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==================== Changes in man-pages-3.80 ====================
Released: 2015-02-21, Munich
Contributors
------------
The following people contributed patches/fixes or (noted in brackets
in the changelog below) reports, notes, and ideas that have been
incorporated in changes in this release:
Akihiro Motoki <amotoki@gmail.com>
Andy Lutomirski <luto@amacapital.net>
Bill McConnaughey <mcconnau@biochem.wustl.edu>
Chris Mayo <aklhfex@gmail.com>
Christophe Blaess <Christophe@blaess.fr>
David Wilson <dw@botanicus.net>
Denys Vlasenko <dvlasenk@redhat.com>
Doug Goldstein <cardoe@gentoo.org>
Eric Wong <normalperson@yhbt.net>
Heinrich Schuchardt <xypron.glpk@gmx.de>
J William Piggott <elseifthen@gmx.com>
James Hunt <james.hunt@ubuntu.com>
Jan Chaloupka <jchaloup@redhat.com>
Jan Stancek <jstancek@redhat.com>
Jeff Layton <jlayton@poochiereds.net>
Jens Thoms Toerring <jt@toerring.de>
Kevin Easton <kevin@guarana.org>
Luke Faraone <lfaraone@debian.org>
Mark Seaborn <mseaborn@chromium.org>
Mathieu Malaterre <malat@debian.org>
Michael Kerrisk <mtk.manpages@gmail.com>
Michal Hocko <mhocko@suse.cz>
Minchan Kim <minchan@kernel.org>
Patrick Horgan <phorgan1@gmail.com>
Peng Haitao <penght@cn.fujitsu.com>
Ralf Baechle <ralf@linux-mips.org>
Rob Somers <uberkermit@gmail.com>
Simon Paillard <spaillard@debian.org>
Stephen Smalley <sds@tycho.nsa.gov>
Tao Ma <tao.ma@oracle.com>
Tobias Herzke <tobias.linuxpatches.2014@gi2.herzkes.de>
Vince Weaver <vincent.weaver@maine.edu>
Vlastimil Babka <vbabka@suse.cz>
Zbigniew Brzeziński <zbigniew.brzezinski@student.put.poznan.pl>
Apologies if I missed anyone!
New and rewritten pages
-----------------------
ioctl_fat.2
Heinrich Schuchardt [Michael Kerrisk]
New man page for the ioctl(2) FAT API
The ioctl(2) system call may be used to retrieve information about
the FAT file system and to set file attributes.
madvise.2
Michael Kerrisk
Summary: this page has been significantly reorganised and rewritten
Michael Kerrisk
Recast discussion of 'advice' into two groups of values
madvise() is one of those system calls that has congealed over
time, as has the man page. It's helpful to split the discussion
of 'advice' into those flags into two groups:
* Those flags that are (1) widespread across implementations;
(2) have counterparts in posix_madvise(3); and (3) were present
in the initial Linux madvise implementation.
* The rest, which are values that (1) may not have counterparts
in other implementations; (2) have no counterparts in
posix_madvise(3); and (3) were added to Linux in more recent
times.
Michael Kerrisk
Explicitly list the five flags provided by posix_fadvise()
Over time, bit rot has afflicted this page. Since the original
text was written many new Linux-specific flags have been added.
So, now it's better to explicitly list the flags that
correspond to the POSIX analog of madvise().
