Annotation of embedaddon/quagga/lib/stream.h, revision 1.1.1.2
1.1 misho 1: /*
2: * Packet interface
3: * Copyright (C) 1999 Kunihiro Ishiguro
4: *
5: * This file is part of GNU Zebra.
6: *
7: * GNU Zebra is free software; you can redistribute it and/or modify it
8: * under the terms of the GNU General Public License as published by the
9: * Free Software Foundation; either version 2, or (at your option) any
10: * later version.
11: *
12: * GNU Zebra is distributed in the hope that it will be useful, but
13: * WITHOUT ANY WARRANTY; without even the implied warranty of
14: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15: * General Public License for more details.
16: *
17: * You should have received a copy of the GNU General Public License
18: * along with GNU Zebra; see the file COPYING. If not, write to the Free
19: * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
20: * 02111-1307, USA.
21: */
22:
23: #ifndef _ZEBRA_STREAM_H
24: #define _ZEBRA_STREAM_H
25:
26: #include "prefix.h"
27:
28: /*
29: * A stream is an arbitrary buffer, whose contents generally are assumed to
30: * be in network order.
31: *
32: * A stream has the following attributes associated with it:
33: *
34: * - size: the allocated, invariant size of the buffer.
35: *
36: * - getp: the get position marker, denoting the offset in the stream where
37: * the next read (or 'get') will be from. This getp marker is
38: * automatically adjusted when data is read from the stream, the
39: * user may also manipulate this offset as they wish, within limits
40: * (see below)
41: *
42: * - endp: the end position marker, denoting the offset in the stream where
43: * valid data ends, and if the user attempted to write (or
44: * 'put') data where that data would be written (or 'put') to.
45: *
46: * These attributes are all size_t values.
47: *
48: * Constraints:
49: *
50: * 1. getp can never exceed endp
51: *
52: * - hence if getp is equal to endp, there is no more valid data that can be
53: * gotten from the stream (though, the user may reposition getp to earlier in
54: * the stream, if they wish).
55: *
56: * 2. endp can never exceed size
57: *
58: * - hence, if endp is equal to size, then the stream is full, and no more
59: * data can be written to the stream.
60: *
61: * In other words the following must always be true, and the stream
62: * abstraction is allowed internally to assert that the following property
63: * holds true for a stream, as and when it wishes:
64: *
65: * getp <= endp <= size
66: *
67: * It is the users responsibility to ensure this property is never violated.
68: *
69: * A stream therefore can be thought of like this:
70: *
71: * ---------------------------------------------------
72: * |XXXXXXXXXXXXXXXXXXXXXXXX |
73: * ---------------------------------------------------
74: * ^ ^ ^
75: * getp endp size
76: *
77: * This shows a stream containing data (shown as 'X') up to the endp offset.
78: * The stream is empty from endp to size. Without adjusting getp, there are
79: * still endp-getp bytes of valid data to be read from the stream.
80: *
81: * Methods are provided to get and put to/from the stream, as well as
82: * retrieve the values of the 3 markers and manipulate the getp marker.
83: *
84: * Note:
85: * At the moment, newly allocated streams are zero filled. Hence, one can
86: * use stream_forward_endp() to effectively create arbitrary zero-fill
87: * padding. However, note that stream_reset() does *not* zero-out the
88: * stream. This property should **not** be relied upon.
89: *
90: * Best practice is to use stream_put (<stream *>, NULL, <size>) to zero out
91: * any part of a stream which isn't otherwise written to.
92: */
93:
94: /* Stream buffer. */
95: struct stream
96: {
97: struct stream *next;
98:
99: /* Remainder is ***private*** to stream
100: * direct access is frowned upon!
101: * Use the appropriate functions/macros
102: */
103: size_t getp; /* next get position */
104: size_t endp; /* last valid data position */
105: size_t size; /* size of data segment */
106: unsigned char *data; /* data pointer */
107: };
108:
109: /* First in first out queue structure. */
110: struct stream_fifo
111: {
112: size_t count;
113:
114: struct stream *head;
115: struct stream *tail;
116: };
117:
118: /* Utility macros. */
119: #define STREAM_SIZE(S) ((S)->size)
120: /* number of bytes which can still be written */
121: #define STREAM_WRITEABLE(S) ((S)->size - (S)->endp)
122: /* number of bytes still to be read */
123: #define STREAM_READABLE(S) ((S)->endp - (S)->getp)
124:
125: /* deprecated macros - do not use in new code */
126: #define STREAM_PNT(S) stream_pnt((S))
127: #define STREAM_DATA(S) ((S)->data)
128: #define STREAM_REMAIN(S) STREAM_WRITEABLE((S))
129:
130: /* Stream prototypes.
