sbase/comm.c

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