During fork, the child process requires the process table to be
initialized for fixup_shms_after_fork, while still allowing subsequent
dlls.load_after_fork to fail silently (for when the "forkable" hardlinks
are not created yet).
pinfo::remember not performing reattach anymore requires explicit
pinfo::reattach now where appropriate.
Prepares to improve "Cygwin: fork: Remember child not before success."
commit f03ea8e1c5, which leads to fork
problems if cygserver is running:
https://cygwin.com/ml/cygwin-patches/2019-q2/msg00155.html
Do not remember the child before it was successfully initialized, or we
would need more sophisticated cleanup on child initialization failure,
like cleaning up the process table and suppressing SIGCHILD delivery
with multiple threads ("waitproc") involved. Compared to that, the
potential slowdown due to an extra yield () call should be negligible.
Pause the child process after performing fork fixups even if there were
no dynamically loaded dlls with extra data/bss transfers to wait for.
This allows the parent process to cancel the current fork call even if
the child process was successfully initialized already.
This is a preparation for when the parent does remember the child no
earlier than after successful child initialization.
In dll_crt0_0, both threadinterface->Init and sigproc_init allocate
windows object handles using unpredictable memory regions, which may
collide with dynamically loaded dlls when they were relocated.
Create process with standard rights, plus
PROCESS_QUERY_LIMITED_INFORMATION for authenticated users. This
allows to fetch basic process information and thus /proc/<PID>/stat
to succeed on foreign processes.
While at it, fix formatting in CreateProcess calls.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
To support in-cygwin package managers, the fork() implementation must
not rely on .exe and .dll files to stay in their original location, as
the package manager's job is to replace these files. Instead, when the
first fork try fails, and we have NTFS, we use hardlinks to the original
binaries in /var/run/cygfork/ to create the child process during the
second fork try, along the main.exe.local file to enable the "DotLocal
Dll Redirection" feature for the dlls.
The (probably few) users that need an update-safe fork manually have to
create the /var/run/cygfork/ directory for now, using:
mkdir --mode=a=rwxt /var/run/cygfork
* child_info.h: Bump CURR_CHILD_INFO_MAGIC.
(enum child_status): Add _CI_SILENTFAIL flag.
(struct child_info): Add silentfail setter and getter.
* winsup.h (child_copy): Add bool silentfail parameter.
* cygheap.cc: Pass silentfail parameter to child_copy.
* dcrt0.cc: Ditto.
* dll_init.h (struct dll): Define public inline method forkedntname.
(struct dll_list): Declare private method find_by_forkedntname.
* dll_init.cc (struct dll_list): Implement find_by_forkedntname.
(dll_list::alloc): Use find_by_forkedntname when in load after fork.
(dll_list::load_after_fork_impl): Load dlls using dll::forkedntname.
* fork.cc (frok::parent): Set silentfail child info flag. Pass
silentfail parameter to child_copy. Use forkedntname of
dlls.main_executable.
(fork): When first dofork run failed and did not use forkables,
run dofork again with_forkables set to true.
(child_copy): Use debug_printf if silentfail is true,
system_printf otherwise.
In preparation to protect fork() against dll- and exe-updates, create
hardlinks to the main executable and each loaded dll in subdirectories
of /var/run/cygfork/, if that one exists on the NTFS file system.
The directory names consist of the user sid, the main executable's NTFS
IndexNumber, and the most recent LastWriteTime of all involved binaries
(dlls and main executable). Next to the main.exe hardlink we create the
empty file main.exe.local to enable dll redirection.
The name of the mutex to synchronize hardlink creation/cleanup also is
assembled from these directory names, to allow for synchronized cleanup
of even orphaned hardlink directories.
The hardlink to each dynamically loaded dll goes into another directory,
named using the NTFS IndexNumber of the dll's original directory.
* Makefile.in (DLL_OFILES): Add forkable.o.
* dll_init.h (struct dll): Declare member variables fbi, fii,
forkable_ntname. Declare methods nominate_forkable,
create_forkable.
