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The existing asm-generic/stat.h specifies st_mtime, etc., as a 32-value, and works well for 32-bit architectures (currently microblaze, score, and 32-bit tile). However, for 64-bit architectures it isn't sufficient to return 32 bits of time_t; this isn't good insurance against the 2037 rollover. (It also makes glibc support less convenient, since we can't use glibc's handy STAT_IS_KERNEL_STAT mode.) This change extends the two "timespec" fields for each of the three atime, mtime, and ctime fields from "int" to "long". As a result, on 32-bit platforms nothing changes, and 64-bit platforms will now work as expected. The only wrinkle is 32-bit userspace under 64-bit kernels taking advantage of COMPAT mode. For these, we leave the "struct stat64" definitions with the "int" versions of the time_t and nsec fields, so that architectures can implement compat_sys_stat64() and friends with sys_stat64(), etc., and get the expected 32-bit structure layout. This requires a field-by-field copy in the kernel, implemented by the code guarded under __ARCH_WANT_STAT64. This does mean that the shape of the "struct stat" and "struct stat64" structures is different on a 64-bit kernel, but only one of the two structures should ever be used by any given process: "struct stat" is meant for 64-bit userspace only, and "struct stat64" for 32-bit userspace only. (On a 32-bit kernel the two structures continue to have the same shape, since "long" is 32 bits.) The alternative is keeping the two structures the same shape on 64-bit kernels, which means a 64-bit time_t in "struct stat64" for 32-bit processes. This is a little unnatural since 32-bit userspace can't do anything with 64 bits of time_t information, since time_t is just "long", not "int64_t"; and in any case 32-bit userspace might expect to be running under a 32-bit kernel, which can't provide the high 32 bits anyway. In the case of a 32-bit kernel we'd then be extending the kernel's 32-bit time_t to 64 bits, then truncating it back to 32 bits again in userspace, for no particular reason. And, as mentioned above, if we have 64-bit time_t for 32-bit processes we can't easily use glibc's STAT_IS_KERNEL_STAT, since glibc's stat structure requires an embedded "struct timespec", which is a pair of "long" (32-bit) values in a 32-bit userspace. "Inventive" solutions are possible, but are pretty hacky. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
73 lines
2.5 KiB
C
73 lines
2.5 KiB
C
#ifndef __ASM_GENERIC_STAT_H
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#define __ASM_GENERIC_STAT_H
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/*
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* Everybody gets this wrong and has to stick with it for all
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* eternity. Hopefully, this version gets used by new architectures
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* so they don't fall into the same traps.
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*
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* stat64 is copied from powerpc64, with explicit padding added.
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* stat is the same structure layout on 64-bit, without the 'long long'
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* types.
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*
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* By convention, 64 bit architectures use the stat interface, while
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* 32 bit architectures use the stat64 interface. Note that we don't
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* provide an __old_kernel_stat here, which new architecture should
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* not have to start with.
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*/
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#include <asm/bitsperlong.h>
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#define STAT_HAVE_NSEC 1
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struct stat {
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unsigned long st_dev; /* Device. */
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unsigned long st_ino; /* File serial number. */
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unsigned int st_mode; /* File mode. */
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unsigned int st_nlink; /* Link count. */
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unsigned int st_uid; /* User ID of the file's owner. */
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unsigned int st_gid; /* Group ID of the file's group. */
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unsigned long st_rdev; /* Device number, if device. */
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unsigned long __pad1;
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long st_size; /* Size of file, in bytes. */
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int st_blksize; /* Optimal block size for I/O. */
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int __pad2;
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long st_blocks; /* Number 512-byte blocks allocated. */
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long st_atime; /* Time of last access. */
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unsigned long st_atime_nsec;
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long st_mtime; /* Time of last modification. */
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unsigned long st_mtime_nsec;
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long st_ctime; /* Time of last status change. */
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unsigned long st_ctime_nsec;
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unsigned int __unused4;
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unsigned int __unused5;
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};
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/* This matches struct stat64 in glibc2.1. Only used for 32 bit. */
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#if __BITS_PER_LONG != 64 || defined(__ARCH_WANT_STAT64)
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struct stat64 {
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unsigned long long st_dev; /* Device. */
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unsigned long long st_ino; /* File serial number. */
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unsigned int st_mode; /* File mode. */
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unsigned int st_nlink; /* Link count. */
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unsigned int st_uid; /* User ID of the file's owner. */
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unsigned int st_gid; /* Group ID of the file's group. */
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unsigned long long st_rdev; /* Device number, if device. */
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unsigned long long __pad1;
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long long st_size; /* Size of file, in bytes. */
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int st_blksize; /* Optimal block size for I/O. */
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int __pad2;
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long long st_blocks; /* Number 512-byte blocks allocated. */
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int st_atime; /* Time of last access. */
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unsigned int st_atime_nsec;
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int st_mtime; /* Time of last modification. */
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unsigned int st_mtime_nsec;
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int st_ctime; /* Time of last status change. */
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unsigned int st_ctime_nsec;
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unsigned int __unused4;
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unsigned int __unused5;
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};
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#endif
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#endif /* __ASM_GENERIC_STAT_H */
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