Jan Chaloupka [Hugh Dickins, Michael Kerrisk]
Starting with Linux 3.5, more file systems support MADV_REMOVE
Michael Kerrisk
Split EINVAL error into separate cases
Michael Kerrisk
Explain MADV_REMOVE in terms of file hole punching
Michael Kerrisk
MADV_REMOVE can be applied only to shared writable mappings
Michael Kerrisk
MADV_REMOVE cannot be applied to locked or Huge TLB pages
Michael Kerrisk [Vlastimil Babka]
Clarify that MADV_DONTNEED has effect on pages only if it succeeds
Michael Kerrisk [Vlastimil Babka]
Clarifications for MADV_DONTNEED
Michael Kerrisk [Michal Hocko]
Improve MADV_DONTNEED description
Michael Kerrisk
MADV_DONTNEED cannot be applied to Huge TLB or locked pages
Michael Kerrisk [Vlastimil Babka]
Remove mention of "shared pages" as a cause of EINVAL for MADV_DONTNEED
Michael Kerrisk [Vlastimil Babka]
Note Huge TLB as a cause of EINVAL for MADV_DONTNEED
Michael Kerrisk [Minchan Kim]
Add mention of VM_PFNMAP in discussion of MADV_DONTNEED and MADV_REMOVE
Michael Kerrisk
Drop sentence saying that kernel may ignore 'advice'
The sentence creates misunderstandings, and does not really
add information.
Michael Kerrisk
Note that some Linux-specific 'advice' change memory-access semantics
Michael Kerrisk
NOTES: Remove crufty text about "command" versus "advice"
The point made in this fairly ancient text is more or less evident
from the DESCRIPTION, and it's not clear what "standard" is being
referred to.
Michael Kerrisk
Mention POSIX.1-2008 addition of POSIX_MADV_NOREUSE
Michael Kerrisk
Remove "POSIX.1b" from CONFORMING TO
Michael Kerrisk
Move mention of posix_fadvise() from CONFORMING TO to SEE ALSO
Michael Kerrisk
ERRORS: add EPERM error case for MADV_HWPOISON
Michael Kerrisk
Note that madvise() is nonstandard, but widespread
Newly documented interfaces in existing pages
---------------------------------------------
proc.5
Michael Kerrisk
(Briefly) document /proc/PID/attr/socketcreate
Michael Kerrisk
(Briefly) document /proc/PID/attr/keycreate
Michael Kerrisk [Stephen Smalley]
Document /proc/PID/attr/{current,exec,fscreate,prev}
Heavily based on Stephen Smalley's text in
https://lwn.net/Articles/28222/
From: Stephen Smalley <sds@epoch.ncsc.mil>
To: LKML and others
Subject: [RFC][PATCH] Process Attribute API for Security Modules
Date: 08 Apr 2003 16:17:52 -0400
Michael Kerrisk
Document /proc/sys/kernel/auto_msgmni
socket.7
David Wilson
Document SO_REUSEPORT socket option
New and changed links
---------------------
get_thread_area.2
Andy Lutomirski
Make get_thread_area.2 a link to rewritten set_thread_area.2 page
Changes to individual pages
---------------------------
time.1
Michael Kerrisk
Make option argument formatting consistent with other pages
access.2
Denys Vlasenko
Explain how access() check treats capabilities
We have users who are terribly confused why their binaries
with CAP_DAC_OVERRIDE capability see EACCESS from access() calls,
but are able to read the file.
The reason is access() isn't the "can I read/write/execute this
file?" question, it is the "(assuming that I'm a setuid binary,)
can *the user who invoked me* read/write/execute this file?"
question.
That's why it uses real UIDs as documented, and why it ignores
capabilities when capability-endorsed binaries are run by non-root
(this patch adds this information).
To make users more likely to notice this less-known detail,
the patch expands the explanation with rationale for this logic
into a separate paragraph.
arch_prctl.2
set_thread_area.2
get_thread_area.2
Andy Lutomirski
Improve TLS documentation
The documentation for set_thread_area was very vague. This
improves it, accounts for recent kernel changes, and merges
it with get_thread_area.2.
get_thread_area.2 now becomes a link.
While I'm at it, clarify the related arch_prctl.2 man page.
cacheflush.2
Ralf Baechle
Update some portability details and bugs
Michael Kerrisk
Refer reader to BUGS in discussion of EINVAL error
capget.2
Michael Kerrisk
Document V3 capabilities constants
Michael Kerrisk
Rewrite discussion of kernel versions that support file capabilities
File capabilities ceased to be optional in Linux 2.6.33.
clone.2
Peng Haitao
Fix description of CLONE_PARENT_SETTID
CLONE_PARENT_SETTID only stores child thread ID in parent memory.
clone.2
execve.2
Kevin Easton
Document interaction of execve(2) with CLONE_FILES
This patch the fact that a successful execve(2) in a process that
is sharing a file descriptor table results in unsharing the table.
