1 .\" Copyright (C) 2004, 2005, 2007, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
2 .\" Copyright (C) 2000, 2001 Internet Software Consortium.
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19 .\" Title: lwres_buffer
21 .\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
27 .TH "LWRES_BUFFER" "3" "2007\-06\-18" "ISC" "BIND9"
28 .\" -----------------------------------------------------------------
29 .\" * Define some portability stuff
30 .\" -----------------------------------------------------------------
31 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
32 .\" http://bugs.debian.org/507673
33 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
34 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
37 .\" -----------------------------------------------------------------
38 .\" * set default formatting
39 .\" -----------------------------------------------------------------
40 .\" disable hyphenation
42 .\" disable justification (adjust text to left margin only)
44 .\" -----------------------------------------------------------------
45 .\" * MAIN CONTENT STARTS HERE *
46 .\" -----------------------------------------------------------------
48 lwres_buffer_init, lwres_buffer_invalidate, lwres_buffer_add, lwres_buffer_subtract, lwres_buffer_clear, lwres_buffer_first, lwres_buffer_forward, lwres_buffer_back, lwres_buffer_getuint8, lwres_buffer_putuint8, lwres_buffer_getuint16, lwres_buffer_putuint16, lwres_buffer_getuint32, lwres_buffer_putuint32, lwres_buffer_putmem, lwres_buffer_getmem \- lightweight resolver buffer management
53 #include <lwres/lwbuffer\&.h>
56 .HP \w'void\ lwres_buffer_init('u
57 .BI "void lwres_buffer_init(lwres_buffer_t\ *" "b" ", void\ *" "base" ", unsigned\ int\ " "length" ");"
58 .HP \w'void\ lwres_buffer_invalidate('u
59 .BI "void lwres_buffer_invalidate(lwres_buffer_t\ *" "b" ");"
60 .HP \w'void\ lwres_buffer_add('u
61 .BI "void lwres_buffer_add(lwres_buffer_t\ *" "b" ", unsigned\ int\ " "n" ");"
62 .HP \w'void\ lwres_buffer_subtract('u
63 .BI "void lwres_buffer_subtract(lwres_buffer_t\ *" "b" ", unsigned\ int\ " "n" ");"
64 .HP \w'void\ lwres_buffer_clear('u
65 .BI "void lwres_buffer_clear(lwres_buffer_t\ *" "b" ");"
66 .HP \w'void\ lwres_buffer_first('u
67 .BI "void lwres_buffer_first(lwres_buffer_t\ *" "b" ");"
68 .HP \w'void\ lwres_buffer_forward('u
69 .BI "void lwres_buffer_forward(lwres_buffer_t\ *" "b" ", unsigned\ int\ " "n" ");"
70 .HP \w'void\ lwres_buffer_back('u
71 .BI "void lwres_buffer_back(lwres_buffer_t\ *" "b" ", unsigned\ int\ " "n" ");"
72 .HP \w'lwres_uint8_t\ lwres_buffer_getuint8('u
73 .BI "lwres_uint8_t lwres_buffer_getuint8(lwres_buffer_t\ *" "b" ");"
74 .HP \w'void\ lwres_buffer_putuint8('u
75 .BI "void lwres_buffer_putuint8(lwres_buffer_t\ *" "b" ", lwres_uint8_t\ " "val" ");"
76 .HP \w'lwres_uint16_t\ lwres_buffer_getuint16('u
77 .BI "lwres_uint16_t lwres_buffer_getuint16(lwres_buffer_t\ *" "b" ");"
78 .HP \w'void\ lwres_buffer_putuint16('u
79 .BI "void lwres_buffer_putuint16(lwres_buffer_t\ *" "b" ", lwres_uint16_t\ " "val" ");"
80 .HP \w'lwres_uint32_t\ lwres_buffer_getuint32('u
81 .BI "lwres_uint32_t lwres_buffer_getuint32(lwres_buffer_t\ *" "b" ");"
82 .HP \w'void\ lwres_buffer_putuint32('u
83 .BI "void lwres_buffer_putuint32(lwres_buffer_t\ *" "b" ", lwres_uint32_t\ " "val" ");"
84 .HP \w'void\ lwres_buffer_putmem('u
85 .BI "void lwres_buffer_putmem(lwres_buffer_t\ *" "b" ", const\ unsigned\ char\ *" "base" ", unsigned\ int\ " "length" ");"
86 .HP \w'void\ lwres_buffer_getmem('u
87 .BI "void lwres_buffer_getmem(lwres_buffer_t\ *" "b" ", unsigned\ char\ *" "base" ", unsigned\ int\ " "length" ");"
90 These functions provide bounds checked access to a region of memory where data is being read or written\&. They are based on, and similar to, the
92 functions in the ISC library\&.
