bsd/man/man2/mprotect.2

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  24 .\"     $NetBSD: mprotect.2,v 1.6 1995/10/12 15:41:08 jtc Exp $
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  57 .\"     @(#)mprotect.2  8.1 (Berkeley) 6/9/93
  58 .\" $FreeBSD: src/lib/libc/sys/mprotect.2,v 1.18 2007/01/09 00:28:15 imp Exp $
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  60 .Dd October 16, 2008
  61 .Dt MPROTECT 2
  62 .Os
  63 .Sh NAME
  64 .Nm mprotect
  65 .Nd control the protection of pages
  66 .Sh SYNOPSIS
  67 .Fd #include <sys/mman.h>
  68 .Ft int
  69 .Fo mprotect
  70 .Fa "void *addr"
  71 .Fa "size_t len"
  72 .Fa "int prot"
  73 .Fc
  74 .Sh DESCRIPTION
  75 The
  76 .Fn mprotect
  77 system call
  78 changes the specified pages to have protection
  79 .Fa prot .
  80 Not all implementations will guarantee protection on a page basis but Mac OS X's
  81 current implementation does.
  82 .Pp
  83 When a program violates the protections of a page, it gets a SIGBUS or SIGSEGV signal.
  84 .Pp
  85 Currently
  86 .Fa prot
  87 can be one or more of the following:
  88 .Pp
  89 .Bl -tag -width ".Dv PROT_WRITE" -compact
  90 .It Dv PROT_NONE
  91 No permissions at all.
  92 .It Dv PROT_READ
  93 The pages can be read.
  94 .It Dv PROT_WRITE
  95 The pages can be written.
  96 .It Dv PROT_EXEC
  97 The pages can be executed.
  98 .El
  99 .Sh RETURN VALUES
 100 Upon successful completion,
 101 a value of 0 is returned.
 102 Otherwise, a value of -1 is returned and
 103 .Va errno
 104 is set to indicate the error.
 105 .Sh ERRORS
 106 .Fn mprotect
 107 will fail if:
 108 .Bl -tag -width Er
 109 .\" ===========
 110 .It Bq Er EACCES
 111 The requested protection conflicts with
 112 the access permissions of the process
 113 on the specified address range.
 114 .\" ===========
 115 .\" .It Bq Er EAGAIN
 116 .\" Insufficient memory resources exist to allow locking a private page
 117 .\" under PROT_WRITE.
 118 .\" ===========
 119 .It Bq Er EINVAL
 120 .Fa addr
 121 is not a multiple of the page size (i.e.
 122 .Fa addr
 123 is not page-aligned).
 124 .\" ===========
 125 .\" .It Bq Er ENOMEM
 126 .\" The specified address range is outside of the address range
 127 .\" of the process or includes an unmapped page.
 128 .\" ===========
 129 .It Bq Er ENOTSUP
 130 The combination of accesses requested in
 131 .Fa prot
 132 is not supported.
 133 .El
 134 .Sh LEGACY SYNOPSIS
 135 .Fd #include <sys/types.h>
 136 .Fd #include <sys/mman.h>
 137 .Pp
 138 The include file
 139 .In sys/types.h
 140 is necessary.
 141 .Pp
 142 .Ft int
 143 .br
 144 .Fo mprotect
 145 .Fa "caddr_t addr"
 146 .Fa "size_t len"
 147 .Fa "int prot"
 148 .Fc ;
 149 .Pp
 150 The type of
 151 .Fa addr
 152 has changed.
 153 .Sh SEE ALSO
 154 .Xr madvise 2 ,
 155 .Xr mincore 2 ,
 156 .Xr msync 2 ,
 157 .Xr munmap 2 ,
 158 .Xr compat 5
 159 .Sh HISTORY
 160 The
 161 .Fn mprotect
 162 function first appeared in 4.4BSD.