[PATCH v2 5/5] linux: Fix sys/mount.h usage with kernel headers
Adhemerval Zanella
adhemerval.zanella@linaro.org
Wed Aug 10 17:24:47 GMT 2022
Now that kernel exports linux/mount.h and includes it on linux/fs.h,
its definitions might clash with glibc exports sys/mount.h. To avoid
the need to rearrange the Linux header to be always after glibc one,
the glibc sys/mount.h is changed to:
1. Undefine the macros also used as enum constants. This covers prior
inclusion of <linux/mount.h> (for instance MS_RDONLY).
2. Include <linux/mount.h> based on the usual __has_include check
(needs to use __has_include ("linux/mount.h") to paper over GCC
bugs.
3. Define enum fsconfig_command only if FSOPEN_CLOEXEC is not defined.
(FSOPEN_CLOEXEC should be a very close proxy.)
4. Define struct mount_attr if MOUNT_ATTR_SIZE_VER0 is not defined.
(Added in the same commit on the Linux side.)
This patch also adds some tests to check if including linux/fs.h and
linux/mount.h after and before sys/mount.h does work.
Checked on x86_64-linux-gnu.
---
sysdeps/unix/sysv/linux/Makefile | 8 +++
sysdeps/unix/sysv/linux/sys/mount.h | 71 +++++++++++++++++---
sysdeps/unix/sysv/linux/tst-mount-compile.py | 66 ++++++++++++++++++
3 files changed, 137 insertions(+), 8 deletions(-)
create mode 100755 sysdeps/unix/sysv/linux/tst-mount-compile.py
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 3f31c19e4a..60e4cb1521 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -265,6 +265,14 @@ $(objpfx)tst-mount-consts.out: ../sysdeps/unix/sysv/linux/tst-mount-consts.py
< /dev/null > $@ 2>&1; $(evaluate-test)
$(objpfx)tst-mount-consts.out: $(sysdeps-linux-python-deps)
+tests-special += $(objpfx)tst-mount-compile.out
+$(objpfx)tst-mount-compile.out: ../sysdeps/unix/sysv/linux/tst-mount-compile.py
+ $(sysdeps-linux-python) \
+ ../sysdeps/unix/sysv/linux/tst-mount-compile.py \
+ $(sysdeps-linux-python-cc) \
+ < /dev/null > $@ 2>&1; $(evaluate-test)
+$(objpfx)tst-mount-compile.out: $(sysdeps-linux-python-deps)
+
tst-rseq-disable-ENV = GLIBC_TUNABLES=glibc.pthread.rseq=0
endif # $(subdir) == misc
diff --git a/sysdeps/unix/sysv/linux/sys/mount.h b/sysdeps/unix/sysv/linux/sys/mount.h
index df6b0dbb42..2e3fd6a7fe 100644
--- a/sysdeps/unix/sysv/linux/sys/mount.h
+++ b/sysdeps/unix/sysv/linux/sys/mount.h
@@ -27,6 +27,13 @@
#include <stddef.h>
#include <sys/ioctl.h>
+#ifdef __has_include
+# if __has_include ("linux/mount.h")
+# include "linux/mount.h"
+# endif
+#endif
+
+
#define BLOCK_SIZE_BITS 10
#define BLOCK_SIZE (1<<BLOCK_SIZE_BITS)
@@ -35,69 +42,98 @@
supported */
enum
{
+#undef MS_RDONLY
MS_RDONLY = 1, /* Mount read-only. */
#define MS_RDONLY MS_RDONLY
+#undef MS_NOSUID
MS_NOSUID = 2, /* Ignore suid and sgid bits. */
#define MS_NOSUID MS_NOSUID
+#undef MS_NODEV
MS_NODEV = 4, /* Disallow access to device special files. */
#define MS_NODEV MS_NODEV
+#undef MS_NOEXEC
MS_NOEXEC = 8, /* Disallow program execution. */
#define MS_NOEXEC MS_NOEXEC
+#undef MS_SYNCHRONOUS
MS_SYNCHRONOUS = 16, /* Writes are synced at once. */
#define MS_SYNCHRONOUS MS_SYNCHRONOUS
+#undef MS_REMOUNT
MS_REMOUNT = 32, /* Alter flags of a mounted FS. */
#define MS_REMOUNT MS_REMOUNT
+#undef MS_MANDLOCK
MS_MANDLOCK = 64, /* Allow mandatory locks on an FS. */
#define MS_MANDLOCK MS_MANDLOCK
+#undef MS_DIRSYNC
MS_DIRSYNC = 128, /* Directory modifications are synchronous. */
#define MS_DIRSYNC MS_DIRSYNC
+#undef MS_NOSYMFOLLOW
MS_NOSYMFOLLOW = 256, /* Do not follow symlinks. */
#define MS_NOSYMFOLLOW MS_NOSYMFOLLOW
+#undef MS_NOATIME
MS_NOATIME = 1024, /* Do not update access times. */
