The original dll_init code was living under the wrong assumption that
dll_dllcrt0_1 and in turn dll_list::alloc will be called for each
LoadLibrary call. The same wrong assumption was made for
cygwin_detach_dll/dll_list::detach called via FreeLibrary.
In reality, dll_dllcrt0_1 gets only called once at first LoadLibrary
and cygwin_detach_dll once at last FreeLibrary.
In effect, reference counting for DLLs was completely broken after fork:
parent:
l1 = dlopen ("lib1"); // LoadLibrary, LoadCount = 1
l2 = dlopen ("lib1"); // LoadLibrary, LoadCount = 2
fork (); // LoadLibrary in the child, LoadCount = 1!
child:
dlclose (l1); // FreeLibrary actually frees the lib
x = dlsym (l2); // SEGV
* Move reference counting to dlopen/dlclose since only those functions
have to keep track of loading/unloading DLLs in the application context.
* Remove broken accounting code from dll_list::alloc and dll_list::detach.
* Fix error handling in dlclose.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This patch alters the behaviour of dll_list::topsort to preserve the
order of dlopen'd units.
The load order of unrelated DLLs is reversed every time fork is called,
since dll_list::topsort finds the tail of the list and then unwinds to
reinsert items. My change takes advantage of what should be undefined
behaviour in dll_list::populate_deps (ndeps non-zero and ndeps and deps
not initialised) to allow the deps field to be initialised prior to the
call and appended to, rather than overwritten.
All DLLs which have been dlopen'd have their deps list initialised with
the list of all previously dlopen'd units. These extra dependencies mean
that the unwind preserves the order of dlopen'd units.
The motivation for this is the FlexDLL linker used in OCaml. The FlexDLL
linker allows a dlopen'd unit to refer to symbols in previously dlopen'd
units and it resolves these symbols in DllMain before anything else has
initialised (including the Cygwin DLL). This means that dependencies may
exist between dlopen'd units (which the OCaml runtime system
understands) but which Windows is unaware of. During fork, the
process-level table which FlexDLL uses to get the symbol table of each
DLL is copied over but because the load order of dlopen'd DLLs is
reversed, it is possible for FlexDLL to attempt to access memory in the
DLL before it has been loaded and hence it fails with an access
violation. Because the list is reversed on each call to fork, it means
that a subsequent call to fork puts the DLLs back into the correct
order, hence "even" invocations of fork work!
An interesting side-effect is that this only occurs if the DLLs load at
their preferred base address - if they have to be rebased, then FlexDLL
works because at the time that the dependent unit is loaded out of
order, there is still in memory the "dummy" DONT_RESOLVE_DLL_REFERENCES
version of the dependency which, as it happens, will contain the correct
symbol table in the data section. For my tests, this initially appeared
to be an x86-only problem, but that was only because the two DLLs on x64
should have been rebased.
Signed-off-by: David Allsopp <david.allsopp@metastack.com>
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>
* dcrt0.cc (initial_env): Reduce size of local path buffers to
PATH_MAX. Allocate debugger_command from process heap.
(init_windows_system_directory): Very early initialize new global
variable global_progname.
* dll_init.cc (dll_list::alloc): Make path buffer static. Explain why.
(dll_list::populate_deps): Use tmp_pathbuf for local path buffer.
* exceptions.cc (debugger_command): Convert to PWCHAR.
(error_start_init): Allocate debugger_command and fill with wide char
strings. Only allocate if NULL.
(try_to_debug): Just check if debugger_command is a NULL pointer to
return. Drop conversion from char to WCHAR and drop local variable
dbg_cmd.
* globals.cc (global_progname): New global variable to store Windows
application path.
* pinfo.cc (pinfo_basic::pinfo_basic): Just copy progname over from
global_progname.
(pinfo::status_exit): Let path_conv create the POSIX path to
avoid local buffer.
* pseudo_reloc.cc (__report_error): Utilize global_progname, drop local
buffer.
* smallprint.cc (__small_vsprintf): Just utilize global_progname for
%P format specifier.
(__small_vswprintf): Ditto.
* strace.cc (PROTECT): Change to reflect x being a pointer. Reformat.
