The interfaces documented in this page are purely glibc.
Reported-by: Colin Watson <cjwatson@ubuntu.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
When a 32-bit app opens a file whose size is too big to be
represented in 31-bits, POSIX.1 specifies the error EOVERFLOW.
Linux used to give EFBIG for this case, but 2.6.24 fixed this.
Also, add some text to describe the error scenario in
more detail.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Some errors were listed under a separate "may" heading.
There's probably no real need to do this; integrate
those errors into the main list.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Most other sockets pages are using the names 'addr'
and 'addrlen'; make these pages do the same.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
If the recvfrom() returned address is truncated, the 'fromlen'
argument indicates the actual size of the address, rather than
a count of the number of bytes in the truncated buffer.
Also clarify that the 'from' argument can be NULL, in which
case 'fromlen' should is unused, and should also be NULL.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
If the returned address is truncated, the 'addrlen' argument
indicates the actual size of the address, rather than a count
of the number of bytes in the truncated buffer.
Also clarify that if 'addr' argument is NULL, then 'addrlen'
should is unused, and should also be NULL.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Many sockets man pages use the name 'sockfd' already.
For consistency, changes the others to do so as well.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Mel Gorman reported that in Linux 2.6.27, 'addr' is rounded
down to a page boundary.
Before kernel 2.6.26, if 'addr' was taken as a hint, it was
rounded up to the next page boundary. Since Linux 2.6.24,
it is rounded down. Therefore, loosen the description of
this point to say that the address is rounded to "a nearby
page boundary".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reported-by: Mel Gorman <mel@csn.ul.ie>
Internet datagram (since Linux 2.4.27/2.6.8),
and netlink (since Linux 2.6.22) sockets support
the MSG_TRUNC flag for recv(2).
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Expand description of setdomainname() and getdomainname().
Note that getdomainname() is implemented as a library function
in glibc.
Note limits on size of domain name.
Reorganize ERRORS list.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Write a paragraph describing sethostname().
Clarify differences between glibc's gethostbyname() and
the kernel gethostbyname() system calls.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
If CLONE_NEWUTS is specified, the IDs are initialized
by duplicating from calling process.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: Serge E. Hallyn <serge@hallyn.com>
Many pages still mention use of the obsolete sysctl(2) system
call, or used the term "sysctls"; rewrite these mentions to
instead be in terms of /proc interfaces.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This was already stated under NOTES, but make it even more
prominent by adding a sentence at the start of the DESCRIPTION.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
When the last process in an IPC namespace is destroyed, the
IPC objects in that namespace are automatically destroyed.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reported-by: Cedric Le Goater <clg@fr.ibm.com>
This is more consistent with the term "mounts namespace"
used in the 2008 ACM SIGOPS paper, "Virtual servers
and and checkpoint/restart in mainstream Linux".
(I avoided the "s", because using the plural strikes me
as klunky English, and anyway we don't talk about
the "PIDs namespace" or the "networks namespace", etc..)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
In recent times, a number of other namespace flags have been
added to clone(2). As such, it is no longer clear to use
the generic term "namespace" to refer to the particular
namespace controlled by CLONE_NEWNS; instead, use the
term "mount-point namespace".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
I submitted a patch to fix this. See the LKML thread
"[patch] Fix type errors in inotify interfaces", 18 Nov 2008
If/when these patches are accepted, the pages need to be updated.
After Loic Domaigne's suggestion for pthread_setaffinity_np(3), add
similar text to this page noting that the system silently
limits the set of CPUs on which the process actually runs to
the set of CPUs physically present and the limits imposed by
cpuset(7).
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reported-by: Loic Domaigne <tech@domaigne.com>
Acked-by: Bert Wesarg <bert.wesarg@googlemail.com>
pthread_setaffinity_np() is preferable for setting
thread CPU affinity if using the POSIX threads API.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Many older pages use a handle_error() macro to do simple
error handling from system and library function calls.
Switch these pages to do similar.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
s/2.6.20/2.6.30/ to fix an earlier typo in the description
of the likely kernel version that will have fully fledged
real-time features.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
s/\.R " "/\\\&/ as a way of getting a blank line after a .SS heading.
(Suggested by Sam Varshavchik <mrsam@courier-mta.com>)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
For sched_setaffinity(), the EINVAL error that occurs
if 'cpusetsize' is smaller than the kernel CPU set size only
occurs with kernels before 2.6.9.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
So on a direct syscall, the EINVAL could also occur for bufsiz < 0.
But at the moment, the error text is sufficiently vague
("bufsiz is not positive") that a change to the man page text
is probably not needed.