#define MS_NOATIME MS_NOATIME
+#undef MS_NODIRATIME
MS_NODIRATIME = 2048, /* Do not update directory access times. */
#define MS_NODIRATIME MS_NODIRATIME
+#undef MS_BIND
MS_BIND = 4096, /* Bind directory at different place. */
#define MS_BIND MS_BIND
+#undef MS_MOVE
MS_MOVE = 8192,
#define MS_MOVE MS_MOVE
+#undef MS_REC
MS_REC = 16384,
#define MS_REC MS_REC
+#undef MS_SILENT
MS_SILENT = 32768,
#define MS_SILENT MS_SILENT
+#undef MS_POSIXACL
MS_POSIXACL = 1 << 16, /* VFS does not apply the umask. */
#define MS_POSIXACL MS_POSIXACL
+#undef MS_UNBINDABLE
MS_UNBINDABLE = 1 << 17, /* Change to unbindable. */
#define MS_UNBINDABLE MS_UNBINDABLE
+#undef MS_PRIVATE
MS_PRIVATE = 1 << 18, /* Change to private. */
#define MS_PRIVATE MS_PRIVATE
+#undef MS_SLAVE
MS_SLAVE = 1 << 19, /* Change to slave. */
#define MS_SLAVE MS_SLAVE
+#undef MS_SHARED
MS_SHARED = 1 << 20, /* Change to shared. */
#define MS_SHARED MS_SHARED
+#undef MS_RELATIME
MS_RELATIME = 1 << 21, /* Update atime relative to mtime/ctime. */
#define MS_RELATIME MS_RELATIME
+#undef MS_KERNMOUNT
MS_KERNMOUNT = 1 << 22, /* This is a kern_mount call. */
#define MS_KERNMOUNT MS_KERNMOUNT
+#undef MS_I_VERSION
MS_I_VERSION = 1 << 23, /* Update inode I_version field. */
#define MS_I_VERSION MS_I_VERSION
+#undef MS_STRICTATIME
MS_STRICTATIME = 1 << 24, /* Always perform atime updates. */
#define MS_STRICTATIME MS_STRICTATIME
+#undef MS_LAZYTIME
MS_LAZYTIME = 1 << 25, /* Update the on-disk [acm]times lazily. */
#define MS_LAZYTIME MS_LAZYTIME
+#undef MS_ACTIVE
MS_ACTIVE = 1 << 30,
#define MS_ACTIVE MS_ACTIVE
+#undef MS_NOUSER
MS_NOUSER = 1 << 31
#define MS_NOUSER MS_NOUSER
};
/* Flags that can be altered by MS_REMOUNT */
+#undef MS_RMT_MASK
#define MS_RMT_MASK (MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_I_VERSION \
|MS_LAZYTIME)
/* Magic mount flag number. Has to be or-ed to the flag values. */
+#undef MS_MGC_VAL
#define MS_MGC_VAL 0xc0ed0000 /* Magic flag number to indicate "new" flags */
#define MS_MGC_MSK 0xffff0000 /* Magic flag number mask */
@@ -106,20 +142,35 @@ enum
is probably as bad and I don't want to create yet another include
file. */
+#undef BLKROSET
#define BLKROSET _IO(0x12, 93) /* Set device read-only (0 = read-write). */
+#undef BLKROGET
#define BLKROGET _IO(0x12, 94) /* Get read-only status (0 = read_write). */
+#undef BLKRRPART
#define BLKRRPART _IO(0x12, 95) /* Re-read partition table. */
+#undef BLKGETSIZE
#define BLKGETSIZE _IO(0x12, 96) /* Return device size. */
+#undef BLKFLSBUF
#define BLKFLSBUF _IO(0x12, 97) /* Flush buffer cache. */
+#undef BLKRASET
#define BLKRASET _IO(0x12, 98) /* Set read ahead for block device. */
+#undef BLKRAGET
#define BLKRAGET _IO(0x12, 99) /* Get current read ahead setting. */
+#undef BLKFRASET
#define BLKFRASET _IO(0x12,100) /* Set filesystem read-ahead. */
+#undef BLKFRAGET
#define BLKFRAGET _IO(0x12,101) /* Get filesystem read-ahead. */
+#undef BLKSECTSET
#define BLKSECTSET _IO(0x12,102) /* Set max sectors per request. */
+#undef BLKSECTGET
#define BLKSECTGET _IO(0x12,103) /* Get max sectors per request. */
+#undef BLKSSZGET
#define BLKSSZGET _IO(0x12,104) /* Get block device sector size. */
+#undef BLKBSZGET
#define BLKBSZGET _IOR(0x12,112,size_t)
+#undef BLKBSZSET
#define BLKBSZSET _IOW(0x12,113,size_t)
+#undef BLKGETSIZE64
#define BLKGETSIZE64 _IOR(0x12,114,size_t) /* return device size. */
@@ -157,6 +208,7 @@ enum
#define MOUNT_ATTR_NOSYMFOLLOW 0x00200000 /* Do not follow symlinks. */
+#ifndef MOUNT_ATTR_SIZE_VER0
/* For mount_setattr. */
struct mount_attr
{
