summaryrefslogtreecommitdiff
path: root/mailsplit.c
blob: a3238c20da27c3348d406066b595cd085e600558 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
/*
 * Totally braindamaged mbox splitter program.
 *
 * It just splits a mbox into a list of files: "0001" "0002" ..
 * so you can process them further from there.
 */
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <assert.h>

static int usage(void)
{
	fprintf(stderr, "mailsplit <mbox> <directory>\n");
	exit(1);
}

static int linelen(const char *map, unsigned long size)
{
	int len = 0, c;

	do {
		c = *map;
		map++;
		size--;
		len++;
	} while (size && c != '\n');
	return len;
}

static int is_from_line(const char *line, int len)
{
	const char *colon;

	if (len < 20 || memcmp("From ", line, 5))
		return 0;

	colon = line + len - 2;
	line += 5;
	for (;;) {
		if (colon < line)
			return 0;
		if (*--colon == ':')
			break;
	}

	if (!isdigit(colon[-4]) ||
	    !isdigit(colon[-2]) ||
	    !isdigit(colon[-1]) ||
	    !isdigit(colon[ 1]) ||
	    !isdigit(colon[ 2]))
		return 0;

	/* year */
	if (strtol(colon+3, NULL, 10) <= 90)
		return 0;

	/* Ok, close enough */
	return 1;
}

static int parse_email(const void *map, unsigned long size)
{
	unsigned long offset;

	if (size < 6 || memcmp("From ", map, 5))
		goto corrupt;

	/* Make sure we don't trigger on this first line */
	map++; size--; offset=1;

	/*
	 * Search for a line beginning with "From ", and 
	 * having something that looks like a date format.
	 */
	do {
		int len = linelen(map, size);
		if (is_from_line(map, len))
			return offset;
		map += len;
		size -= len;
		offset += len;
	} while (size);
	return offset;

corrupt:
	fprintf(stderr, "corrupt mailbox\n");
	exit(1);
}

int main(int argc, char **argv)
{
	int fd, nr;
	struct stat st;
	unsigned long size;
	void *map;

	if (argc != 3)
		usage();
	fd = open(argv[1], O_RDONLY);
	if (fd < 0) {
		perror(argv[1]);
		exit(1);
	}
	if (chdir(argv[2]) < 0)
		usage();
	if (fstat(fd, &st) < 0) {
		perror("stat");
		exit(1);
	}
	size = st.st_size;
	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
	if (map == MAP_FAILED) {
		perror("mmap");
		close(fd);
		exit(1);
	}
	close(fd);
	nr = 0;
	do {
		char name[10];
		unsigned long len = parse_email(map, size);
		assert(len <= size);
		sprintf(name, "%04d", ++nr);
		fd = open(name, O_WRONLY | O_CREAT | O_EXCL, 0600);
		if (fd < 0) {
			perror(name);
			exit(1);
		}
		if (write(fd, map, len) != len) {
			perror("write");
			exit(1);
		}
		close(fd);
		map += len;
		size -= len;
	} while (size > 0);
	return 0;
}