A bug report against our downstream tree turned out to have its root
cause in plain mainstream code: envlist_unsetenv() does a prefix-match
lookup that drops the wrong entry when one stored name happens to be a
prefix of another. The downstream symptom is specific to our setup and
isn't interesting here -- the underlying lookup mistake is the part
worth fixing, and it is reachable from a normal qemu-user invocation
through the -U command-line option, so the fix belongs upstream.
Patch 1 fixes the lookup: each entry now stores its name length at
insertion time, and a tiny helper compares with explicit length
equality plus memcmp. envlist_setenv()'s self-search was accidentally
safe (it included the '=' byte in its strncmp window and that '='
served as a boundary) but is converted to the same helper so the name
boundary becomes a structural property of the entry rather than a
property of its byte layout. Without that, the two sites can easily
drift apart again.
Patch 2 backfils test coverage for util/envlist -- there was none --
in tests/unit/test-envlist. I verified that the regression case
(envlist_unsetenv("FOO") vs. a stored "FOOBAR=...") fails against the
pre-fix code and passes after the fix.
Signed-off-by: Denis V. Lunev <[email protected]>
Cc: Stefan Hajnoczi <[email protected]>
Cc: Markus Armbruster <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Denis V. Lunev (2):
util/envlist: fix prefix-match in envlist_unsetenv() name lookup
tests/unit: add test-envlist covering setenv/unsetenv name matching
tests/unit/meson.build | 1 +
tests/unit/test-envlist.c | 196 ++++++++++++++++++++++++++++++++++++++
util/envlist.c | 19 +++-
3 files changed, 212 insertions(+), 4 deletions(-)
create mode 100644 tests/unit/test-envlist.c
--
2.51.0
