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sysvshmem on GNU/Hurd
- From: "Alfred M\. Szmidt" <ams at gnu dot org>
- To: libc-alpha at sources dot redhat dot com
- Date: Fri, 04 Nov 2005 21:59:26 +0100
- Subject: sysvshmem on GNU/Hurd
- Reply-to: ams at gnu dot org
The following has been tested on Debian GNU/Hurd, could someone apply
it? I think it is OK.
2005-07-11 Marcus Brinkmann <marcus@gnu.org>
* hurd/Makefile (routines): Add sysvshm.
(distribute): Add sysvshm.h.
* hurd/sysvshm.h: New file.
* hurd/sysvshm.c: New file.
* sysdeps/mach/hurd/bits/stat.h (S_IMMAP0): New macro.
(S_ISPARE): Unset the S_IMMAP0 flag.
* sysdeps/mach/hurd/ftok.c: New file.
* sysdeps/mach/hurd/shmat.c: New file.
* sysdeps/mach/hurd/shmctl.c: New file.
* sysdeps/mach/hurd/shmdt.c: New file.
diff -rupN libc/hurd/Makefile libc-shm/hurd/Makefile
--- libc/hurd/Makefile 2002-10-14 03:03:09.000000000 +0200
+++ libc-shm/hurd/Makefile 2005-07-12 12:27:06.000000000 +0200
@@ -60,6 +60,7 @@ routines = hurdstartup hurdinit \
vpprintf \
ports-get ports-set hurdports hurdmsg \
errno-loc \
+ sysvshm \
$(sig) $(dtable) $(inlines) port-cleanup report-wait
sig = hurdsig hurdfault siginfo hurd-raise preempt-sig \
trampoline longjmp-ts catch-exc exc2signal hurdkill sigunwind \
@@ -68,7 +69,7 @@ dtable = dtable port2fd new-fd alloc-fd
getdport openport \
fd-close fd-read fd-write hurdioctl ctty-input ctty-output
inlines = $(inline-headers:%.h=%-inlines)
-distribute = hurdstartup.h hurdfault.h hurdhost.h \
+distribute = hurdstartup.h hurdfault.h hurdhost.h sysvshm.h \
faultexc.defs intr-rpc.defs intr-rpc.h intr-msg.h Notes
# XXX this is a temporary hack; see hurdmalloc.h
diff -rupN libc/hurd/sysvshm.c libc-shm/hurd/sysvshm.c
--- libc/hurd/sysvshm.c 1970-01-01 01:00:00.000000000 +0100
+++ libc-shm/hurd/sysvshm.c 2005-07-11 22:57:25.000000000 +0200
@@ -0,0 +1,96 @@
+/* Copyright (C) 2005 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include <sys/shm.h>
+
+
+/* Description of an shm attachment. */
+struct sysvshm_attach
+{
+ /* Linked list. */
+ struct sysvshm_attach *next;
+
+ /* Map address. */
+ void *addr;
+
+ /* Map size. */
+ size_t size;
+};
+
+/* List of attachments. */
+static struct sysvshm_attach *attach_list;
+
+/* A lock to protect the linked list of shared memory attachments. */
+static struct mutex sysvshm_lock = MUTEX_INITIALIZER;
+
+
+/* Adds a segment attachment. */
+error_t
+__sysvshm_add (void *addr, size_t size)
+{
+ struct sysvshm_attach *shm;
+
+ shm = malloc (sizeof (*shm));
+ if (!shm)
+ return errno;
+
+ __mutex_lock (&sysvshm_lock);
+ shm->addr = addr;
+ shm->size = size;
+ shm->next = attach_list;
+ attach_list = shm;
+ __mutex_unlock (&sysvshm_lock);
+
+ return 0;
+}
+
+/* Removes a segment attachment. Returns its size if found, or EINVAL
+ otherwise. */
+error_t
+__sysvshm_remove (void *addr, size_t *size)
+{
+ struct sysvshm_attach *shm;
+ struct sysvshm_attach **pshm = &attach_list;
+
+ __mutex_lock (&sysvshm_lock);
+ shm = attach_list;
+ while (shm)
+ {
+ shm = *pshm;
+ if (shm->addr == addr)
+ {
+ *pshm = shm->next;
+ *size = shm->size;
+ __mutex_unlock (&sysvshm_lock);
+ return 0;
+ }
+ pshm = &shm->next;
+ shm = shm->next;
+ }
+ __mutex_unlock (&sysvshm_lock);
+ return EINVAL;
+}
diff -rupN libc/hurd/sysvshm.h libc-shm/hurd/sysvshm.h
--- libc/hurd/sysvshm.h 1970-01-01 01:00:00.000000000 +0100
+++ libc-shm/hurd/sysvshm.h 2005-07-11 22:57:25.000000000 +0200
@@ -0,0 +1,47 @@
+/* Copyright (C) 2005 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <paths.h>
+#include <hurd.h>
+
+/* The area (from top to bottom) that is used for private keys. These
+ are all keys that have the second highest bit set. */
+#define SHM_PRIV_KEY_START INT_MAX
+#define SHM_PRIV_KEY_END ((INT_MAX / 2) + 1)
+
+#define SHM_PREFIX "shm-"
+#define SHM_DIR _PATH_DEV "shm/"
+
+/* The maximum number of characters in a shared memory segment file name.
