busybox/coreutils/tail.c
Eric Andersen 67991cf824 This patch, put together by Manuel Novoa III, is a merge of work
done by Evin Robertson (bug#1105) and work from Manuel to make
usage messages occupy less space and simplify how usage messages
are displayed.
2001-02-14 21:23:06 +00:00

254 lines
5.8 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini tail implementation for busybox
*
*
* Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include "busybox.h"
#include <fcntl.h>
#include <getopt.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
static const struct suffix_mult tail_suffixes[] = {
{ "b", 512 },
{ "k", 1024 },
{ "m", 1048576 },
{ NULL, 0 }
};
#ifndef BB_FEATURE_SIMPLE_TAIL
static const struct suffix_mult null_suffixes[] = {
{ NULL, 0 }
};
#endif
static const int BYTES = 0;
static const int LINES = 1;
static char *tailbuf;
static int taillen;
static int newline;
void tailbuf_append(char *buf, int len)
{
tailbuf = xrealloc(tailbuf, taillen + len);
memcpy(tailbuf + taillen, buf, len);
taillen += len;
}
void tailbuf_trunc()
{
char *s;
s = memchr(tailbuf, '\n', taillen);
memmove(tailbuf, s + 1, taillen - ((s + 1) - tailbuf));
taillen -= (s + 1) - tailbuf;
newline = 0;
}
int tail_main(int argc, char **argv)
{
int from_top = 0, units = LINES, count = 10, sleep_period = 1;
int show_headers = 0, hide_headers = 0, follow = 0;
int *fds, nfiles = 0, status = EXIT_SUCCESS, nread, nwrite, seen = 0;
char *s, *start, *end, buf[BUFSIZ];
int i, opt;
while ((opt = getopt(argc, argv, "c:fhn:q:s:v")) > 0) {
switch (opt) {
case 'f':
follow = 1;
break;
#ifndef BB_FEATURE_SIMPLE_TAIL
case 'c':
units = BYTES;
/* FALLS THROUGH */
#endif
case 'n':
count = parse_number(optarg, tail_suffixes);
if (count < 0)
count = -count;
if (optarg[0] == '+')
from_top = 1;
break;
#ifndef BB_FEATURE_SIMPLE_TAIL
case 'q':
hide_headers = 1;
break;
case 's':
sleep_period = parse_number(optarg, null_suffixes);
break;
case 'v':
show_headers = 1;
break;
#endif
default:
show_usage();
}
}
/* open all the files */
fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1));
if (argc == optind) {
fds[nfiles++] = STDIN_FILENO;
argv[optind] = "standard input";
} else {
for (i = optind; i < argc; i++) {
if (strcmp(argv[i], "-") == 0) {
fds[nfiles++] = STDIN_FILENO;
argv[i] = "standard input";
} else if ((fds[nfiles++] = open(argv[i], O_RDONLY)) < 0) {
perror_msg("%s", argv[i]);
status = EXIT_FAILURE;
}
}
}
#ifndef BB_FEATURE_SIMPLE_TAIL
/* tail the files */
if (!from_top && units == BYTES)
tailbuf = xmalloc(count);
#endif
for (i = 0; i < nfiles; i++) {
if (fds[i] == -1)
continue;
seen = 0;
if (show_headers || (!hide_headers && nfiles > 1))
printf("%s==> %s <==\n", i == 0 ? "" : "\n", argv[optind + i]);
while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
if (from_top) {
#ifndef BB_FEATURE_SIMPLE_TAIL
if (units == BYTES) {
if (count - 1 <= seen)
nwrite = nread;
else if (count - 1 <= seen + nread)
nwrite = nread + seen - (count - 1);
else
nwrite = 0;
seen += nread;
} else {
#else
{
#endif
if (count - 1 <= seen)
nwrite = nread;
else {
nwrite = 0;
for (s = memchr(buf, '\n', nread); s != NULL;
s = memchr(s+1, '\n', nread - (s + 1 - buf))) {
if (count - 1 <= ++seen) {
nwrite = nread - (s + 1 - buf);
break;
}
}
}
}
if (full_write(STDOUT_FILENO, buf + nread - nwrite,
nwrite) < 0) {
perror_msg("write");
status = EXIT_FAILURE;
break;
}
} else {
#ifndef BB_FEATURE_SIMPLE_TAIL
if (units == BYTES) {
if (nread < count) {
memmove(tailbuf, tailbuf + nread, count - nread);
memcpy(tailbuf + count - nread, buf, nread);
} else {
memcpy(tailbuf, buf + nread - count, count);
}
seen += nread;
} else {
#else
{
#endif
for (start = buf, end = memchr(buf, '\n', nread);
end != NULL; start = end+1,
end = memchr(start, '\n', nread - (start - buf))) {
if (newline && count <= seen)
tailbuf_trunc();
tailbuf_append(start, end - start + 1);
seen++;
newline = 1;
}
if (newline && count <= seen && nread - (start - buf) > 0)
tailbuf_trunc();
tailbuf_append(start, nread - (start - buf));
}
}
}
if (nread < 0) {
perror_msg("read");
status = EXIT_FAILURE;
}
#ifndef BB_FEATURE_SIMPLE_TAIL
if (!from_top && units == BYTES) {
if (count < seen)
seen = count;
if (full_write(STDOUT_FILENO, tailbuf + count - seen, seen) < 0) {
perror_msg("write");
status = EXIT_FAILURE;
}
}
#endif
if (!from_top && units == LINES) {
if (full_write(STDOUT_FILENO, tailbuf, taillen) < 0) {
perror_msg("write");
status = EXIT_FAILURE;
}
}
taillen = 0;
}
while (follow) {
sleep(sleep_period);
for (i = 0; i < nfiles; i++) {
if (fds[i] == -1)
continue;
if ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
if (show_headers || (!hide_headers && nfiles > 1))
printf("\n==> %s <==\n", argv[optind + i]);
do {
full_write(STDOUT_FILENO, buf, nread);
} while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0);
}
if (nread < 0) {
perror_msg("read");
status = EXIT_FAILURE;
}
}
}
return status;
}