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 #include <stdio.h>
39 #include <stdarg.h>
40 #include <smbsrv/libsmb.h>
41 
42 /*
43  * smb_ctxbuf_init
44  *
45  * Initialize the buffer context structure.
46  * This must be called before any of the other
47  * buffer routines can be used.
48  *
49  * Returns -1 if invalid parameters, 0 otherwise
50  */
51 int
smb_ctxbuf_init(smb_ctxbuf_t * ctx,unsigned char * buf,size_t buflen)52 smb_ctxbuf_init(smb_ctxbuf_t *ctx, unsigned char *buf, size_t buflen)
53 {
54 	if (ctx == 0 || buf == 0 || buflen == 0)
55 		return (-1);
56 
57 	buf[0] = '\0';
58 
59 	ctx->basep = buf;
60 	ctx->curp = buf;
61 	ctx->endp = &buf[buflen];
62 
63 	return (0);
64 }
65 
66 /*
67  * smb_ctxbuf_len
68  *
69  * Return the amount of data stored in the buffer,
70  * excluding the terminating null character. Similar
71  * to strlen()
72  *
73  * Returns 0 if the ctx is invalid.
74  */
75 int
smb_ctxbuf_len(smb_ctxbuf_t * ctx)76 smb_ctxbuf_len(smb_ctxbuf_t *ctx)
77 {
78 	if (ctx == 0 || ctx->basep == 0 ||
79 	    ctx->curp == 0 || ctx->endp == 0)
80 		return (0);
81 	else
82 		/*LINTED E_PTRDIFF_OVERFLOW*/
83 		return (ctx->curp - ctx->basep);
84 }
85 
86 /*
87  * smb_ctxbuf_printf
88  *
89  * Move formatted output (based on fmt string) to the buffer
90  * identified in ctxbuf.  Any output characters beyond the buffer
91  * are discarded and a null character is written at the end of the
92  * characters actually written.
93  *
94  * Returns
95  * Always return the number of bytes actually written (excluding the
96  * terminating null).
97  */
98 int
smb_ctxbuf_printf(smb_ctxbuf_t * ctx,const char * fmt,...)99 smb_ctxbuf_printf(smb_ctxbuf_t   *ctx, const char *fmt, ...)
100 {
101 	int n;
102 	va_list args;
103 
104 	if (ctx == 0 || ctx->basep == 0 ||
105 	    ctx->curp == 0 || ctx->endp == 0)
106 		return (-1);
107 
108 	va_start(args, fmt);
109 	/*LINTED E_PTRDIFF_OVERFLOW*/
110 	n = vsnprintf((char *)ctx->curp, ctx->endp-ctx->curp, fmt, args);
111 	ctx->curp += n;
112 	va_end(args);
113 
114 	/*
115 	 * return the number of bytes moved into the buffer.
116 	 */
117 	return (n);
118 }
119