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