diff options
Diffstat (limited to 'winsup/cygwin/posix_ipc.cc')
| -rw-r--r-- | winsup/cygwin/posix_ipc.cc | 237 |
1 files changed, 219 insertions, 18 deletions
diff --git a/winsup/cygwin/posix_ipc.cc b/winsup/cygwin/posix_ipc.cc index c286b2483..492b96a49 100644 --- a/winsup/cygwin/posix_ipc.cc +++ b/winsup/cygwin/posix_ipc.cc @@ -8,12 +8,8 @@ This software is a copyrighted work licensed under the terms of the Cygwin license. Please consult the file "CYGWIN_LICENSE" for details. */ -/* TODO: POSIX semaphores are implemented in thread.cc right now. The - implementation in thread.cc disallows implementing kernel - persistent semaphores, so in the long run we should move the - implementation here, using file based shared memory instead. */ - #include "winsup.h" +#include "thread.h" #include "path.h" #include "cygerrno.h" #include "cygtls.h" @@ -29,22 +25,24 @@ details. */ #include <unistd.h> #include <stdarg.h> #include <mqueue.h> +#include <semaphore.h> struct { const char *prefix; + const size_t max_len; const char *description; } ipc_names[] = { - { "/dev/shm", "POSIX shared memory object" }, - { "/dev/mqueue", "POSIX message queue" }, - { "/dev/sem", "POSIX semaphore" } + { "/dev/shm", CYG_MAX_PATH - 10, "POSIX shared memory object" }, + { "/dev/mqueue", CYG_MAX_PATH - 13, "POSIX message queue" }, + { "/dev/shm", CYG_MAX_PATH - 14, "POSIX semaphore" } }; enum ipc_type_t { shmem, mqueue, - sem + semaphore }; static bool @@ -69,20 +67,21 @@ check_path (char *res_name, ipc_type_t type, const char *name) return false; } /* Name must start with a single slash. */ - if (!name || name[0] != '/' || name[1] == '/') + if (!name || name[0] != '/' || name[1] == '/' || !name[1]) { debug_printf ("Invalid %s name '%s'", ipc_names[type].description, name); set_errno (EINVAL); return false; } - if (strlen (name) > CYG_MAX_PATH - sizeof (ipc_names[type].prefix)) + if (strlen (name) > ipc_names[type].max_len) { debug_printf ("%s name '%s' too long", ipc_names[type].description, name); set_errno (ENAMETOOLONG); return false; } - strcpy (res_name, ipc_names[type].prefix); - strcat (res_name, name); + __small_sprintf (res_name, "%s/%s%s", ipc_names[type].prefix, + type == semaphore ? "sem." : "", + name + 1); return true; } @@ -133,7 +132,6 @@ static int ipc_cond_init (HANDLE *pevt, const char *name) { char buf[CYG_MAX_PATH]; - strcpy (buf, wincap.has_terminal_services () ? "Global\\" : ""); __small_sprintf (buf, "%scyg_pevt/%s", wincap.has_terminal_services () ? "Global\\" : "", name); *pevt = CreateEvent (&sec_all, TRUE, FALSE, buf); @@ -195,6 +193,30 @@ ipc_cond_close (HANDLE evt) return CloseHandle (evt) ? 0 : geterrno_from_win_error (); } +class ipc_flock +{ + struct __flock64 fl; + +public: + ipc_flock () { memset (&fl, 0, sizeof fl); } + + int lock (int fd, size_t size) + { + fl.l_type = F_WRLCK; + fl.l_whence = SEEK_SET; + fl.l_start = 0; + fl.l_len = size; + return fcntl (fd, F_SETLKW, &fl); + } + int unlock (int fd) + { + if (!fl.l_len) + return 0; + fl.l_type = F_UNLCK; + return fcntl (fd, F_SETLKW, &fl); + } +}; + /* POSIX shared memory object implementation. */ extern "C" int @@ -242,7 +264,7 @@ struct mq_hdr long mqh_free; /* index of first free message */ long mqh_nwait; /* #threads blocked in mq_receive() */ pid_t mqh_pid; /* nonzero PID if mqh_event set */ - char mqh_uname[20]; /* unique name used to identify synchronization + char mqh_uname[36]; /* unique name used to identify synchronization objects connected to this queue */ struct sigevent mqh_event; /* for mq_notify() */ }; @@ -288,6 +310,7 @@ mq_open (const char *name, int oflag, ...) struct msg_hdr *msghdr; struct mq_attr *attr; struct mq_info *mqinfo; + LUID luid; char mqname[CYG_MAX_PATH]; if (!check_path (mqname, mqueue, name)) @@ -295,8 +318,9 @@ mq_open (const char *name, int oflag, ...) myfault efault; if (efault.faulted (EFAULT)) - return (mqd_t) -1; + return (mqd_t) -1; + oflag &= (O_CREAT | O_EXCL | O_NONBLOCK); created = 0; nonblock = oflag & O_NONBLOCK; oflag &= ~O_NONBLOCK; @@ -358,7 +382,14 @@ again: mqhdr->mqh_attr.mq_curmsgs = 0; mqhdr->mqh_nwait = 0; mqhdr->mqh_pid = 0; - __small_sprintf (mqhdr->mqh_uname, "cyg%016X", hash_path_name (0,mqname)); + if (!AllocateLocallyUniqueId (&luid)) + { + __seterrno (); + goto err; + } + __small_sprintf (mqhdr->mqh_uname, "cyg%016X%08x%08x", + hash_path_name (0,mqname), + luid.HighPart, luid.LowPart); mqhdr->mqh_head = 0; index = sizeof (struct mq_hdr); mqhdr->mqh_free = index; @@ -402,7 +433,7 @@ exists: { if (errno == ENOENT && (oflag & O_CREAT)) { - close(fd); + close (fd); goto again; } goto err; @@ -847,3 +878,173 @@ mq_unlink (const char *name) return 0; } +/* POSIX named semaphore implementation. Loosely based on Richard W. STEPHENS + implementation as far as sem_open is concerned, but under the hood using + the already existing semaphore class in thread.cc. Using a file backed + solution allows to implement kernel persistent named semaphores. */ + +struct sem_finfo +{ + unsigned int value; + unsigned long long hash; + LUID luid; +}; + +extern "C" sem_t * +sem_open (const char *name, int oflag, ...) +{ + int i, fd, created; + va_list ap; + mode_t mode = 0; + unsigned int value = 0; + struct __stat64 statbuff; + sem_t *sem = SEM_FAILED; + sem_finfo sf; + char semname[CYG_MAX_PATH]; + bool wasopen = false; + ipc_flock file; + + if (!check_path (semname, semaphore, name)) + return SEM_FAILED; + + myfault efault; + if (efault.faulted (EFAULT)) + return SEM_FAILED; + + created = 0; + oflag &= (O_CREAT | O_EXCL); + +again: + if (oflag & O_CREAT) + { + va_start (ap, oflag); /* init ap to final named argument */ + mode = va_arg (ap, mode_t) & ~S_IXUSR; + value = va_arg (ap, unsigned int); + va_end (ap); + + /* Open and specify O_EXCL and user-execute */ + fd = open (semname, oflag | O_EXCL | O_RDWR, mode | S_IXUSR); + if (fd < 0) + { + if (errno == EEXIST && (oflag & O_EXCL) == 0) + goto exists; /* already exists, OK */ + return SEM_FAILED; + } + created = 1; + /* First one to create the file initializes it. */ + if (!AllocateLocallyUniqueId (&sf.luid)) + { + __seterrno (); + goto err; + } + sf.value = value; + sf.hash = hash_path_name (0, semname); + if (write (fd, &sf, sizeof sf) != sizeof sf) + goto err; + sem = semaphore::open (sf.hash, sf.luid, fd, oflag, mode, value, wasopen); + if (sem == SEM_FAILED) + goto err; + /* Initialization complete, turn off user-execute bit */ + if (fchmod (fd, mode) == -1) + goto err; + /* Don't close (fd); */ + return sem; + } + +exists: + /* Open the file and fetch the semaphore name. */ + if ((fd = open (semname, O_RDWR)) < 0) + { + if (errno == ENOENT && (oflag & O_CREAT)) + goto again; + goto err; + } + /* Make certain initialization is complete */ + for (i = 0; i < MAX_TRIES; i++) + { + if (stat64 (semname, &statbuff) == -1) + { + if (errno == ENOENT && (oflag & O_CREAT)) + { + close (fd); + goto again; + } + goto err; + } + if ((statbuff.st_mode & S_IXUSR) == 0) + break; + sleep (1); + } + if (i == MAX_TRIES) + { + set_errno (ETIMEDOUT); + goto err; + } + if (file.lock (fd, sizeof sf)) + goto err; + if (read (fd, &sf, sizeof sf) != sizeof sf) + goto err; + sem = semaphore::open (sf.hash, sf.luid, fd, oflag, mode, sf.value, wasopen); + file.unlock (fd); + if (sem == SEM_FAILED) + goto err; + /* If wasopen is set, the semaphore was already opened and we already have + an open file descriptor pointing to the file. This means, we have to + close the file descriptor created in this call. It won't be stored + anywhere anyway. */ + if (wasopen) + close (fd); + return sem; + +err: + /* Don't let following function calls change errno */ + save_errno save; + + file.unlock (fd); + if (created) + unlink (semname); + if (sem != SEM_FAILED) + semaphore::close (sem); + close (fd); + return SEM_FAILED; +} + +int +_sem_close (sem_t *sem, bool do_close) +{ + sem_finfo sf; + int fd, ret = -1; + ipc_flock file; + + if (semaphore::getinternal (sem, &fd, &sf.hash, &sf.luid, &sf.value) == -1) + return -1; + if (!file.lock (fd, sizeof sf) + && lseek64 (fd, 0LL, SEEK_SET) != (_off64_t) -1 + && write (fd, &sf, sizeof sf) == sizeof sf) + ret = do_close ? semaphore::close (sem) : 0; + + /* Don't let following function calls change errno */ + save_errno save; + file.unlock (fd); + close (fd); + + return ret; +} + +extern "C" int +sem_close (sem_t *sem) +{ + return _sem_close (sem, true); +} + +extern "C" int +sem_unlink (const char *name) +{ + char semname[CYG_MAX_PATH]; + + if (!check_path (semname, semaphore, name)) + return -1; + if (unlink (semname) == -1) + return -1; + return 0; +} |