+ 32 is the max number of characters in a 128 bit number in hex. */
+#if __WORDSIZE > 128
+#error Need to increase SHM_NAMEMAX.
+#else
+#define SHM_NAMEMAX (sizeof (SHM_PREFIX) - 1 + 32 + 1)
+#endif
+
+/* Use this with printf and its variants. */
+#define SHM_NAMEPRI SHM_PREFIX "%0x"
+
+
+/* Adds a segment attachment. */
+error_t __sysvshm_add (void *addr, size_t size);
+
+/* Removes a segment attachment. Returns its size if found, or EINVAL
+ otherwise. */
+error_t __sysvshm_remove (void *addr, size_t *size);
diff -rupN libc/sysdeps/mach/hurd/bits/stat.h libc-shm/sysdeps/mach/hurd/bits/stat.h
--- libc/sysdeps/mach/hurd/bits/stat.h 2005-07-11 23:39:36.000000000 +0200
+++ libc-shm/sysdeps/mach/hurd/bits/stat.h 2005-07-11 22:58:05.000000000 +0200
@@ -1,4 +1,4 @@
-/* Copyright (C) 1992, 93, 94, 96, 97, 99, 2000 Free Software Foundation, Inc.
+/* Copyright (C) 1992,93,94,96,97,99,2000,2005 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -182,8 +182,11 @@ struct stat64
/* All the bits relevant to translators */
#define S_ITRANS 000070000000
+/* Definitely no mmaps to this. */
+#define S_IMMAP0 000100000000
+
/* ALL the unused bits. */
-#define S_ISPARE (~(S_IFMT|S_ITRANS|S_INOCACHE| \
+#define S_ISPARE (~(S_IFMT|S_ITRANS|S_INOCACHE|S_IMMAP0| \
S_IUSEUNK|S_IUNKNOWN|07777))
#endif
diff -rupN libc/sysdeps/mach/hurd/ftok.c libc-shm/sysdeps/mach/hurd/ftok.c
--- libc/sysdeps/mach/hurd/ftok.c 1970-01-01 01:00:00.000000000 +0100
+++ libc-shm/sysdeps/mach/hurd/ftok.c 2005-07-11 22:57:25.000000000 +0200
@@ -0,0 +1,43 @@
+/* Copyright (C) 1995, 1996, 2000, 2005 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <sys/ipc.h>
+#include <sys/stat.h>
+
+
+/* In the Hurd, we use the second-to-most-significant bit as flag for
+ private keys. We use a different order of the components so that
+ the biggest one---the inode number---is affected by this. */
+
+key_t
+ftok (pathname, proj_id)
+ const char *pathname;
+ int proj_id;
+{
+ struct stat64 st;
+ key_t key;
+
+ if (__xstat64 (_STAT_VER, pathname, &st) < 0)
+ return (key_t) -1;
+
+ key = ((st.st_dev & 0xff) | ((proj_id & 0xff) << 8)
+ | ((st.st_ino & 0x3fff) << 16));
+
+ return key;
+}
diff -rupN libc/sysdeps/mach/hurd/shmat.c libc-shm/sysdeps/mach/hurd/shmat.c
--- libc/sysdeps/mach/hurd/shmat.c 1970-01-01 01:00:00.000000000 +0100
+++ libc-shm/sysdeps/mach/hurd/shmat.c 2005-07-12 12:28:20.000000000 +0200
@@ -0,0 +1,78 @@
+/* Copyright (C) 2005 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <errno.h>
+#include <utime.h>
+#include <stdio.h>
+#include <assert.h>
+#include <sys/mman.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <sys/time.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "sysvshm.h"
+
+/* Attach the shared memory segment associated with SHMID to the data
+ segment of the calling process. SHMADDR and SHMFLG determine how
+ and where the segment is attached. */
+void *
+__shmat (int shmid, const void *shmaddr, int shmflg)
+{
+ error_t err;
+ char filename[sizeof (SHM_DIR) - 1 + SHM_NAMEMAX];
+ int fd;
+ void *addr;