(struct dll_list): Declare enum forkables_needs. Declare member
variables forkables_dirx_size, forkables_dirx_ntname,
forkables_mutex_name, forkables_mutex. Declare private methods
forkable_ntnamesize, prepare_forkables_nomination,
update_forkables_needs, update_forkables, create_forkables,
denominate_forkables, close_mutex, try_remove_forkables,
set_forkables_inheritance, request_forkables. Declare public
static methods ntopenfile, read_fii, read_fbi. Declare public
methods release_forkables, cleanup_forkables. Define public
inline method setup_forkables.
* dll_init.cc (dll_list::alloc): Allocate memory to hold the
name of the hardlink in struct dll member forkable_ntname.
Initialize struct dll members fbi, fii.
(dll_list::load_after_fork): Call release_forkables method.
* fork.cc: Rename public fork function to static dofork, add
with_forkables as bool pointer parameter. Add new fork function
calling dofork. (struct frok): Add bool pointer member
with_forkables, add as constructor parameter.
(frok::parent): Call dlls.setup_forkables before CreateProcessW,
dlls.release_forkables afterwards.
* pinfo.cc (pinfo::exit): Call dlls.cleanup_forkables.
* syscalls.cc (_unlink_nt): Rename public unlink_nt function to
static _unlink_nt, with 'shareable' as additional argument.
(unlink_nt): New, wrap _unlink_nt for original behaviour.
(unlink_nt_shareable): New, wrap _unlink_nt to keep a binary
file still loadable while removing one of its hardlinks.
* forkable.cc: New file.
Implement static functions mkdirs, rmdirs, rmdirs_synchronized,
stat_real_file_once, format_IndexNumber, rootname, sidname,
exename, lwtimename. Define static array forkable_nameparts.
(struct dll): Implement nominate_forkable, create_forkable.
(struct dll_list): Implement static methods ntopenfile,
read_fii, read_fbi. Implement forkable_ntnamesize,
Even for the main executable and cygwin1.dll store the file name as full
NT path. Create the child process using the main executable's file name
converted from the full NT path stored before.
* dll_init.cc (dll_list::alloc): Search for DLL_SELF type entry
with module name like for DLL_LINK, use full NT path to search
for DLL_LOAD type only. For DLL_SELF type do not indicate
having a destructor to be called.
(dll_list::find): Ignore DLL_SELF type entries.
(dll_list::init): Ditto. Call track_self method.
(dll_list::track_self): New.
(dll_list::load_after_fork): Call track_self method.
* dll_init.h (enum dll_type): Add DLL_SELF, for the main
executable and cygwin1.dll.
(struct dll_list): Declare private method track_self. Declare
member variable main_executable.
* fork.cc (frok::parent): Use ntname from dlls.main_executable
to create child process, converted to short path using
dll_list::buffered_shortname.
Store loaded dll's file name as full NT path.
* dll_init.h (struct dll): Rename member variable name to ntname.
(struct dll_list): Declare private static member variable
nt_max_path_buffer. Declare public static methods form_ntname,
form_shortname. Define public static methods nt_max_path_buf,
buffered_shortname.
(dll_list::operator []): Use PCWCHAR rather than const PWCHAR.
(dll_list::find_by_modname): Ditto.
* dll_init.cc (in_load_after_fork): Define earlier in file.
(struct dll_list): Rename member variable name to ntname.
Define nt_max_path_buffer variable.
Implement static methods form_ntname, form_shortname.
(dll_list::operator []): Use PCWCHAR rather than const PWCHAR.
(dll_list::find_by_modname): Ditto.
(reserve_at): Ditto.
(release_at): Ditto.
(dll_list::alloc): Use nt_max_path_buf method instead of local
buffer. Store module file name as full NT path, convert using
the form_ntname static method.
(dll_list::load_after_fork): Call load_after_fork_impl only when
reload_on_fork is set.
* fork.cc (frok::child): Call dlls.load_after_fork even without
need to dynamically load dlls.
(frok::parent): Move syscall_printf into the retry loop.
Move TerminateProcess call into cleanup code to make sure child
doesn't linger in some border cases.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
When fork finally fails although both CreateProcess and creating the
"cygpid.N" shared memory section succeeded, we have to release that
shared memory section as well - before releasing the process handle.
Otherways we leave an orphan "cygpid.N" shared memory section, and any
subsequent cygwin process receiving the same PID fails to initialize.
* fork.cc (frok::parent): Call child.allow_remove in cleanup code.
