Annotation of embedaddon/quagga/lib/stream.h, revision 1.1
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);
! 149: extern void stream_forward_getp (struct stream *, size_t);
! 150: extern void stream_forward_endp (struct stream *, size_t);
! 151:
! 152: /* steam_put: NULL source zeroes out size_t bytes of stream */
! 153: extern void stream_put (struct stream *, const void *, size_t);
! 154: extern int stream_putc (struct stream *, u_char);
! 155: extern int stream_putc_at (struct stream *, size_t, u_char);
! 156: extern int stream_putw (struct stream *, u_int16_t);
! 157: extern int stream_putw_at (struct stream *, size_t, u_int16_t);
! 158: extern int stream_putl (struct stream *, u_int32_t);
! 159: extern int stream_putl_at (struct stream *, size_t, u_int32_t);
! 160: extern int stream_putq (struct stream *, uint64_t);
! 161: extern int stream_putq_at (struct stream *, size_t, uint64_t);
! 162: extern int stream_put_ipv4 (struct stream *, u_int32_t);
! 163: extern int stream_put_in_addr (struct stream *, struct in_addr *);
! 164: extern int stream_put_prefix (struct stream *, struct prefix *);
! 165:
! 166: extern void stream_get (void *, struct stream *, size_t);
! 167: extern u_char stream_getc (struct stream *);
! 168: extern u_char stream_getc_from (struct stream *, size_t);
! 169: extern u_int16_t stream_getw (struct stream *);
! 170: extern u_int16_t stream_getw_from (struct stream *, size_t);
! 171: extern u_int32_t stream_getl (struct stream *);
! 172: extern u_int32_t stream_getl_from (struct stream *, size_t);
! 173: extern uint64_t stream_getq (struct stream *);
! 174: extern uint64_t stream_getq_from (struct stream *, size_t);
! 175: extern u_int32_t stream_get_ipv4 (struct stream *);
! 176:
! 177: #undef stream_read
! 178: #undef stream_write
! 179:
! 180: /* Deprecated: assumes blocking I/O. Will be removed.
! 181: Use stream_read_try instead. */
! 182: extern int stream_read (struct stream *, int, size_t);
! 183:
! 184: /* Deprecated: all file descriptors should already be non-blocking.
! 185: Will be removed. Use stream_read_try instead. */
! 186: extern int stream_read_unblock (struct stream *, int, size_t);
! 187:
! 188: /* Read up to size bytes into the stream.
! 189: Return code:
! 190: >0: number of bytes read
! 191: 0: end-of-file
! 192: -1: fatal error
! 193: -2: transient error, should retry later (i.e. EAGAIN or EINTR)
! 194: This is suitable for use with non-blocking file descriptors.
! 195: */
! 196: extern ssize_t stream_read_try(struct stream *s, int fd, size_t size);
! 197:
! 198: extern ssize_t stream_recvmsg (struct stream *s, int fd, struct msghdr *,
! 199: int flags, size_t size);
! 200: extern ssize_t stream_recvfrom (struct stream *s, int fd, size_t len,
! 201: int flags, struct sockaddr *from,
! 202: socklen_t *fromlen);
! 203: extern size_t stream_write (struct stream *, const void *, size_t);
! 204:
! 205: /* reset the stream. See Note above */
! 206: extern void stream_reset (struct stream *);
! 207: extern int stream_flush (struct stream *, int);
! 208: extern int stream_empty (struct stream *); /* is the stream empty? */
! 209:
! 210: /* deprecated */
! 211: extern u_char *stream_pnt (struct stream *);
! 212:
! 213: /* Stream fifo. */
! 214: extern struct stream_fifo *stream_fifo_new (void);
! 215: extern void stream_fifo_push (struct stream_fifo *fifo, struct stream *s);
! 216: extern struct stream *stream_fifo_pop (struct stream_fifo *fifo);
! 217: extern struct stream *stream_fifo_head (struct stream_fifo *fifo);
! 218: extern void stream_fifo_clean (struct stream_fifo *fifo);
! 219: extern void stream_fifo_free (struct stream_fifo *fifo);
! 220:
! 221: #endif /* _ZEBRA_STREAM_H */
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