https://github.com/python/cpython/commit/0d540afcec0ead73620edb675ebdc47925ba581f
commit: 0d540afcec0ead73620edb675ebdc47925ba581f
branch: main
author: Bernát Gábor <[email protected]>
committer: FFY00 <[email protected]>
date: 2026-06-22T16:39:08+01:00
summary:
gh-140006: Harden fish prompt against shadowed builtins (#150936)
A user function that shadows the `.`/`source` builtin hijacks the
activate.fish prompt. fish resolves functions ahead of builtins, so the
`echo "exit $status" | .` line that restores the exit status pipes into
the user function instead of sourcing. Dot-style directory navigators
redefine `.`, which made the prompt list the directory on every command
and dropped the exit status handed to the original prompt.
Route every builtin the prompt path uses (`source`, `echo`, `printf`,
`set_color`, `functions`) through `builtin` so no user function can
intercept them. These have all been fish builtins with a stable
interface since fish 2.0.0, the version the script already required
through `functions --copy`, so the minimum supported fish version does
not change.
files:
A Misc/NEWS.d/next/Library/2026-06-04-19-24-13.gh-issue-140006.TD8HKl.rst
M Lib/test/test_venv.py
M Lib/venv/scripts/common/activate.fish
diff --git a/Lib/test/test_venv.py b/Lib/test/test_venv.py
index 8075a1947918be..58ae85fb268042 100644
--- a/Lib/test/test_venv.py
+++ b/Lib/test/test_venv.py
@@ -773,6 +773,46 @@ def test_special_chars_csh(self):
self.assertTrue(env_name.encode() in lines[0])
self.assertEndsWith(lines[1], env_name.encode())
+ # gh-140006: the fish prompt override must keep working when a user
+ # function shadows a builtin it relies on.
+ @unittest.skipIf(os.name == 'nt', 'fish is not available on Windows')
+ def test_fish_activate_shadowed_builtins(self):
+ """
+ The fish prompt override restores the exit status through `source` and
+ prints through `printf`/`echo`/`set_color`. A user function that
+ shadows one of those builtins (a common pattern for `.`-style directory
+ navigators) must not hijack the prompt or break status restoration.
+ """
+ fish = shutil.which('fish')
+ if fish is None:
+ self.skipTest('fish required for this test')
+ rmtree(self.env_dir)
+ builder = venv.EnvBuilder(clear=True)
+ builder.create(self.env_dir)
+ activate = os.path.join(self.env_dir, self.bindir, 'activate.fish')
+ test_script = os.path.join(self.env_dir, 'test_shadowed_builtins.fish')
+ with open(test_script, "w") as f:
+ f.write(
+ # The pre-existing prompt reports the status it receives;
+ # activation copies it to _old_fish_prompt.
+ 'function fish_prompt; builtin echo "OLDSTATUS=$status"; end\n'
+ f'source {shlex.quote(activate)}\n'
+ # Shadow every builtin the override uses. A dot-navigator that
+ # lists the directory is the reported failure.
+ 'function .; builtin echo DOT_LEAK; end\n'
+ 'function source; builtin echo SOURCE_LEAK; end\n'
+ 'function echo; command echo ECHO_LEAK; end\n'
+ 'function printf; command printf PRINTF_LEAK; end\n'
+ 'function set_color; command true; end\n'
+ 'function _exit7; return 7; end\n'
+ '_exit7\n'
+ 'fish_prompt\n'
+ )
+ out, err = check_output([fish, '--no-config', test_script])
+ text = out.decode()
+ self.assertNotIn('LEAK', text)
+ self.assertIn('OLDSTATUS=7', text)
+
# gh-124651: test quoted strings on Windows
@unittest.skipUnless(os.name == 'nt', 'only relevant on Windows')
def test_special_chars_windows(self):
diff --git a/Lib/venv/scripts/common/activate.fish
b/Lib/venv/scripts/common/activate.fish
index e8225f6db5b565..8d364ff88f8b82 100644
--- a/Lib/venv/scripts/common/activate.fish
+++ b/Lib/venv/scripts/common/activate.fish
@@ -15,10 +15,10 @@ function deactivate -d "Exit virtual environment and
return to normal shell env
if test -n "$_OLD_FISH_PROMPT_OVERRIDE"
set -e _OLD_FISH_PROMPT_OVERRIDE
# prevents error when using nested fish instances (Issue #93858)
- if functions -q _old_fish_prompt
- functions -e fish_prompt
- functions -c _old_fish_prompt fish_prompt
- functions -e _old_fish_prompt
+ if builtin functions -q _old_fish_prompt
+ builtin functions -e fish_prompt
+ builtin functions -c _old_fish_prompt fish_prompt
+ builtin functions -e _old_fish_prompt
end
end
@@ -26,7 +26,7 @@ function deactivate -d "Exit virtual environment and return
to normal shell env
set -e VIRTUAL_ENV_PROMPT
if test "$argv[1]" != "nondestructive"
# Self-destruct!
- functions -e deactivate
+ builtin functions -e deactivate
end
end
@@ -52,18 +52,21 @@ if test -z "$VIRTUAL_ENV_DISABLE_PROMPT"
# fish uses a function instead of an env var to generate the prompt.
# Save the current fish_prompt function as the function _old_fish_prompt.
- functions -c fish_prompt _old_fish_prompt
+ builtin functions -c fish_prompt _old_fish_prompt
# With the original prompt function renamed, we can override with our own.
+ # Call every builtin through `builtin` so a user function that shadows
+ # `printf`, `set_color`, `echo`, or `source`/`.` cannot hijack the prompt
+ # (Issue #140006).
function fish_prompt
# Save the return status of the last command.
set -l old_status $status
# Output the venv prompt; color taken from the blue of the Python logo.
- printf "%s(%s)%s " (set_color 4B8BBE) __VENV_PROMPT__ (set_color
normal)
+ builtin printf "%s(%s)%s " (builtin set_color 4B8BBE) __VENV_PROMPT__
(builtin set_color normal)
# Restore the return status of the previous command.
- echo "exit $old_status" | .
+ builtin echo "exit $old_status" | builtin source -
# Output the original/"old" prompt.
_old_fish_prompt
end
diff --git
a/Misc/NEWS.d/next/Library/2026-06-04-19-24-13.gh-issue-140006.TD8HKl.rst
b/Misc/NEWS.d/next/Library/2026-06-04-19-24-13.gh-issue-140006.TD8HKl.rst
new file mode 100644
index 00000000000000..6d8d66b29b1990
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-06-04-19-24-13.gh-issue-140006.TD8HKl.rst
@@ -0,0 +1,4 @@
+The :mod:`venv` ``activate.fish`` script now calls fish builtins through
+``builtin`` so a user function that shadows ``.``/``source``, ``echo``,
+``printf``, ``set_color``, or ``functions`` can no longer hijack the virtual
+environment prompt or break exit-status reporting.
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