From b9a50eabc4ce7666ebb2038dd21601998fe5cc55 Mon Sep 17 00:00:00 2001
From: Jack Platten <jack@platten.me>
Date: Thu, 16 Jul 2026 14:50:14 -0700
Subject: [PATCH] fix(vcs): scrub control chars from jj/pwd output (#65)
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## Summary
- jj commit descriptions and bookmark/tag names are freeform text
(unlike git refnames, which forbid control characters), so a crafted
description or bookmark in a repo you merely `cd` into could inject raw
terminal escape sequences (title rewrite, cursor manipulation, clipboard
tricks) since they previously flowed straight through to `echo -ns`.
- Directory names can also legally contain control/ESC bytes on Unix, so
`$PWD` components get the same treatment.
- Both fixes are a single `string replace -ra` pass over the
already-split data (`$raw_lines` in the jj backend, `$split_pwd` in
`_tide_pwd`) — no forks, negligible cost. The jj fix preserves `\t`
since that's the template's field separator; the pwd fix has no such
exception.

## Test plan
- [x] `mise run all` (fmt, lint, install, full littlecheck suite) — all
green
- [x] New regression case in `tests/_tide_item_vcs.test.fish`: a mocked
`jj` emits a description containing a raw ESC byte; asserts the rendered
item shows the text with the byte stripped.
- [x] New regression case in `tests/_tide_item_pwd.test.fish`: a
directory literally named with an embedded ESC byte; asserts `_tide_pwd`
strips it.
- [x] Verified in isolation (outside the test suite) that the regex
actually strips the byte in both cases, confirming the new tests
exercise real behavior.

🤖 Generated with [Claude Code](https://claude.com/claude-code)
---
 functions/_tide_internal_vcs_jj.fish | 6 ++++++
 functions/_tide_pwd.fish             | 4 ++++
 tests/_tide_item_pwd.test.fish       | 4 ++++
 tests/_tide_item_vcs.test.fish       | 9 +++++++++
 4 files changed, 23 insertions(+)

diff --git a/functions/_tide_internal_vcs_jj.fish b/functions/_tide_internal_vcs_jj.fish
index 213e8f5..8ed42b3 100644
--- a/functions/_tide_internal_vcs_jj.fish
+++ b/functions/_tide_internal_vcs_jj.fish
@@ -48,6 +48,12 @@ if(self.contained_in("::trunk() & ~::@"),
         -T $tmpl 2>/dev/null)
     or return 1
 
+    # Descriptions/bookmarks/tags are freeform text (unlike git refnames),
+    # so scrub control/ESC bytes before they ever reach the terminal -- a
+    # crafted commit description could otherwise inject escape sequences.
+    # \t is preserved: it's this template's field separator.
+    set raw_lines (string replace -ra '[\x00-\x08\x0b-\x1f\x7f]' '' -- $raw_lines)
+
     # Colors
     # if bg color is normal, we can use matching jj colors
     if test $tide_jj_bg_color = normal
diff --git a/functions/_tide_pwd.fish b/functions/_tide_pwd.fish
index 0ac2c50..fe7b51f 100644
--- a/functions/_tide_pwd.fish
+++ b/functions/_tide_pwd.fish
@@ -8,6 +8,10 @@ set -l pwd_icon $tide_pwd_icon' '
 
 eval "function _tide_pwd
     if set -l split_pwd (string replace -r '^$HOME' '~' -- \$PWD | string split /)
+        # Directory names may legally contain control/ESC bytes; scrub them
+        # before they reach the terminal (no \t exception here -- unlike the
+        # jj item, nothing downstream splits on tabs).
+        set split_pwd (string replace -ra '[\\x00-\\x1f\\x7f]' '' -- \$split_pwd)
         test -w . && set -f split_output \"$pwd_icon\$split_pwd[1]\" \$split_pwd[2..] ||
             set -f split_output \"$unwritable_icon\$split_pwd[1]\" \$split_pwd[2..]
         set split_output[-1] \"$color_anchors\$split_output[-1]$reset_to_color_dirs\"
diff --git a/tests/_tide_item_pwd.test.fish b/tests/_tide_item_pwd.test.fish
index cff454b..b49cbc2 100644
--- a/tests/_tide_item_pwd.test.fish
+++ b/tests/_tide_item_pwd.test.fish
@@ -141,5 +141,9 @@ _pwd $tmpdir/tmp/noread/$longDir # CHECK: ~/t/n/a/b/c/d/e/f/golf/hotel/india/jul
 chmod 700 $tmpdir/tmp/noread
 command rm -r $tmpdir/tmp/noread
 
+# ---------- Control/ESC bytes in a directory name are scrubbed ----------
+mkdir -p (printf '%s/tmp/evil\033dir/foo' $tmpdir)
+_pwd (printf '%s/tmp/evil\033dir/foo' $tmpdir) # CHECK: ~/tmp/evildir/foo
+
 # ------------------------------------Cleanup------------------------------------
 command rm -r $tmpdir
diff --git a/tests/_tide_item_vcs.test.fish b/tests/_tide_item_vcs.test.fish
index 04e176d..8c20bc1 100644
--- a/tests/_tide_item_vcs.test.fish
+++ b/tests/_tide_item_vcs.test.fish
@@ -119,5 +119,14 @@ _vcs_item # CHECK: (@ abc123 main def456 * ↑1)
 touch .disable-jj-prompt
 _vcs_item # CHECK:
 
+# -------- jj description control-char scrubbing --------
+# Regression test: a crafted commit description could otherwise inject a raw
+# ESC byte straight into the terminal (see _tide_internal_vcs_jj.fish).
+mkdir -p $dir/jj-scrub-repo/.jj
+printf '#!/bin/sh\ncmd="$*"\ncase "$cmd" in\n  *"workspace list"*) printf "default\\n" ;;\n  *"log"*) printf "abc123\\t.\\tbookmark/main\\tdefault\\tdef456\\t*\\tfalse\\tevil\\033[31mdesc\\n" ;;\n  *) exit 0 ;;\nesac\n' >$dir/bin/jj
+cd $dir/jj-scrub-repo
+set -e tide_jj_show_description
+_vcs_item # CHECK: (@ abc123 main def456 * evil[31mdesc ↑1)
+
 # ------ cleanup ------
 command rm -r $dir
-- 
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