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| Commit | Line | Data |
|---|---|---|
| cf908fd1 WJ |
1 | /* ps_alloc.c - allocate a presentation stream */ |
| 2 | ||
| 3 | #ifndef lint | |
| 4 | static char *rcsid = "$Header: /f/osi/psap/RCS/ps_alloc.c,v 7.1 91/02/22 09:36:31 mrose Interim $"; | |
| 5 | #endif | |
| 6 | ||
| 7 | /* | |
| 8 | * $Header: /f/osi/psap/RCS/ps_alloc.c,v 7.1 91/02/22 09:36:31 mrose Interim $ | |
| 9 | * | |
| 10 | * | |
| 11 | * $Log: ps_alloc.c,v $ | |
| 12 | * Revision 7.1 91/02/22 09:36:31 mrose | |
| 13 | * Interim 6.8 | |
| 14 | * | |
| 15 | * Revision 7.0 89/11/23 22:13:19 mrose | |
| 16 | * Release 6.0 | |
| 17 | * | |
| 18 | */ | |
| 19 | ||
| 20 | /* | |
| 21 | * NOTICE | |
| 22 | * | |
| 23 | * Acquisition, use, and distribution of this module and related | |
| 24 | * materials are subject to the restrictions of a license agreement. | |
| 25 | * Consult the Preface in the User's Manual for the full terms of | |
| 26 | * this agreement. | |
| 27 | * | |
| 28 | */ | |
| 29 | ||
| 30 | ||
| 31 | /* LINTLIBRARY */ | |
| 32 | ||
| 33 | #include <stdio.h> | |
| 34 | #include "psap.h" | |
| 35 | ||
| 36 | ||
| 37 | /* A Presentatation Stream (or PStream) is the second generation of | |
| 38 | "generic" I/O stream-based handling. (For the first attempt, | |
| 39 | take a look at the prototype implementation of the TTI Trusted Mail | |
| 40 | Agent.) The idea is to present a common, simple I/O paradigm (i.e., | |
| 41 | the UNIX v7 philosophy) to protocol-translation entities regardless of | |
| 42 | the underlying medium (files, pipes, sockets, or strings). | |
| 43 | ||
| 44 | New streams are created by a call to ps_alloc(). It allocates memory | |
| 45 | and calls an open routine. This routine fills in the dispatch vectors | |
| 46 | for read/write and (optionally) close. It can also fill in any other | |
| 47 | part of the stream's structure it likes. | |
| 48 | ||
| 49 | Once created, I/O is done using the macros ps_read/ps_write. These | |
| 50 | return either NOTOK or OK; depending on how things went. The read/write | |
| 51 | routines are invoked as: | |
| 52 | ||
| 53 | int iofunc (ps, data, n, in_line) | |
| 54 | PS ps; | |
| 55 | PElementData data; | |
| 56 | PElementLen n; | |
| 57 | int in_line; | |
| 58 | ||
| 59 | They should read/write upto len bytes, starting at data, and return the | |
| 60 | number of bytes processed, or NOTOK on error. The routine ps_io() will | |
| 61 | make successive calls to fill/flush the data. If the read/write routine | |
| 62 | returns NOTOK, it should set ps_errno as well. | |
| 63 | ||
| 64 | Streams are removed by a call to ps_free (). It calls the close | |
| 65 | routine, if any, which should de-commission any parts of the stream's | |
| 66 | structure that are in use. ps_free() will then free the allocated | |
| 67 | memory. | |
| 68 | */ | |
| 69 | ||
| 70 | /* \f */ | |
| 71 | ||
| 72 | PS ps_alloc (io) | |
| 73 | register IFP io; | |
| 74 | { | |
| 75 | register PS ps; | |
| 76 | ||
| 77 | if ((ps = (PS) calloc (1, sizeof *ps)) == NULLPS) | |
| 78 | return NULLPS; | |
| 79 | ||
| 80 | if ((*io) (ps) == NOTOK) { | |
| 81 | ps_free (ps); | |
| 82 | return NULLPS; | |
| 83 | } | |
| 84 | ||
| 85 | return ps; | |
| 86 | } |