openpam_readline.c revision 115619 
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#2 $
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
52char *
53openpam_readline(FILE *f, int *lineno, size_t *lenp)
54{
55	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		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 */
155