setenv can call malloc and is not safe to call here. Glibc is usually
tolerant of this and we haven't had problems before, but if you use
GLIBC_TUNABLES glibc.malloc.check=1 (or any alternate malloc / libc
which serializes) then you would see hangs if starting multiple
libguestfs handles from different threads at the same time.
This commit also updates the common submodule to pick up:
commit 3c64bcdeaf684f05f46f3928b55aadafdfe72720
Author: Richard W.M. Jones <rjones@redhat.com>
Date: Fri Oct 14 11:07:21 2022 +0100
utils: Add function for copying the environment and adding new entries
libguestfs is currently calling setenv at an unsafe location between
fork and exec. To fix this we need a way to copy and modify the
environment before fork and then we can pass the modified environ to
execve-like functions. nbdkit already does the same so use that code.
This function is copied and adapted from here under a compatible license:
https://gitlab.com/nbdkit/nbdkit/-/blob/master/common/utils/environ.c
Thanks: Siddhesh Poyarekar
e1c9bbb3d1