mirror of https://github.com/mkerrisk/man-pages
119 lines
4.2 KiB
Plaintext
119 lines
4.2 KiB
Plaintext
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.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "MPROTECT" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" mprotect
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.SH NAME
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mprotect \- set protection of memory mapping
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.SH SYNOPSIS
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.LP
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\fB#include <sys/mman.h>
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.br
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.sp
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int mprotect(void *\fP\fIaddr\fP\fB, size_t\fP \fIlen\fP\fB, int\fP
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\fIprot\fP\fB); \fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fImprotect\fP() function shall change the access protections
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to be that specified by \fIprot\fP for those whole pages
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containing any part of the address space of the process starting at
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address \fIaddr\fP and continuing for \fIlen\fP bytes. The
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parameter \fIprot\fP determines whether read, write, execute, or some
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combination of accesses are permitted to the data being
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mapped. The \fIprot\fP argument should be either PROT_NONE or the
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bitwise-inclusive OR of one or more of PROT_READ, PROT_WRITE,
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and PROT_EXEC.
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.LP
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If an implementation cannot support the combination of access types
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specified by \fIprot\fP, the call to \fImprotect\fP()
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shall fail.
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.LP
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An implementation may permit accesses other than those specified by
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\fIprot\fP; however, no implementation shall permit a write
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to succeed where PROT_WRITE has not been set or shall permit any access
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where PROT_NONE alone has been set. Implementations shall
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support at least the following values of \fIprot\fP: PROT_NONE, PROT_READ,
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PROT_WRITE, and the bitwise-inclusive OR of PROT_READ
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and PROT_WRITE. If PROT_WRITE is specified, the application shall
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ensure that it has opened the mapped objects in the specified
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address range with write permission, unless MAP_PRIVATE was specified
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in the original mapping, regardless of whether the file
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descriptors used to map the objects have since been closed.
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.LP
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The implementation shall require that \fIaddr\fP be a multiple of
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the page size as returned by \fIsysconf\fP().
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.LP
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The behavior of this function is unspecified if the mapping was not
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established by a call to \fImmap\fP().
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.LP
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When \fImprotect\fP() fails for reasons other than [EINVAL], the protections
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on some of the pages in the range
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[\fIaddr\fP,\fIaddr\fP+\fIlen\fP) may have been changed.
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.SH RETURN VALUE
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.LP
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Upon successful completion, \fImprotect\fP() shall return 0; otherwise,
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it shall return -1 and set \fIerrno\fP to indicate the
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error.
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.SH ERRORS
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.LP
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The \fImprotect\fP() function shall fail if:
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.TP 7
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.B EACCES
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The \fIprot\fP argument specifies a protection that violates the access
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permission the process has to the underlying memory
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object.
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.TP 7
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.B EAGAIN
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The \fIprot\fP argument specifies PROT_WRITE over a MAP_PRIVATE mapping
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and there are insufficient memory resources to reserve
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for locking the private page.
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.TP 7
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.B EINVAL
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The \fIaddr\fP argument is not a multiple of the page size as returned
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by \fIsysconf\fP().
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.TP 7
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.B ENOMEM
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Addresses in the range [\fIaddr\fP,\fIaddr\fP+\fIlen\fP) are invalid
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for the address space of a process, or specify one or
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more pages which are not mapped.
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.TP 7
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.B ENOMEM
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The \fIprot\fP argument specifies PROT_WRITE on a MAP_PRIVATE mapping,
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and it would require more space than the system is able
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to supply for locking the private pages, if required.
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.TP 7
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.B ENOTSUP
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The implementation does not support the combination of accesses requested
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in the \fIprot\fP argument.
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.sp
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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The [EINVAL] error above is marked EX because it is defined as an
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optional error in the POSIX Realtime Extension.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fImmap\fP() , \fIsysconf\fP() , the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, \fI<sys/mman.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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