Using the Windows PID as Cygwin PID has a few drawbacks:
- the PIDs on Windows get reused quickly. Some POSIX applications choke
on that, so we need extra code to avoid too quick PID reuse.
- The code to avoid PID reuse keeps parent process handles and
(depending on a build option) child processes open unnecessarily.
- After an execve, the process has a split personality: Its Windows PID
is a new PID, while its Cygwin PID is the PID of the execve caller
process. This requires to keep two procinfo shared sections open, the
second just to redirect process info requests to the first, correct
one.
This patch changes the way Cygwin PIDs are generated:
- Cygwin PIDs are generated independently of the Windows PID, in a way
expected by POSIX processes. The PIDs are created incrementally in
the range between 2 and 65535, round-robin.
- On startup of the first Cygwin process, choose a semi-random start PID
for the first process in the lower PID range to make the PIDs slightly
unpredictable. This may not be necessary but it seems kind of inviting
to know that the first Cygwin process always starts with PID 2.
- Every process not only creates the shared procinfo section, but also a
symlink in the NT namespace, symlinking the Windows PID to the Cygwin
PID. This drops the need for the extra procinfo section after execve.
- Don't keep other process handles around unnecessarily.
- Simplify the code creating/opening the shared procinfo section and
make a clear distinction between interfaces getting a Cygwin PID and
interfaces getting a Windows PID.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
- Rename files timer.* to posix_timer.*.
- Reimplement using an OS timer rather than a handcrafted wait loop.
- Use a Slim R/W Lock for synchronization.
- Drop timer chaining. It doesn't server a purpose since all timers
are local only.
- Rename ttstart to itimer_tracker to better reflect its purpose.
It's not the anchor for a timer chain anymore anyway.
- Drop fixup_timers_after_fork. Everything is process-local, nothing
gets inherited.
- Rename timer_tracker::disarm_event to disarm_overrun_event for
better readability.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
When fork fails, we can use "%s" now with system_sprintf for the errmsg
rather than a (potentially too small) buffer for the format string.
* fork.cc (fork): Use "%s" with system_printf now.
So far we copy *_impure_ptr into _main_tls->local_clib if the child
process has been forked from a pthread. But that's not required.
The local_clib area of the new thread is on the stack and the stack
gets copied from the parent anyway (in frok::parent). So we only
have to make sure _main_tls is pointing to the right address and
do the simple post-fork thread init.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Bump GPLv2+ to GPLv3+ for some files, clarify BSD 2-clause.
Everything else stays under GPLv3+.
New Linking Exception exempts resulting executables from LGPLv3 section 4.
Add CONTRIBUTORS file to keep track of licensing.
Remove 'Copyright Red Hat Inc' comments.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* child_info.h (struct child_info): Add member from_main.
* fork.cc (frok::child): Check from_main rather than stackaddr.
(frok::parent): Set ch.from_main if running in the main thread.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* child_info.h (CURR_CHILD_INFO_MAGIC): Align to below change.
(class child_info_fork): Rename stacktop to stacklimit. Rename
stackbottom to stackbase. Accommodate name change throughout Cygwin.
Rephrase comments to be clearer.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* cygtls.h (_tlsbase): Remove. Replace throughout with
NtCurrentTeb()->Tib.StackBase.
(_tlstop): Remove. Replace throughout with
NtCurrentTeb()->Tib.StackLimit.
* dcrt0.cc (child_info_fork::alloc_stack): Move definition of local
teb variable up to be used throughout.
* include/cygwin/config.h (__getreent): Use inline function on both
architectures.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* fork.cc (frok::parent): Set stacktop value based on requested stack
pointer value in child. Explain why.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* fork.cc (frok::parent): When initializing pinfo for child new PID_NEW flag +
actual defined constant rather than raw number. Don't set start_time here.
* pinfo.cc (pinfo::thisproc): Use PID_NEW when initializing pinfo. Avoid
checking h for NULL multiple times. Don't set start_time here.
(pinfo_init): Aways set ppid last. Tweak strace output.
(pinfo::init): Handle new PID_NEW flag. Wait for shared memory to contain
useful information. Set start_time if PID_NEW.
(_onreturn:h): Define as HANDLE rather than HANDLE *.
