sbase/tail.c
2014-11-20 23:09:42 +00:00

102 lines
1.8 KiB
C

/* See LICENSE file for copyright and license details. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "text.h"
#include "util.h"
static void dropinit(FILE *, const char *, long);
static void taketail(FILE *, const char *, long);
static void
usage(void)
{
eprintf("usage: %s [-n lines] [file]\n", argv0);
}
int
main(int argc, char *argv[])
{
long n = 10;
FILE *fp;
void (*tail)(FILE *, const char *, long) = taketail;
char *lines;
int ret = 0;
int newline, many;
ARGBEGIN {
case 'n':
lines = EARGF(usage());
n = abs(estrtol(lines, 0));
if (lines[0] == '+')
tail = dropinit;
break;
ARGNUM:
n = ARGNUMF(0);
break;
default:
usage();
} ARGEND;
if (argc == 0) {
tail(stdin, "<stdin>", n);
} else {
many = argc > 1;
for (newline = 0; argc > 0; argc--, argv++) {
if (!(fp = fopen(argv[0], "r"))) {
weprintf("fopen %s:", argv[0]);
ret = 1;
continue;
}
if (many)
printf("%s==> %s <==\n",
newline ? "\n" : "", argv[0]);
newline = 1;
tail(fp, argv[0], n);
fclose(fp);
}
}
return ret;
}
static void
dropinit(FILE *fp, const char *str, long n)
{
char *buf = NULL;
size_t size = 0;
ssize_t len;
unsigned long i = 0;
while (i < n && ((len = getline(&buf, &size, fp)) != -1))
if (len && buf[len - 1] == '\n')
i++;
free(buf);
concat(fp, str, stdout, "<stdout>");
}
static void
taketail(FILE *fp, const char *str, long n)
{
char **ring = NULL;
long i, j;
size_t *size = NULL;
ring = ecalloc(n, sizeof *ring);
size = ecalloc(n, sizeof *size);
for (i = j = 0; getline(&ring[i], &size[i], fp) != -1; i = j = (i + 1) % n)
;
if (ferror(fp))
eprintf("%s: read error:", str);
do {
if (ring[j]) {
fputs(ring[j], stdout);
free(ring[j]);
}
} while ((j = (j+1)%n) != i);
free(ring);
free(size);
}