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      1 /*	$NetBSD: openpam_straddch.c,v 1.4 2023/06/30 21:46:20 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2012 Dag-Erling Smrgrav
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. The name of the author may not be used to endorse or promote
     16  *    products derived from this software without specific prior written
     17  *    permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #ifdef HAVE_CONFIG_H
     33 # include "config.h"
     34 #endif
     35 
     36 #include <sys/cdefs.h>
     37 __RCSID("$NetBSD: openpam_straddch.c,v 1.4 2023/06/30 21:46:20 christos Exp $");
     38 
     39 #include <errno.h>
     40 #include <stdlib.h>
     41 
     42 #include <security/pam_appl.h>
     43 
     44 #include "openpam_impl.h"
     45 
     46 #define MIN_STR_SIZE	32
     47 
     48 /*
     49  * OpenPAM extension
     50  *
     51  * Add a character to a string, expanding the buffer if needed.
     52  */
     53 
     54 int
     55 openpam_straddch(char **str, size_t *size, size_t *len, int ch)
     56 {
     57 	size_t tmpsize;
     58 	char *tmpstr;
     59 
     60 	if (*str == NULL) {
     61 		/* initial allocation */
     62 		tmpsize = MIN_STR_SIZE;
     63 		if ((tmpstr = malloc(tmpsize)) == NULL) {
     64 			errno = ENOMEM;
     65 			return (-1);
     66 		}
     67 		*str = tmpstr;
     68 		*size = tmpsize;
     69 		*len = 0;
     70 	} else if (ch != 0 && *len + 1 >= *size) {
     71 		/* additional space required */
     72 		tmpsize = *size * 2;
     73 		if ((tmpstr = realloc(*str, tmpsize)) == NULL) {
     74 			errno = ENOMEM;
     75 			return (-1);
     76 		}
     77 		*size = tmpsize;
     78 		*str = tmpstr;
     79 	}
     80 	if (ch != 0) {
     81 		(*str)[*len] = (char)ch;
     82 		++*len;
     83 	}
     84 	(*str)[*len] = '\0';
     85 	return (0);
     86 }
     87 
     88 /**
     89  * The =openpam_straddch function appends a character to a dynamically
     90  * allocated NUL-terminated buffer, reallocating the buffer as needed.
     91  *
     92  * The =str argument points to a variable containing either a pointer to
     93  * an existing buffer or =NULL.
     94  * If the value of the variable pointed to by =str is =NULL, a new buffer
     95  * is allocated.
     96  *
     97  * The =size and =len argument point to variables used to hold the size
     98  * of the buffer and the length of the string it contains, respectively.
     99  *
    100  * The final argument, =ch, is the character that should be appended to
    101  * the string.  If =ch is 0, nothing is appended, but a new buffer is
    102  * still allocated if =str is NULL.  This can be used to "bootstrap" the
    103  * string.
    104  *
    105  * If a new buffer is allocated or an existing buffer is reallocated to
    106  * make room for the additional character, =str and =size are updated
    107  * accordingly.
    108  *
    109  * The =openpam_straddch function ensures that the buffer is always
    110  * NUL-terminated.
    111  *
    112  * If the =openpam_straddch function is successful, it increments the
    113  * integer variable pointed to by =len (unless =ch was 0) and returns 0.
    114  * Otherwise, it leaves the variables pointed to by =str, =size and =len
    115  * unmodified, sets :errno to =ENOMEM and returns -1.
    116  *
    117  * AUTHOR DES
    118  */
    119