| b6b9d458 |
1 | .\" -*-nroff-*- |
| 2 | .TH selbuf 3mLib "23 May 1999" mLib |
| 3 | .SH NAME |
| 4 | selbuf \- line-buffering input selector |
| 5 | .SH SYNOPSIS |
| 6 | .nf |
| 7 | .B "#include <mLib/selbuf.h>" |
| 8 | |
| 9 | .BI "void selbuf_enable(selbuf *" b ); |
| 10 | .BI "void selbuf_disable(selbuf *" b ); |
| 11 | .BI "void selbuf_init(selbuf *" b , |
| 12 | .BI " sel_state *" s , |
| 13 | .BI " int " fd , |
| 14 | .BI " void (*" func ")(char *" s ", void *" p ), |
| 15 | .BI " void *" p ); |
| 16 | .fi |
| 17 | .SH DESCRIPTION |
| 18 | The |
| 19 | .B selbuf |
| 20 | subsystem is a selector which integrates with the |
| 21 | .BR sel (3mLib) |
| 22 | system for I/O multiplexing. It reads entire text lines from a file |
| 23 | descriptor and passes them to a caller-defined function. It uses the |
| 24 | line buffer described in |
| 25 | .BR lbuf (3mLib) |
| 26 | to do its work: you should read about it in order to understand exactly |
| 27 | what gets considered to be a line of text and what doesn't, and the |
| 28 | exact rules about what your line handling function should and shouldn't |
| 29 | do. |
| 30 | .PP |
| 31 | All the data for a |
| 32 | .B selbuf |
| 33 | selector is stored in an object of type |
| 34 | .BR selbuf . |
| 35 | This object must be allocated by the caller, and initialized using the |
| 36 | .B selbuf_init |
| 37 | function. This requires a fair few arguments: |
| 38 | .TP |
| 39 | .I b |
| 40 | Pointer to the |
| 41 | .B selbuf |
| 42 | object to initialize. |
| 43 | .TP |
| 44 | .I s |
| 45 | Pointer to a multiplexor object (type |
| 46 | .BR sel_state ) |
| 47 | to which this selector should be attached. See |
| 48 | .BR sel (3mLib) |
| 49 | for more details about multiplexors, and how this whole system works. |
| 50 | .TP |
| 51 | .I fd |
| 52 | The file descriptor of the stream the selector should read from. |
| 53 | .TP |
| 54 | .I func |
| 55 | The |
| 56 | .I "line handler" |
| 57 | function. It is passed a pointer to each line read from the file (or |
| 58 | null to indicate end-of-file) and an arbitrary pointer (the |
| 59 | .I p |
| 60 | argument to |
| 61 | .B selbuf_init |
| 62 | described below). |
| 63 | .TP |
| 64 | .I p |
| 65 | A pointer argument passed to |
| 66 | .I func |
| 67 | for each line read from the file. Apart from this, the pointer is not |
| 68 | used at all. |
| 69 | .PP |
| 70 | The |
| 71 | .B selbuf |
| 72 | selector is immediately active. Subsequent calls to |
| 73 | .B sel_select |
| 74 | on the same multiplexor will cause any complete lines read from the file |
| 75 | to be passed to your handling function. This function can at any time |
| 76 | call |
| 77 | .B selbuf_disable |
| 78 | to stop itself from being called any more. The selector is then |
| 79 | disengaged from the I/O multiplexor and won't do anything until |
| 80 | .B selbuf_enable |
| 81 | is called. Note that |
| 82 | .B selbuf_enable |
| 83 | may well immediately start emitting complete lines of text which were |
| 84 | queued up from the last I/O operation: it doesn't necessarily wait for |
| 85 | the next |
| 86 | .B sel_select |
| 87 | call. |
| 88 | .SH AUTHOR |
| 89 | Mark Wooding, <mdw@nsict.org> |
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