The previous format/wording for the includes wasn't very clear.
Improve it a bit following Branden's proposal.
It also helps reduce lines of code.
Add a subsection in NOTES explaining the conventions used.
Remove the comment for helping maintain the page,
as the NOTES section is now clear enough.
Reported-by: G. Branden Robinson <g.branden.robinson@gmail.com>
Reported-by: Dave Martin <Dave.Martin@arm.com>
Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Returning its argument without further checks is almost always
wrong for la_version.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Signed-off-by: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The contents of each type are a logical block that is indented as
a block. They are not separate paragraphs that happen to be
indented separately, but a set of continuous paragraphs, all at
the same level, indented as a block from the list entry--the name
of the type--. Therefore, it makes more sense to use block
indentation, represented by .RS/.RE, rather than indenting each
paragraph separately. That way it's also easier to further indent
a separate paragraph inside a block, which happens for example in
the case of float_t & double_t. It's simply much easier now to
use .IP specifically in those cases where you want to indent just
a single paragraph.
Also added an ending separator comment line just after the last
type.
[mtk: minor edits to commit message]
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Use \(aq to get an unslanted single quote inside monospace code
blocks. Using a simple ' results in a slanted quote inside PDFs.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The existing text comes straight from POSIX. In copyright terms,
this is at least a gray area, and in any case, simply reproducing
the text of the standard has limited value, since people can
consult the standard directly. So, rewrite the text, to simply
quote the description from fenv(3).
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The implementation shall support one or more programming
environments where these types are no wider than 'long'.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
A limit can be defined by other than POSIX
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Add note about length modifiers and conversions to [u]intmax_t,
and add a corresponding example.
Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Note: There are a few members of this structure that are
not required by POSIX (XSI extensions, and such).
I simply chose to not document them at all.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
SO_PEERSEC was introduced for AF_UNIX stream sockets connected via
connect(2) in Linux 2.6.2 [1] and later augmented to support
AF_UNIX stream and datagram sockets created via socketpair(2) in
Linux 4.18 [2]. Document SO_PEERSEC in the socket.7 and unix.7
man pages following the example of the existing SO_PEERCRED
descriptions. SO_PEERSEC is also supported on AF_INET sockets
when using labeled IPSEC or NetLabel but defer adding a
description of that support to a separate patch.
The module-independent description of the security context
returned by SO_PEERSEC is from Simon McVittie.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=da6e57a2e6bd7939f610d957afacaf6a131e75ed
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0b811db2cb2aabc910e53d34ebb95a15997c33e7
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Cowritten-by: Simon McVittie <smcv@collabora.com>
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The initial version documents sigval, ssize_t, suseconds_t,
time_t, timer_t, timespec, and timeval.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Let's move to the 21st century. Instead of casting system data
types to long/long long/etc. in printf() calls, instead cast to
intmax_t or uintmax_t, the largest available signed/unsigned
integer types.
[mtk: rewrote commit message]
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Use printf()'s '#' flag character to prepend the string "0x".
However, when the number is printed in uppercase, and the prefix
is in lowercase, the string "0x" needs to be manually written.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
For consistency.
The types are written both with and without the redundant 'int' keyword
all over the man-pages. However, the most used form, by far, is the one
without 'int'.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Casting `void *` to `struct child_args *` is already done implicitly.
Explicitly casting can silence warnings when mistakes are made, so it's
better to remove those casts when possible.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The type `struct sockaddr_nl *` is implicitly casted to `void *`.
Explicitly casting can silence warnings when mistakes are made, so it's
better to remove those casts when possible.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
It doesn't make any sense to pass a pointer to the array to
read(2).
It might make sense to pass a pointer to the first element of the
array, but that is already implicitly done when passing the array,
which decays to that pointer, so it's simpler to pass the array.
And anyway, the cast was unneeded, as any pointer is implicitly
cast to `void *`.
