projects / apple / libc.git / blame
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1 | .\" Copyright (c) 1994 SigmaSoft, Th. Lockert <tholo@sigmasoft.com> |
| 2 | .\" 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 | .\" 3. The name of the author may not be used to endorse or promote products | |
| 13 | .\" derived from this software without specific prior written permission. | |
| 14 | .\" | |
| 15 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
| 16 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
| 17 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
| 18 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| 19 | .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |
| 20 | .\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; | |
| 21 | .\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, | |
| 22 | .\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR | |
| 23 | .\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF | |
| 24 | .\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 25 | .\" | |
| 9385eb3d | 26 | .\" $FreeBSD: src/lib/libc/gen/ftok.3,v 1.15 2002/10/19 13:33:12 tjr Exp $ |
| e9ce8d39 | 27 | .Dd June 24, 1994 |
| e9ce8d39 | 28 | .Os |
| 5b2abdfb | 29 | .Dt FTOK 3 |
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30 | .Sh NAME |
| 31 | .Nm ftok | |
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32 | .Nd create IPC identifier from path name |
| 33 | .Sh LIBRARY | |
| 34 | .Lb libc | |
| e9ce8d39 | 35 | .Sh SYNOPSIS |
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36 | .In sys/types.h |
| 37 | .In sys/ipc.h | |
| e9ce8d39 | 38 | .Ft key_t |
| 5b2abdfb | 39 | .Fn ftok "const char *path" "int id" |
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40 | .Sh DESCRIPTION |
| 41 | The | |
| 42 | .Fn ftok | |
| 43 | function attempts to create a unique key suitable for use with the | |
| 5b2abdfb | 44 | .Xr msgget 3 , |
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45 | .Xr semget 2 |
| 46 | and | |
| 47 | .Xr shmget 2 | |
| 48 | functions given the | |
| 49 | .Fa path | |
| 50 | of an existing file and a user-selectable | |
| 51 | .Fa id . | |
| 52 | .Pp | |
| 53 | The specified | |
| 54 | .Fa path | |
| 5b2abdfb | 55 | must specify an existing file that is accessible to the calling process |
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56 | or the call will fail. Also, note that links to files will return the |
| 57 | same key, given the same | |
| 58 | .Fa id . | |
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59 | .Sh RETURN VALUES |
| 60 | The | |
| 61 | .Fn ftok | |
| 5b2abdfb | 62 | function will return -1 if |
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63 | .Fa path |
| 64 | does not exist or if it cannot be accessed by the calling process. | |
| 65 | .Sh SEE ALSO | |
| e9ce8d39 | 66 | .Xr semget 2 , |
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67 | .Xr shmget 2 , |
| 68 | .Xr msgget 3 | |
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69 | .Sh HISTORY |
| 70 | The | |
| 71 | .Fn ftok | |
| 5b2abdfb | 72 | function originates with System V and is typically used by programs |
| e9ce8d39 | 73 | that use the System V IPC routines. |
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74 | .Sh AUTHORS |
| 75 | .An Thorsten Lockert Aq tholo@sigmasoft.com | |
| e9ce8d39 | 76 | .Sh BUGS |
| 5b2abdfb | 77 | The returned key is computed based on the device minor number and inode of the |
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78 | specified |
| 79 | .Fa path | |
| 5b2abdfb | 80 | in combination with the lower 8 bits of the given |
| e9ce8d39 | 81 | .Fa id . |
| 5b2abdfb | 82 | Thus it is quite possible for the routine to return duplicate keys. |