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glibc/io/closefrom.c

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io: Add closefrom [BZ #10353] 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] https://github.com/systemd/systemd/blob/5238e9575906297608ff802a27e2ff9effa3b338/src/basic/fd-util.c#L217 [2] https://github.com/lxc/lxc/blob/ddf4b77e11a4d08f09b7b9cd13e593f8c047edc5/src/lxc/start.c#L236 [3] https://github.com/python/cpython/blob/9e4f2f3a6b8ee995c365e86d976937c141d867f8/Modules/_posixsubprocess.c#L220 [4] https://github.com/rust-lang/rust/blob/5f47c0613ed4eb46fca3633c1297364c09e5e451/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
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/* Close a range of file descriptors.
Update copyright dates with scripts/update-copyrights I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 7061 files FOO. I then removed trailing white space from math/tgmath.h, support/tst-support-open-dev-null-range.c, and sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following obscure pre-commit check failure diagnostics from Savannah. I don't know why I run into these diagnostics whereas others evidently do not. remote: *** 912-#endif remote: *** 913: remote: *** 914- remote: *** error: lines with trailing whitespace found ... remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
2022-01-02 02:54:23 +08:00
Copyright (C) 2021-2022 Free Software Foundation, Inc.
io: Add closefrom [BZ #10353] 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] https://github.com/systemd/systemd/blob/5238e9575906297608ff802a27e2ff9effa3b338/src/basic/fd-util.c#L217 [2] https://github.com/lxc/lxc/blob/ddf4b77e11a4d08f09b7b9cd13e593f8c047edc5/src/lxc/start.c#L236 [3] https://github.com/python/cpython/blob/9e4f2f3a6b8ee995c365e86d976937c141d867f8/Modules/_posixsubprocess.c#L220 [4] https://github.com/rust-lang/rust/blob/5f47c0613ed4eb46fca3633c1297364c09e5e451/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
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This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
io: Refactor close_range and closefrom Now that Hurd implementis both close_range and closefrom (f2c996597d), we can make close_range() a base ABI, and make the default closefrom() implementation on top of close_range(). The generic closefrom() implementation based on __getdtablesize() is moved to generic close_range(). On Linux it will be overriden by the auto-generation syscall while on Hurd it will be a system specific implementation. The closefrom() now calls close_range() and __closefrom_fallback(). Since on Hurd close_range() does not fail, __closefrom_fallback() is an empty static inline function set by__ASSUME_CLOSE_RANGE. The __ASSUME_CLOSE_RANGE also allows optimize Linux __closefrom_fallback() implementation when --enable-kernel=5.9 or higher is used. Finally the Linux specific tst-close_range.c is moved to io and enabled as default. The Linuxism and CLOSE_RANGE_UNSHARE are guarded so it can be built for Hurd (I have not actually test it). Checked on x86_64-linux-gnu, i686-linux-gnu, and with a i686-gnu build.
2021-11-08 21:20:23 +08:00
#include <stdbool.h>
io: Add closefrom [BZ #10353] 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] https://github.com/systemd/systemd/blob/5238e9575906297608ff802a27e2ff9effa3b338/src/basic/fd-util.c#L217 [2] https://github.com/lxc/lxc/blob/ddf4b77e11a4d08f09b7b9cd13e593f8c047edc5/src/lxc/start.c#L236 [3] https://github.com/python/cpython/blob/9e4f2f3a6b8ee995c365e86d976937c141d867f8/Modules/_posixsubprocess.c#L220 [4] https://github.com/rust-lang/rust/blob/5f47c0613ed4eb46fca3633c1297364c09e5e451/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
2021-03-10 23:26:32 +08:00
#include <stdio.h>
io: Refactor close_range and closefrom Now that Hurd implementis both close_range and closefrom (f2c996597d), we can make close_range() a base ABI, and make the default closefrom() implementation on top of close_range(). The generic closefrom() implementation based on __getdtablesize() is moved to generic close_range(). On Linux it will be overriden by the auto-generation syscall while on Hurd it will be a system specific implementation. The closefrom() now calls close_range() and __closefrom_fallback(). Since on Hurd close_range() does not fail, __closefrom_fallback() is an empty static inline function set by__ASSUME_CLOSE_RANGE. The __ASSUME_CLOSE_RANGE also allows optimize Linux __closefrom_fallback() implementation when --enable-kernel=5.9 or higher is used. Finally the Linux specific tst-close_range.c is moved to io and enabled as default. The Linuxism and CLOSE_RANGE_UNSHARE are guarded so it can be built for Hurd (I have not actually test it). Checked on x86_64-linux-gnu, i686-linux-gnu, and with a i686-gnu build.