131: * For stream_{put,get}S, the S suffix mean:
132: *
133: * c: character (unsigned byte)
134: * w: word (two bytes)
135: * l: long (two words)
136: * q: quad (four words)
137: */
138: extern struct stream *stream_new (size_t);
139: extern void stream_free (struct stream *);
140: extern struct stream * stream_copy (struct stream *, struct stream *src);
141: extern struct stream *stream_dup (struct stream *);
142: extern size_t stream_resize (struct stream *, size_t);
143: extern size_t stream_get_getp (struct stream *);
144: extern size_t stream_get_endp (struct stream *);
145: extern size_t stream_get_size (struct stream *);
146: extern u_char *stream_get_data (struct stream *);
147:
148: extern void stream_set_getp (struct stream *, size_t);
1.1.1.2 ! misho 149: extern void stream_set_endp (struct stream *, size_t);
1.1 misho 150: extern void stream_forward_getp (struct stream *, size_t);
151: extern void stream_forward_endp (struct stream *, size_t);
152:
153: /* steam_put: NULL source zeroes out size_t bytes of stream */
154: extern void stream_put (struct stream *, const void *, size_t);
155: extern int stream_putc (struct stream *, u_char);
156: extern int stream_putc_at (struct stream *, size_t, u_char);
157: extern int stream_putw (struct stream *, u_int16_t);
158: extern int stream_putw_at (struct stream *, size_t, u_int16_t);
159: extern int stream_putl (struct stream *, u_int32_t);
160: extern int stream_putl_at (struct stream *, size_t, u_int32_t);
161: extern int stream_putq (struct stream *, uint64_t);
162: extern int stream_putq_at (struct stream *, size_t, uint64_t);
163: extern int stream_put_ipv4 (struct stream *, u_int32_t);
164: extern int stream_put_in_addr (struct stream *, struct in_addr *);
165: extern int stream_put_prefix (struct stream *, struct prefix *);
166:
167: extern void stream_get (void *, struct stream *, size_t);
168: extern u_char stream_getc (struct stream *);
169: extern u_char stream_getc_from (struct stream *, size_t);
170: extern u_int16_t stream_getw (struct stream *);
171: extern u_int16_t stream_getw_from (struct stream *, size_t);
172: extern u_int32_t stream_getl (struct stream *);
173: extern u_int32_t stream_getl_from (struct stream *, size_t);
174: extern uint64_t stream_getq (struct stream *);
175: extern uint64_t stream_getq_from (struct stream *, size_t);
176: extern u_int32_t stream_get_ipv4 (struct stream *);
177:
178: #undef stream_read
179: #undef stream_write
180:
181: /* Deprecated: assumes blocking I/O. Will be removed.
182: Use stream_read_try instead. */
183: extern int stream_read (struct stream *, int, size_t);
184:
185: /* Deprecated: all file descriptors should already be non-blocking.
186: Will be removed. Use stream_read_try instead. */
187: extern int stream_read_unblock (struct stream *, int, size_t);
188:
189: /* Read up to size bytes into the stream.
190: Return code:
191: >0: number of bytes read
192: 0: end-of-file
193: -1: fatal error
194: -2: transient error, should retry later (i.e. EAGAIN or EINTR)
195: This is suitable for use with non-blocking file descriptors.
196: */
197: extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
198:
199: extern ssize_t stream_recvmsg (struct stream *s, int fd, struct msghdr *,
200: int flags, size_t size);
201: extern ssize_t stream_recvfrom (struct stream *s, int fd, size_t len,
202: int flags, struct sockaddr *from,
203: socklen_t *fromlen);
204: extern size_t stream_write (struct stream *, const void *, size_t);
205:
206: /* reset the stream. See Note above */
207: extern void stream_reset (struct stream *);
208: extern int stream_flush (struct stream *, int);
209: extern int stream_empty (struct stream *); /* is the stream empty? */
210:
211: /* deprecated */
212: extern u_char *stream_pnt (struct stream *);
213:
214: /* Stream fifo. */
215: extern struct stream_fifo *stream_fifo_new (void);
216: extern void stream_fifo_push (struct stream_fifo *fifo, struct stream *s);
217: extern struct stream *stream_fifo_pop (struct stream_fifo *fifo);
218: extern struct stream *stream_fifo_head (struct stream_fifo *fifo);
219: extern void stream_fifo_clean (struct stream_fifo *fifo);
220: extern void stream_fifo_free (struct stream_fifo *fifo);
221:
222: #endif /* _ZEBRA_STREAM_H */
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