mirror of
https://github.com/morgan9e/systemd
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81995fbb96
Newer kernels support a new flag for name_to_handle_at(): AT_HANDLE_FID. This flag is supposed to return an identifier for an inode that we can use for checking inode identity. It's supposed to be a replacement for checking .st_ino which doesn't work anymore today because inode numbers are no longer unique on file systems (not on overlayfs, and not on btrfs for example). Hence, be a good citizen and add infrastructure to support AT_HANDLE_FID. Unfortunately that doesn't work for old kernels, hence add a fallback logic: if we can use the flag, use it. If we cannot use name_to_handle_at() without it, which might give us a good ID too. But of course tha tcan fail as well, which callers have to check.
99 lines
3.0 KiB
C
99 lines
3.0 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include <fcntl.h>
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#ifndef F_LINUX_SPECIFIC_BASE
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#define F_LINUX_SPECIFIC_BASE 1024
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#endif
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#ifndef F_SETPIPE_SZ
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#define F_SETPIPE_SZ (F_LINUX_SPECIFIC_BASE + 7)
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#endif
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#ifndef F_GETPIPE_SZ
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#define F_GETPIPE_SZ (F_LINUX_SPECIFIC_BASE + 8)
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#endif
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#ifndef F_ADD_SEALS
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#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
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#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10)
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#define F_SEAL_SEAL 0x0001 /* prevent further seals from being set */
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#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */
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#define F_SEAL_GROW 0x0004 /* prevent file from growing */
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#define F_SEAL_WRITE 0x0008 /* prevent writes */
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#endif
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#ifndef F_SEAL_FUTURE_WRITE
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#define F_SEAL_FUTURE_WRITE 0x0010 /* prevent future writes while mapped */
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#endif
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#ifndef F_SEAL_EXEC
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#define F_SEAL_EXEC 0x0020 /* prevent chmod modifying exec bits */
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#endif
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#ifndef F_OFD_GETLK
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#define F_OFD_GETLK 36
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#define F_OFD_SETLK 37
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#define F_OFD_SETLKW 38
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#endif
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#ifndef MAX_HANDLE_SZ
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#define MAX_HANDLE_SZ 128
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#endif
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/* The precise definition of __O_TMPFILE is arch specific; use the
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* values defined by the kernel (note: some are hexa, some are octal,
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* duplicated as-is from the kernel definitions):
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* - alpha, parisc, sparc: each has a specific value;
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* - others: they use the "generic" value.
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*/
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#ifndef __O_TMPFILE
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#if defined(__alpha__)
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#define __O_TMPFILE 0100000000
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#elif defined(__parisc__) || defined(__hppa__)
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#define __O_TMPFILE 0400000000
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#elif defined(__sparc__) || defined(__sparc64__)
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#define __O_TMPFILE 0x2000000
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#else
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#define __O_TMPFILE 020000000
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#endif
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#endif
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/* a horrid kludge trying to make sure that this will fail on old kernels */
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#ifndef O_TMPFILE
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#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
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#endif
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/* So O_LARGEFILE is generally implied by glibc, and defined to zero hence, because we only build in LFS
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* mode. However, when invoking fcntl(F_GETFL) the flag is ORed into the result anyway — glibc does not mask
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* it away. Which sucks. Let's define the actual value here, so that we can mask it ourselves.
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*
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* The precise definition is arch specific, so we use the values defined in the kernel (note that some
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* are hexa and others are octal; duplicated as-is from the kernel definitions):
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* - alpha, arm, arm64, m68k, mips, parisc, powerpc, sparc: each has a specific value;
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* - others: they use the "generic" value (defined in include/uapi/asm-generic/fcntl.h) */
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#if O_LARGEFILE != 0
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#define RAW_O_LARGEFILE O_LARGEFILE
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#else
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#if defined(__alpha__) || defined(__arm__) || defined(__aarch64__) || defined(__m68k__)
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#define RAW_O_LARGEFILE 0400000
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#elif defined(__mips__)
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#define RAW_O_LARGEFILE 0x2000
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#elif defined(__parisc__) || defined(__hppa__)
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#define RAW_O_LARGEFILE 000004000
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#elif defined(__powerpc__)
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#define RAW_O_LARGEFILE 0200000
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#elif defined(__sparc__)
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#define RAW_O_LARGEFILE 0x40000
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#else
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#define RAW_O_LARGEFILE 00100000
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#endif
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#endif
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#ifndef AT_HANDLE_FID
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#define AT_HANDLE_FID AT_REMOVEDIR
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#endif
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