contrib/openpam/lib/openpam_straddch.c

   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  *    in this position and unchanged.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. The name of the author may not be used to endorse or promote
  15  *    products derived from this software without specific prior written
  16  *    permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  *
  30  * $Id: openpam_straddch.c 568 2012-04-05 14:35:53Z des $
  31  */
  32
  33 #ifdef HAVE_CONFIG_H
  34 # include "config.h"
  35 #endif
  36
  37 #include <errno.h>
  38 #include <stdlib.h>
  39
  40 #include <security/pam_appl.h>
  41
  42 #include "openpam_impl.h"
  43
  44 #define MIN_STR_SIZE    32
  45
  46 /*
  47  * OpenPAM extension
  48  *
  49  * Add a character to a string, expanding the buffer if needed.
  50  */
  51
  52 int
  53 openpam_straddch(char **str, size_t *size, size_t *len, int ch)
  54 {
  55         size_t tmpsize;
  56         char *tmpstr;
  57
  58         if (*str == NULL) {
  59                 /* initial allocation */
  60                 tmpsize = MIN_STR_SIZE;
  61                 if ((tmpstr = malloc(tmpsize)) == NULL) {
  62                         openpam_log(PAM_LOG_ERROR, "malloc(): %m");
  63                         errno = ENOMEM;
  64                         return (-1);
  65                 }
  66                 *str = tmpstr;
  67                 *size = tmpsize;
  68                 *len = 0;
  69         } else if (*len + 1 >= *size) {
  70                 /* additional space required */
  71                 tmpsize = *size * 2;
  72                 if ((tmpstr = realloc(*str, tmpsize)) == NULL) {
  73                         openpam_log(PAM_LOG_ERROR, "realloc(): %m");
  74                         errno = ENOMEM;
  75                         return (-1);
  76                 }
  77                 *size = tmpsize;
  78                 *str = tmpstr;
  79         }
  80         (*str)[*len] = ch;
  81         ++*len;
  82         (*str)[*len] = '\0';
  83         return (0);
  84 }
  85
  86 /**
  87  * The =openpam_straddch function appends a character to a dynamically
  88  * allocated NUL-terminated buffer, reallocating the buffer as needed.
  89  *
  90  * The =str argument points to a variable containing either a pointer to
  91  * an existing buffer or =NULL.
  92  * If the value of the variable pointed to by =str is =NULL, a new buffer
  93  * is allocated.
  94  *
  95  * The =size and =len argument point to variables used to hold the size
  96  * of the buffer and the length of the string it contains, respectively.
  97  *
  98  * If a new buffer is allocated or an existing buffer is reallocated to
  99  * make room for the additional character, =str and =size are updated
 100  * accordingly.
 101  *
 102  * The =openpam_straddch function ensures that the buffer is always
 103  * NUL-terminated.
 104  *
 105  * If the =openpam_straddch function is successful, it increments the
 106  * integer variable pointed to by =len and returns 0.
 107  * Otherwise, it leaves the variables pointed to by =str, =size and =len
 108  * unmodified, sets :errno to =ENOMEM and returns -1.
 109  *
 110  * AUTHOR DES
 111  */