@@ -165,6 +217,7 @@ struct mount_attr
uint64_t propagation;
uint64_t userns_fd;
};
+#endif
#define MOUNT_ATTR_SIZE_VER0 32 /* sizeof first published struct */
@@ -185,26 +238,28 @@ struct mount_attr
#define FSPICK_EMPTY_PATH 0x00000008
+#ifndef FSOPEN_CLOEXEC
/* The type of fsconfig call made. */
enum fsconfig_command
{
FSCONFIG_SET_FLAG = 0, /* Set parameter, supplying no value */
-#define FSCONFIG_SET_FLAG FSCONFIG_SET_FLAG
+# define FSCONFIG_SET_FLAG FSCONFIG_SET_FLAG
FSCONFIG_SET_STRING = 1, /* Set parameter, supplying a string value */
-#define FSCONFIG_SET_STRING FSCONFIG_SET_STRING
+# define FSCONFIG_SET_STRING FSCONFIG_SET_STRING
FSCONFIG_SET_BINARY = 2, /* Set parameter, supplying a binary blob value */
-#define FSCONFIG_SET_BINARY FSCONFIG_SET_BINARY
+# define FSCONFIG_SET_BINARY FSCONFIG_SET_BINARY
FSCONFIG_SET_PATH = 3, /* Set parameter, supplying an object by path */
-#define FSCONFIG_SET_PATH FSCONFIG_SET_PATH
+# define FSCONFIG_SET_PATH FSCONFIG_SET_PATH
FSCONFIG_SET_PATH_EMPTY = 4, /* Set parameter, supplying an object by (empty) path */
-#define FSCONFIG_SET_PATH_EMPTY FSCONFIG_SET_PATH_EMPTY
+# define FSCONFIG_SET_PATH_EMPTY FSCONFIG_SET_PATH_EMPTY
FSCONFIG_SET_FD = 5, /* Set parameter, supplying an object by fd */
-#define FSCONFIG_SET_FD FSCONFIG_SET_FD
+# define FSCONFIG_SET_FD FSCONFIG_SET_FD
FSCONFIG_CMD_CREATE = 6, /* Invoke superblock creation */
-#define FSCONFIG_CMD_CREATE FSCONFIG_CMD_CREATE
+# define FSCONFIG_CMD_CREATE FSCONFIG_CMD_CREATE
FSCONFIG_CMD_RECONFIGURE = 7, /* Invoke superblock reconfiguration */
-#define FSCONFIG_CMD_RECONFIGURE FSCONFIG_CMD_RECONFIGURE
+# define FSCONFIG_CMD_RECONFIGURE FSCONFIG_CMD_RECONFIGURE
};
+#endif
/* open_tree flags. */
#define OPEN_TREE_CLONE 1 /* Clone the target tree and attach the clone */
diff --git a/sysdeps/unix/sysv/linux/tst-mount-compile.py b/sysdeps/unix/sysv/linux/tst-mount-compile.py
new file mode 100755
index 0000000000..0ec74d4e0b
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-mount-compile.py
@@ -0,0 +1,66 @@
+#!/usr/bin/python3
+# Check if glibc provided sys/mount.h can be used along related kernel
+# headers.
+# Copyright (C) 2022 Free Software Foundation, Inc.
+# 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/>.
+
+import argparse
+import sys
+
+import glibcextract
+
+
+def main():
+ """The main entry point."""
+ parser = argparse.ArgumentParser(
+ description='Check if glibc provided sys/mount.h can be '
+ ' used along related kernel headers.')
+ parser.add_argument('--cc', metavar='CC',
+ help='C compiler (including options) to use')
+ args = parser.parse_args()
+
+ if glibcextract.compile_c_snippet(
+ '#include <linux/mount.h>',
+ args.cc).returncode != 0:
+ sys.exit (77)
+
+ def check(testname, snippet):
+ # Add -Werror to catch macro redefinitions and _ISOMAC to avoid
+ # internal glibc definitions.
+ r = glibcextract.compile_c_snippet(snippet, args.cc,
+ '-Werror -D_ISOMAC')
+ if r.returncode != 0:
+ print('error: test {}:\n{}'.format(testname, r.output.decode()))
+ return r.returncode
+
+ status = max(
+ check("sys/mount.h + linux/mount.h",
+ "#include <sys/mount.h>\n"
+ "#include <linux/mount.h>"),
+ check("sys/mount.h + linux/fs.h",
+ "#include <sys/mount.h>\n"
+ "#include <linux/fs.h>"),
+ check("linux/mount.h + sys/mount.h",
+ "#include <linux/mount.h>\n"
+ "#include <sys/mount.h>"),
+ check("linux/fs.h + sys/mount.h",
+ "#include <linux/fs.h>\n"
+ "#include <sys/mount.h>"))
+ sys.exit(status)
+
+if __name__ == '__main__':
+ main()
--
2.34.1
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