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| author | Karl Williamson <khw@cpan.org> | 2020-03-06 14:18:45 -0700 |
|---|---|---|
| committer | Karl Williamson <khw@cpan.org> | 2020-03-11 09:52:12 -0600 |
| commit | 24f3e849b5ce9f3bf6b6be5d3e730562e927aa79 (patch) | |
| tree | 2aeee9a5124aea2f9617971dc2f3421fd8a0e858 /util.c | |
| parent | 2bc5f86adf5f1c0feb76d83e1a627e5649e6beab (diff) | |
| download | perl-24f3e849b5ce9f3bf6b6be5d3e730562e927aa79.tar.gz | |
Add thread safety to some environment accesses
The previous commit added a mutex specifically for protecting against
simultaneous accesses of the environment. This commit changes the
normal getenv, putenv, and clearenv functions to use it, to avoid races.
This makes the code simpler in places where we've gotten burned and
added stuff to avoid races. Other places where we haven't known we were
getting burned could have existed until now. Now that comes
automatically, and we can remove the special cases we earlier stumbled
over.
getenv() returns a pointer to static memory, which can be overwritten at
any moment from another thread, or even another getenv from the same
thread. This commit changes the accesses to be under control of a
mutex, and in the case of getenv, a mortalized copy is created so that
there is no possible race.
Diffstat (limited to 'util.c')
| -rw-r--r-- | util.c | 6 |
1 files changed, 4 insertions, 2 deletions
@@ -2139,7 +2139,8 @@ Perl_my_setenv(pTHX_ const char *nam, const char *val) # endif # ifdef USE_ITHREADS - /* only parent thread can modify process environment */ + /* only parent thread can modify process environment, so no need to use a + * mutex */ if (PL_curinterp == aTHX) # endif { @@ -5169,7 +5170,8 @@ Perl_my_clearenv(pTHX) # else /* ! (PERL_IMPLICIT_SYS || WIN32) */ # if defined(USE_ENVIRON_ARRAY) # if defined(USE_ITHREADS) - /* only the parent thread can clobber the process environment */ + /* only the parent thread can clobber the process environment, so no need + * to use a mutex */ if (PL_curinterp == aTHX) # endif /* USE_ITHREADS */ { |