1/* See LICENSE file for copyright and license details. */
  2
  3
  4#include <stdio.h>
  5#include <stdlib.h>
  6#include <string.h>
  7
  8#include "text.h"
  9#include "util.h"
 10
 11static int show = 0x07;
 12
 13static void
 14printline(int pos, struct line *line)
 15{
 16	int i;
 17
 18	if (!(show & (0x1 << pos)))
 19		return;
 20
 21	for (i = 0; i < pos; i++) {
 22		if (show & (0x1 << i))
 23			putchar('\t');
 24	}
 25	fwrite(line->data, 1, line->len, stdout);
 26}
 27
 28static void
 29usage(void)
 30{
 31	eprintf("usage: %s [-123] file1 file2\n", argv0);
 32}
 33
 34// ?man comm: compare two sorted files
 35// ?man arguments: file1 file2
 36// ?man compare two sorted files line by line
 37int
 38main(int argc, char *argv[])
 39{
 40	FILE *fp[2];
 41	static struct line line[2];
 42	size_t linecap[2] = { 0, 0 };
 43	ssize_t len;
 44	int ret = 0, i, diff = 0, seenline = 0;
 45
 46	ARGBEGIN {
 47	// ?man -1: specify option flag
 48	case '1':
 49	// ?man -2: specify option flag
 50	case '2':
 51	// ?man -3: specify option flag
 52	case '3':
 53		show &= 0x07 ^ (1 << (ARGC() - '1'));
 54		break;
 55	default:
 56		usage();
 57	} ARGEND
 58
 59	if (argc != 2)
 60		usage();
 61
 62	for (i = 0; i < 2; i++) {
 63		if (!strcmp(argv[i], "-")) {
 64			argv[i] = "<stdin>";
 65			fp[i] = stdin;
 66		} else if (!(fp[i] = fopen(argv[i], "r"))) {
 67			eprintf("fopen %s:", argv[i]);
 68		}
 69	}
 70
 71	for (;;) {
 72		for (i = 0; i < 2; i++) {
 73			if (diff && i == (diff < 0))
 74				continue;
 75			if ((len = getline(&(line[i].data), &linecap[i],
 76			                   fp[i])) > 0) {
 77				line[i].len = len;
 78				seenline = 1;
 79				continue;
 80			}
 81			if (ferror(fp[i]))
 82				eprintf("getline %s:", argv[i]);
 83			if ((diff || seenline) && line[!i].data[0])
 84				printline(!i, &line[!i]);
 85			while ((len = getline(&(line[!i].data), &linecap[!i],
 86			                      fp[!i])) > 0) {
 87				line[!i].len = len;
 88				printline(!i, &line[!i]);
 89			}
 90			if (ferror(fp[!i]))
 91				eprintf("getline %s:", argv[!i]);
 92			goto end;
 93		}
 94		diff = linecmp(&line[0], &line[1]);
 95		LIMIT(diff, -1, 1);
 96		seenline = 0;
 97		printline((2 - diff) % 3, &line[MAX(0, diff)]);
 98	}
 99end:
100	ret |= fshut(fp[0], argv[0]);
101	ret |= (fp[0] != fp[1]) && fshut(fp[1], argv[1]);
102	ret |= fshut(stdout, "<stdout>");
103
104	return ret;
105}