1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1980, 1988, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/types.h>
33#include <ctype.h>
34#include <err.h>
35#include <pwd.h>
36#include <stdio.h>
37#include <stdlib.h>
38#include <paths.h>
39#include <string.h>
40#include <unistd.h>
41
42static int match(const char *, const char *);
43static void usage(void) __dead2;
44
45int
46main(int argc, char **argv)
47{
48	FILE *mbox;
49	struct passwd *pwd;
50	int ch, count, newline;
51	const char *file;
52	char *sender, *p;
53#if MAXPATHLEN > BUFSIZ
54	char buf[MAXPATHLEN];
55#else
56	char buf[BUFSIZ];
57#endif
58
59	file = sender = NULL;
60	count = -1;
61	while ((ch = getopt(argc, argv, "cf:s:")) != -1)
62		switch (ch) {
63		case 'c':
64			count = 0;
65			break;
66		case 'f':
67			file = optarg;
68			break;
69		case 's':
70			sender = optarg;
71			for (p = sender; *p; ++p)
72				*p = tolower(*p);
73			break;
74		case '?':
75		default:
76			usage();
77		}
78	argc -= optind;
79	argv += optind;
80
81	if (file == NULL) {
82		if (argc) {
83			(void)snprintf(buf, sizeof(buf), "%s/%s", _PATH_MAILDIR, *argv);
84			file  = buf;
85		} else {
86			if (!(file = getenv("MAIL"))) {
87				if (!(pwd = getpwuid(getuid())))
88					errx(1, "no password file entry for you");
89				file = pwd->pw_name;
90				(void)snprintf(buf, sizeof(buf),
91				    "%s/%s", _PATH_MAILDIR, file);
92				file = buf;
93			}
94		}
95	}
96
97	/* read from stdin */
98	if (strcmp(file, "-") == 0) {
99		mbox = stdin;
100	}
101	else if ((mbox = fopen(file, "r")) == NULL) {
102		errx(1, "can't read %s", file);
103	}
104	for (newline = 1; fgets(buf, sizeof(buf), mbox);) {
105		if (*buf == '\n') {
106			newline = 1;
107			continue;
108		}
109		if (newline && !strncmp(buf, "From ", 5) &&
110		    (!sender || match(buf + 5, sender))) {
111			if (count != -1)
112				count++;
113			else
114				printf("%s", buf);
115		}
116		newline = 0;
117	}
118	if (count != -1)
119		printf("There %s %d message%s in your incoming mailbox.\n",
120		    count == 1 ? "is" : "are", count, count == 1 ? "" : "s");
121	fclose(mbox);
122	exit(0);
123}
124
125static void
126usage(void)
127{
128	fprintf(stderr, "usage: from [-c] [-f file] [-s sender] [user]\n");
129	exit(1);
130}
131
132static int
133match(const char *line, const char *sender)
134{
135	char ch, pch, first;
136	const char *p, *t;
137
138	for (first = *sender++;;) {
139		if (isspace(ch = *line))
140			return(0);
141		++line;
142		ch = tolower(ch);
143		if (ch != first)
144			continue;
145		for (p = sender, t = line;;) {
146			if (!(pch = *p++))
147				return(1);
148			ch = tolower(*t);
149			t++;
150			if (ch != pch)
151				break;
152		}
153	}
154	/* NOTREACHED */
155}
156