(CHECK): Ditto. Reformat.
(strace::activate): Utilize global_progname, drop local buffer.
Fix formatting.
(strace::vsprntf): Reduce size of local progname buffer to NAME_MAX.
Copy and, if necessary, convert only the last path component to
progname.
(strace_buf_guard): New muto.
(buf): New static pointer.
(strace::vprntf): Use buf under strace_buf_guard lock only. Allocate
buffer space for buf on Windows heap.
* wow64.cc (wow64_respawn_process): Utilize global_progname, drop
local path buffer.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
* dcrt0.cc (cygwin_atexit): Use d->handle with __cxa_atexit.
* dll_init.cc (dll_list::detach): Use d->handle with __cxa_finalize.
* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Use 274 for
__cxa_finalize as well.
accommodate process with all runtime loaded DLLs already dlclosed
at fork time.
* gendef (_sigfe_maybe): Fix code handling early return if we don't
have a tls, broken on 2013-05-21.
Explain why. Add code to check if a DLL with the same basename but
different path is the same DLL. Bail out if not.
(in_load_after_fork): New static NO_COPY bool to allow to differ
between linked and loaded DLL at fork.
(dll_list::load_after_fork): Set in_load_after_fork accordingly.
(dll_dllcrt0_1): Don't treat DLL as linked if in_load_after_fork is set.
Drop test for in_forkee.
(dll_list::operator[]): Add long comment to explain the misery.
(dll_list::alloc): Skip long pathname prefix potentially returned by
GetModuleFileNameW.
* dll_init.h (dll_list::find_by_modname): Add back declaration.
* dll_init.cc: Throughout, use modname where it was used before.
(dll_list::operator[]): Use modname. Move comment from dll_list::alloc
here and remove hint about GetModuleBaseNameW.
(dll_list::alloc): Store full path in name, pointer to basename in
modname. Search dll using modname.
(dll_list::find_by_modname): Remove.
(dll_list::alloc): Only store module basename in name. Add comment to
explain why. Simplify address check. Fix formatting in comment.
* dll_init.h (struct dll): Drop modname and find_by_modname.
dynamically loaded since fork() doesn't work in that scenario anyway.
(dll_dllcrt0_1): Don't accommodate dynamically loaded dlls.
* exceptions.cc (ctrl_c_handler): Don't lock the process; there's too much risk
of deadlock.
* sigproc.cc (_cygtls::remove_wq): Don't try to remove anything from the waitq
if there is obviously nothing there.
* strace.cc (strace::activate): Allow stracing dynamically loaded cygwin1.dll.
(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.
for a module name only (no path).
(dll_list::alloc): Initialize newly-added members of struct dll.
(dll_list::append): New function to factor out the append operation
(used by dll_list::topsort).
(dll_list::populate_deps): New function to identify dll dependencies.
(dll_list::topsort): New function to sort the dll list topologically by
dependencies.
(dll_list::topsort_visit): New helper function for the above.
* dll_init.h (dll::ndeps): New class member.
(dll::deps): Ditto.
(dll::modname): Ditto.
(dll_list::find_by_modname): New function related to topsort.
(dll_list::populate_all_deps): Ditto.
(dll_list::populate_deps): Ditto.
(dll_list::topsort): Ditto.
(dll_list::topsort_visit): Ditto.
(dll_list::append): Ditto.
(pefile): New struct allowing simple introspection of dll images.
* fork.cc (fork): Topologically sort the dll list before forking
* child_info.h (CURR_CHILD_INFO_MAGIC): Refresh.
(child_info::refresh_cygheap): New function.
* spawn.cc (spawn_guts): Call refresh_cygheap before creating a new process to
ensure that cygheap_max is up-to-date.
* fork.cc (frok::parent): Ditto.
(reserve_at): Don't reserve space needed by the target dll if the latter
overlaps the free region to be blocked.
(dll_list::load_after_fork): Use new version of reserve_at.
* dll_init.h (dll::image_size): New member.
(pefile): New struct.
(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 for tracking reservations
made while trying to make dlls land where they belong.
(dll_list::load_after_fork_impl): Ditto.
(dll_list::alloc): Initialize image base field.
* dll_init.h (struct dll_list): declare new functions.
