Fix two problems.
Rather than "larger than", better English is "greater than".
Then there is a wordinig error on the following line: "then lowfd"
appears to be cruft.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The function closes all open file descriptors greater than or equal to
input argument. Negative values are clamped to 0, i.e, it will close
all file descriptors.
As indicated by the bug report, this is a common symbol provided by
different systems (Solaris, OpenBSD, NetBSD, FreeBSD) and, although
its has inherent issues with not taking in consideration internal libc
file descriptors (such as syslog), this is also a common feature used
in multiple projects [1][2][3][4][5].
The Linux fallback implementation iterates over /proc and close all
file descriptors sequentially. Although it was raised the questioning
whether getdents on /proc/self/fd might return disjointed entries
when file descriptor are closed; it does not seems the case on my
testing on multiple kernel (v4.18, v5.4, v5.9) and the same strategy
is used on different projects [1][2][3][5].
Also, the interface is set a fail-safe meaning that a failure in the
fallback results in a process abort.
Checked on x86_64-linux-gnu and i686-linux-gnu on kernel 5.11 and 4.15.
[1] 5238e95759/src/basic/fd-util.c (L217)
[2] ddf4b77e11/src/lxc/start.c (L236)
[3] 9e4f2f3a6b/Modules/_posixsubprocess.c (L220)
[4] 5f47c0613e/src/libstd/sys/unix/process2.rs (L303-L308)
[5] https://github.com/openjdk/jdk/blob/master/src/java.base/unix/native/libjava/childproc.c#L82
It was added on Linux 5.9 (278a5fbaed89) with CLOSE_RANGE_CLOEXEC
added on 5.11 (582f1fb6b721f). Although FreeBSD has added the same
syscall, this only adds the symbol on Linux ports. This syscall is
required to provided a fail-safe way to implement the closefrom
symbol (BZ #10353).
Checked on x86_64-linux-gnu and i686-linux-gnu on kernel 5.11 and 4.15.
Previously, the source file nptl/cancellation.c was compiled multiple
times, for libc, libpthread, librt. This commit switches to a single
implementation, with new __pthread_enable_asynccancel@@GLIBC_PRIVATE,
__pthread_disable_asynccancel@@GLIBC_PRIVATE exports.
The almost-unused CANCEL_ASYNC and CANCEL_RESET macros are replaced
by LIBC_CANCEL_ASYNC and LIBC_CANCEL_ASYNC macros. They call the
__pthread_* functions unconditionally now. The macros are still
needed because shared code uses them; Hurd has different definitions.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This is a thorough revision of all the material relating to the
functions time, stime, gettimeofday, settimeofday, clock_gettime,
clock_getres, clock_settime, and difftime, spilling over into the
discussion of time-related data types (which now get their own
section) and touching the adjtime family as well (which deserves its
own thorough revision, but I'd have to do a bunch of research first).
Substantive changes are:
* Document clock_gettime, clock_getres, and clock_settime. (Only
CLOCK_REALTIME and CLOCK_MONOTONIC are documented; the others are
either a bit too Linux-specific, or have more to do with measuring
CPU/processor time. That section _also_ deserves its own thorough
revision but again I'd have to do a bunch of research first.)
* Present gettimeofday, settimeofday, and struct timeval as obsolete
relative to clock_*.
* Remove the documentation of struct timezone. Matching POSIX,
say that the type of the second argument to gettimeofday and
settimeofday is [const] void *.
* Clarify ISO C and POSIX's requirements on time_t. Clarify the
circumstances under which difftime is equivalent to simple
subtraction.
* Consolidate documentation of most of the time-related data types
into a new section "Time Types," right after "Time Basics." (The
exceptions are struct tm, which stays in "Broken-down Time," and
struct times, which stays in "Processor And CPU Time."
* The "Elapsed Time" section is now called "Calculating Elapsed Time"
and includes only difftime and the discussion of how to compute
timeval differences by hand.
* Fold the "Simple Calendar Time," "High Resolution Calendar," and
"High Accuracy Clock" sections together into two new sections titled
"Getting the Time" and "Setting and Adjusting the Time."