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Rather than:
sometype x;
for (x = ....; ...)
use
for (sometype x = ...; ...)
This brings the declaration and use closer together (thus aiding
readability) and also clearly indicates the scope of the loop
counter variable.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Rather than writing things such as:
struct sometype *x;
...
x = malloc(sizeof(*x));
let's use C99 style so that the type info is in the same line as
the allocation:
struct sometype *x = malloc(sizeof(*x));
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Use ``sizeof`` consistently through all the examples in the following
way:
- Use the name of the variable instead of its type as argument for
``sizeof``.
Rationale:
https://www.kernel.org/doc/html/v5.8/process/coding-style.html#allocating-memory
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Use ``sizeof`` consistently through all the examples in the following
way:
- Use the name of the variable instead of its type as argument for
``sizeof``.
Rationale:
https://www.kernel.org/doc/html/v5.8/process/coding-style.html#allocating-memory
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Use ``sizeof`` consistently through all the examples in the following
way:
- Use the name of the variable instead of its type as argument for
``sizeof``.
Rationale:
https://www.kernel.org/doc/html/v5.8/process/coding-style.html#allocating-memory
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Document fanotify_init(2) flag FAN_REPORT_NAME and the format of
the event info type FAN_EVENT_INFO_TYPE_DFID_NAME.
The fanotify_fid.c example is extended to also report the name of
the created file or subdirectory.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Document fanotify_init(2) flag FAN_REPORT_DIR_FID and event info
type FAN_EVENT_INFO_TYPE_DFID.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
With fanotify_init(2) flag FAN_REPORT_FID, the group identifies
filesystem objects by file handles in a single event info record
of type FAN_EVENT_INFO_TYPE_FID.
We intend to add support for new fanotify_init(2) flags for which
the group identifies filesystem objects by file handles and add
more event info record types.
To that end, start by changing the language of the man page to
refer to a "group that identifies filesystem objects by file
handles" instead of referring to the FAN_REPORT_FID flag and
document the extended event format structure in a more generic
manner that allows more than a single event info record and not
only a record of type FAN_EVENT_INFO_TYPE_FID.
Clarify that the object identified by the file handle refers to
the directory in directory entry modification events.
Remove a note about directory entry modification events and
monitoring a mount point that I found to be too confusing and out
of context.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Jakub points out that my last resync may accidentally have been
against an old version of the kernel source, since the resync
resulted in many deleted lines. I suspect he may be right.
Let's resync against today's current kernel.
Reported-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Use ``sizeof`` consistently through all the examples in the
following way:
- Never use a space after ``sizeof``, and always use parentheses
around the argument.
Rationale:
https://www.kernel.org/doc/html/v5.8/process/coding-style.html#spaces
Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This header is used inconsistently -- man pages are UTF-8 encoded
but not setting this marker. It's only respected by the man-db
package, and seems a bit anachronistic at this point when UTF-8
is the standard default nowadays.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
A naked tilde ("~") renders poorly in PDF. Instead use "\(ti",
which renders better in a PDF, and produces the same glyph
when rendering on a terminal.
Reported-by: Geoff Clare <gwc@opengroup.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Explicitly mention CONFIG_LEGACY_PTYS, and note that it is disabled
by default since Linux 2.6.30.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The paragraph noting applications that use pseudoterminals is better
placed in NOTES than in the DESCRTIPTION.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Historically, a comment of the following form at the top of a
manual page was used to indicate too man(1) that the use of tbl(1)
was required in order to process tables:
'\" t
However, at least as far back as 2001 (according to Branden),
man-db's man(1) automatically uses tbl(1) as needed, rendering
this comment unnecessary. And indeed many existing pages in
man-pages that have tables don't have this comment at the top of
the file. So, drop the comment from those files where it is
present.
