Because I actually managed to hit deadlock in libvirt's child
process due to glibc's mutex use in user database lookup, I
figured it is worth documenting the issue for others to be
aware of when writing a privileged multithreaded parent app
that spawns child processes owned by non-privileged ids.
* doc/glibc-functions/initgroups.texi (initgroups): Mention
multithread safety.
* doc/posix-functions/getpwuid.texi (getpwuid): Likewise.
* doc/posix-functions/getpwuid_r.texi (getpwuid_r): Likewise.
* doc/glibc-functions/getgrouplist.texi (getgrouplist): Mention
getugroups.
* doc/posix-functions/getgroups.texi (getgroups): Mention
multithread safety and mgetgroups.
Signed-off-by: Eric Blake <eblake@redhat.com>
FreeBSD 7.2 mistakenly succeeds on getgroups(-1,ptr) (POSIX
requires EINVAL failure since -1 is less than the proper result).
* lib/getgroups.c (rpl_getgroups): Work around the bug.
* m4/getgroups.m4 (gl_FUNC_GETGROUPS): Detect the bug.
* doc/posix-functions/getgroups.texi (getgroups): Document it.
* tests/test-getgroups.c (main): Fix buffer overrun.
Signed-off-by: Eric Blake <ebb9@byu.net>
These days, most systems already declare getgroups with gid_t*.
But in the rare case that GETGROUPS_T is still int but gid_t
is short, the user should not have to uglify their code; let
the replacement hide all the magic.
Tested by configuring with ac_cv_type_getgroups=uint64_t on a
platform with 32-bit gid_t, and ignoring compiler warnings.
However, since we don't replace setgroups, the GETGROUPS_T
workaround is still needed there for now.
* lib/getgroups.c (rpl_getgroups): Change signature. Copy array
an element at a time if GETGROUPS_T is wrong size.
* lib/getugroups.h (getugroups): Change signature.
* lib/unistd.in.h (getgroups): Likewise.
* m4/getgroups.m4 (gl_FUNC_GETGROUPS): Use replacement if
signature needs fixing.
* m4/getugroups.m4 (gl_GETUGROUPS): No longer need
AC_TYPE_GETGROUPS.
* modules/group-member (Depends-on): Add getgroups.
* lib/group-member.c (group_info, get_group_info): Use gid_t.
(group_member): Rely on getgroups replacement.
* lib/getugroups.c (getugroups): Use gid_t.
* tests/test-getgroups.c (main): Likewise.
* NEWS: Mention the signature change.
* doc/posix-functions/getgroups.texi (getgroups): Mention the
problem with signature.
* doc/glibc-functions/setgroups.texi (setgroups): Mention that
GETGROUPS_T is still useful for setgroups.
Signed-off-by: Eric Blake <ebb9@byu.net>
