 +47,9 @@ makeGhci = do
       , std_in = CreatePipe
       , std_out = UseHandle pipeIn
       , std_err = UseHandle pipeIn }
+  hPutStrLn stdinH ":set -interactive-print=Yahb2Defs.limitedPrint"
+  hPutStrLn stdinH ":m"
+  hFlush stdinH
   return Ghci { ghciProc = proch
               , ghciStdin = stdinH
               , ghciStdout = pipeOut }
-- 
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