openpam_readline.c revision 228690 
1/*-
2 * Copyright (c) 2003 Networks Associates Technology, Inc.
3 * Copyright (c) 2004-2011 Dag-Erling Sm��rgrav
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 473 2011-11-03 10:48:25Z des $
36 */
37
38#ifdef HAVE_CONFIG_H
39# include "config.h"
40#endif
41
42#include <ctype.h>
43#include <stdio.h>
44#include <stdlib.h>
45
46#include <security/pam_appl.h>
47#include "openpam_impl.h"
48
49#define MIN_LINE_LENGTH 128
50
51/*
52 * OpenPAM extension
53 *
54 * Read a line from a file.
55 */
56
57char *
58openpam_readline(FILE *f, int *lineno, size_t *lenp)
59{
60	char *line;
61	size_t len, size;
62	int ch;
63
64	if ((line = malloc(MIN_LINE_LENGTH)) == NULL)
65		return (NULL);
66	size = MIN_LINE_LENGTH;
67	len = 0;
68
69#define line_putch(ch) do { \
70	if (len >= size - 1) { \
71		char *tmp = realloc(line, size *= 2); \
72		if (tmp == NULL) \
73			goto fail; \
74		line = tmp; \
75	} \
76	line[len++] = ch; \
77	line[len] = '\0'; \
78} while (0)
79
80	for (;;) {
81		ch = fgetc(f);
82		/* strip comment */
83		if (ch == '#') {
84			do {
85				ch = fgetc(f);
86			} while (ch != EOF && ch != '\n');
87		}
88		/* eof */
89		if (ch == EOF) {
90			/* done */
91			break;
92		}
93		/* eol */
94		if (ch == '\n') {
95			if (lineno != NULL)
96				++*lineno;
97			/* skip blank lines */
98			if (len == 0)
99				continue;
100			/* continuation */
101			if (line[len - 1] == '\\') {
102				line[--len] = '\0';
103				continue;
104			}
105			/* done */
106			break;
107		}
108		/* whitespace */
109		if (isspace(ch)) {
110			/* ignore leading whitespace */
111			/* collapse linear whitespace */
112			if (len > 0 && line[len - 1] != ' ')
113				line_putch(' ');
114			continue;
115		}
116		/* anything else */
117		line_putch(ch);
118	}
119
120	/* remove trailing whitespace */
121	while (len > 0 && isspace((unsigned char)line[len - 1]))
122		--len;
123	line[len] = '\0';
124	if (len == 0)
125		goto fail;
126	if (lenp != NULL)
127		*lenp = len;
128	return (line);
129fail:
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 *
141 *  - Comments (introduced by a hash sign) are stripped, as is leading and
142 *    trailing whitespace.
143 *  - Any amount of linear whitespace is collapsed to a single space.
144 *  - Blank lines are ignored.
145 *  - If a line ends in a backslash, the backslash is stripped and the
146 *    next line is appended.
147 *
148 * If =lineno is not =NULL, the integer variable it points to is
149 * incremented every time a newline character is read.
150 *
151 * If =lenp is not =NULL, the length of the line (not including the
152 * terminating NUL character) is stored in the variable it points to.
153 *
154 * The caller is responsible for releasing the returned buffer by passing
155 * it to =free.
156 */
157