From a979b72747e34add3433a23c0966490cd809120f Mon Sep 17 00:00:00 2001 From: Sergey Bugaev Date: Mon, 30 Jan 2023 15:52:16 +0300 Subject: hurd: Implement SHM_ANON This adds a special SHM_ANON value that can be passed into shm_open () in place of a name. When called in this way, shm_open () will create a new anonymous shared memory file. The file will be created in the same way that other shared memory files are created (i.e., under /dev/shm/), except that it is not given a name and therefore cannot be reached from the file system, nor by other calls to shm_open (). This is accomplished by utilizing O_TMPFILE. This is intended to be compatible with FreeBSD's API of the same name. Signed-off-by: Sergey Bugaev Message-Id: <20230130125216.6254-4-bugaevc@gmail.com> --- posix/shm-directory.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) (limited to 'posix') diff --git a/posix/shm-directory.c b/posix/shm-directory.c index 47e2355d0d..86d9fd8e4f 100644 --- a/posix/shm-directory.c +++ b/posix/shm-directory.c @@ -23,17 +23,34 @@ #include #include #include +#include +#include int __shm_get_name (struct shmdir_name *result, const char *name, bool sem_prefix) { + struct alloc_buffer buffer; + size_t namelen; + + buffer = alloc_buffer_create (result->name, sizeof (result->name)); + alloc_buffer_copy_bytes (&buffer, SHMDIR, strlen (SHMDIR)); + +#if defined (SHM_ANON) && defined (O_TMPFILE) + if (name == SHM_ANON) + { + /* For SHM_ANON, we want shm_open () to pass O_TMPFILE to open (), + with SHMDIR itself as the path. So, leave it at that. */ + alloc_buffer_add_byte (&buffer, 0); + if (alloc_buffer_has_failed (&buffer)) + return -1; + return 0; + } +#endif + while (name[0] == '/') ++name; - size_t namelen = strlen (name); + namelen = strlen (name); - struct alloc_buffer buffer - = alloc_buffer_create (result->name, sizeof (result->name)); - alloc_buffer_copy_bytes (&buffer, SHMDIR, strlen (SHMDIR)); if (sem_prefix) alloc_buffer_copy_bytes (&buffer, "sem.", strlen ("sem.")); alloc_buffer_copy_bytes (&buffer, name, namelen + 1); -- cgit 1.4.1