+ struct stat statbuf;
+ int res;
+
+ sprintf (filename, SHM_DIR SHM_NAMEPRI, shmid);
+ fd = __open (filename, (shmflg & SHM_RDONLY) ? O_RDONLY : O_RDWR);
+ if (fd < 0)
+ {
+ if (errno == ENOENT)
+ errno = EINVAL;
+ return (void *) -1;
+ }
+
+ res = __fstat (fd, &statbuf);
+ if (res < 0)
+ {
+ __close (fd);
+ return (void *) -1;
+ }
+
+ addr = __mmap ((void *) shmaddr, statbuf.st_size,
+ PROT_READ | ((shmflg & SHM_RDONLY) ? 0 : PROT_WRITE),
+ MAP_SHARED, fd, 0);
+ __close (fd);
+ if (addr == MAP_FAILED)
+ return (void *) -1;
+
+ err = __sysvshm_add (addr, statbuf.st_size);
+ if (err)
+ {
+ munmap (addr, statbuf.st_size);
+ return (void *) -1;
+ }
+
+ return addr;
+}
+
+weak_alias(__shmat, shmat)
diff -rupN libc/sysdeps/mach/hurd/shmctl.c libc-shm/sysdeps/mach/hurd/shmctl.c
--- libc/sysdeps/mach/hurd/shmctl.c 1970-01-01 01:00:00.000000000 +0100
+++ libc-shm/sysdeps/mach/hurd/shmctl.c 2005-07-12 12:28:25.000000000 +0200
@@ -0,0 +1,132 @@
+/* Copyright (C) 2005 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "sysvshm.h"
+
+/* Provide operations to control over shared memory segments. */
+int
+__shmctl (int id, int cmd, struct shmid_ds *buf)
+{
+ error_t err = 0;
+ int fd;
+ int res;
+ char filename[sizeof (SHM_DIR) - 1 + SHM_NAMEMAX];
+ struct stat statbuf;
+
+ sprintf (filename, SHM_DIR SHM_NAMEPRI, id);
+ /* SysV requires read access for IPC_STAT. */
+ fd = __open (filename, O_NORW);
+ if (fd < 0)
+ {
+ if (errno == ENOENT)
+ errno = EINVAL;
+ return -1;
+ }
+
+ res = __fstat (fd, &statbuf);
+ if (res < 0)
+ {
+ err = errno;
+ __close (fd);
+ errno = err;
+ return -1;
+ }
+
+ switch (cmd)
+ {
+ case IPC_STAT:
+
+ buf->shm_perm.__key = id;
+ buf->shm_perm.uid = statbuf.st_uid;
+ buf->shm_perm.gid = statbuf.st_gid;
+
+ /* We do not support the creator. */
+ buf->shm_perm.cuid = statbuf.st_uid;
+ buf->shm_perm.cgid = statbuf.st_gid;
+
+ /* We just want the protection bits. */
+ buf->shm_perm.mode = statbuf.st_mode & 0777;
+ /* Hopeless. We do not support a sequence number. */
+ buf->shm_perm.__seq = statbuf.st_ino;
+ buf->shm_segsz = statbuf.st_size;
+
+ /* Hopeless. We do not support any of these. */
+ buf->shm_atime = statbuf.st_atime;
+ buf->shm_dtime = statbuf.st_mtime;
+ /* Well, this comes at least close. */
+ buf->shm_ctime = statbuf.st_ctime;
+
+ /* We do not support the PID. */
+ buf->shm_cpid = 0;
+ buf->shm_lpid = 0;
+
+ if (statbuf.st_mode & S_IMMAP0)
+ buf->shm_nattch = 0;
+ else
+ /* 42 is the answer. Of course this is bogus, but for most
+ applications, this should be fine. */
+ buf->shm_nattch = 42;
+
+ break;
+
+ case IPC_SET:
+ if (statbuf.st_uid != buf->shm_perm.uid
+ || statbuf.st_gid != buf->shm_perm.gid)
+ {
+ res = __fchown (fd,
+ (statbuf.st_uid != buf->shm_perm.uid)
+ ? buf->shm_perm.uid : -1,
+ (statbuf.st_gid != buf->shm_perm.gid)
+ ? buf->shm_perm.gid : -1);
+ if (res < 0)
+ err = errno;
+ }
+
+ if (!err && statbuf.st_mode & 0777 != buf->shm_perm.mode & 0777)
+ {
+ res = __fchmod (fd, (statbuf.st_mode & ~0777)
+ | (buf->shm_perm.mode & 0777));
+ if (res < 0)
+ err = errno;