(_onreturn::~onreturn): Accommodate h definition change.
(_onreturn::no_close_handle): Rename from no_close_p_handle. Take a pinfo arg
and set hProcess to h before zeroing.
(winpids::add): Don't open a handle to our own process. Change logic
associated with when a handle gets closed. Accommodate no_close_handle
changes.
(winpids::enum_processes): Simplify process enumeration loop.
(winpids::set): Eliminate ill-considered malloc locking.
* sigproc.cc (proc_subproc): Always set ppid last.
stacksize to SIZE_T. Cast to SIZE_T in pointer arithmetic. Slightly
enhance output in case of a fatal error.
* fork.cc (frok::parent): Always set ch.stackaddr to DeallocationStack
value of current thread to help stack reservation in
child_info_fork::alloc_stack_hard_way along. Simplify subsequent code
storing stack values in ch. Print guardsize in hex, too.
* pinfo.cc (pinfo::init): Reuse shared memory if the state is marked with
PID_REAPED.
* spawn.cc (child_info_spawn::worker): Don't duplicate myself_pinfo into
non-cygwin child.
* fork.cc (frok::parent): Improve error output.
* fork.cc (frok::parent): Call postfork to do all of the manipulation required
prior to calling pinfo::remember.
* pinfo.h (pinfo::set_rd_proc_pipe): Just set pinfo's rd_proc_pipe. Don't
bother setting it to NULL.
* sigproc.cc (child_info_spawn::wait_for_myself): Call postfork to set up
myself for waiting.
* spawn.cc (child_info_spawn::worker): Avoid now-unnecessary global lock.
Consistently test mode rather than chtype when making wr_proc_pipe decisions.
Call postfork() to set up stuff prior to pinfo::remember.
(dtable::release): "Close" standard handle if appropriate.
* dcrt0.cc (dll_crt0_0): Fix minor switch formatting problem.
* fork.cc (frok::parent): Make minor comment indentation change.
(child_info::rd_proc_pipe): Declare new field.
(child_info::wr_proc_pipe): Ditto.
(child_info::prefork): Declare new function, derived from previous pinfo
version.
* dcrt0.cc (child_info_fork::handle_fork): Close previous wr_proc_pipe when
appropriate and assign new one from passed-in child_info block.
(child_info_spawn::handle_spawn): Assign our wr_proc_pipe handle from passed-in
child_info block.
* fork.cc (child_info::prefork): Define new function.
(frok::child): Clear rd_proc_pipe and wr_proc_pipe so they will not be closed
by the child_info destructor.
(frok::parent): Use child_info prefork handling, outside of retry loop. Set
rd_proc_pipe in child's pinfo after successful CreateProcess. Eliminate
postfork call.
* globals.cc (my_wr_proc_pipe): Define/declare new variable.
* pinfo.cc (pinfo::pending_rd_proc_pipe): Delete.
(pinfo::pending_wr_proc_pipe): Ditto.
(pinfo::prefork): Ditto.
(pinfo::postfork): Ditto.
(pinfo::postexec): Ditto.
(pinfo::wait): Assume that rd_proc_pipe is set up correctly prior to call.
(_pinfo::alert_parent): Replace "wr_proc_pipe" with "my_wr_proc_pipe".
* pinfo.h (_pinfo::_wr_proc_pipe): Delete declaration.
(_pinfo::set_rd_proc_pipe): Define new function.
(pinfo::pending_rd_proc_pipe): Delete declaration.
(pinfo::pending_wr_proc_pipe): Ditto.
(pinfo::prefork): Ditto.
(pinfo::postfork): Ditto.
(pinfo::postexec): Ditto.
(pinfo::wr_proc_pipe): Ditto.
* sigproc.cc (child_info::child_info): Clear rd_proc_pipe and wr_proc_pipe.
(child_info::cleanup): Close rd_proc_pipe and wr_proc_pipe if necessary.
(child_info_fork::child_info_fork): Set forker_finished to NULL by default.
(child_info_spawn::child_info_spawn): Use my_wr_proc_pipe rather than
myself->wr_proc_pipe.
(child_info::sync): Ditto.
(child_info_spawn::cleanup): Call child_info::cleanup.
