openpam_straddch.c revision 348980 
1/*-
2 * Copyright (c) 2012 Dag-Erling Sm��rgrav
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote
14 *    products derived from this software without specific prior written
15 *    permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $OpenPAM: openpam_straddch.c 938 2017-04-30 21:34:42Z des $
30 */
31
32#ifdef HAVE_CONFIG_H
33# include "config.h"
34#endif
35
36#include <errno.h>
37#include <stdlib.h>
38
39#include <security/pam_appl.h>
40
41#include "openpam_impl.h"
42
43#define MIN_STR_SIZE	32
44
45/*
46 * OpenPAM extension
47 *
48 * Add a character to a string, expanding the buffer if needed.
49 */
50
51int
52openpam_straddch(char **str, size_t *size, size_t *len, int ch)
53{
54	size_t tmpsize;
55	char *tmpstr;
56
57	if (*str == NULL) {
58		/* initial allocation */
59		tmpsize = MIN_STR_SIZE;
60		if ((tmpstr = malloc(tmpsize)) == NULL) {
61			openpam_log(PAM_LOG_ERROR, "malloc(): %m");
62			errno = ENOMEM;
63			return (-1);
64		}
65		*str = tmpstr;
66		*size = tmpsize;
67		*len = 0;
68	} else if (ch != 0 && *len + 1 >= *size) {
69		/* additional space required */
70		tmpsize = *size * 2;
71		if ((tmpstr = realloc(*str, tmpsize)) == NULL) {
72			openpam_log(PAM_LOG_ERROR, "realloc(): %m");
73			errno = ENOMEM;
74			return (-1);
75		}
76		*size = tmpsize;
77		*str = tmpstr;
78	}
79	if (ch != 0) {
80		(*str)[*len] = ch;
81		++*len;
82	}
83	(*str)[*len] = '\0';
84	return (0);
85}
86
87/**
88 * The =openpam_straddch function appends a character to a dynamically
89 * allocated NUL-terminated buffer, reallocating the buffer as needed.
90 *
91 * The =str argument points to a variable containing either a pointer to
92 * an existing buffer or =NULL.
93 * If the value of the variable pointed to by =str is =NULL, a new buffer
94 * is allocated.
95 *
96 * The =size and =len argument point to variables used to hold the size
97 * of the buffer and the length of the string it contains, respectively.
98 *
99 * The final argument, =ch, is the character that should be appended to
100 * the string.  If =ch is 0, nothing is appended, but a new buffer is
101 * still allocated if =str is NULL.  This can be used to "bootstrap" the
102 * string.
103 *
104 * If a new buffer is allocated or an existing buffer is reallocated to
105 * make room for the additional character, =str and =size are updated
106 * accordingly.
107 *
108 * The =openpam_straddch function ensures that the buffer is always
109 * NUL-terminated.
110 *
111 * If the =openpam_straddch function is successful, it increments the
112 * integer variable pointed to by =len (unless =ch was 0) and returns 0.
113 * Otherwise, it leaves the variables pointed to by =str, =size and =len
114 * unmodified, sets :errno to =ENOMEM and returns -1.
115 *
116 * AUTHOR DES
117 */
118