112 lines
2.3 KiB
Groff
112 lines
2.3 KiB
Groff
.\" @(#)msync.3 1.1 94/10/31 SMI;
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.TH MSYNC 3 "21 January 1990"
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.SH NAME
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msync \- synchronize memory with physical storage
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.SH SYNOPSIS
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.LP
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.nf
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.ft B
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#include <sys/types.h>
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#include <sys/mman.h>
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.ft
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.fi
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.LP
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.nf
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.ft B
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int msync(addr, len, flags)
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caddr_t addr; size_t len; int flags;
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.ft R
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.fi
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.SH DESCRIPTION
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.IX "msync()" "" "\fLmsync()\fR \(em synchronize memory with physical storage" ""
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.IX "synchronize" "memory with physical storage"
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.IX "memory" "synchronize with physical storage"
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.IX "storage" "synchronize with memory"
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.LP
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.B msync(\|)
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writes all modified copies of pages over the range
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[\fIaddr, addr + len\fP\^)
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to their permanent storage locations.
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.B msync(\|)
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optionally invalidates any copies so that further references to the pages
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will be obtained by the system from their permanent
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storage locations.
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.LP
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Values for
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.I flags
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are defined in
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.B <sys/mman.h>
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as:
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.LP
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.nf
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.ta 25n 35n
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.ft B
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#define \s-1MS_ASYNC\s0 0x1 /* Return immediately */
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#define \s-1MS_INVALIDATE\s0 0x2 /* Invalidate mappings */
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.ft R
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.fi
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.LP
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and are used to control the behavior of
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.BR msync(\|) .
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One or more flags may
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be specified in a single call.
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.LP
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.SB MS_ASYNC
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returns
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immediately once all I/O operations are
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scheduled; normally,
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.B msync(\|)
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will not return until all I/O operations are complete.
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.SB MS_INVALIDATE
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invalidates all cached copies of data
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from memory objects,
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requiring them to be re-obtained from the object's permanent
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storage location upon the next reference.
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.LP
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.B msync(\|)
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should be used by programs that require a memory object to
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be
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in a known state, for example in building transaction facilities.
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.SH RETURN VALUES
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.LP
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.B msync(\|)
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returns:
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.TP
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0
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on success.
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.TP
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\-1
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on failure and sets
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.B errno
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to indicate the error.
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.SH ERRORS
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.TP 15
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.SM EINVAL
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.I addr
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is not a multiple of the page size as returned by
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.BR getpagesize (2).
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.IP
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.I flags
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is not some combination of
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.SB MS_ASYNC
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or
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.SB MS_INVALIDATE.
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.TP
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.SM EIO
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An I/O error occurred while reading from or writing to the file system.
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.TP
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.SM ENOMEM
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Addresses in the range
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[\fIaddr, addr + len\fP\^)
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are outside the valid range for
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the address space of a process, or specify one or more pages that are not
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mapped.
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.TP
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.SM EPERM
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.SB MS_INVALIDATE
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was specified and one or more of the pages is locked in memory.
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.SH SEE ALSO
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.BR mctl (2),
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.BR mmap (2)
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