* spawn.cc (child_info_spawn::worker): Remove call to myself.prefork(). Set
wr_proc_pipe when execing or set up new rd_proc_pipe/wr_proc_pipe via
child_info::prefork when spawning. Remove call to pinfo::postexec. Set
rd_proc_pipe in child pinfo when spawning. Use my_wr_proc_pipe rather than
myself->wr_proc_pipe. Remove call to postfork.
lock object handle explicitely in case of called during fork. Add
comment to explain why.
* fork.cc (frok::child): Drop declaration of fixup_lockf_after_fork.
* fhandler.h: Use #pragma once rather than ifdef guards.
(fhandler_console::tc_getpgid): Return our pgid if we have never opened a
console.
* fork.cc: Rearrange includes to accommodate fhandler.h use of pinfo.h.
* sigproc.cc: Ditto.
* spawn.cc: Ditto.
(child_info_spawn::worker): Query myself->pgid rather than calling expensive
function.
* thread.h: Use #pragma once rather than ifdef guards.
* pinfo.h: Use #pragma once rather than ifdef guards.
(pinfo::remember): Don't define if sigproc.h has not been included.
(pinfo::reattach): Ditto.
* sigproc.h: Use #pragma once rather than ifdef guards. Use different test to
see if pinfo.h has been included.
Throughout, change syscalls to report on return values using new %R format
option.
* smallprint.cc (__small_vsprintf): Add parsing for %R to report on return
values and possible errno from syscalls.
* errno.cc (errmap): Add PRIVILEGE_NOT_HELD.
* fhandler_tty.cc (fhandler_pty_master::setup): When creating a thread use
shorter name to reduce debuggging output.
* select.cc (start_thread_pipe): Ditto.
(start_thread_serial): Ditto.
(start_thread_socket): Ditto.
(start_thread_mailslot): Ditto.
* sigproc.cc (talktome): Ditto.
process of setting up the DLL and no name is known.
* dcrt0.cc (initial_env): Remove CYGWIN_SLEEP stuff.
(get_cygwin_startup_info): Activate strace here as appropriate.
(dll_crt0_0): Move get_cygwin_startup_info as early as possible to avoid
missing strace output.
* fork.cc (frok::child): Move debugging statement to point where ppid will be
set.
* pinfo.cc (pinfo::thisproc): Remove obsolete call to strace.hello. Tweak
debug output slightly.
* select.cc (select_stuff::wait): Allow APCS to be triggered while waiting
since we use them now. Report when that happens.
* sigproc.cc (child_info::child_info): Use strace.active() rather than
strace.attached().
* spawn.cc (child_info_spawn::worker): Only write strace child pid when we know
it's a cygwin process. Accommodate change to write_child argument list.
* strace.cc (strace::hello): Delete. Move functionality...
(strace::activate): ...to here.
(mypid): Just use raw GetCurrentProcessId () if myself isn't set.
(strace::write_childpid): Don't wait for subproc_ready. Remove arg which was
required for it.
* include/sys/strace.h (strace::hello): Delete.
(strace::write_childpid): Delete first argument.
Throughout rename _PROC_* to _CH_*.
* child_info.h: Include "pinfo.h".
(child_info_types): Rename _PROC_* -> _CH_* to avoid confusion with similarly
named constants.
(_PROC_*): Delete unneeded aliases.
(PROC_*): Ditto.
(CURR_CHILD_INFO_MAGIC): Ditto.
(cchildren): Define using "pinfo_minimal".
(child_info::set_saw_ctrl_c): Move to
(child_info_spawn::set_saw_ctrl_c): Here.
(child_info_spawn::lock): New field.
(child_info_spawn::hExeced): Ditto.
(child_info_spawn::ev): Ditto.
(child_info_spawn::~child_info_spawn): Move to sigproc.cc.
(child_info_spawn::child_info_spawn): Ditto.
(child_info_spawn::cleanup): Declare new function.
(child_info_spawn::set_saw_ctrl_c): Move to this class. Set flag only when
execed and return true when we have set the flag.
(child_info_spawn::child_info_spawn::signal_myself_exited): New function.
(child_info_spawn::wait_for_myself): Ditto.
(child_info_spawn::has_execed_cygwin): Ditto.