94 A buffer is a region of memory, together with a set of related subregions\&. The
98 region are disjoint, and their union is the buffer\*(Aqs region\&. The used region extends from the beginning of the buffer region to the last used byte\&. The available region extends from one byte greater than the last used byte to the end of the buffer\*(Aqs region\&. The size of the used region can be changed using various buffer commands\&. Initially, the used region is empty\&.
100 The used region is further subdivided into two disjoint regions: the
101 \fIconsumed region\fR
103 \fIremaining region\fR\&. The union of these two regions is the used region\&. The consumed region extends from the beginning of the used region to the byte before the
105 offset (if any)\&. The
107 region the current pointer to the end of the used region\&. The size of the consumed region can be changed using various buffer commands\&. Initially, the consumed region is empty\&.
111 is an (optional) subregion of the remaining region\&. It extends from the current offset to an offset in the remaining region\&. Initially, the active region is empty\&. If the current offset advances beyond the chosen offset, the active region will also be empty\&.
117 /\-\-\-\-\-\-\-\-\-\-\-\-entire length\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\e\e
118 /\-\-\-\-\- used region \-\-\-\-\-\e\e/\-\- available \-\-\e\e
119 +\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-+
120 | consumed | remaining | |
121 +\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-+
132 a == base of buffer\&.
133 b == current pointer\&. Can be anywhere between a and d\&.
134 c == active pointer\&. Meaningful between b and d\&.
136 e == length of buffer\&.
146 a\-e == entire length of buffer\&.
147 a\-d == used region\&.
148 a\-b == consumed region\&.
149 b\-d == remaining region\&.
150 b\-c == optional active region\&.
156 \fBlwres_buffer_init()\fR
158 \fBlwres_buffer_t\fR\fI*b\fR
159 and assocates it with the memory region of size
161 bytes starting at location
164 \fBlwres_buffer_invalidate()\fR
167 as invalid\&. Invalidating a buffer after use is not required, but makes it possible to catch its possible accidental use\&.
170 \fBlwres_buffer_add()\fR
172 \fBlwres_buffer_subtract()\fR
173 respectively increase and decrease the used space in buffer
178 \fBlwres_buffer_add()\fR
179 checks for buffer overflow and
180 \fBlwres_buffer_subtract()\fR
181 checks for underflow\&. These functions do not allocate or deallocate memory\&. They just change the value of
184 A buffer is re\-initialised by
185 \fBlwres_buffer_clear()\fR\&. The function sets
192 \fBlwres_buffer_first\fR
193 makes the consumed region of buffer
197 to zero (the start of the buffer)\&.
199 \fBlwres_buffer_forward()\fR
200 increases the consumed region of buffer
204 bytes, checking for overflow\&. Similarly,
205 \fBlwres_buffer_back()\fR
207 \fIb\fR\*(Aqs consumed region by
209 bytes and checks for underflow\&.
211 \fBlwres_buffer_getuint8()\fR
212 reads an unsigned 8\-bit integer from
215 \fBlwres_buffer_putuint8()\fR
216 writes the unsigned 8\-bit integer
221 \fBlwres_buffer_getuint16()\fR
223 \fBlwres_buffer_getuint32()\fR
225 \fBlwres_buffer_putuint8()\fR
226 except that they respectively read an unsigned 16\-bit or 32\-bit integer in network byte order from
227 \fIb\fR\&. Similarly,
228 \fBlwres_buffer_putuint16()\fR
230 \fBlwres_buffer_putuint32()\fR
231 writes the unsigned 16\-bit or 32\-bit integer
234 \fIb\fR, in network byte order\&.
236 Arbitrary amounts of data are read or written from a lightweight resolver buffer with
237 \fBlwres_buffer_getmem()\fR
239 \fBlwres_buffer_putmem()\fR
241 \fBlwres_buffer_putmem()\fR
247 \fIb\fR\&. Conversely,
248 \fBlwres_buffer_getmem()\fR
257 \fBInternet Systems Consortium, Inc\&.\fR
260 Copyright \(co 2004, 2005, 2007, 2014, 2015 Internet Systems Consortium, Inc. ("ISC")
262 Copyright \(co 2000, 2001 Internet Software Consortium.