sbase/tail.c
Hiltjo Posthuma d6aff89bbb tail: allow tail -n 0 or tail -0
fix a crash, but allow this option.
2015-03-30 21:24:46 +02:00

160 lines
3.0 KiB
C

/* See LICENSE file for copyright and license details. */
#include <sys/stat.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "text.h"
#include "utf.h"
#include "util.h"
static int fflag = 0;
static size_t num = 10;
static char mode = 'n';
static void
dropinit(FILE *fp, const char *str)
{
Rune r;
char *buf = NULL;
size_t size = 0, i = 0;
ssize_t len;
if (mode == 'n') {
while (i < num && (len = getline(&buf, &size, fp)) > 0)
if (len > 0 && buf[len - 1] == '\n')
i++;
} else {
while (i < num && (len = efgetrune(&r, fp, str)))
i++;
}
free(buf);
concat(fp, str, stdout, "<stdout>");
}
static void
taketail(FILE *fp, const char *str)
{
Rune *r = NULL;
char **ring = NULL;
size_t i, j, *size = NULL;
if (mode == 'n') {
ring = ecalloc(num, sizeof *ring);
size = ecalloc(num, sizeof *size);
for (i = j = 0; getline(&ring[i], &size[i], fp) > 0; )
i = j = (i + 1) % num;
} else {
r = ecalloc(num, sizeof *r);
for (i = j = 0; efgetrune(&r[i], fp, str); )
i = j = (i + 1) % num;
}
if (ferror(fp))
eprintf("%s: read error:", str);
do {
if (ring && ring[j]) {
fputs(ring[j], stdout);
free(ring[j]);
} else if (r) {
efputrune(&r[j], stdout, "<stdout>");
}
} while ((j = (j + 1) % num) != i);
free(ring);
free(size);
free(r);
}
static void
usage(void)
{
eprintf("usage: %s [-f] [-c num | -n num | -num] [file ...]\n", argv0);
}
int
main(int argc, char *argv[])
{
struct stat st1, st2;
FILE *fp;
size_t tmpsize;
int ret = 0, newline, many;
char *numstr, *tmp;
void (*tail)(FILE *, const char *) = taketail;
ARGBEGIN {
case 'f':
fflag = 1;
break;
case 'c':
case 'n':
mode = ARGC();
numstr = EARGF(usage());
num = MIN(llabs(estrtonum(numstr, LLONG_MIN + 1, MIN(LLONG_MAX, SIZE_MAX))), SIZE_MAX);
if (strchr(numstr, '+'))
tail = dropinit;
break;
ARGNUM:
num = ARGNUMF();
break;
default:
usage();
} ARGEND;
if (!num)
return 0;
if (!argc)
tail(stdin, "<stdin>");
else {
if ((many = argc > 1) && fflag)
usage();
for (newline = 0; *argv; argc--, argv++) {
if (!(fp = fopen(*argv, "r"))) {
weprintf("fopen %s:", *argv);
ret = 1;
continue;
}
if (many)
printf("%s==> %s <==\n", newline ? "\n" : "", *argv);
if (stat(*argv, &st1) < 0)
eprintf("stat %s:", *argv);
if (!(S_ISFIFO(st1.st_mode) || S_ISREG(st1.st_mode)))
fflag = 0;
newline = 1;
tail(fp, *argv);
if (!fflag) {
fclose(fp);
continue;
}
for (tmp = NULL, tmpsize = 0;;) {
while (getline(&tmp, &tmpsize, fp) > 0) {
fputs(tmp, stdout);
fflush(stdout);
}
if (ferror(fp))
eprintf("readline %s:", *argv);
clearerr(fp);
/* ignore error in case file was removed, we continue
* tracking the existing open file descriptor */
if (!stat(*argv, &st2)) {
if (st2.st_size < st1.st_size) {
fprintf(stderr, "%s: file truncated\n", *argv);
rewind(fp);
}
st1 = st2;
}
sleep(1);
}
}
}
return ret;
}