2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
102 lines
3.1 KiB
Groff
102 lines
3.1 KiB
Groff
.\" $NetBSD: alloca.3,v 1.13 2010/05/03 06:11:38 jruoho Exp $
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.\"
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.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)alloca.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd May 3, 2010
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.Dt ALLOCA 3
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.Os
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.Sh NAME
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.Nm alloca
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.Nd memory allocator
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdlib.h
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.Ft void *
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.Fn alloca "size_t size"
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.Sh DESCRIPTION
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The
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.Fn alloca
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function
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allocates
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.Fa size
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bytes of space in the stack frame of the caller.
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This temporary space is automatically freed on
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return.
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.Sh RETURN VALUES
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The
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.Fn alloca
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function returns a pointer to the beginning of the allocated space.
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If the allocation failed, a
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.Dv NULL
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pointer is returned.
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.Sh SEE ALSO
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.Xr brk 2 ,
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.Xr calloc 3 ,
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.Xr getpagesize 3 ,
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.Xr malloc 3 ,
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.Xr realloc 3
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.Sh CAVEATS
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Few limitations can be mentioned:
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.Bl -bullet
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.It
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The
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.Fn alloca
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function
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is machine dependent; its use is discouraged.
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.It
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The
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.Fn alloca
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function is slightly unsafe because it cannot ensure that the pointer
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returned points to a valid and usable block of memory.
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The allocation made may exceed the bounds of the stack, or even go
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further into other objects in memory, and
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.Fn alloca
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cannot determine such an error.
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Avoid
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.Fn alloca
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with large unbounded allocations.
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.It
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Since
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.Fn alloca
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modifies the stack at runtime,
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it causes problems to certain security features.
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See
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.Xr security 8
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for a discussion.
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.El
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.\" .Sh HISTORY
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.\" The
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.\" .Fn alloca
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.\" function appeared in
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.\" .Bx ?? .
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.\" The function appeared in 32v, pwb and pwb.2 and in 3bsd 4bsd
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.\" The first man page (or link to a man page that I can find at the
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.\" moment is 4.3...
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