(child_info_spawn::has_execed): Ditto. Replaces "hExeced" test.
(child_info_spawn::operator HANDLE&): New operator.
(child_info_spawn::worker): Define old "spawn_guts" as class member.
(ch_spawn): Declare.
(have_execed): Define.
(have_execed_cygwin): Ditto.
* cygheap.h: Update comment.
* dcrt0.cc (get_cygwin_startup_info): Use _CH_* enums.
(child_info_spawn::handle_spawn): Ditto.
(dll_crt0_0): Ditto.
(multiple_cygwin_problem): Ditto.
* exceptions.cc (chExeced): Delete obsolete declaration.
(ctrl_c_handler): Reference set_saw_ctrl_c via new ch_spawn global.
* globals.cc (hExeced): Delete.
* pinfo.cc (pinfo::thisproc): Refer to cygheap as ::cygheap for consistency in
handle naming when -DDEBUGGING.
(pinfo::init): Accommodate case where myself.h is known but h0 is passed in.
(pinfo::pinfo): New constructor for setting up a pinfo passed in by previous
exec'or.
(pinfo::proc_waiter): Don't handle subprocess if we're in the process of
exiting due to an exec of a cygwin process. Don't close rd_proc_pipe here.
Close it when we actually are finished with the process. Use new
ch_spawn.signal_myself_exited function to let exec stub know that subprocess
has exited.
(pinfo::wait): Clarify debugging output.
(pinfo::release): Use "close_h" to close all handles to avoid races.
(winpids::add): Assume that elements of the array do not need to be zeroed and
are properly initialized or suffer problems on pinfo::release. Don't close
hProcess since release does that now.
* pinfo.h: Update comment.
(pinfo_minimal): Move some elements from pinfo here so that child_info_spawn
can use them.
(pinfo): Inherit from pinfo_minimal.
(pinfo::pinfo): Modify to accommodate new pinfo_minimal.
(pinfo::allow_remove): New function.
* sigproc.cc (proc_subproc): Use boolean values for true/false. Implement
PROC_EXEC_CLEANUP.
(proc_terminate): Set ppid = 1 since the procs list will only be iterated when
the process has not execed. Don't do any cleanup here since it is now handled
in pinfo::release.
(sigproc_init): Initialize sync_proc_subproc earlier.
(child_info::child_info): Assume that all important fields are properly
initialized and avoid memset().
(child_info_spawn::child_info_spawn): Specifically test for execing and then
set up appropriate fields in the struct.
(child_info_spawn::cleanup): Define new function.
(child_info_spawn::record_children): Specifically test for being execed here.
Fill in pinfo_minimal part of children array.
(child_info_spawn::reattach_children): Use constructor to duplicate information
for previous exec'or. Add more debugging output.
(remove_proc): Force deletion of thread when exiting due to exec. Rely on
pinfo::cleanup in release.
* sigproc.h (PROC_EXEC_CLEANUP): New enum.
(PROC_DETACHED_CHILD): Delete.
* spawn.cc (chExeced): Delete.
(child_info_spawn::worker): Rename from spawn_guts. Use elements of
child_info_spawn throughout rather than ch.whatever. Use ::cygheap to refer to
global rather than element of child_info. Use wait_for_myself() rather than
waitpid(). Call child_info_spawn::cleanup on function return.
(spawnve): Reflect movement of spawn_guts functionality into
child_info_spawn::worker.
* syscalls.cc (popen): Ditto.
* winsup.h (spawn_guts): Delete declaration.
(release_upto): Ditto.
(dll_list::reserve_space): New function to reserve space needed by DLL_LOAD
dlls early in the fork process.
(dll_list::load_after_fork): Rewrite to use recursion to track reservations it
makes while trying to make dlls land where they belong.
(dll_list::load_after_fork_impl): New function used by load_after_fork.
(dll_list::alloc): Initialize image base field.
* dll_init.h (dll_list::prefered_base): New field.
(dll_list::reserve_space): Declare new function.
(dll_list::load_after_fork): Declare new function.
* fork.cc (frok::child): call dll_list::reserve_space early, so we can retry if
it fails.
Michael Haubenwallner
Ken Brown
Corinna Vinschen
Sergejs Lukanihins
Christopher Faylor