I discovered this through testing and verified it by source
inspection - there is a call to unshare_files() early in
do_execve_common().
fcntl.2
Michael Kerrisk [Jeff Layton]
Clarify cases of conflict between traditional record and OFD locks
Verified by experiment on Linux 3.15 and 3.19rc4.
fork.2
Michal Hocko
EAGAIN is not reported when task allocation fails
I am not sure why we have:
"EAGAIN fork() cannot allocate sufficient memory to copy
the parent's page tables and allocate a task structure
or the child."
The text seems to be there from the time when man-pages
were moved to git so there is no history for it.
And it doesn't reflect reality: the kernel reports both
dup_task_struct and dup_mm failures as ENOMEM to the
userspace. This seems to be the case from early 2.x times
so let's simply remove this part.
Heinrich Schuchardt
Child and parent run in separate memory spaces
fork.2 should clearly point out that child and parent
process run in separate memory spaces.
Michael Kerrisk
NOTES: add "C library/kernel ABI differences" subheading
getpid.2
Michael Kerrisk
NOTES: add "C library/kernel ABI differences" subheading
getxattr.2
Michael Kerrisk
Various rewordings plus one or two details clarified
Michael Kerrisk
Add pointer to example in listxattr(2)
killpg.2
Michael Kerrisk
NOTES: add "C library/kernel ABI differences" subheading
listxattr.2
Heinrich Schuchardt
Provide example program
Michael Kerrisk
Reword discussion of size==0 case
Michael Kerrisk
Add note on handling increases in sizes of keys or values
Michael Kerrisk
Remove mention of which filesystems implement ACLs
Such a list will only become outdated (as it already was).
migrate_pages.2
Jan Stancek
Document EFAULT and EINVAL errors
I encountered these errors while writing testcase for migrate_pages
syscall for LTP (Linux test project).
I checked stable kernel tree 3.5 to see which paths return these.
Both can be returned from get_nodes(), which is called from:
SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
const unsigned long __user *, old_nodes,
const unsigned long __user *, new_nodes)
The testcase does following:
EFAULT
a) old_nodes/new_nodes is area mmaped with PROT_NONE
b) old_nodes/new_nodes is area not mmapped in process address
space, -1 or area that has been just munmmaped
EINVAL
a) maxnodes overflows kernel limit
b) new_nodes contain node, which has no memory or does not exist
or is not returned for get_mempolicy(MPOL_F_MEMS_ALLOWED).
modify_ldt.2
Andy Lutomirski
Overhaul the documentation
This clarifies the behavior and documents all four functions.
Andy Lutomirski
Clarify the lm bit's behavior
The lm bit should never have existed in the first place. Sigh.
mprotect.2
Mark Seaborn
Mention effect of READ_IMPLIES_EXEC personality flag
I puzzled over mprotect()'s effect on /proc/*/maps for a while
yesterday -- it was setting "x" without PROT_EXEC being specified.
Here is a patch to add some explanation.
msgget.2
Michael Kerrisk
Add details of MSGMNI default value
msgop.2
Michael Kerrisk
Clarify wording of MSGMAX and MSGMNB limits
perf_event_open.2
Vince Weaver
Clarify PERF_EVENT_IOC_REFRESH behavior
Currently the PERF_EVENT_IOC_REFRESH ioctl, when applied to a group
leader, will refresh all children. Also if a refresh value of 0
is chosen then the refresh becomes infinite (never runs out).
Back in 2011 PAPI was relying on these behaviors but I was told
that both were unsupported and subject to being removed at any time.
(See https://lkml.org/lkml/2011/5/24/337 )
However the behavior has not been changed.