The kernel is evolving this interface (e.g., removal of the
restriction on cross-device copies), and keeping up with that
is difficult. Applications which need the function should
run kernels which support the system call instead of relying on
the imperfect glibc emulation.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
@var is intended for placeholders (such as function parameters).
Actual variables need to use @code because @var causes upper-case
output, resulting in a different C identifier.
This patch fixes the OFD ("file private") locks for architectures that
support non-LFS flock definition (__USE_FILE_OFFSET64 not defined). The
issue in this case is both F_OFD_{GETLK,SETLK,SETLKW} and
F_{SET,GET}L{W}K64 expects a flock64 argument and when using old
F_OFD_* flags with a non LFS flock argument the kernel might interpret
the underlying data wrongly. Kernel idea originally was to avoid using
such flags in non-LFS syscall, but since GLIBC uses fcntl with LFS
semantic as default it is possible to provide the functionality and
avoid the bogus struct kernel passing by adjusting the struct manually
for the required flags.
The idea follows other LFS interfaces that provide two symbols:
1. A new LFS fcntl64 is added on default ABI with the usual macros to
select it for FILE_OFFSET_BITS=64.
2. The Linux non-LFS fcntl use a stack allocated struct flock64 for
F_OFD_{GETLK,SETLK,SETLKW} copy the results on the user provided
struct.
3. Keep a compat symbol with old broken semantic for architectures
that do not define __OFF_T_MATCHES_OFF64_T.
So for architectures which defines __USE_FILE_OFFSET64, fcntl64 will
aliased to fcntl and no adjustment would be required. So to actually
use F_OFD_* with LFS support the source must be built with LFS support
(_FILE_OFFSET_BITS=64).
Also F_OFD_SETLKW command is handled a cancellation point, as for
F_SETLKW{64}.
Checked on x86_64-linux-gnu and i686-linux-gnu.
[BZ #20251]
* NEWS: Mention fcntl64 addition.
* csu/check_fds.c: Replace __fcntl_nocancel by __fcntl64_nocancel.
* login/utmp_file.c: Likewise.
* sysdeps/posix/fdopendir.c: Likewise.
* sysdeps/posix/opendir.c: Likewise.
* sysdeps/unix/pt-fcntl.c: Likewise.
* include/fcntl.h (__libc_fcntl64, __fcntl64,
__fcntl64_nocancel_adjusted): New prototype.
(__fcntl_nocancel_adjusted): Remove prototype.
* io/Makefile (routines): Add fcntl64.
(CFLAGS-fcntl64.c): New rule.
* io/Versions [GLIBC_2.28] (fcntl64): New symbol.
[GLIBC_PRIVATE] (__libc_fcntl): Rename to __libc_fcntl64.
* io/fcntl.h (fcntl64): Add prototype and redirect if
__USE_FILE_OFFSET64 is defined.
* io/fcntl64.c: New file.
* manual/llio.text: Add a note for which commands fcntl acts a
cancellation point.
* nptl/Makefile (CFLAGS-fcntl64.c): New rule.
* sysdeps/mach/hurd/fcntl.c: Alias fcntl to fcntl64 symbols.
* sysdeps/mach/hurd/i386/libc.abilist [GLIBC_2.28] (fcntl, fcntl64):
New symbols.
* sysdeps/unix/sysv/linux/fcntl.c (__libc_fcntl): Fix F_GETLK64,
F_OFD_GETLK, F_SETLK64, F_SETLKW64, F_OFD_SETLK, and F_OFD_SETLKW for
non-LFS case.
* sysdeps/unix/sysv/linux/fcntl64.c: New file.
* sysdeps/unix/sysv/linux/fcntl_nocancel.c (__fcntl_nocancel): Rename
to __fcntl64_nocancel.
(__fcntl_nocancel_adjusted): Rename to __fcntl64_nocancel_adjusted.
* sysdeps/unix/sysv/linux/not-cancel.h (__fcntl_nocancel): Rename
to __fcntl64_nocancel.