The page was phrased in a few places to describe the child as
holding the parent's memory until the child does an execve(2)
or an _exit(2). The latter case should really be the more
general process termimation (i.e., either _exit(2) or abnormal
termination).
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reported-by: Valdis.Kletnieks@vt.edu
Some file systems provide partial support for 'dt_type',
returning DT_UNKNOWN for cases they don't support.
Update the discussion of 'd_type' and DT_UNKNOWN to
support this.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The man page was not explicit about how the memory used by
the child is released back to the parent.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reported-by: Halesh S <halesh.s@india.com>
In some cases, EINVAL can occur if 'optval' is invalid.
Note this, and point reader to an example in ip(7).
In response to:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=216092
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reported-by: Christian Grigis <glove@earthling.net>
Add ".SS Program source" to clearly distinguish shell session and
descriptive text from actual program code.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Strategic calls to sched_yield() can be used to improve
performance, but unnecessary use should be avoided.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The text formerly described the operation of sched_yield() in
terms of processes. It should be in terms of threads.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The page didn't previously clearly explain the scope of the
signal mask that is affected by sa_mask.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The first sentence of the page was vague on the scope of the
attribute changed by sigprocmask(). Reword to make this
clearer and add a sentence in NOTES to explicitly state that
the signal mask is a per-thread attribute.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Refer the reader to socket(2) for a description of the SOCK_CLOEXEC
and SOCK_NONBLOCK flags, which are supported by socketpair() since
Linux 2.6.27.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Remove sentence saying that glibc adds a flags argument to the syscall;
that was only relevant for the older eventfd() system call.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Remove sentence saying that glibc adds a flags argument to the syscall;
that was only relevant for the older signalfd() system call.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Linux 2.6.27 added signalfd4(), which supports a flags argument
that signalfd() did not provide. The flags so far implemented
are SFD_NONBLOCK and SFD_CLOEXEC.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The eventfd.2 page has some details on the eventfd2() system call,
which was new in Linux 2.6.27.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Linux 2.6.27 added eventfd(), which supports a flags argument
that eventfd() did not provide. The flags so far implemented
are EFD_NONBLOCK and EFD_CLOEXEC,
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The current wording suggests that only a single fcntl()
operation is needed to set the FD_CLOEXEC flag, when "proper"
usage would be fcntl(F_GETFD) + fcntl(F_SETFD) to get the
flags and then update them. So change the wording to indicate
that more than one fcntl() operation is required.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Supply a little more explanation about why the 'size' argument
of epoll_create() is nowadays ignored.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Glibc doesn't (and quite probably won't) include a wrapper for this
system call. Therefore, point out that potential callers will need
to use syscall(2), and rewrite the RETURN VALUE text to show things
as they would be if syscall() is used.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Add a para to start of page that points out that this is the
low-level, Linux-specific API, and point the reader to posix_fallocate(3)
for the portable API.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Describe per-process namespaces, including discussion
of clone() and unshare CLONE_NEWNS, and /proc/PID/mounts.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The length of this page means that it's becoming difficult to parse
which info is specific to mount() versus umount()/umount2(), so split
the umount material out into its own page.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Refer the reader to new text in execve(2) that describes how
(since Linux 2.6.23) RLIMIT_STACK determines the value of ARG_MAX.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
POSIX.1-2001 says that the values returned by sysconf()
are constant for the life of the process.
But the fact that, since Linux 2.6.23, ARG_MAX is settable
via RLIMIT_STACK means _SC_ARG_MAX is no longer constant,
since it can change at each execve().
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Starting with Linux 2.6.23, the ARG_MAX limit became settable via
(1/4 of) RLIMIT_STACK. This broke ABI compatibility if RLIMIT_STACK
was set such that ARG_MAX was < 32 pages. Document the fact that
since 2.6.25 Linux imposes a floor on ARG_MAX, so that the old limit
of 32 pages is guaranteed.
For some background on the changes to ARG_MAX in kernels 2.6.23 and
2.6.25, see:
http://sourceware.org/bugzilla/show_bug.cgi?id=5786http://bugzilla.kernel.org/show_bug.cgi?id=10095http://thread.gmane.org/gmane.linux.kernel/646709/focus=648101,
checked into 2.6.25 as commit a64e715fc74b1a7dcc5944f848acc38b2c4d4ee2.
Also some reordering/rewording of the discussion of ARG_MAX.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The old sentence sat on its own in an odd place, and anyway the
modern BSDs use the name RLIMIT_NOFILE.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk