* spawn.cc (_spawnve): Ditto.
* passwd.cc: Remove static from `passwd_in_memory_p'.
(read_etc_passwd): Remove static.
* uinfo.cc: Move global declaration of `read_etc_group' and
`group_in_memory_p' into `uinfo_init'.
(internal_getlogin): Try to get SID from current process first.
(uinfo_init): Don't set uid and gid if `myself' has a valid SID.
Only load /etc/passwd and /etc/group in that case.
for existing user hive.
Use MAX_PATH instead of numerical constant for array size.
Use return code of RegLoadKeyA instead of GetLastError for error output.
and `RegLoadKeyA'.
* registry.cc (get_registry_hive_path): New function.
(load_registry_hive): Ditto.
* security.cc (convert_sid_to_string_sid): New function.
(get_ssid): Renamed to `convert_string_sid_to_sid'.
(get_pw_sid): Call `convert_string_sid_to_sid' instead of `get_ssid'.
(get_gr_sid): Ditto.
(get_admin_sid): Ditto.
(get_system_sid): Ditto.
(get_creator_owner_sid): Ditto.
(get_world_sid): Ditto.
* shared.h: New prototypes for `get_registry_hive_path' and
`load_registry_hive'.
* spawn.cc (spawn_guts): Set child->psid to NULL to force calling
`internal_getlogin' from child process in case of changing user context.
Call `load_registry_hive' in case of changing user context.
(_spawnve): Copy user infos only if user context remains the same.
* uinfo.cc: Add load statement for `NetUserGetInfo'.
Remove load statement for `NetGetDCName'.
(internal_getlogin): Rewrite to speed up process startup
and to correct user environment in case user context changes.
(uinfo_init): Call internal_getlogin only if myself->psid is NULL,
that is user context changes.
* winsup.h: Add prototypes for `convert_sid_to_string_sid',
`convert_string_sid_to_sid' and `get_pw_sid'.
`cygwin_set_impersonation_token'.
* dcrt0.cc (dll_crt0_1): Eliminate superfluous conditional
statements.
Add load statements for `ImpersonateLoggedOnUser', `LogonUserA'
and `RevertToSelf'.
* fork.cc (fork): Care for correct impersonation of parent
and child process.
* security.cc (cygwin_set_impersonation_token): New function.
(cygwin_logon_user): Ditto.
shared.h (class pinfo): New members `orig_uid', `orig_gid',
`real_uid' nad `real_gid'.
spawn.cc (spawn_guts): Care for impersonation when starting
child process in a different user context.
* syscalls.cc (setgid): Call `setegid' now. Set real_gid.
(setuid): Call `seteuid' now. Set real_uid.
(seteuid): Functionality moved from setuid to here. Care for
correct impersonation.
(setegid): Functionality moved from setgid to here.
* uinfo.cc (uinfo_init): Initialization of additional pinfo
members.
(getuid): Return real uid.
(getgid): Return real gid.
(geteuid): Return effective uid.
(getegid): Return effective gid.
include/sys/cygwin.h: Add prototypes for `cygwin_logon_user' and
`cygwin_set_impersonation_token'.
include/cygwin/version.h: Bumb API minor version to 22.