* sysdeps/unix/sysv/linux/tst-ofdlocks.c: New file.
* sysdeps/unix/sysv/linux/tst-ofdlocks-compat.c: Likewise.
* sysdeps/unix/sysv/linux/Makefile (tests): Add tst-ofdlocks.
(tests-internal): Add tst-ofdlocks-compat.
* sysdeps/unix/sysv/linux/aarch64/libc.abilist [GLIBC_2.28]
(fcntl64): New symbol.
* sysdeps/unix/sysv/linux/alpha/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/ia64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist: Likewise.
* sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/arm/libc.abilist [GLIBC_2.28] (fcntl,
fcntl64): Likewise.
* sysdeps/unix/sysv/linux/hppa/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/i386/libc.abilis: Likewise.
* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/microblaze/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/nios2/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist:
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist:
Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/sh/libc.abilist: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist: Likewise.
The system call is somewhat obscure because it is closely related
to file descriptor sealing. However, it is also the recommended
way to create alias mappings, which is why it has more general use.
No emulation is provided. Except for the name of the
/proc/self/fd links, it would be possible to implement an
approximation using O_TMPFILE and tmpfs, but this does not appear
to be worth the added complexity.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Also remove a comment about performance. fwrite vs writev performance
is a very complex topic and cannot be reduced to a simple advice based
on transfer size.
Linux 4.12 (b745fafaf70c0a98a2e1e7ac8cb14542889ceb0e) adds a new
p{read,write}v2 flag RWF_NOWAIT. This patch adds it for linux
uio-ext.h header.
Checked on x86_64-linux-gnu (on a 4.10 kernel).
[BZ #21738]
* manual/llio.texi (RWF_NOWAIT): New item.
* misc/tst-preadvwritev2-common.c (do_test_with_invalid_flags):
Add RWF_NOWAIT check.
* sysdeps/unix/sysv/linux/bits/uio-ext.h (RWF_NOWAIT): New flag.
The Summary is now generated from @standards, and syntax-checking is
performed. If invalid @standards syntax is detected, summary.pl will
fail, reporting all errors. Failure and error reporting is disabled
for now, however, since much of the manual is still incomplete
wrt. header and standards annotations.
Note that the sorting order of the Summary has changed; summary.pl
respects the locale, like summary.awk did, but the use of LC_ALL=C is
introduced in the Makefile. Other notable deviations are improved
detection of the annotated elements' names, which are used for
sorting, and improved detection of the @node used to reference into
the manual. The most noticeable difference in the rendered Summary is
that entries may now contain multiple lines, one for each header and
standard combination.
summary.pl accepts a `--help' option, which details the expected
syntax of @standards. If errors are reported, the user is directed to
this feature for further information.
* manual/Makefile: Generate summary.texi with summary.pl.
Force use of the C locale. Update Perl dependency comment.
* manual/header.texi: Update reference to summary.awk.
* manual/macros.texi: Refer authors to `summary.pl --help'.
* manual/summary.awk: Remove file.
* manual/summary.pl: New file. Generate summary.texi, and
check for @standards-related syntax errors.
* manual/argp.texi: Convert header and standards @comments to
@standards.
* manual/arith.texi: Likewise.
* manual/charset.texi: Likewise.
* manual/conf.texi: Likewise.
* manual/creature.texi: Likewise.
* manual/crypt.texi: Likewise.
* manual/ctype.texi: Likewise.
* manual/debug.texi: Likewise.
* manual/errno.texi: Likewise.
* manual/filesys.texi: Likewise.
* manual/getopt.texi: Likewise.
* manual/job.texi: Likewise.
* manual/lang.texi: Likewise.
* manual/llio.texi: Likewise.
* manual/locale.texi: Likewise.
* manual/math.texi: Likewise.
* manual/memory.texi: Likewise.
* manual/message.texi: Likewise.
* manual/pattern.texi: Likewise.
* manual/pipe.texi: Likewise.
