openpam_readline.c revision 174832 
1/*-
2 * Copyright (c) 2003 Networks Associates Technology, Inc.
3 * Copyright (c) 2004-2007 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 408 2007-12-21 11:36:24Z des $
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
53char *
54openpam_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(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 (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((int)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((int)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 (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 */
156