History log of /freebsd-10.2-release/lib/libc/sys/shm_open.2
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# 285830 23-Jul-2015 gjb

- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

# 256281 10-Oct-2013 gjb

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation


# 235140 08-May-2012 gjb

General mdoc(7) and typo fixes.

PR: 167713
Submitted by: Nobuyuki Koganemaru (kogane!jp.freebsd.org)


# 233462 25-Mar-2012 joel

Remove superfluous paragraph macro.


# 211397 16-Aug-2010 joel

Fix typos, spelling, formatting and mdoc mistakes found by Nobuyuki while
translating these manual pages. Minor corrections by me.

Submitted by: Nobuyuki Koganemaru <n-kogane@syd.odn.ne.jp>


# 203161 29-Jan-2010 rwatson

You must include fcntl.h (in practice) to be able to do anything useful
with shm_open(2), as otherwise the O_ flags are undefined.

MFC after: 3 days


# 175164 08-Jan-2008 jhb

Add a new file descriptor type for IPC shared memory objects and use it to
implement shm_open(2) and shm_unlink(2) in the kernel:
- Each shared memory file descriptor is associated with a swap-backed vm
object which provides the backing store. Each descriptor starts off with
a size of zero, but the size can be altered via ftruncate(2). The shared
memory file descriptors also support fstat(2). read(2), write(2),
ioctl(2), select(2), poll(2), and kevent(2) are not supported on shared
memory file descriptors.
- shm_open(2) and shm_unlink(2) are now implemented as system calls that
manage shared memory file descriptors. The virtual namespace that maps
pathnames to shared memory file descriptors is implemented as a hash
table where the hash key is generated via the 32-bit Fowler/Noll/Vo hash
of the pathname.
- As an extension, the constant 'SHM_ANON' may be specified in place of the
path argument to shm_open(2). In this case, an unnamed shared memory
file descriptor will be created similar to the IPC_PRIVATE key for
shmget(2). Note that the shared memory object can still be shared among
processes by sharing the file descriptor via fork(2) or sendmsg(2), but
it is unnamed. This effectively serves to implement the getmemfd() idea
bandied about the lists several times over the years.
- The backing store for shared memory file descriptors are garbage
collected when they are not referenced by any open file descriptors or
the shm_open(2) virtual namespace.

Submitted by: dillon, peter (previous versions)
Submitted by: rwatson (I based this on his version)
Reviewed by: alc (suggested converting getmemfd() to shm_open())


# 140505 20-Jan-2005 ru

Sort sections.


# 131635 05-Jul-2004 ru

Fix the NAME section making whatis(1) happy in particular.


# 131504 02-Jul-2004 ru

Mechanically kill hard sentence breaks.


# 84306 01-Oct-2001 ru

mdoc(7) police: Use the new .In macro for #include statements.


# 80898 01-Aug-2001 sheldonh

MFS: in HISTORY section, fix release number of first appearance


# 73090 26-Feb-2001 ru

``.St -p1003.1b'' -> ``.St -p1003.1b-93''.


# 68946 20-Nov-2000 ru

mdoc(7) police: Nm -> Fn where appropriate.


# 68854 17-Nov-2000 ru

mdoc(7) police: use certified section headers wherever possible.


# 67967 30-Oct-2000 asmodai

Whitespace only change: trim trailing whitespace.


# 59551 23-Apr-2000 wollman

Spell MAP_NOSYNC correctly.

Submitted by: allenc@verinet.com


# 59527 23-Apr-2000 wollman

.Lb-ify


# 59497 22-Apr-2000 wollman

Add shm_open(3) and shm_unlink(3). The documentation could use a good
bit of work (and is stylistically probably the worst manual page
I've ever written).