* manual/process.texi: Likewise.
* manual/resource.texi: Likewise.
* manual/search.texi: Likewise.
* manual/setjmp.texi: Likewise.
* manual/signal.texi: Likewise.
* manual/socket.texi: Likewise.
* manual/startup.texi: Likewise.
* manual/stdio.texi: Likewise.
* manual/string.texi: Likewise.
* manual/sysinfo.texi: Likewise.
* manual/syslog.texi: Likewise.
* manual/terminal.texi: Likewise.
* manual/threads.texi: Likewise.
* manual/time.texi: Likewise.
* manual/users.texi: Likewise.
This patch adds support of preadv2 and pwritev2 which are similar to
preadv/pwritev but with an extra flag argument. As for preadv/pwritev
both interfaces are added a non-standard GNU API.
For default 'posix' implementation trying to emulate the Linux supported
flags is troublesome:
* We can not temporary change the file state of the O_DSYNC and O_SYNC
flags to emulate RWF_{D}SYNC (attempts to change the state of using
fcntl are silently ignored).
* IOCB_HIPRI requires the file opened in O_DIRECT and uses an internal
semantic not provided by any other flag (O_NONBLOCK for instance).
So default sysdeps/posix implementations fails with EOPNOTSUPP for any non
supported flag (which are none currently) calls generic preadv/pwritev.
Basically this implementation supports only preadv2 called as preadv (with
flags sets to 0).
The Linux one uses the preadv2/pwritev2 syscall if defined, otherwise it
call preadv/writev. Instead of using the previous __ASSUME_* to
unconditionally issue the syscall (and avoid building the fallback routine),
it call pread/write if the preadv2/pwritev2 syscalls fails. The idea
is just avoid adding another __ASSUME_* and checking each architecture
on every kernel bump and simplify code conditionals.
Checked on x86_64-linux-gnu and on i686-linux-gnu and a check with
run-built-tests=no on aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabihf,
ia64-linux-gnu, m68k-linux-gnu, microblaze-linux-gnu, mips{64,64n32}-linux-gnu,
nios2-linux-gnu, powerpc{64,64le}-linux-gnu, s390{x}-linux-gnu,
sparc{64,v9}-linux-gnu, tile{gx,pro}-linux-gnu, and sh4-linux-gnu (all using
gcc 6.3).
* NEWS: Add note about pwritev2 and preadv2 inclusion.
* misc/Makefile (routines): Add preadv2, preadv64v2, pwritev2, and
pwritev64v2.
(tests): Add tst-preadvwritev2 and tst-preadvwritev64v2.
* misc/Versions (GLIBC_2.26): Add preadv2, preadv64v2, pwritev2, and
pwritev64v2.
* misc/preadv2.c: New file.
* misc/preadv64v2.c: Likewise.
* misc/pwritev2.c: Likewise.
* misc/pwritev64v2.c: Likewise.
* misc/tst-preadvwritev2.c: Likewise.
* misc/tst-preadvwritev64v2.c: Likewise.
* manual/llio.texi: Add preadv2 and pwritev2 documentation.
* misc/sys/uio.h [__USE_GNU && !__USE_FILE_OFFSET64] (preadv2): New
prototype.
[__USE_GNU && !__USE_FILE_OFFSET64] (pwritev2): Likewise.
[__USE_GNU && __USE_FILE_OFFSET64] (preadv64v2): Likewise.
[__USE_GNU && __USE_FILE_OFFSET64] (pwritev64v2): Likewise.
* misc/tst-preadvwritev-common.c (PREADV): Define if not defined.
(PWRITEV): Likewise.
(do_test_with_offset): Use PREADV and PWRITEV macros and check for
ENOSYS.
* nptl/tst-cancel4.c (tf_pwritev2): New test.
(tf_preadv2): Likewise.
(tf_fsync): Add tf_pwritev2 and tf_preadv2.
* sysdeps/posix/preadv2.c: Likewise.
* sysdeps/posix/preadv64v2.c: Likewise.
* sysdeps/posix/pwritev2.c: Likewise.