(dll::image_size): New member.
for a module name only (no path).
(dll_list::alloc): Initialize newly-added members of struct dll.
(dll_list::append): New function to factor out the append operation
(used by dll_list::topsort).
(dll_list::populate_deps): New function to identify dll dependencies.
(dll_list::topsort): New function to sort the dll list topologically by
dependencies.
(dll_list::topsort_visit): New helper function for the above.
* dll_init.h (dll::ndeps): New class member.
(dll::deps): Ditto.
(dll::modname): Ditto.
(dll_list::find_by_modname): New function related to topsort.
(dll_list::populate_all_deps): Ditto.
(dll_list::populate_deps): Ditto.
(dll_list::topsort): Ditto.
(dll_list::topsort_visit): Ditto.
(dll_list::append): Ditto.
(pefile): New struct allowing simple introspection of dll images.
* fork.cc (fork): Topologically sort the dll list before forking.
* fork.cc (frok::errmsg): Rename from 'error'.
(frok::error): New function. Handle conditional printing of error messages.
(frok::parent): Record hchild handle for use by error function. Use
throughout. Use error function rather than setting error pointer directly.
(fork): Clear is_forkee here. Accommodate rename of 'error' to 'errmsg'.
* sigproc.cc (child_info::proc_retry): Detect EXITCODE_FORK_FAILED.
* child_info.h: Redefine CURR_CHILD_INFO_MAGIC.
(child_info_fork::abort): Rename from handle_failure. Change arguments.
* cygtls.h (_local_storage::ttybuf): New field.
* dcrt0.cc (vapi_fatal): Split api_fatal. Add "in forked process" to message
when appropriate.
(api_fatal): Use vapi_fatal.
* devices.h: Make multiple inclusion safe.
(fh_devices): Add FH_CONS* stuff. Reorder slightly.
(device): Eliminate anonymous union. Add more ways to access minor/major.
(device::setunit): Accommodate no-longer-anonymous union.
(device::is_fs): Ditto.
(device::is_fs_special): Ditto.
(device::major): New function.
(device::minor): Ditto.
(device::is_device): New function.
(device::not_device): Ditto.
(device::operator int): New operator.
(device::operator fh_devices): Ditto.
(device::operator bool): Ditto.
(device::operator DWORD): Ditto.
(device::operator =): Ditto.
(isproc_dev): New function.
(isprocsys_dev): Ditto.
(iscons_dev): Ditto.
(istty_slave_dev): Ditto.
* devices.in: Add new "/dev/cons*" strings. Accommodate no-longer-anonymous
union throughout.
(BRACK): Use more precise method for initialization.
* devices.cc: Regenerate.
* dtable.cc (dtable::stdio_init): Use get_cttyp instead of get_tty.
(dtable::find_archetype): Use new DWORD operator in device to test archetypes.
(dtable::init_std_file_from_handle): Use different method to initialize 'dev'.
Adapt to different ctty handling and accommodate /dev/cons*.
(fh_alloc): Accommodate no-longer-anonymous union. Adapt to new /dev/cons*.
(build_fh_pc): Make debugging output more useful.
* exceptions.cc (ctrl_c_handler): Use get_cttyp instead of get_tty.
* external.cc (fillout_pinfo): Accommodate new cons* stuff.
* fhandler.cc (fhandler_base::read): Eliminate is_slow() test.
* fhandler.h (fhandler_base::*): Adapt to changes in device.h.
(fhandler_*::is_slow): Delete.
( fhandler_proc::get_proc_fhandler): Return fh_devices type.
* fhandler_console.cc (open_shared_console): New function.
(console_unit): New class.
(console_unit::console_unit): New constructor.
(enum_windows): New function. Declare as friend to console_unit.
(fhandler_console::set_unit): New function.
(fhandler_console::get_tty_stuff): Call set_unit to set the unit number and
determine if initialization is needed. Eliminate flags parameter.
(tty_list::get_cttyp): Rename (sorta) from get_tty. Return pointer to correct
tty_min.
(fhandler_console::open): Adapt to elimination of argument to get_tty_stuff.
(fhandler_console::output_tcsetattr): Properly detect error condition.
