* posix_ipc.cc: Include thread.h and semaphore.h. Remove TODO
comment.
(ipc_names): Add max_len member. Set to maximum length of the path
before tacking on the prefix path. Set prefix path for named semaphors
to /dev/shm, as on Linux.
(enum ipc_type_t): Change sem to semaphore to avoid name conflicts.
(check_path): Detect empty paths. Use ipc_names's max_len member.
Use __small_sprintf to create full object path name. Special case
semaphores.
(ipc_cond_init): Drop superfluous strcpy.
(class ipc_flock): New class to simplify file locking in subsequent
code.
(struct mq_hdr): Raise size of mqh_uname to allow adding a unique
LUID to the name.
(mq_open): Fix formatting. Create unique synchronization object names
using AllocateLocallyUniqueId.
(struct sem_finfo): New structure defining named semaphore file content.
(sem_open): Move here. Rework implementation to allow kernel
persistent implementation of POSIX named semaphores.
(_sem_close): Implement sem_close.
(sem_close): Move here. Just call _sem_close with do_close parameter
set to true.
(sem_unlink): New function.
* pthread.cc (mangle_sem_name): Remove.
(sem_open): Move to posix_ipc.cc.
(sem_close): Ditto.
* syscalls.cc (close_all_files): Call semaphore::terminate here.
* thread.cc: Fix formatting. Rearrange semaphore functions so that
they are close together.
(semaphore::semaphore): Rework to play nicely with new named semaphore
implementation.
(semaphore::_terminate): Call _sem_close if semaphore is a named
semaphore.
(semaphore::destroy): Don't destroy named semaphores. Return EINVAL
instead.
(semaphore::close): Only destroy named semaphores. Return EINVAL
otherwise.
(semaphore::open): Rework to play nicely with new named semaphore
implementation. Loop through existing semaphores to be able to
return same sem_t pointer as a former call on the same named semaphore.
(semaphore::getinternal): New function called from _sem_close.
* thread.h (class List): Make mx and head public.
(class semaphore): Fix formatting. Align method declarations with
implementation in thread.cc. Add members used for named semaphores.
(semaphore::terminate): New static method.
* include/semaphore.h: Redefine SEM_FAILED. Fix formatting.
(sem_unlink): Add declaration.
* include/cygwin/version.h: Bump API minor number.
(ipc_cond_init): Ditto.
(struct mq_hdr): Add mqh_uname member to store synchronization object
name.
(mq_open): Create unique synchronization object name and store in
mq_hdr->mqh_uname. Use this name in calls to ipc_mutex_init and
ipc_cond_init.
