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Correctly lock around umask

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umask can only be set, never just queried. Thus we need to lock around
calls to it.

Also guess the value; if we guess right we don't need to reset it.
This commit is contained in:
ridiculousfish 2019-04-14 16:08:29 -07:00
parent 020d4a2848
commit 2fac0f0b39
1 changed files with 8 additions and 3 deletions
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11
src/env.cpp
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@ -112,9 +112,14 @@ static maybe_t<env_var_t> get_electric(const wcstring &key, const environment_t
return env_var_t(L"status", to_string(proc_get_last_status()));
} else if (key == L"umask") {
// note umask() is an absurd API: you call it to set the value and it returns the old value.
// Thus we have to call it twice, to reset the value. TODO: lock!
mode_t res = umask(0);
umask(res);
// Thus we have to call it twice, to reset the value.
// We need to lock since otherwise this races.
// Guess what the umask is; if we guess right we don't need to reset it.
static std::mutex umask_lock;
scoped_lock locker(umask_lock);
int guess = 022;
mode_t res = umask(guess);
if (res != guess) umask(res);
return env_var_t(L"umask", format_string(L"0%0.3o", res));
}
// We should never get here unless the electric var list is out of sync with the above code.