This patch updates the manpage to still list the behavior as
unsupported, but removes the inaccurate description of it
only being a problem with 2.6 kernels.
prctl.2
Michael Kerrisk [Bill McConnaughey]
Mention file capabilities in discussion of PR_SET_DUMPABLE
Michael Kerrisk
Greatly expand discussion of "dumpable" flag
In particular, detail the interactions with
/proc/sys/fs/suid_dumpable.
Michael Kerrisk
Reorder paragraphs describing PR_SET_DUMPABLE
Michael Kerrisk
Mention SUID_DUMP_DISABLE and SUID_DUMP_USER under PR_SET_DUMPABLE
Michael Kerrisk
Executing a file with capabilities also resets the parent death signal
ptrace.2
James Hunt
Explain behaviour should ptrace tracer call execve(2)
This behaviour was verified by reading the kernel source and
confirming the behaviour using a test program.
Denys Vlasenko
Add information on PTRACE_SEIZE versus PTRACE_ATTACH differences
Extend description of PTRACE_SEIZE with the short summary of its
differences from PTRACE_ATTACH.
The following paragraph:
PTRACE_EVENT_STOP
Stop induced by PTRACE_INTERRUPT command, or group-stop, or ini-
tial ptrace-stop when a new child is attached (only if attached
using PTRACE_SEIZE), or PTRACE_EVENT_STOP if PTRACE_SEIZE was used.
has an editing error (the part after last comma makes no sense).
Removing it.
Mention that legacy post-execve SIGTRAP is disabled by PTRACE_SEIZE.
sched_setattr.2
Michael Kerrisk [Christophe Blaess]
SYNOPSIS: remove 'const' from 'attr' sched_getattr() argument
semget.2
Michael Kerrisk
Note default value for SEMMNI and SEMMSL
semop.2
Michael Kerrisk
Note defaults for SEMOPM and warn against increasing > 1000
sendfile.2
Eric Wong
Caution against modifying sent pages
setxattr.2
Michael Kerrisk
ERRORS: add ENOTSUP for invalid namespace prefix
Michael Kerrisk
Remove redundant text under ENOTSUP error
Michael Kerrisk
Note that zero-length attribute values are permitted
Michael Kerrisk
Rework text describing 'flags' argument
stat.2
Michael Kerrisk
NOTES: add "C library/kernel ABI differences" subheading
statfs.2
Michael Kerrisk [Jan Chaloupka]
Document the 'f_flags' field added in Linux 2.6.36
Michael Kerrisk
Clarify that 'statfs' structure has some padding bytes
The number of padding bytes has changed over tyme, as some
bytes are used, so describe this aspect of the structure
less explicitly.
Tao Ma
Add OCFS2_SUPER_MAGIC
Michael Kerrisk
Use __fsword_t in statfs structure definition
This more closely matches modern glibc reality.
Michael Kerrisk
Add a note on the __fsword_t type
Michael Kerrisk
Document 'f_spare' more vaguely
wait.2
Michael Kerrisk
Note that waitpid() is a wrapper for wait4()
Michael Kerrisk
Note that wait() is a library function implemented via wait4()
wait4.2
Michael Kerrisk
NOTES: add "C library/kernel ABI differences" subheading
encrypt.3
Rob Somers
Improve code example
I (and some others) found that the original example code
did not seem to work as advertised. The new code (used by
permission of the original author, Jens Thoms Toerring)
was found on comp.os.linux.development.
mktemp.3
Luke Faraone
DESCRIPTION reference to BUGS corrected
mktemp(3)'s DESCRIPTION referenced NOTES, but no such
section exists. Corrected to refer to BUGS.
pthread_attr_setschedparam.3
Tobias Herzke
Describe EINVAL in ERRORS
resolver.3
host.conf.5
Simon Paillard
host.conf 'order' option deprecated, replaced by nsswitch.conf(5)
http://www.sourceware.org/bugzilla/show_bug.cgi?id=2389
http://repo.or.cz/w/glibc.git/commit/b9c65d0902e5890c4f025b574725154032f8120a
Reported at http://bugs.debian.org/270368,
http://bugs.debian.org/396633, and http://bugs.debian.org/344233.
statvfs.3
Michael Kerrisk
Document missing 'f_flag' bit values
And reorganize information relating to which flags are in
POSIX.1.
