113 lines
2.0 KiB
C
113 lines
2.0 KiB
C
/* See LICENSE file for copyright and license details. */
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <limits.h>
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#include "util.h"
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#define CLAMP(x, l, h) MIN(h, MAX(l, x))
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static void printline(int, char *);
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static char *nextline(char *, int, FILE *, char *);
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static void finish(int, FILE *, char *);
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static int show = 0x07;
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static void
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usage(void)
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{
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eprintf("usage: %s [-123] file1 file2\n", argv0);
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}
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int
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main(int argc, char *argv[])
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{
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int i, diff = 0;
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FILE *fp[2];
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char lines[2][LINE_MAX+1];
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ARGBEGIN {
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case '1':
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case '2':
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case '3':
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show &= 0x07 ^ (1 << (ARGC() - '1'));
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break;
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default:
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usage();
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} ARGEND;
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if (argc != 2)
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usage();
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for (i = 0; i < LEN(fp); i++) {
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if (argv[i][0] == '-')
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argv[i] = "/dev/fd/0";
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if (!(fp[i] = fopen(argv[i], "r")))
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eprintf("comm: '%s':", argv[i]);
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}
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for (;;) {
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if (diff <= 0) {
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lines[0][0] = '\0';
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if (!nextline(lines[0], sizeof(lines[0]),
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fp[0], argv[0])) {
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if (lines[1][0] != '\0')
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printline(1, lines[1]);
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finish(1, fp[1], argv[1]);
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}
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}
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if (diff >= 0) {
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lines[1][0] = '\0';
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if (!nextline(lines[1], sizeof(lines[1]),
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fp[1], argv[1])) {
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if (lines[0][0] != '\0')
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printline(0, lines[0]);
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finish(0, fp[0], argv[0]);
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}
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}
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diff = strcmp(lines[0], lines[1]);
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diff = CLAMP(diff, -1, 1);
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printline((2-diff) % 3, lines[MAX(0, diff)]);
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}
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return 0;
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}
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static void
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printline(int pos, char *line)
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{
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int i;
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if (!(show & (0x1 << pos)))
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return;
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for (i = 0; i < pos; i++) {
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if (show & (0x1 << i))
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putchar('\t');
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}
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printf("%s", line);
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}
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static char *
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nextline(char *buf, int n, FILE *f, char *name)
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{
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buf = fgets(buf, n, f);
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if (!buf && !feof(f))
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eprintf("comm: '%s':", name);
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if (buf && !strchr(buf, '\n'))
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eprintf("comm: '%s': line too long.\n", name);
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return buf;
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}
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static void
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finish(int pos, FILE *f, char *name)
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{
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char buf[LINE_MAX+1];
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while (nextline(buf, sizeof(buf), f, name))
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printline(pos, buf);
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exit(1);
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}
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