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gh-106045: Fix venv path discovery for symlinked executables - #156483
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Use the resolved base executable when locating the base installation instead of relying on the home directory in pyvenv.cfg. Add tests covering relocated Python installations and misleading standard-library landmarks near executable symlinks.
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brettcannon
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Aug 27, 2026
| ns.add_known_file("/venv/pyvenv.cfg", [ | ||
| "home = /public/bin", | ||
| ]) | ||
| expected = dict( |
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Why the dict() calls when a dict literal would have worked?
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Good catch! A dictionary literal {...} is cleaner, more pythonic, and slightly faster than calling dict(). I'll update this line to use a literal instead.
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The dict() call matches the pattern established in the existing tests.
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(agree it makes sense to match all the other tests in the file instead)
ambv
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needs backport to 3.14
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GH-160002 is a backport of this pull request to the 3.15 branch. |
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GH-160003 is a backport of this pull request to the 3.14 branch. |
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…H-156483) (#160002) Use the resolved base executable when locating the base installation instead of relying on the home directory in pyvenv.cfg. Add tests covering relocated Python installations and misleading standard-library landmarks near executable symlinks. (cherry picked from commit e07817d) Co-authored-by: Jonathan J. Helmus <jjhelmus@gmail.com>
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itamaro
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… executable has no stdlib pythonGH-156483 searches for a venv's base installation relative to the resolved base executable. When that executable lives outside the installation tree that 'home' in pyvenv.cfg points into (e.g. a launcher binary symlinked into it), nothing is found there and discovery falls back to the compiled-in PREFIX. Only prefer the resolved executable's directory when a standard library landmark is found from there; otherwise keep searching from 'home'. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01A93JzpSGH27i6PNX8re4YV
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…table has no stdlib (#160123) GH-156483 made `getpath` locate a venv's base installation relative to the *resolved* base executable instead of the `home` key in `pyvenv.cfg`. When the resolved executable lives outside the installation tree (e.g. a launcher binary symlinked into it), nothing is found there and discovery falls back to the compiled-in `PREFIX`. The venv then either fails to start or silently runs with another installation's standard library. This PR: - Keeps GH-156483's behavior when the resolved executable's directory locates a standard library (`pybuilddir.txt`, the stdlib zip, or `os.py`). Otherwise it keeps searching from `home`, as before GH-156483. - In that fallback case, still searches the resolved executable's directory for `lib-dynload` when determining `exec_prefix`: after `prefix`, before `home` and the compiled-in `EXEC_PREFIX`. Layouts with a separate exec prefix (e.g. `./configure --exec-prefix`) then keep loading extension modules from the right place, and a stale `lib-dynload` near the `home` symlink can't take precedence over the one beside the resolved executable. The tests added by GH-156483 pass unchanged. Three new `test_getpath` cases cover the launcher-outside-the-installation and separate-exec-prefix layouts, and a misleading `lib-dynload` near `home`; each fails without this change. <details> <summary>Reproducer</summary> On `main` (0a86a34), with a plain `./configure --prefix=$HOME/py-under-test && make && make install`: ```sh #!/bin/sh # Usage: venv-home-repro.sh <installed-prefix> <X.Y> set -eu PREFIX=$1; VER=$2 W=$(mktemp -d) mkdir -p "$W/runtime/bin" "$W/runtime/lib" "$W/launcher" cp -R "$PREFIX/lib/python$VER" "$W/runtime/lib/" cp "$PREFIX/bin/python$VER" "$W/launcher/python3" ln -s "$W/launcher/python3" "$W/runtime/bin/python3" PYTHONHOME="$W/runtime" "$W/runtime/bin/python3" -m venv --without-pip "$W/venv" grep '^home' "$W/venv/pyvenv.cfg" echo "expected base_prefix: $W/runtime" "$W/venv/bin/python" -c 'import os, sys; print("actual base_prefix:", sys.base_prefix); print("os.py loaded from:", os.__file__)' ``` Before: ``` home = /tmp/tmp.NFug9wEr4h/runtime/bin expected base_prefix: /tmp/tmp.NFug9wEr4h/runtime actual base_prefix: /home/user/py-under-test os.py loaded from: /home/user/py-under-test/lib/python3.16/os.py ``` (With `$HOME/py-under-test/lib/python3.16` removed, the venv instead fails with `ModuleNotFoundError: No module named 'encodings'`.) After: ``` home = /tmp/tmp.8Zne2otFrw/runtime/bin expected base_prefix: /tmp/tmp.8Zne2otFrw/runtime actual base_prefix: /tmp/tmp.8Zne2otFrw/runtime os.py loaded from: /tmp/tmp.8Zne2otFrw/runtime/lib/python3.16/os.py ``` </details>
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Use the resolved base executable when locating the base installation instead of relying on the home directory in
pyvenv.cfg.Add tests covering relocated Python installations and misleading standard-library landmarks near executable symlinks.