+ }
+ break;
+
+ case IPC_RMID:
+ res = __unlink (filename);
+ /* FIXME: Check error (mapping ENOENT to EINVAL). */
+ break;
+
+ default:
+ err = EINVAL;
+ }
+
+ __close (fd);
+ errno = err;
+ return err ? -1 : 0;
+}
+
+weak_alias(__shmctl, shmctl)
diff -rupN libc/sysdeps/mach/hurd/shmdt.c libc-shm/sysdeps/mach/hurd/shmdt.c
--- libc/sysdeps/mach/hurd/shmdt.c 1970-01-01 01:00:00.000000000 +0100
+++ libc-shm/sysdeps/mach/hurd/shmdt.c 2005-07-11 22:57:25.000000000 +0200
@@ -0,0 +1,51 @@
+/* Copyright (C) 2005 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <stdio.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <assert.h>
+#include <sys/mman.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <sys/time.h>
+#include <sys/stat.h>
+
+#include "sysvshm.h"
+
+/* Detach shared memory segment starting at address specified by
+ SHMADDR from the caller's data segment. */
+int
+__shmdt (const void *shmaddr)
+{
+ error_t err;
+ size_t size;
+
+ err = __sysvshm_remove ((void *) shmaddr, &size);
+ if (err)
+ {
+ errno = err;
+ return -1;
+ }
+
+ __munmap ((void *) shmaddr, size);
+ return 0;
+}
+
+weak_alias(__shmdt, shmdt)
diff -rupN libc/sysdeps/mach/hurd/shmget.c libc-shm/sysdeps/mach/hurd/shmget.c
--- libc/sysdeps/mach/hurd/shmget.c 1970-01-01 01:00:00.000000000 +0100
+++ libc-shm/sysdeps/mach/hurd/shmget.c 2005-07-11 22:57:25.000000000 +0200
@@ -0,0 +1,245 @@
+/* Copyright (C) 2005 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/shm.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <limits.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <hurd/fd.h>
+
+#include "sysvshm.h"
+
+/* Create a new shared memory segment file without linking it into the
+ filesystem. Return the directory and file ports in R_DIR and R_FILE. */
+static error_t
+create_shm_file (size_t size, int flags, file_t *r_dir, file_t *r_file)
+{
+ error_t err;
+ file_t dir;
+ file_t file;
+
+ flags &= 0777;
+
+ /* Get a port to the directory that will contain the file. */
+ dir = __file_name_lookup (SHM_DIR, 0, 0);
+ if (dir == MACH_PORT_NULL)
+ return errno;
+
+ /* Create an unnamed file in the directory. */
+ err = __dir_mkfile (dir, O_RDWR, flags, &file);
+ if (err)
+ {
+ __mach_port_deallocate (__mach_task_self (), dir);
+ return err;
+ }
+
+ err = __file_set_size (file, size);
+ if (err)
+ {
+ __mach_port_deallocate (__mach_task_self (), file);
+ __mach_port_deallocate (__mach_task_self (), dir);
+
+ return err;
+ }
+
+ *r_dir = dir;
+ *r_file = file;
+
+ return 0;
+}
+
+
+/* Open the shared memory segment *R_KEY and return a file descriptor
+ to it in R_FD. If KEY is IPC_PRIVATE, use a private key and return
+ it in R_KEY. */
+static error_t
+get_exclusive (int shmflags, size_t size, key_t *r_key, int *r_fd)
+{
+ error_t err;
+ file_t dir;
+ file_t file;
+ char filename[SHM_NAMEMAX];
+ key_t key = *r_key;
+ bool is_private;
+
+ /* Create the shared memory segment. */
+ err = create_shm_file (size, shmflags, &dir, &file);
+ if (err)
+ return err;
+
+ if (key == IPC_PRIVATE)
+ {
+ is_private = true;