[mtk: completely rewrote commit message]
Reported-by: G. Branden Robinson <g.branden.robinson@gmail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The \" comment produces blank lines. Use the .\" that the vast
majority of the codebase uses instead.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
CAP_SYS_RESOURCE also allows overriding /proc/sys/fs/mqueue/msg_max
and /proc/sys/fs/mqueue/msgsize_max.
Signed-off-by: Saikiran Madugula <hummerbliss@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Change '-' to '\-' for the prefix of names to indicate an option.
Change '-' to '\(en' for a range.
Signed-off-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
cgroups-v1/v2 documentation got moved to the "admin-guide" subfolder
and converted from .txt files to .rst
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
As reported by mail from Geoff Clare, there are some details that
need correcting:
Subject: standards(7) (was: man-pages-5.07 released)
Date: Wed, 10 Jun 2020 10:53:14 +0100
From: Geoff Clare <gwc@opengroup.org>
...
The first isn't really a problem, just an oddity. You list
POSIX.1b as "formerly known as POSIX.4", but you don't do the
equivalent for POSIX.1c ("formerly known as POSIX.4a").
There are several problems with the XPG3 entry:
"first significant release" - although I suppose XPG3 could
be considered more significant than XPG2 because it was the
first one to incorporate POSIX.1, I don't think it's fair to
imply that XPG2 was not significant. (E.g. XPG2 was
significant in that it was the first release to include
I18N, and the first that had a conformance test suite.)
"produced by the X/Open Company, a multivendor consortium" -
this conflates two different things called X/Open. X/Open
Company Limited is the UK company that did the editing work,
organised meetings, etc. X/Open Group is the consortium
whose members developed the technical content.
"This multivolume guide was based on the POSIX standards" -
at the time there was only one POSIX standard, namely
POSIX.1-1988. The first release to incorporate POSIX.2 was
XPG4 (which you may consider worth noting in the XPG4
entry).
To fix these problems I would suggest changing the entry to:
XPG3 Released in 1989, this was the first release of the X/Open
Portability Guide to be based on a POSIX standard
(POSIX.1-1988). This multivolume guide was developed by the
X/Open Group, a multivendor consortium.
Under SUSv2 I would suggest changing:
Sometimes also referred to as XPG5.
to:
Sometimes also referred to (incorrectly) as XPG5.
Under POSIX.1-2001, SUSv3: "XSI conformance constitutes the Single
UNIX Specification version 3 (SUSv3)" is problematic. I think I
touched on this in the previous discussion. I would suggest
deleting that sentence and instead inserting, before "Two
Technical Corrigenda ...", the following:
The Single UNIX Specification version 3 (SUSv3) comprises the
Base Specifications containing XBD, XSH, XCU and XRAT as
above, plus X/Open Curses Issue 4 version 2 as an extra volume
that is not in POSIX.1-2001.
Something similar is needed in the POSIX.1-2008, SUSv4 entry where
it talks about "the same four parts". The extra volume this time
is X/Open Curses Issue 7.
]]
Cowritten-by: Geoff Clare <gwc@opengroup.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The fact that a more negative nice value means higher
priority is a continuing source of confusion.
Reported-by: Dan Kenigsberg <danken@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Trim tailing space in "strings".
There is no change in the output from "nroff" and "groff".
###
Output is from: test-groff -b -mandoc -T utf8 -rF0 -t -w w -z
[ "test-groff" is a developmental version of "groff" ]
troff: <attributes.7>:510: warning: trailing space
troff: <attributes.7>:512: warning: trailing space
troff: <attributes.7>:513: warning: trailing space
troff: <attributes.7>:516: warning: trailing space
troff: <attributes.7>:649: warning: trailing space
troff: <attributes.7>:681: warning: trailing space
troff: <attributes.7>:720: warning: trailing space
####
troff: <environ.7>:181: warning: trailing space
troff: <environ.7>:182: warning: trailing space
####
troff: <ip.7>:820: warning: trailing space
####
troff: <signal.7>:316: warning: trailing space
Signed-off-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is>
####
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Traditionally, magic links have not been a well-understood topic
in Linux. This helps clarify some of the terminology used in
openat2.2.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Reorder full wordings to match the order of abbreviations.
