dist/openpam/lib/openpam_readline.c

   1 /*-
   2  * Copyright (c) 2003 Networks Associates Technology, Inc.
   3  * Copyright (c) 2004-2007 Dag-Erling Smørgrav
   4  * All rights reserved.
   5  *
   6  * This software was developed for the FreeBSD Project by ThinkSec AS and
   7  * Network Associates Laboratories, the Security Research Division of
   8  * Network Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
   9  * ("CBOSS"), as part of the DARPA CHATS research program.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. The name of the author may not be used to endorse or promote
  20  *    products derived from this software without specific prior written
  21  *    permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  * $Id: openpam_readline.c,v 1.5 2008/01/27 01:22:59 christos Exp $
  36  */
  37
  38 #include <ctype.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41
  42 #include <security/pam_appl.h>
  43 #include "openpam_impl.h"
  44
  45 #define MIN_LINE_LENGTH 128
  46
  47 /*
  48  * OpenPAM extension
  49  *
  50  * Read a line from a file.
  51  */
  52
  53 char *
  54 openpam_readline(FILE *f, int *lineno, size_t *lenp)
  55 {
  56         char *line;
  57         size_t len, size;
  58         int ch;
  59
  60         if ((line = malloc((size_t)MIN_LINE_LENGTH)) == NULL)
  61                 return (NULL);
  62         size = MIN_LINE_LENGTH;
  63         len = 0;
  64
  65 #define line_putch(ch) do { \
  66         if (len >= size - 1) { \
  67                 char *tmp = realloc(line, size *= 2); \
  68                 if (tmp == NULL) \
  69                         goto fail; \
  70                 line = tmp; \
  71         } \
  72         line[len++] = ch; \
  73         line[len] = '\0'; \
  74 } while (/*CONSTCOND*/0)
  75
  76         for (;;) {
  77                 ch = fgetc(f);
  78                 /* strip comment */
  79                 if (ch == '#') {
  80                         do {
  81                                 ch = fgetc(f);
  82                         } while (ch != EOF && ch != '\n');
  83                 }
  84                 /* eof */
  85                 if (ch == EOF) {
  86                         /* remove trailing whitespace */
  87                         while (len > 0 && isspace((unsigned char)line[len - 1]))
  88                                 --len;
  89                         line[len] = '\0';
  90                         if (len == 0)
  91                                 goto fail;
  92                         break;
  93                 }
  94                 /* eol */
  95                 if (ch == '\n') {
  96                         if (lineno != NULL)
  97                                 ++*lineno;
  98
  99                         /* remove trailing whitespace */
 100                         while (len > 0 && isspace((unsigned char)line[len - 1]))
 101                                 --len;
 102                         line[len] = '\0';
 103                         /* skip blank lines */
 104                         if (len == 0)
 105                                 continue;
 106                         /* continuation */
 107                         if (line[len - 1] == '\\') {
 108                                 line[--len] = '\0';
 109                                 /* fall through to whitespace case */
 110                         } else {
 111                                 break;
 112                         }
 113                 }
 114                 /* whitespace */
 115                 if (isspace(ch)) {
 116                         /* ignore leading whitespace */
 117                         /* collapse linear whitespace */
 118                         if (len > 0 && line[len - 1] != ' ')
 119                                 line_putch(' ');
 120                         continue;
 121                 }
 122                 /* anything else */
 123                 line_putch(ch);
 124         }
 125
 126         if (lenp != NULL)
 127                 *lenp = len;
 128         return ((char *)line);
 129  fail:
 130         FREE(line);
 131         return (NULL);
 132 }
 133
 134 /**
 135  * The =openpam_readline function reads a line from a file, and returns it
 136  * in a NUL-terminated buffer allocated with =malloc.
 137  *
 138  * The =openpam_readline function performs a certain amount of processing
 139  * on the data it reads.
 140  * Comments (introduced by a hash sign) are stripped, as is leading and
 141  * trailing whitespace.
 142  * Any amount of linear whitespace is collapsed to a single space.
 143  * Blank lines are ignored.
 144  * If a line ends in a backslash, the backslash is stripped and the next
 145  * line is appended.
 146  *
 147  * If =lineno is not =NULL, the integer variable it points to is
 148  * incremented every time a newline character is read.
 149  *
 150  * If =lenp is not =NULL, the length of the line (not including the
 151  * terminating NUL character) is stored in the variable it points to.
 152  *
 153  * The caller is responsible for releasing the returned buffer by passing
 154  * it to =free.
 155  */