+ key = SHM_PRIV_KEY_START;
+
+ /* Try to link the shared memory segment into the filesystem
+ (exclusively). Private segments have negative keys. */
+ do
+ {
+ sprintf (filename, SHM_NAMEPRI, key);
+ err = __dir_link (dir, file, filename, 1);
+ if (!err)
+ {
+ /* We are done. */
+ *r_key = key;
+ break;
+ }
+ else if (err == EEXIST)
+ {
+ /* Check if we ran out of keys. If not, try again with new
+ key. */
+ if (key == SHM_PRIV_KEY_END)
+ err = ENOSPC;
+ else
+ err = 0;
+
+ key--;
+ }
+ }
+ while (!err);
+ }
+ else
+ {
+ /* Try to link the shared memory segment into the filesystem
+ (exclusively) under the given key. */
+ sprintf (filename, SHM_NAMEPRI, key);
+ err = __dir_link (dir, file, filename, 1);
+ }
+
+ __mach_port_deallocate (__mach_task_self (), dir);
+
+ if (!err)
+ {
+ int fd;
+
+ /* Get a file descriptor for that port. */
+ fd = _hurd_intern_fd (file, O_RDWR, 1); /* dealloc on error */
+ if (fd < 0)
+ err = errno;
+ else
+ *r_fd = fd;
+ }
+
+ return err;
+}
+
+
+/* Open the shared memory segment KEY (creating it if it doesn't yet
+ exist) and return a file descriptor to it in R_FD. */
+static error_t
+get_shared (int shmflags, size_t size, key_t key, int *r_fd)
+{
+ error_t err = 0;
+ char filename[sizeof (SHM_DIR) - 1 + SHM_NAMEMAX];
+ int fd = -1;
+ int create_flag;
+
+ create_flag = (shmflags & IPC_CREAT) ? O_CREAT : 0;
+ sprintf (filename, SHM_DIR SHM_NAMEPRI, key);
+
+ do
+ {
+ fd = __open (filename, O_NORW | create_flag, shmflags & 0777);
+
+ if (fd < 0 && errno != ENOENT)
+ /* We give up. */
+ return errno;
+ else if (fd >= 0)
+ {
+ int res;
+ struct stat statbuf;
+
+ /* Check the size (we only need to do this if we did not
+ create the shared memory segment file ourselves). */
+ res = __fstat (fd, &statbuf);
+ if (res < 0)
+ {
+ err = errno;
+ __close (fd);
+ return err;
+ }
+
+ if (statbuf.st_size < size)
+ {
+ __close (fd);
+ return EINVAL;
+ }
+ }
+ else
+ {
+ /* The memory segment doesn't exist. */
+ if (create_flag)
+ {
+ /* Try to create it exclusively. */
+ err = get_exclusive (shmflags, size, &key, &fd);
+ if (err == EEXIST)
+ /* If somebody created it in the meanwhile, just try again. */
+ err = 0;
+ }
+ else
+ err = ENOENT;
+ }
+ }
+ while (fd < 0 && !err);
+
+ if (!err)
+ *r_fd = fd;
+ else
+ *r_fd = -1;
+
+ return err;
+}
+
+/* Return an identifier for an shared memory segment of at least size
+ SIZE which is associated with KEY. */
+int
+__shmget (key_t key, size_t size, int shmflags)
+{
+ error_t err;
+ int fd;
+
+ if (key == IPC_PRIVATE || shmflags & IPC_EXCL)
+ /* An exclusive shared memory segment must be created. */
+ err = get_exclusive (shmflags, size, &key, &fd);
+ else
+ err = get_shared (shmflags, size, key, &fd);
+
+ if (err)
+ {
+ errno = err;
+ return -1;
+ }
+
+ /* From here, we can't fail. That's important, as otherwise we
+ would need to unlink the file if we created it (in that case, the
+ code above would have to be changed to pass a "created" flag down
+ to the caller). */
+
+ __close (fd);
+
+ return key;
+}
+
+weak_alias(__shmget, shmget)