Signed-off-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
From an email conversation with Léo Stefanesco:
> In the man7.org version of the man page for user_namespaces(7), it reads:
>
> there are many privileged operations that affect
> resources that are not associated with any namespace type,
> for example, changing the system time
> (governed by CAP_SYS_TIME)
>
> which is not consistent with time_namespaces(7).
In fact, strictly peaking the text still is correct, even after
the arrival of time namespaces.
Time namespaces virtualize only the boot-time and monotonic
clocks, not the "real time" (i.e., calendar time), which is the
time referred in the passage you quote.
That said, the text is perhaps now a little misleading, and
a little clarification would help. I changed the text to:
there are many privileged operations that affect
resources are not associated with any namespace type,
for example, changing the system **(i.e., calendar)** time
(governed by CAP_SYS_TIME)
Reported-by: Léo Stefanesco <leo.lveb@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
FAN_ONDIR was an input only flag before introducing
FAN_REPORT_FID. Since the introduction of FAN_REPORT_FID, it can
also be in output mask.
Move the text describing its role in the output mask to fanotify.7
where the other output mask bits are documented.
[mtk: commit message tidy-up]
Reviewed-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This reverts commit a93e5c9593.
FAN_DIR_MODIFY was disabled for v5.7 release by kernel commit
f17936993af0 ("fanotify: turn off support for FAN_DIR_MODIFY").
Reviewed-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
EXAMPLES appears to be the wider majority usage across various
projects' manual pages, and is also what is used in the POSIX
manual pages.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
man-pages doesn't have a REPORTING BUGS section in manual pages,
but many other projects do. Make some recommendations about
placement of that section.
man-pages doesn't use COPYRIGHT sections in manual pages, but
various projects do. Make some recommendations about placement
of the section.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Although man-pages doesn't use AUTHORS sections, many projects do
use an AUTHORS section in their manual pages, so mention it in
man-pages to suggest some guidance on the position at which
to place that section.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The terms POSIX.1-{2003,2004,2013,2016} were inventions of
my imagination, as confirmed by consulting Geoff Clare of
The Open Group. Remove these names.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Adding description of new directories (/run, /usr/libexec,
/usr/share/color,/usr/share/ppd, /var/lib/color), stating
/usr/X11R6 as removed and updating URL to and version of FHS.
See https://bugzilla.kernel.org/show_bug.cgi?id=206693
Reported-by: Gary Perkins <glperkins@lit.edu>
Signed-off-by: Thomas Piekarski <t.piekarski@deloquencia.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This is a sequel to commit baf17bc4f2, addressing the
issues with missing commas in the middle of SEE ALSO lists that
emerged since.
The awk script from the original commit was not working and had to
be slightly modified (s/["]SEE ALSO["]/"?SEE ALSO/), otherwise it
works like a charm. Here's the fixed script and its output just
before this commit:
for f in man*/*; do
awk '
/^.SH "?SEE ALSO/ {
sa=1; print "== " FILENAME " =="; print; next
}
/^\.(PP|SH)/ {
sa=0; no=0; next
}
/^\.BR/ {
if (sa==1) {
print;
if (no == 1)
print "Missing comma in " FILENAME " +" FNR-1; no=0
}
}
/^\.BR .*)$/ {
if (sa==1)
no=1;
next
}
/\.\\"/ {next}
/.*/ {
if (sa==1) {
print; next
}
}
' $f; done | grep Missing
Missing comma in man1/memusage.1 +272
Missing comma in man2/adjtimex.2 +597
Missing comma in man2/adjtimex.2 +598
Missing comma in man2/mkdir.2 +252
Missing comma in man2/sigaction.2 +1045
Missing comma in man2/sigaction.2 +1047
Missing comma in man3/mbsnrtowcs.3 +198
Missing comma in man3/ntp_gettime.3 +142
Missing comma in man3/strcmp.3 +219
Missing comma in man3/strtol.3 +302
Missing comma in man3/wcstombs.3 +120
Missing comma in man7/user_namespaces.7 +1378
Missing comma in man7/xattr.7 +198
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The page of attr(1) is relevant to xattrs, therefore add it to the
SEE ALSO section.
attr(1) command works for other filesystems as well.
