Commit | Line | Data |
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b6b9d458 | 1 | .\" -*-nroff-*- |
fbf20b5b | 2 | .TH selbuf 3 "23 May 1999" "Straylight/Edgeware" "mLib utilities library" |
b6b9d458 | 3 | .SH NAME |
4 | selbuf \- line-buffering input selector | |
08da152e | 5 | .\" @selbuf_enable |
6 | .\" @selbuf_disable | |
31e83d07 | 7 | .\" @selbuf_setsize |
08da152e | 8 | .\" @selbuf_init |
31e83d07 | 9 | .\" @selbuf_destroy |
b6b9d458 | 10 | .SH SYNOPSIS |
11 | .nf | |
12 | .B "#include <mLib/selbuf.h>" | |
13 | ||
4729aa69 MW |
14 | .B "typedef struct { ...\& } selbuf;" |
15 | ||
b6b9d458 | 16 | .BI "void selbuf_enable(selbuf *" b ); |
17 | .BI "void selbuf_disable(selbuf *" b ); | |
cededfbe | 18 | .BI "void selbuf_setsize(selbuf *" b ", size_t " sz ); |
2b1924c2 MW |
19 | .ds mT \fBvoid selbuf_init( |
20 | .BI "\*(mTselbuf *" b ", sel_state *" s ", int " fd , | |
21 | .BI "\h'\w'\*(mT'u'lbuf_func *" func ", void *" p ); | |
cededfbe | 22 | .BI "void selbuf_destroy(selbuf *" b ); |
b6b9d458 | 23 | .fi |
24 | .SH DESCRIPTION | |
25 | The | |
26 | .B selbuf | |
27 | subsystem is a selector which integrates with the | |
08da152e | 28 | .BR sel (3) |
b6b9d458 | 29 | system for I/O multiplexing. It reads entire text lines from a file |
30 | descriptor and passes them to a caller-defined function. It uses the | |
31 | line buffer described in | |
08da152e | 32 | .BR lbuf (3) |
b6b9d458 | 33 | to do its work: you should read about it in order to understand exactly |
34 | what gets considered to be a line of text and what doesn't, and the | |
35 | exact rules about what your line handling function should and shouldn't | |
36 | do. | |
37 | .PP | |
31e83d07 | 38 | The data for a line selector is stored in an object of type |
b6b9d458 | 39 | .BR selbuf . |
40 | This object must be allocated by the caller, and initialized using the | |
41 | .B selbuf_init | |
42 | function. This requires a fair few arguments: | |
43 | .TP | |
ff76c38f | 44 | .BI "selbuf *" b |
b6b9d458 | 45 | Pointer to the |
46 | .B selbuf | |
47 | object to initialize. | |
48 | .TP | |
ff76c38f | 49 | .BI "sel_state *" s |
b6b9d458 | 50 | Pointer to a multiplexor object (type |
51 | .BR sel_state ) | |
52 | to which this selector should be attached. See | |
08da152e | 53 | .BR sel (3) |
b6b9d458 | 54 | for more details about multiplexors, and how this whole system works. |
55 | .TP | |
ff76c38f | 56 | .BI "int " fd |
b6b9d458 | 57 | The file descriptor of the stream the selector should read from. |
58 | .TP | |
b342b114 | 59 | .BI "lbuf_func *" func |
b6b9d458 | 60 | The |
61 | .I "line handler" | |
62 | function. It is passed a pointer to each line read from the file (or | |
b342b114 | 63 | null to indicate end-of-file), the length of the line, and an arbitrary |
64 | pointer (the | |
b6b9d458 | 65 | .I p |
66 | argument to | |
67 | .B selbuf_init | |
b342b114 | 68 | described below). For full details, see |
69 | .BR lbuf (3). | |
b6b9d458 | 70 | .TP |
ff76c38f | 71 | .BI "void *" p |
b6b9d458 | 72 | A pointer argument passed to |
73 | .I func | |
74 | for each line read from the file. Apart from this, the pointer is not | |
75 | used at all. | |
76 | .PP | |
77 | The | |
78 | .B selbuf | |
79 | selector is immediately active. Subsequent calls to | |
80 | .B sel_select | |
81 | on the same multiplexor will cause any complete lines read from the file | |
82 | to be passed to your handling function. This function can at any time | |
83 | call | |
84 | .B selbuf_disable | |
85 | to stop itself from being called any more. The selector is then | |
86 | disengaged from the I/O multiplexor and won't do anything until | |
87 | .B selbuf_enable | |
88 | is called. Note that | |
89 | .B selbuf_enable | |
90 | may well immediately start emitting complete lines of text which were | |
91 | queued up from the last I/O operation: it doesn't necessarily wait for | |
92 | the next | |
93 | .B sel_select | |
94 | call. | |
cededfbe | 95 | .PP |
96 | The line buffer has a finite amount of memory for reading strings. The | |
97 | size of this buffer is set by calling | |
98 | .B selbuf_setsize | |
99 | with the requested size. The default buffer size is 256 bytes. | |
100 | .PP | |
101 | When it's finished with, a line buffer selector must be destroyed by | |
102 | calling | |
103 | .BR selbuf_destroy . | |
08da152e | 104 | .SH "SEE ALSO" |
105 | .BR lbuf (3), | |
106 | .BR sel (3), | |
107 | .BR mLib (3). | |
b6b9d458 | 108 | .SH AUTHOR |
9b5ac6ff | 109 | Mark Wooding, <mdw@distorted.org.uk> |