1 /*-
2  * Copyright (c) 2012 Dag-Erling Smørgrav
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 
30 #ifdef HAVE_CONFIG_H
31 # include "config.h"
32 #endif
33 
34 #include <errno.h>
35 #include <stdlib.h>
36 
37 #include <security/pam_appl.h>
38 
39 #include "openpam_impl.h"
40 
41 #define MIN_STR_SIZE	32
42 
43 /*
44  * OpenPAM extension
45  *
46  * Add a character to a string, expanding the buffer if needed.
47  */
48 
49 int
50 openpam_straddch(char **str, size_t *size, size_t *len, int ch)
51 {
52 	size_t tmpsize;
53 	char *tmpstr;
54 
55 	if (*str == NULL) {
56 		/* initial allocation */
57 		tmpsize = MIN_STR_SIZE;
58 		if ((tmpstr = malloc(tmpsize)) == NULL) {
59 			errno = ENOMEM;
60 			return (-1);
61 		}
62 		*str = tmpstr;
63 		*size = tmpsize;
64 		*len = 0;
65 	} else if (ch != 0 && *len + 1 >= *size) {
66 		/* additional space required */
67 		tmpsize = *size * 2;
68 		if ((tmpstr = realloc(*str, tmpsize)) == NULL) {
69 			errno = ENOMEM;
70 			return (-1);
71 		}
72 		*size = tmpsize;
73 		*str = tmpstr;
74 	}
75 	if (ch != 0) {
76 		(*str)[*len] = ch;
77 		++*len;
78 	}
79 	(*str)[*len] = '\0';
80 	return (0);
81 }
82 
83 /**
84  * The =openpam_straddch function appends a character to a dynamically
85  * allocated NUL-terminated buffer, reallocating the buffer as needed.
86  *
87  * The =str argument points to a variable containing either a pointer to
88  * an existing buffer or =NULL.
89  * If the value of the variable pointed to by =str is =NULL, a new buffer
90  * is allocated.
91  *
92  * The =size and =len argument point to variables used to hold the size
93  * of the buffer and the length of the string it contains, respectively.
94  *
95  * The final argument, =ch, is the character that should be appended to
96  * the string.  If =ch is 0, nothing is appended, but a new buffer is
97  * still allocated if =str is NULL.  This can be used to "bootstrap" the
98  * string.
99  *
100  * If a new buffer is allocated or an existing buffer is reallocated to
101  * make room for the additional character, =str and =size are updated
102  * accordingly.
103  *
104  * The =openpam_straddch function ensures that the buffer is always
105  * NUL-terminated.
106  *
107  * If the =openpam_straddch function is successful, it increments the
108  * integer variable pointed to by =len (unless =ch was 0) and returns 0.
109  * Otherwise, it leaves the variables pointed to by =str, =size and =len
110  * unmodified, sets :errno to =ENOMEM and returns -1.
111  *
112  * AUTHOR DES
113  */
114