2021-11-08 21:20:23 +08:00
#include <sys/param.h>
io: Add closefrom [BZ #10353] 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] https://github.com/systemd/systemd/blob/5238e9575906297608ff802a27e2ff9effa3b338/src/basic/fd-util.c#L217 [2] https://github.com/lxc/lxc/blob/ddf4b77e11a4d08f09b7b9cd13e593f8c047edc5/src/lxc/start.c#L236 [3] https://github.com/python/cpython/blob/9e4f2f3a6b8ee995c365e86d976937c141d867f8/Modules/_posixsubprocess.c#L220 [4] https://github.com/rust-lang/rust/blob/5f47c0613ed4eb46fca3633c1297364c09e5e451/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
2021-03-10 23:26:32 +08:00
#include <unistd.h>
void
__closefrom (int lowfd)
{
io: Refactor close_range and closefrom Now that Hurd implementis both close_range and closefrom (f2c996597d), we can make close_range() a base ABI, and make the default closefrom() implementation on top of close_range(). The generic closefrom() implementation based on __getdtablesize() is moved to generic close_range(). On Linux it will be overriden by the auto-generation syscall while on Hurd it will be a system specific implementation. The closefrom() now calls close_range() and __closefrom_fallback(). Since on Hurd close_range() does not fail, __closefrom_fallback() is an empty static inline function set by__ASSUME_CLOSE_RANGE. The __ASSUME_CLOSE_RANGE also allows optimize Linux __closefrom_fallback() implementation when --enable-kernel=5.9 or higher is used. Finally the Linux specific tst-close_range.c is moved to io and enabled as default. The Linuxism and CLOSE_RANGE_UNSHARE are guarded so it can be built for Hurd (I have not actually test it). Checked on x86_64-linux-gnu, i686-linux-gnu, and with a i686-gnu build.
2021-11-08 21:20:23 +08:00
int l = MAX (0, lowfd);
io: Add closefrom [BZ #10353] 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] https://github.com/systemd/systemd/blob/5238e9575906297608ff802a27e2ff9effa3b338/src/basic/fd-util.c#L217 [2] https://github.com/lxc/lxc/blob/ddf4b77e11a4d08f09b7b9cd13e593f8c047edc5/src/lxc/start.c#L236 [3] https://github.com/python/cpython/blob/9e4f2f3a6b8ee995c365e86d976937c141d867f8/Modules/_posixsubprocess.c#L220 [4] https://github.com/rust-lang/rust/blob/5f47c0613ed4eb46fca3633c1297364c09e5e451/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
2021-03-10 23:26:32 +08:00
io: Refactor close_range and closefrom Now that Hurd implementis both close_range and closefrom (f2c996597d), we can make close_range() a base ABI, and make the default closefrom() implementation on top of close_range(). The generic closefrom() implementation based on __getdtablesize() is moved to generic close_range(). On Linux it will be overriden by the auto-generation syscall while on Hurd it will be a system specific implementation. The closefrom() now calls close_range() and __closefrom_fallback(). Since on Hurd close_range() does not fail, __closefrom_fallback() is an empty static inline function set by__ASSUME_CLOSE_RANGE. The __ASSUME_CLOSE_RANGE also allows optimize Linux __closefrom_fallback() implementation when --enable-kernel=5.9 or higher is used. Finally the Linux specific tst-close_range.c is moved to io and enabled as default. The Linuxism and CLOSE_RANGE_UNSHARE are guarded so it can be built for Hurd (I have not actually test it). Checked on x86_64-linux-gnu, i686-linux-gnu, and with a i686-gnu build.
2021-11-08 21:20:23 +08:00
int r = __close_range (l, ~0U, 0);
if (r == 0)
return ;
if (!__closefrom_fallback (l, true))
__fortify_fail ("closefrom failed to close a file descriptor");
io: Add closefrom [BZ #10353] 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] https://github.com/systemd/systemd/blob/5238e9575906297608ff802a27e2ff9effa3b338/src/basic/fd-util.c#L217 [2] https://github.com/lxc/lxc/blob/ddf4b77e11a4d08f09b7b9cd13e593f8c047edc5/src/lxc/start.c#L236 [3] https://github.com/python/cpython/blob/9e4f2f3a6b8ee995c365e86d976937c141d867f8/Modules/_posixsubprocess.c#L220 [4] https://github.com/rust-lang/rust/blob/5f47c0613ed4eb46fca3633c1297364c09e5e451/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
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}
weak_alias (__closefrom, closefrom)
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