| | 1 | .\" Copyright (c) 1980, 1991, 1993 |
| | 2 | .\" The Regents of the University of California. All rights reserved. |
| | 3 | .\" |
| | 4 | .\" Redistribution and use in source and binary forms, with or without |
| | 5 | .\" modification, are permitted provided that the following conditions |
| | 6 | .\" are met: |
| | 7 | .\" 1. Redistributions of source code must retain the above copyright |
| | 8 | .\" notice, this list of conditions and the following disclaimer. |
| | 9 | .\" 2. Redistributions in binary form must reproduce the above copyright |
| | 10 | .\" notice, this list of conditions and the following disclaimer in the |
| | 11 | .\" documentation and/or other materials provided with the distribution. |
| | 12 | .\" 4. Neither the name of the University nor the names of its contributors |
| | 13 | .\" may be used to endorse or promote products derived from this software |
| | 14 | .\" without specific prior written permission. |
| | 15 | .\" |
| | 16 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| | 17 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| | 18 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| | 19 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| | 20 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| | 21 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| | 22 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| | 23 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| | 24 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| | 25 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| | 26 | .\" SUCH DAMAGE. |
| | 27 | .\" |
| | 28 | .\" @(#)alloca.3 8.1 (Berkeley) 6/4/93 |
| | 29 | .\" $FreeBSD: src/lib/libc/stdlib/alloca.3,v 1.13 2007/01/09 00:28:09 imp Exp $ |
| | 30 | .\" |
| | 31 | .Dd September 5, 2006 |
| | 32 | .Dt ALLOCA 3 |
| | 33 | .Os |
| | 34 | .Sh NAME |
| | 35 | .Nm alloca |
| | 36 | .Nd memory allocator |
| | 37 | .Sh SYNOPSIS |
| | 38 | .In alloca.h |
| | 39 | or |
| | 40 | .br |
| | 41 | .In stdlib.h |
| | 42 | .Ft void * |
| | 43 | .Fn alloca "size_t size" |
| | 44 | .Sh DESCRIPTION |
| | 45 | The |
| | 46 | .Fn alloca |
| | 47 | macro |
| | 48 | allocates |
| | 49 | .Fa size |
| | 50 | bytes of space in the stack frame of the caller. |
| | 51 | This temporary space is automatically freed on |
| | 52 | return. |
| | 53 | .Sh RETURN VALUES |
| | 54 | .Fn alloca |
| | 55 | returns a pointer to the beginning of the allocated space. |
| | 56 | .Sh SEE ALSO |
| | 57 | .Xr brk 2 , |
| | 58 | .Xr calloc 3 , |
| | 59 | .Xr getpagesize 3 , |
| | 60 | .Xr malloc 3 , |
| | 61 | .Xr realloc 3 |
| | 62 | .Sh HISTORY |
| | 63 | .Fn alloca |
| | 64 | appeared in |
| | 65 | .At 32v . |
| | 66 | .\" .Bx ?? . |
| | 67 | .\" The function appeared in 32v, pwb and pwb.2 and in 3bsd 4bsd |
| | 68 | .\" The first man page (or link to a man page that I can find at the |
| | 69 | .\" moment is 4.3... |
| | 70 | .Sh BUGS |
| | 71 | .Fn alloca |
| | 72 | is machine and compiler dependent; |
| | 73 | its use is discouraged. |
| | 74 | .Pp |
| | 75 | .Fn alloca |
| | 76 | is slightly unsafe because it cannot ensure that the pointer |
| | 77 | returned points to a valid and usable block of memory. |
| | 78 | The allocation made may exceed the bounds of the stack, or even go |
| | 79 | further into other objects in memory, and |
| | 80 | .Fn alloca |
| | 81 | cannot determine such an error. |
| | 82 | Avoid |
| | 83 | .Fn alloca |
| | 84 | with large unbounded allocations. |
| | 85 | .Pp |
| | 86 | The use of C99 variable-length arrays and |
| | 87 | .Fn alloca |
| | 88 | in the same function will cause the lifetime of alloca's storage to be limited to the block containing the |
| | 89 | .Fn alloca |
projects / apple / libc.git / blame_incremental