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1 | .\" -*-nroff-*- |
| 2 | .TH selpk 3 "23 May 1999" mLib |
| 3 | .SH NAME |
| 4 | selpk \- packet-buffering input selector |
| 5 | .\" @selpk_enable |
| 6 | .\" @selpk_disable |
| 7 | .\" @selpk_want |
| 8 | .\" @selpk_init |
| 9 | .\" @selpk_destroy |
| 10 | .SH SYNOPSIS |
| 11 | .nf |
| 12 | .B "#include <mLib/selpk.h>" |
| 13 | |
| 14 | .BI "void selpk_enable(selpk *" pk ); |
| 15 | .BI "void selpk_disable(selpk *" pk ); |
| 16 | .BI "void selpk_want(selpk *" pk ", size_t " sz ); |
| 17 | .BI "void selpk_init(selpk *" pk , |
| 18 | .BI " sel_state *" s , |
| 19 | .BI " int " fd , |
| 20 | .BI " void (*" func ")(octet *" b ", size_t " sz ", pkbuf *" pk , |
| 21 | .BI " size_t *" keep ", void *" p ), |
| 22 | .BI " void *" p ); |
| 23 | .BI "void selpk_destroy(selpk *" b ); |
| 24 | .fi |
| 25 | .SH DESCRIPTION |
| 26 | The |
| 27 | .B selpk |
| 28 | subsystem is a selector which integrates with the |
| 29 | .BR sel (3) |
| 30 | system for I/O multiplexing. It reads packets from a file descriptor |
| 31 | and passes them to a caller-defined function. It uses the packet buffer |
| 32 | described in |
| 33 | .BR pkbuf (3) |
| 34 | to do its work: you should read about it in order to understand exactly |
| 35 | how the packet buffer decides how much data is in each packet and the |
| 36 | exact rules about what your packet handling function should and |
| 37 | shouldn't do. |
| 38 | .PP |
| 39 | The data for a packet selector is stored in an object of type |
| 40 | .BR selpk . |
| 41 | This object must be allocated by the caller, and initialized using the |
| 42 | .B selpk_init |
| 43 | function. This requires a fair few arguments: |
| 44 | .TP |
| 45 | .BI "selpk *" pk |
| 46 | Pointer to the |
| 47 | .B selpk |
| 48 | object to initialize. |
| 49 | .TP |
| 50 | .BI "sel_state *" s |
| 51 | Pointer to a multiplexor object (type |
| 52 | .BR sel_state ) |
| 53 | to which this selector should be attached. See |
| 54 | .BR sel (3) |
| 55 | for more details about multiplexors, and how this whole system works. |
| 56 | .TP |
| 57 | .BI "int " fd |
| 58 | The file descriptor of the stream the selector should read from. |
| 59 | .TP |
| 60 | .nf |
| 61 | .BI "void (*" func ")(octet *" b ", size_t " sz ", pkbuf *" p , |
| 62 | .BI " size_t *" keep ", void *" p ) |
| 63 | .fi |
| 64 | The |
| 65 | .I "packet handler" |
| 66 | function. It is passed a pointer to each packet read from the file (or |
| 67 | null to indicate end-of-file) and an arbitrary pointer (the |
| 68 | .I p |
| 69 | argument to |
| 70 | .B selpk_init |
| 71 | described below). |
| 72 | .TP |
| 73 | .BI "void *" p |
| 74 | A pointer argument passed to |
| 75 | .I func |
| 76 | for each packet read from the file. Apart from this, the pointer is not |
| 77 | used at all. |
| 78 | .PP |
| 79 | The |
| 80 | .B selpk |
| 81 | selector is immediately active. Subsequent calls to |
| 82 | .B sel_select |
| 83 | on the same multiplexor will cause any packets read from the file to be |
| 84 | passed to your handling function. This function can at any time call |
| 85 | .B selpk_disable |
| 86 | to stop itself from being called any more. The selector is then |
| 87 | disengaged from the I/O multiplexor and won't do anything until |
| 88 | .B selpk_enable |
| 89 | is called. Note that |
| 90 | .B selpk_enable |
| 91 | may well immediately start emitting complete packets of text which were |
| 92 | queued up from the last I/O operation: it doesn't necessarily wait for |
| 93 | the next |
| 94 | .B sel_select |
| 95 | call. |
| 96 | .PP |
| 97 | The size of packets read by the buffer is set by calling |
| 98 | .BR selpk_want . |
| 99 | See |
| 100 | .BR pkbuf (3) |
| 101 | for more details about how packet buffering works. |
| 102 | .PP |
| 103 | When it's finished with, a packet selector must be destroyed by calling |
| 104 | .BR selpk_destroy . |
| 105 | .SH "SEE ALSO" |
| 106 | .BR pkbuf (3), |
| 107 | .BR sel (3), |
| 108 | .BR selbuf (3), |
| 109 | .BR mLib (3). |
| 110 | .SH AUTHOR |
| 111 | Mark Wooding, <mdw@nsict.org> |
~mdw / mLib / blame