Signed-off-by: Achilles Gaikwad <agaikwad@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Used Bird's source code, kernel source code, iproute2 source code
and iproute2 manpages to find meanings of these new attributes.
Signed-off-by: Jan Moskyto Matejka <mq@ucw.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Document the details of the new FAN_DIR_MODIFY event, which
introduces entry name information to the fanotify event
reporting format.
Enhance the fanotify_fid.c example to also report this event.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
- The condition for printing "subdirectory created" was always
true.
- The arguments and error check of open_by_handle_at() were
incorrect.
- Fix example description inconsistencies.
- Nicer indentation of example output.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The cgroup.sane_behavior file returns the hard-coded value "0" and
is kept for legacy purposes. Mention this in the man-page.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The display of the /proc/PID/ns renders very wide. Make it
narrower by eliminating some nonessential info via some
awk(1) filtering.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Andrei Vagin implemented a change I suggested:
clock-IDs are now be expressed in symbolic form (e.g.,
"monotonic") instead of numeric form (e.g., 1) when reading
/proc/PID/timerns_offsets, and can be expressed either
symbolically or numerically when writing to that file.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
In particular, note the ERANGE restrictions reported by
Thomas Gleixner.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
signal.7: Which signal is delivered in response to a CPU exception
is under-documented and does not always make sense. See
<https://bugzilla.kernel.org/show_bug.cgi?id=205831> for an
example where it doesn’t make sense; per the discussion there,
this cannot be changed because of backward compatibility concerns,
so let’s instead document the problem.
sigaction.2: For related reasons, the kernel doesn’t always fill
in all of the fields of the siginfo_t when delivering signals from
CPU exceptions. Document this as well. I imagine this one
_could_ be fixed, but the problem would still be relevant to
anyone using an older kernel.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The example is misleading. It is not a good idea to unlink an
existing socket because we might try to start the server multiple
times. In this case it is preferable to receive an error.
We could add code that removes the socket when the server process
is killed but that would stretch the example too far.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Note the kernel version that added SO_TIMESTAMPNS,
and (from the kernel commit) note tha SO_TIMESTAMPNS and
SO_TIMESTAMP are mutually exclusive.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
===========
DESCRIPTION
===========
I added a paragraph for ``SO_TIMESTAMP``, and modified the
paragraph for ``SIOCGSTAMP`` in relation to ``SO_TIMESTAMPNS``.
I based the documentation on the existing ``SO_TIMESTAMP``
documentation, and
on my experience using ``SO_TIMESTAMPNS``.
I asked a question on stackoverflow, which helped me understand
``SO_TIMESTAMPNS``:
https://stackoverflow.com/q/60971556/6872717
Testing of the feature being documented
=======================================
I wrote a simple server and client test.
In the client side, I connected a socket specifying
``SOCK_STREAM`` and ``"tcp"``.
