contrib/openpam/lib/openpam_readline.c

   1 /*-
   2  * Copyright (c) 2003 Networks Associates Technology, Inc.
   3  * All rights reserved.
   4  *
   5  * This software was developed for the FreeBSD Project by ThinkSec AS and
   6  * Network Associates Laboratories, the Security Research Division of
   7  * Network Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
   8  * ("CBOSS"), as part of the DARPA CHATS research program.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. The name of the author may not be used to endorse or promote
  19  *    products derived from this software without specific prior written
  20  *    permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $P4: //depot/projects/openpam/lib/openpam_readline.c#3 $
  35  */
  36
  37 #include <ctype.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40
  41 #include <security/pam_appl.h>
  42 #include "openpam_impl.h"
  43
  44 #define MIN_LINE_LENGTH 128
  45
  46 /*
  47  * OpenPAM extension
  48  *
  49  * Read a line from a file.
  50  */
  51
  52 char *
  53 openpam_readline(FILE *f, int *lineno, size_t *lenp)
  54 {
  55         unsigned char *line;
  56         size_t len, size;
  57         int ch;
  58
  59         if ((line = malloc(MIN_LINE_LENGTH)) == NULL)
  60                 return (NULL);
  61         size = MIN_LINE_LENGTH;
  62         len = 0;
  63
  64 #define line_putch(ch) do { \
  65         if (len >= size - 1) { \
  66                 unsigned char *tmp = realloc(line, size *= 2); \
  67                 if (tmp == NULL) \
  68                         goto fail; \
  69                 line = tmp; \
  70         } \
  71         line[len++] = ch; \
  72         line[len] = '\0'; \
  73 } while (0)
  74
  75         for (;;) {
  76                 ch = fgetc(f);
  77                 /* strip comment */
  78                 if (ch == '#') {
  79                         do {
  80                                 ch = fgetc(f);
  81                         } while (ch != EOF && ch != '\n');
  82                 }
  83                 /* eof */
  84                 if (ch == EOF) {
  85                         /* remove trailing whitespace */
  86                         while (len > 0 && isspace(line[len - 1]))
  87                                 --len;
  88                         line[len] = '\0';
  89                         if (len == 0)
  90                                 goto fail;
  91                         break;
  92                 }
  93                 /* eol */
  94                 if (ch == '\n') {
  95                         if (lineno != NULL)
  96                                 ++*lineno;
  97
  98                         /* remove trailing whitespace */
  99                         while (len > 0 && isspace(line[len - 1]))
 100                                 --len;
 101                         line[len] = '\0';
 102                         /* skip blank lines */
 103                         if (len == 0)
 104                                 continue;
 105                         /* continuation */
 106                         if (line[len - 1] == '\\') {
 107                                 line[--len] = '\0';
 108                                 /* fall through to whitespace case */
 109                         } else {
 110                                 break;
 111                         }
 112                 }
 113                 /* whitespace */
 114                 if (isspace(ch)) {
 115                         /* ignore leading whitespace */
 116                         /* collapse linear whitespace */
 117                         if (len > 0 && line[len - 1] != ' ')
 118                                 line_putch(' ');
 119                         continue;
 120                 }
 121                 /* anything else */
 122                 line_putch(ch);
 123         }
 124
 125         if (lenp != NULL)
 126                 *lenp = len;
 127         return (line);
 128  fail:
 129         FREE(line);
 130         return (NULL);
 131 }
 132
 133 /**
 134  * The =openpam_readline function reads a line from a file, and returns it
 135  * in a NUL-terminated buffer allocated with =malloc.
 136  *
 137  * The =openpam_readline function performs a certain amount of processing
 138  * on the data it reads.
 139  * Comments (introduced by a hash sign) are stripped, as is leading and
 140  * trailing whitespace.
 141  * Any amount of linear whitespace is collapsed to a single space.
 142  * Blank lines are ignored.
 143  * If a line ends in a backslash, the backslash is stripped and the next
 144  * line is appended.
 145  *
 146  * If =lineno is not =NULL, the integer variable it points to is
 147  * incremented every time a newline character is read.
 148  *
 149  * If =lenp is not =NULL, the length of the line (not including the
 150  * terminating NUL character) is stored in the variable it points to.
 151  *
 152  * The caller is responsible for releasing the returned buffer by passing
 153  * it to =free.
 154  */