aboutsummaryrefslogtreecommitdiff
path: root/coreutils/comm.c
blob: 8b938017501fd6d3519f35c0a9a270bbf45edb75 (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
/* vi: set sw=4 ts=4: */
/*
 * Mini comm implementation for busybox
 *
 * Copyright (C) 2005 by Robert Sullivan <cogito.ergo.cogito@gmail.com>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "busybox.h"

#define COMM_OPT_1 0x01
#define COMM_OPT_2 0x02
#define COMM_OPT_3 0x04

/* These three variables control behaviour if non-zero */

static int only_file_1;
static int only_file_2;
static int both;

/* writeline outputs the input given, appropriately aligned according to class */
static void writeline(char *line, int class)
{
	if (class == 0) {
		if (!only_file_1)
			return;
	} else if (class == 1) {
		if (!only_file_2)
			return;
		if (only_file_1)
			putchar('\t');
	}
	else /*if (class == 2)*/ {
		if (!both)
			return;
		if (only_file_1)
			putchar('\t');
		if (only_file_2)
			putchar('\t');
	}
	fputs(line, stdout);
}

/* This is the real core of the program - lines are compared here */
static void cmp_files(char **infiles)
{
#define LINE_LEN 100
#define BB_EOF_0 0x1
#define BB_EOF_1 0x2
	char thisline[2][LINE_LEN];
	FILE *streams[2];
	int i;

	for (i = 0; i < 2; ++i) {
		streams[i] = ((infiles[i][0] == '=' && infiles[i][1]) ? stdin : bb_xfopen(infiles[i], "r"));
		fgets(thisline[i], LINE_LEN, streams[i]);
	}

	while (*thisline[0] || *thisline[1]) {
		int order = 0;

		i = 0;
		if (feof(streams[0])) i |= BB_EOF_0;
		if (feof(streams[1])) i |= BB_EOF_1;

		if (!*thisline[0])
			order = 1;
		else if (!*thisline[1])
			order = -1;
		else {
			int tl0_len, tl1_len;
			tl0_len = strlen(thisline[0]);
			tl1_len = strlen(thisline[1]);
			order = memcmp(thisline[0], thisline[1], tl0_len < tl1_len ? tl0_len : tl1_len);
			if (!order)
				order = tl0_len < tl1_len ? -1 : tl0_len != tl1_len;
		}

		if (order == 0 && !i)
			writeline(thisline[1], 2);
		else if (order > 0 && !(i & BB_EOF_1))
			writeline(thisline[1], 1);
		else if (order < 0 && !(i & BB_EOF_0))
			writeline(thisline[0], 0);

		if (i & BB_EOF_0 & BB_EOF_1) {
			break;

		} else if (i) {
			i = (i & BB_EOF_0 ? 1 : 0);
			while (!feof(streams[i])) {
				if ((order < 0 && i) || (order > 0 && !i))
					writeline(thisline[i], i);
				fgets(thisline[i], LINE_LEN, streams[i]);
			}
			break;

		} else {
			if (order >= 0)
				fgets(thisline[1], LINE_LEN, streams[1]);
			if (order <= 0)
				fgets(thisline[0], LINE_LEN, streams[0]);
		}
	}

	fclose(streams[0]);
	fclose(streams[1]);
}

int comm_main(int argc, char **argv)
{
	unsigned long flags;

	flags = bb_getopt_ulflags(argc, argv, "123");

	if (optind + 2 != argc)
		bb_show_usage();

	only_file_1 = !(flags & COMM_OPT_1);
	only_file_2 = !(flags & COMM_OPT_2);
	both = !(flags & COMM_OPT_3);

	cmp_files(argv + optind);
	exit(EXIT_SUCCESS);
}