* sysdeps/posix/pwritev64v2.c: Likewise.
* sysdeps/unix/sysv/linux/kernel-features.h: Add comment for syscall
support in kernel.
* sysdeps/unix/sysv/linux/preadv2.c: Likewise.
* sysdeps/unix/sysv/linux/preadv64v2.c: Likewise.
* sysdeps/unix/sysv/linux/pwritev2.c: Likewise.
* sysdeps/unix/sysv/linux/pwritev64v2.c: Likewise.
* sysdeps/unix/sysv/linux/preadv.c (preadv): Add libc_hidden_def.
* sysdeps/unix/sysv/linux/preadv64.c (preadv64): Likewise.
* sysdeps/unix/sysv/linux/pwritev.c (pwritev): Likewise.
* sysdeps/unix/sysv/linux/pwritev64.c (pwritev64): Likewise.
* sysdeps/unix/sysv/linux/bits/uio.h: Add supported preadv2/pwritev2
support flags on Linux.
* sysdeps/unix/sysv/linux/aarch64/libc.abilist (GLIBC_2.26): Add
preadv2, preadv64v2, pwritev2, pwritev64v2.
* sysdeps/unix/sysv/linux/alpha/libc.abilist (GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/arm/libc.abilist (GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/hppa/libc.abilist (GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/i386/libc.abilist (GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/ia64/libc.abilist (GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/microblaze/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/nios2/libc.abilist (GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
(GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
(GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
(GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/sh/libc.abilist (GLIBC_2.26): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/sysv/linux/tile/tilegx/tilegx32/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/sysv/linux/tile/tilegx/tilegx64/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist (GLIBC_2.26):
Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist (GLIBC_2.26):
Likewise.
Texinfo @vindex commands add entries to the Variable and Constant
Macro Index. Similarly, @items in @vtables are automatically indexed.
A number of @tables exist where all @items are @vindexed or all @items
are variables, but not indexed, suggesting an optimization by
converting such @tables to @vtables and dropping the @vindex.
Using a @vtable provides a context for processing @items whereby it
can be known the @items should have header and standards annotations.
This commit converts @tables of such @items to @vtables in order to
establish a framework for automated processing.
A pleasant consequence of these changes is that @items previously
lacking a @vindex are present in the Variable and Constant Macro Index
now. @vindex entries previously detected by summary.awk will still be
detected as @items with appropriate annotations.
The @vtable of the NSS databases is converted to a @table because 1)
those @items are not variables (and will no longer appear in the
Variable and Constant Macro Index) and 2) they do not need header and
standards annotations, so the incorrect context is fixed.
* manual/nss.texi: Change incorrect @vtable to @table.
* manual/arith.texi: Convert @tables of variables to @vtables
and remove unnecessary indexing.
* manual/filesys.texi: Likewise.
* manual/llio.texi: Likewise.
* manual/memory.texi: Likewise.
* manual/process.texi: Likewise.
* manual/resource.texi: Likewise.
* manual/search.texi: Likewise.
* manual/signal.texi: Likewise.
* manual/socket.texi: Likewise.
* manual/stdio.texi: Likewise.
* manual/sysinfo.texi: Likewise.
* manual/syslog.texi: Likewise.
* manual/terminal.texi: Likewise.
* manual/time.texi: Likewise.
* manual/users.texi: Likewise.
We add Linux-realted comments about the atomicity of
write with respect to file offsets. As of Linux 3.14
the file offset update is atomic. That means that
multiple threads calling the write syscall can not possibly
get the same file offset. Therefore the writes should
not overlap and data should not be lost as is required
by POSIX.
Add Linux-specific comments about the atomicity of write() and
the POSIX requirements.
2014-10-29 Carlos O'Donell <carlos@redhat.com>
* manual/llio.texi: Add comments discussing why write() may be
considered MT-unsafe on Linux.
Open file description locks have been merged into the Linux kernel for
v3.15. Add the appropriate command-value definitions and an update to
the manual that describes their usage.