Then I enabled timestamp in ns:
.. code-block:: c
int enable = 1;
if (setsockopt(sd, SOL_SOCKET, SO_TIMESTAMPNS, &enable,
sizeof(enable)))
goto err;
Then I prepared the msg header:
.. code-block:: c
char buf[BUFSIZ];
char cbuf[BUFSIZ];
struct msghdr msg;
struct iovec iov;
memset(buf, 0, ARRAY_BYTES(buf));
iov.iov_len = ARRAY_BYTES(buf) - 1;
iov.iov_base = buf;
msg.msg_name = NULL;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = cbuf;
msg.msg_controllen = ARRAY_BYTES(cbuf);
And got some times before and after receiving the msg:
.. code-block:: c
struct timespec tm_before, tm_recvmsg, tm_after, tm_msg;
clock_gettime(CLOCK_REALTIME, &tm_before);
usleep(500000);
clock_gettime(CLOCK_REALTIME, &tm_recvmsg);
n = recvmsg(sd, &msg, MSG_WAITALL);
if (n < 0)
goto err;
usleep(1000000);
clock_gettime(CLOCK_REALTIME, &tm_after);
After that I read the timestamp of the msg:
.. code-block:: c
struct cmsghdr *cmsg;
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg;
cmsg = CMSG_NXTHDR(&msg, cmsg)) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SO_TIMESTAMPNS) {
memcpy(&tm_msg, CMSG_DATA(cmsg), sizeof(tm_msg));
break;
}
}
if (!cmsg)
goto err;
And finally printed the results:
.. code-block:: c
double tdiff;
printf("%s\n", buf);
tdiff = timespec_diff_ms(&tm_before, &tm_recvmsg);
printf("tm_r - tm_b = %lf ms\n", tdiff);
tdiff = timespec_diff_ms(&tm_before, &tm_after);
printf("tm_a - tm_b = %lf ms\n", tdiff);
tdiff = timespec_diff_ms(&tm_before, &tm_msg);
printf("tm_m - tm_b = %lf ms\n", tdiff);
Which printed:
::
asdasdfasdfasdfadfgdfghfthgujty 6, 0;
tm_r - tm_b = 500.000000 ms
tm_a - tm_b = 1500.000000 ms
tm_m - tm_b = 18.000000 ms
System:
::
Linux debian 5.4.0-4-amd64 #1 SMP Debian 5.4.19-1 (2020-02-13) x86_64
GNU/Linux
gcc (Debian 9.3.0-8) 9.3.0
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Linux 5.6 added the new well-known VMADDR_CID_LOCAL for
local communication.
This patch explains how to use it and removes the legacy
VMADDR_CID_RESERVED no longer available.
Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Add a '.RE' macro to terminate the last .RS block.
There is no change in the output.
Signed-off-by: Bjarni Ingi Gislason <bjarniig@rhi.hi.is>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
In many cases, these don't improve readability, and (when stacked)
they sometimes have the side effect of sometimes forcing text
to be justified within a narrow column range.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
PVS-Studio reports that in
char buf[8192];
/* ... */
nh = (struct nlmsghdr *) buf,
the pointer 'buf' is cast to a more strictly aligned pointer type.
This is undefined behaviour. One possible solution to make sure
that buf is correctly aligned is to declare buf as an array of
struct nlmsghdr. Other solutions include allocating the array on
the heap, use an union, or stdalign features. With this patch,
the buffer still contains 8192 bytes.
This was raised on Stack Overflow:
https://stackoverflow.com/questions/57745580/netlink-receive-buffer-alignment
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The definition of the tpacket_auxdata struct in the manpage is not
the same as the definition found in
/include/uapi/linux/if_packet.h.
In particular, instead of a tp_padding field, there is a
tp_vlan_tpid field. An example of a project using this field is
libpcap[1].
[1]: https://github.com/the-tcpdump-group/libpcap/blob/master/pcap-linux.c#L349
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The structure 'struct sockaddr_vm' has additional element
'unsigned char svm_zero[]' since version v3.9-rc1
(include/uapi/linux/vm_sockets.h). Linux kernel checks that this
element is zeroed (net/vmw_vsock/vsock_addr.c). Reflect this on
the vsock man page.
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=205583
Signed-off-by: Mikhail Golubev <Mikhail.Golubev@opensynergy.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
In the given example, the second recvmsg(2) call should receive four bytes,
as the third sendmsg(2) call only sends four.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Jakub Wilk