1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26/*
27 * Buffer manipulation routines. These routines can be used to format
28 * data within a data buffer without worrying about overrunning the
29 * buffer.
30 *
31 * A ctxbuf_t structure is used to track the current location within
32 * the buffer. The ctxbuf_init() must be called first to initialize the
33 * context structure. ctxbuf_printf() can then be called to fill the buffer.
34 * ctxbuf_printf will discard any data that would overrun the buffer and
35 * the buffer will always be null terminated.
36 */
37
38#pragma ident	"%Z%%M%	%I%	%E% SMI"
39
40#include <stdio.h>
41#include <stdarg.h>
42#include <smbsrv/libsmb.h>
43
44/*
45 * smb_ctxbuf_init
46 *
47 * Initialize the buffer context structure.
48 * This must be called before any of the other
49 * buffer routines can be used.
50 *
51 * Returns -1 if invalid parameters, 0 otherwise
52 */
53int
54smb_ctxbuf_init(smb_ctxbuf_t *ctx, unsigned char *buf, size_t buflen)
55{
56	if (ctx == 0 || buf == 0 || buflen == 0)
57		return (-1);
58
59	buf[0] = '\0';
60
61	ctx->basep = buf;
62	ctx->curp = buf;
63	ctx->endp = &buf[buflen];
64
65	return (0);
66}
67
68/*
69 * smb_ctxbuf_len
70 *
71 * Return the amount of data stored in the buffer,
72 * excluding the terminating null character. Similar
73 * to strlen()
74 *
75 * Returns 0 if the ctx is invalid.
76 */
77int
78smb_ctxbuf_len(smb_ctxbuf_t *ctx)
79{
80	if (ctx == 0 || ctx->basep == 0 ||
81	    ctx->curp == 0 || ctx->endp == 0)
82		return (0);
83	else
84		/*LINTED E_PTRDIFF_OVERFLOW*/
85		return (ctx->curp - ctx->basep);
86}
87
88/*
89 * smb_ctxbuf_printf
90 *
91 * Move formatted output (based on fmt string) to the buffer
92 * identified in ctxbuf.  Any output characters beyond the buffer
93 * are discarded and a null character is written at the end of the
94 * characters actually written.
95 *
96 * Returns
97 * Always return the number of bytes actually written (excluding the
98 * terminating null).
99 */
100int
101smb_ctxbuf_printf(smb_ctxbuf_t   *ctx, const char *fmt, ...)
102{
103	int n;
104	va_list args;
105
106	if (ctx == 0 || ctx->basep == 0 ||
107	    ctx->curp == 0 || ctx->endp == 0)
108		return (-1);
109
110	va_start(args, fmt);
111	/*LINTED E_PTRDIFF_OVERFLOW*/
112	n = vsnprintf((char *)ctx->curp, ctx->endp-ctx->curp, fmt, args);
113	ctx->curp += n;
114	va_end(args);
115
116	/*
117	 * return the number of bytes moved into the buffer.
118	 */
119	return (n);
120}
121