(fhandler_console::fixup_after_fork_exec): Adapt to get_tty_stuff() setting tc
automatically.
* fhandler_proc.cc: Use FH_BAD rather than 0 throughout where using fh_devices
enum.
(fhandler_proc::get_proc_fhandler): Return fh_devices. Adapt to devices.h
changes.
* fhandler_process.cc: Adapt to devices.h changes. Use FH_BAD rather than 0
throughout where using fh_devices enum.
* fhandler_procnet.cc: Ditto.
* fhandler_procsys.cc: Ditto.
* fhandler_procsysvipc.cc: Ditto.
* fhandler_tape.cc (fhandler_dev_tape::fhandler_dev_tape): Ditto.
* fhandler_termios.cc (handler_termios::bg_check): Use tc->ttyname() rather
than assuming that we can construct a tty.
* fhandler_tty.cc (fhandler_tty_master::fhandler_tty_master): Just return
get_minor() of dev.
(fhandler_pty_master::process_slave_output): Add slightly more debugging info.
(fhandler_tty_slave::fhandler_tty_slave): Change name from ntty to unit.
(fhandler_pty_master::open): Ditto.
(fhandler_tty_slave::ioctl): Adapt to change which causes ctty to represent a
complete device.
(fhandler_tty_master::init_console): Add debugging for failure path.
(fhandler_pty_master::setup): Use get_unit() to retrieve unit number rather
than relying on raw ntty.
(fhandler_pty_master::setup): Ditto.
* fhandler_virtual.h (virt_tab_t): Redefine fhandler as fh_devices.
* fork.cc: Remove obsolete vfork stuff.
(frok::child): Don't assume that a ctty == 0 is valid.
* mount.cc (mount_info::conv_to_win32_path): Adapt to device struct changes.
(mount_info::conv_to_win32_path): Ditto.
* path.cc (path_conv::check): Retrive major/minor numbers via a method rather
than accessing them directly from device. Rely on dev operators to
set/retrieve device information as required by device struct change.
* path.h (isproc_dev): Move to devices.h.
(isprocsys_dev): Ditto.
(isvirtual_dev): Ditto.
(path_conv:{isdevice,isfifo,isspecial,iscygdrive,issocket,get_devn,get_unitn}):
Use device methods to access/manipulate devices.
* pinfo.cc (pinfo::exit): Don't assume that ctty == 0 is valid. Use iscons_dev
to determine if a device is a console.
(_pinfo::_ctty): Use device::parse to generate tty/cons name.
(_pinfo::set_ctty): Don't assume that ctty == 0 is valid. Remove redundant
info from debugging.
* shared.cc (offsets): Remove console offset.
* shared_info.h (shared_locations): Ditto.
* syscalls.cc (umask): Use device methods to manipulate device information.
(ctermid): Use device::parse to generate term device name.
* tlsoffsets.h: Regenerate.
* tty.cc (ttyslot): Return minor number of ctty since ctty now represents a
full device.
(tty::create_master): Set ctty to a complete device.
(tty_list::attach): Rework to detect new /dev/cons* stuff.
(tty_list::terminate): Adapt to changes to ctty.
(tty_list::init): Adapt to change to setntty - pass in device major number.
(tty::exists): Use get_unit() to retrive tty unit number.
(tty::open_mutex): Ditto.
(tty::open_inuse): Ditto.
(tty::create_inuse): Ditto.
(tty::get_event): Ditto.
(tty_min::ttyname): Define new function.
* tty.h (tty_min::ntty): Redefine as fh_devices.
(tty::exists): Use get_unit() to retrive tty unit number.
(tty::open_mutex): Ditto.
(tty::open_inuse): Ditto.
(tty::create_inuse): Ditto.
(tty::get_event): Ditto.
(tty_min::ttyname): Declare new function.
(tty::getntty): Declare as const.
(tty_list::operator []): Assure that only minor part of argument is used.
* dll_init.cc (dll_list::alloc): Detect mismatch of data segments early issuing
an explicit error message if necessary.
* heap.cc (heap_init): Adapt to changes from fork->handle_failure to
fork->abort.
