This patch isolates the since/version related fixes as requested.
This change introduces the following delta:
* The page states it was added in 2.6.32 but it is only added
2.6.33 (ref: http://kernelnewbies.org/Linux_2_6_33)
* The MSG_WAITFORONE flag was in turn only added in 2.6.34
(ref: http://kernelnewbies.org/Linux_2_6_34)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The return error EDQUOT is not documented in open(2), write(2),
symlink(2) etc..
Whether inodes or disk blocks are required for each function
is something I based on received wisdom and BSD documentation,
rather than tracing the code to the kernel. For symlink(2)
this certainly depends on the file system type.
This patch was previously sent to the linux-man mailing list
as an RFC in September 2010.
Signed-off-by: Mark Hills <mark@pogo.org.uk>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The example uses sendmmsg() to send out a string "onetwo"
on a first datagram, where both halves originate from
distinct buffers and a second datagram contains "three",
coming from a single buffer.
Tested with netcat listening:
root@ubuntu:~# nc -l -u -p 1234
onetwothree
And tcpdump peeking:
root@ubuntu:~# tcpdump -c 2 -s 0 -X -ni lo tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 65535 bytes
18:45:16.632134 IP 127.0.0.1.34715 > 127.0.0.1.1234: UDP, length 6
0x0000: 4500 0022 c21c 4000 4011 7aac 7f00 0001 E.."..@.@.z.....
0x0010: 7f00 0001 879b 04d2 000e fe21 6f6e 6574 ...........!onet
0x0020: 776f wo
18:45:16.633267 IP 127.0.0.1.34715 > 127.0.0.1.1234: UDP, length 5
0x0000: 4500 0021 c21d 4000 4011 7aac 7f00 0001 E..!..@.@.z.....
0x0010: 7f00 0001 879b 04d2 000d fe20 7468 7265 ............thre
0x0020: 65 e
2 packets captured
4 packets received by filter
0 packets dropped by kernel
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
SYSLOG_ACTION_SIZE_UNREAD returns the number of bytes
available for reading via SYSLOG_ACTION_READ.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The SYSLOG_ACTION_CLEAR command (5) does not really clear
the ring buffer; rather it affects the semantics of what
is returned by commands 3 (SYSLOG_ACTION_READ_ALL) and
4 (SYSLOG_ACTION_READ_CLEAR).
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Upon encountering the RLIMIT_CPU soft limit when a SIGXCPU handler
has been installed, Linux invokes the signal handler *and* raises
the soft limit by one second. This behavior repeats until the
limit is encountered. No other implementation that I tested
(Solaris 10, FreeBSD 9.0, OpenBSD 5.0) does this, and it seems
unlikely to be POSIX-conformant. The (Linux-specific)
RLIMIT_RTTIME soft limit exhibits similar behavior.
Reported-by: Trevor Woerner <twoerner@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The EOVERFLOW error is not only for st_size, but also
inode and block size fields. See glibc source file
sysdeps/unix/sysv/linux/xstatconv.c and kernel source
file fs/stat.c. Also, fix bit/byte confusion
See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=604928
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
PTRACE_GETREGS, PTRACE_SETGREFS, PTRACE_GETFPREGS,
and PTRACE_GETSPREGS are not present on all architectures.
PTRACE_SYSEMU and PTRACE_SYSEMU_SINGLESTEP are present only
on x86.
See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=122383
Simon Paillard <spaillard@debian.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Recommend clock_gettime(2), not gettimeofday(2) as alternative to times(2).
From times(2):
"To measure changes in elapsed time, use gettimeofday(2)
instead."
From gettimeofday(2):
"POSIX.1-2008 marks gettimeofday() as obsolete, recommending the
use of clock_gettime(2) instead."
Some context, showing how use of gettimeofday() causes actual bugs
(also read comments):
http://blog.habets.pp.se/2010/09/gettimeofday-should-never-be-used-to-measure-time
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This adds a short description of the no_new_privs bit,
as described in Documentation/prctl/no_new_privs.txt.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Note type of 'arg3' for SECCOMP_MODE_FILTER.
