1 #include <u.h>
2 #include <libc.h>
3 #include <bio.h>
4 
5 #define LB 2048
6 int	one;
7 int	two;
8 int	three;
9 
10 char	ldr[3][4] = { "", "\t", "\t\t" };
11 
12 Biobuf *ib1;
13 Biobuf *ib2;
14 Biobuf *openfil(char*);
15 int	rd(Biobuf*, char*);
16 void	wr(char*, int);
17 void	copy(Biobuf*, char*, int);
18 int	compare(char*, char*);
19 
20 void
21 main(int argc, char *argv[])
22 {
23 	int l;
24 	char	lb1[LB],lb2[LB];
25 
26 	l = 1;
27 	ARGBEGIN{
28 	case '1':
29 		if(!one) {
30 			one = 1;
31 			ldr[1][0] =
32 			ldr[2][l--] = '\0';
33 		}
34 		break;
35 
36 	case '2':
37 		if(!two) {
38 			two = 1;
39 			ldr[2][l--] = '\0';
40 		}
41 		break;
42 
43 	case '3':
44 		three = 1;
45 		break;
46 
47 	default:
48 		goto Usage;
49 
50 	}ARGEND
51 
52 	if(argc < 2) {
53     Usage:
54 		fprint(2, "usage: comm [-123] file1 file2\n");
55 		exits("usage");
56 	}
57 
58 	ib1 = openfil(argv[0]);
59 	ib2 = openfil(argv[1]);
60 
61 
62 	if(rd(ib1,lb1) < 0){
63 		if(rd(ib2,lb2) < 0)
64 			exits(0);
65 		copy(ib2,lb2,2);
66 	}
67 	if(rd(ib2,lb2) < 0)
68 		copy(ib1,lb1,1);
69 
70 	for(;;){
71 		switch(compare(lb1,lb2)) {
72 		case 0:
73 			wr(lb1,3);
74 			if(rd(ib1,lb1) < 0) {
75 				if(rd(ib2,lb2) < 0)
76 					exits(0);
77 				copy(ib2,lb2,2);
78 			}
79 			if(rd(ib2,lb2) < 0)
80 				copy(ib1,lb1,1);
81 			continue;
82 
83 		case 1:
84 			wr(lb1,1);
85 			if(rd(ib1,lb1) < 0)
86 				copy(ib2,lb2,2);
87 			continue;
88 
89 		case 2:
90 			wr(lb2,2);
91 			if(rd(ib2,lb2) < 0)
92 				copy(ib1,lb1,1);
93 			continue;
94 		}
95 	}
96 }
97 
98 int
99 rd(Biobuf *file, char *buf)
100 {
101 	int i, c;
102 
103 	i = 0;
104 	while((c = Bgetc(file)) != Beof) {
105 		*buf = c;
106 		if(c == '\n' || i > LB-2) {
107 			*buf = '\0';
108 			return 0;
109 		}
110 		i++;
111 		buf++;
112 	}
113 	return -1;
114 }
115 
116 void
117 wr(char *str, int n)
118 {
119 
120 	switch(n){
121 		case 1:
122 			if(one)
123 				return;
124 			break;
125 
126 		case 2:
127 			if(two)
128 				return;
129 			break;
130 
131 		case 3:
132 			if(three)
133 				return;
134 	}
135 	print("%s%s\n", ldr[n-1],str);
136 }
137 
138 void
139 copy(Biobuf *ibuf, char *lbuf, int n)
140 {
141 	do
142 		wr(lbuf,n);
143 	while(rd(ibuf,lbuf) >= 0);
144 	exits(0);
145 }
146 
147 int
148 compare(char *a, char *b)
149 {
150 	while(*a == *b){
151 		if(*a == '\0')
152 			return 0;
153 		a++;
154 		b++;
155 	}
156 	if(*a < *b)
157 		return 1;
158 	return 2;
159 }
160 
161 Biobuf*
162 openfil(char *s)
163 {
164 	Biobuf *b;
165 
166 	if(s[0]=='-' && s[1]==0)
167 		s = unsharp("#d/0");
168 	b = Bopen(s, OREAD);
169 	if(b)
170 		return b;
171 	fprint(2,"comm: cannot open %s: %r\n",s);
172 	exits("open");
173 	return 0;	/* shut up ken */
174 }