* pinfo.h (EXITCODE_FORK_FAILED): New enum. (from Ryan Johnson)
* sigproc.cc (child_info_fork::abort): Rename from handle_failure. Change
arguments to allow passing in a printf-like message.
* winsup.h (api_fatal): Delete macro definition.
(api_fatal): Redefine from __api_fatal.
(vapi_fatal): Declare new function.
* include/sys/strace.h (strace_vprintf): Define new macro.
* ntdll.h (_SYSTEM_INFORMATION_CLASS): Add SystemHandleInformation.
don't use archetypes and this will just result in double frees.
* dll_init.cc (dll_list::protect): Define.
(dll_list::alloc): Guard list access.
(dll_list::detach): Ditto.
* dll_init.h (dll_list::protect): Declare new muto.
(dll_list::guard): Define/declare function to guard list access.
* fhandler_termios.cc (fhandler_termios::sigflush): Avoid SEGV in pathological
condition of get_ttyp() == NULL.
(load_after_fork): If the DLL was loaded higher than the required address,
assume that it loaded at it's base address and also reserve memory there to
force it to be relocated.
* dcrt0.cc (child_info_fork::handle_fork): Call _pei386_runtime_relocator here.
(dll_crt0_1): Ditto for non-fork case.
* dll_init.cc (dll::init): Complain more in comment. Clean up slightly.
(dll_dllcrt0_1): Call _pei386_runtime_relocator when we know we have a
filled-in per_process structure.
* globals.cc (__cygwin_user_data): Accommodate new fields for
_pei386_runtime_relocator.
* pseudo-reloc.cc: New file adapted from old lib/pseudo-reloc.c. Include
winsup.h directly. Collapse #ifdef __CYGWIN__ into one block. Perform minor
whitespace code reformatting.
(__report_error): Use small_printf to output error.
(_pei386_runtime_relocator): Conditionalize for cygwin to take per_process
pointer parameter.
* winsup.h (_pei386_runtime_relocator): Declare.
* include/cygwin/version.h
(CYGWIN_VERSION_PER_PROCESS_API_VERSION_COMBINED): New macro.
(CYGWIN_VERSION_USER_API_VERSION_COMBINED): Use above macro.
(CYGWIN_VERSION_USE_PSEUDO_RELOC_IN_DLL): New macro.
(CYGWIN_VERSION_API_MINOR): Bump to 227.
* include/sys/cygwin.h: Remove obsolete comment.
(per_process::unused2): Shorten.
(per_process::pseudo_reloc_start): New field.
(per_process::pseudo_reloc_end): Ditto.
(per_process::image_base): Ditto.
* lib/_cygwin_crt0_common.cc: Declare pseudo runtime externs needed for
per_process structure.
(_cygwin_crt0_common): Fill in pseudo_reloc runtime constants.
* lib/pseudo-reloc-dummy.c: New file. Dummy function to satisify ld.
* lib/pseudo-reloc.c: Delete.
* dcrt0.cc (cygwin_exit): Set exit_state to ES_EXIT_STARTING prior to calling
real exit.
* dll_init.cc (dll_list::detach): Remove dll from linked list and call
destructors even if exiting. Don't call __cxa_finalize in exiting case.
(_cygtls::andreas): Convert to a pointer.
(san): Convert to a real class with methods. Use a linked list to keep track
of previous handlers on the "stack".
(myfault): Rewrite to use new san class rather than calling directly into
_cygtls.
* cygtls.cc (_cygtls::init_exception_handler): Just assume that we're always
using the standard exception handler.
(_cygtls::init_thread): Reflect loss of argument to init_exception_handler.
* dcrt0.cc (dll_crt0_1): Ditto.
* dfcn.cc (dlopen): Ditto.
(dlclose): Reset the exception handler after FreeLibrary.
* dll_init.cc (dll_list::detach): Make sure that the exception handler is
initialized before calling destructors.
* exceptions.cc (_cygtls::handle_exceptions): Accommodate new andreas pointer.
* thread.cc (verifyable_object_isvalid): Pass objectptr to faulted for explicit
NULL pointer checking.
* tlsoffsets.h: Regenerate.
Corinna Vinschen
David Allsopp
Yaakov Selkowitz
Christopher Faylor