Michael Kerrisk [Jan Chaloupka]
statvfs() now populates 'f_flag' from statfs()'s f_flag field
These changes came with glibc 2.13, and the kernel's addition of
a 'f_flags' field in Linux 2.6.36.
syslog.3
Michael Kerrisk [Doug Goldstein]
Remove unneeded <stdarg.h>
vsyslog() does not need this.
tzset.3
J William Piggott
Add offset format
tzset.3 does not illustrate the POSIX offset format.
Specifically, there is no indication in the manual
what the optional components of it are.
random.4
Michael Kerrisk
Note maximum number of bytes returned by read(2) on /dev/random
Michael Kerrisk [Mathieu Malaterre]
Since Linux 3.16, reads from /dev/urandom return at most 32 MB
See https://bugs.debian.org/775328 and
https://bugzilla.kernel.org/show_bug.cgi?id=80981#c9
core.5
Michael Kerrisk [Bill McConnaughey]
Executing a file that has capabilities also prevents core dumps
Michael Kerrisk
Document "%i" and "%I" core_pattern specifiers
intro.5
Michael Kerrisk
Remove words "and protocols"
There are no protocol descriptions in Section 5. Protocols are
in Section 7.
proc.5
Michael Kerrisk
Add reference to prctl(2) in discussion of /proc/sys/fs/suid_dumpable
And note that /proc/sys/fs/suid_dumpable defines the
value assigned to the process "dumpable" flag in certain
circumstances.
Michael Kerrisk
Note that CAP_SYS_ADMIN is required to list /proc/PID/map_files
This might however change in the future; see the Jan 2015 LKML thread:
Re: [RFC][PATCH v2] procfs: Always expose /proc/<pid>/map_files/
and make it readable
resolv.conf.5
Michael Kerrisk
SEE ALSO: add nsswitch.conf(5)
capabilities.7
Michael Kerrisk
Mention SECBIT_KEEP_CAPS as an alternative to prctl() PR_SET_KEEPCAPS
Chris Mayo
NOTES: add last kernel versions for obsolete options
The CONFIG_SECURITY_CAPABILITIES option was removed by
commit 5915eb53861c5776cfec33ca4fcc1fd20d66dd27
The CONFIG_SECURITY_FILE_CAPABILITIES option removed in
Linux 2.6.33 as already mentioned in DESCRIPTION.
pthreads.7
Michael Kerrisk
SEE ALSO: add fork(2)
socket.7
Michael Kerrisk
Add some details for SO_REUSEPORT
unix.7
Jan Chaloupka
Mention SOCK_STREAM socket for ioctl_type of ioctl()
from https://bugzilla.redhat.com/show_bug.cgi?id=1110401.
unix.7 is not clear about socket type of ioctl_type argument of
ioctl() function. The description of SIOCINQ is applicable only
for SOCK_STREAM socket. For SOCK_DGRAM, udp(7) man page gives
correct description of SIOCINQ
ldconfig.8
Michael Kerrisk
Place options in alphabetical order
Michael Kerrisk
Note glibc version number for '-l' option
Michael Kerrisk
Document -c/--format option
Michael Kerrisk
Add long form of some options
Michael Kerrisk [Patrick Horgan]
ld.so.conf uses only newlines as delimiters
mtk: confirmed by reading source of parse_conf() in
elf/ldconfig.c.
Michael Kerrisk
Document -V/--version option
Michael Kerrisk
Document -i/--ignore-aux-cache option
ld.so.8
Michael Kerrisk
Relocate "Hardware capabilities" to be a subsection under notes
This is more consistent with standard man-pages headings
and layout.
Michael Kerrisk
(Briefly) document LD_TRACE_PRELINKING
Michael Kerrisk
Remove duplicate description of LD_BIND_NOT
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