Add pointer to Documentation/prctl/seccomp_filter.txt.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This adds a short summary of the arguments used
for "mode 2" (BPF) seccomp.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The line(s) in the NAME section should only use capitals
where English usage dictates that. Otherwise, use
lowercase throughout.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Existing pages variously use "userspace or "user space".
But, "userspace" is not quite an English word.
So change "userspace" to "user space" or, when used
attributively, "user-space".
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
There is now nothing left of the original FSF-copyrighted
page. So, change the copyright and license.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Rusty notes that O_NONBLOCK is almost always used in
practice. Therefore, it would be better to reorganize
the page to consider that "the default".
Reviewed-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
Reviewed-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
For a better visual result, disable justification and hyphenation
in SEE ALSO where page names are long.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Eric Dumazet noted that EINVAL was not documented. Some further
digging shows that it's also not diagnosed consistently.
See https://bugzilla.kernel.org/show_bug.cgi?id=47111.
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Executive summary: a sane application can't rely on any
particular behavior if another thread closes a file descriptor
being monitored by select().
See https://bugzilla.kernel.org/show_bug.cgi?id=40852
Reported-by: Stephane Fillod <fillods@users.sf.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
As reported by Fredrik (and as far as I can tell the problem
went back to 2.6.0):
The timeout argument has an upper limit. Any values above that
limit are treated the same as -1, i.e. to wait indefinitely.
The limit is given by:
#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, \
(LONG_MAX - 999ULL) / HZ)
That is, the limit depends on the size of a long and the timer
frequency. Assuming the a long is never smaller than 32 bits
and HZ never larger than 1000, the worst case is 35 minutes.
I think this should be mentioned under "BUGS".
Although this is likely to be fixed in the future
(http://lkml.org/lkml/2010/8/8/144), the problem exists in
at least 2.6.14 - 2.6.35. I don't know if select(2) and poll(2)
are affected.
https://bugzilla.kernel.org/show_bug.cgi?id=20762
Reported-by: Fredrik Arnerup <arnerup@kth.se>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
As reported by Rasmus:
Both my system's man-pages (3.22) and the latest online
(3.41) show:
int mprotect(const void *addr, size_t len, int prot);
as the prototype for mprotect(2). However, POSIX [1] and the
actual sys/mman.h (on all the systems I checked) do not have
the const qualifier on the first argument.
Reported-by: Rasmus Villemoes <Rasmus.Villemoes@decode.is>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The syntax .UR http://example.com paired with .UE will create
links which one can interact, if the pager allows that. One
way to see the effect is ask the man(1) command to use browser
display, e.g.:
man -H man7/uri.7
("\:" is optional groff syntax to permit hyphenless line breaks.)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
I didn't like ithe "SIGKILL operates similarly, with exceptions"
phrase (if it's different, then it's not "similar", right?),
and now I got around to changing it. Now it says simply:
"SIGKILL does not generate signal-delivery-stop and therefore
the tracer can't suppress it."
Replaced "why WNOHANG is not reliable" example with a more
realistic one (the one which actually inspired to add this
information to man page in the first place): we got
ESRCH - process is gone! - but waitpid(WNOHANG) can still
confusingly return 0 "no processes to wait for".
Replaced "This means that unneeded trailing arguments may
be omitted" part with a much better recommendation
to never do that and to supply zero arguments instead.
(The part about "undocumentedness" of gcc behavior was bogus,
btw - deleted).
Expanded BUGS section with the explanation and an example
of visible strace behavior on the buggy syscalls which
exit with EINTR on ptrace attach. I hope this will lead
to people submitting better bug reports to lkml about
such syscalls.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
For IOPRIO_WHO_PROCESS, who==0 means operate on the caller.
For IOPRIO_WHO_PGRP, who==0 means operate on the caller's
process group.
See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=652443
Reported-by: Марк Коренберг <socketpair@gmail.com>
Reported-by: Kalle Olavi Niemitalo <kon@iki.fi>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk