/*
* 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
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+/* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
*
+ * Pretty much rewritten to fix numerous bugs and reduce realloc() calls.
+ * Bugs fixed (although I may have forgotten one or two... it was pretty bad)
+ * 1) mixing printf/write without fflush()ing stdout
+ * 2) no check that any open files are present
+ * 3) optstring had -q taking an arg
+ * 4) no error checking on write in some cases, and a warning even then
+ * 5) q and s interaction bug
+ * 6) no check for lseek error
+ * 7) lseek attempted when count==0 even if arg was +0 (from top)
*/
+//config:config TAIL
+//config: bool "tail"
+//config: default y
+//config: help
+//config: tail is used to print the last specified number of lines
+//config: from files.
+//config:
+//config:config FEATURE_FANCY_TAIL
+//config: bool "Enable -q, -s, -v, and -F options"
+//config: default y
+//config: depends on TAIL
+//config: help
+//config: These options are provided by GNU tail, but
+//config: are not specific in the SUSv3 standard:
+//config: -q Never output headers giving file names
+//config: -s SEC Wait SEC seconds between reads with -f
+//config: -v Always output headers giving file names
+//config: -F Same as -f, but keep retrying
+
+//applet:IF_TAIL(APPLET(tail, BB_DIR_USR_BIN, BB_SUID_DROP))
+//kbuild:lib-$(CONFIG_TAIL) += tail.o
-#include <fcntl.h>
-#include <getopt.h>
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <sys/types.h>
-#include "busybox.h"
+/* BB_AUDIT SUSv3 compliant (need fancy for -c) */
+/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
+/* http://www.opengroup.org/onlinepubs/007904975/utilities/tail.html */
-static const struct suffix_mult tail_suffixes[] = {
- { "b", 512 },
- { "k", 1024 },
- { "m", 1048576 },
- { NULL, 0 }
-};
+//usage:#define tail_trivial_usage
+//usage: "[OPTIONS] [FILE]..."
+//usage:#define tail_full_usage "\n\n"
+//usage: "Print last 10 lines of each FILE (or stdin) to stdout.\n"
+//usage: "With more than one FILE, precede each with a filename header.\n"
+//usage: "\n -f Print data as file grows"
+//usage: "\n -c [+]N[kbm] Print last N bytes"
+//usage: "\n -n N[kbm] Print last N lines"
+//usage: "\n -n +N[kbm] Start on Nth line and print the rest"
+//usage: IF_FEATURE_FANCY_TAIL(
+//usage: "\n -q Never print headers"
+//usage: "\n -s SECONDS Wait SECONDS between reads with -f"
+//usage: "\n -v Always print headers"
+//usage: "\n -F Same as -f, but keep retrying"
+//usage: "\n"
+//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
+//usage: )
+//usage:
+//usage:#define tail_example_usage
+//usage: "$ tail -n 1 /etc/resolv.conf\n"
+//usage: "nameserver 10.0.0.1\n"
-static const int BYTES = 0;
-static const int LINES = 1;
+#include "libbb.h"
+#include "common_bufsiz.h"
-static char *tailbuf;
-static int taillen;
-static int newline;
+struct globals {
+ bool from_top;
+ bool exitcode;
+} FIX_ALIASING;
+#define G (*(struct globals*)bb_common_bufsiz1)
+#define INIT_G() do { setup_common_bufsiz(); } while (0)
-static void tailbuf_append(char *buf, int len)
+static void tail_xprint_header(const char *fmt, const char *filename)
{
- tailbuf = xrealloc(tailbuf, taillen + len);
- memcpy(tailbuf + taillen, buf, len);
- taillen += len;
+ if (fdprintf(STDOUT_FILENO, fmt, filename) < 0)
+ bb_perror_nomsg_and_die();
+}
+
+static ssize_t tail_read(int fd, char *buf, size_t count)
+{
+ ssize_t r;
+
+ r = full_read(fd, buf, count);
+ if (r < 0) {
+ bb_perror_msg(bb_msg_read_error);
+ G.exitcode = EXIT_FAILURE;
+ }
+
+ return r;
}
-static void tailbuf_trunc()
+#define header_fmt_str "\n==> %s <==\n"
+
+static unsigned eat_num(const char *p)
{
- char *s;
- s = memchr(tailbuf, '\n', taillen);
- memmove(tailbuf, s + 1, taillen - ((s + 1) - tailbuf));
- taillen -= (s + 1) - tailbuf;
- newline = 0;
+ if (*p == '-')
+ p++;
+ else if (*p == '+') {
+ p++;
+ G.from_top = 1;
+ }
+ return xatou_sfx(p, bkm_suffixes);
}
+int tail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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];
+ unsigned count = 10;
+ unsigned sleep_period = 1;
+ const char *str_c, *str_n;
+
+ char *tailbuf;
+ size_t tailbufsize;
+ unsigned header_threshhold = 1;
+ unsigned nfiles;
int i, opt;
- while ((opt = getopt(argc, argv, "c:fhn:q:s:v")) > 0) {
- switch (opt) {
- case 'f':
- follow = 1;
- break;
-#ifdef BB_FEATURE_FANCY_TAIL
- case 'c':
- units = BYTES;
- /* FALLS THROUGH */
+ int *fds;
+ const char *fmt;
+ int prev_fd;
+
+ INIT_G();
+
+#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
+ /* Allow legacy syntax of an initial numeric option without -n. */
+ if (argv[1] && (argv[1][0] == '+' || argv[1][0] == '-')
+ && isdigit(argv[1][1])
+ ) {
+ count = eat_num(argv[1]);
+ argv++;
+ argc--;
+ }
#endif
- case 'n':
- count = parse_number(optarg, tail_suffixes);
- if (count < 0)
- count = -count;
- if (optarg[0] == '+')
- from_top = 1;
- break;
-#ifdef BB_FEATURE_FANCY_TAIL
- case 'q':
- hide_headers = 1;
- break;
- case 's':
- sleep_period = parse_number(optarg, 0);
- break;
- case 'v':
- show_headers = 1;
- break;
+
+ /* -s NUM, -F imlies -f */
+ IF_FEATURE_FANCY_TAIL(opt_complementary = "Ff";)
+ opt = getopt32(argv, "fc:n:" IF_FEATURE_FANCY_TAIL("qs:+vF"),
+ &str_c, &str_n IF_FEATURE_FANCY_TAIL(,&sleep_period));
+#define FOLLOW (opt & 0x1)
+#define COUNT_BYTES (opt & 0x2)
+ //if (opt & 0x1) // -f
+ if (opt & 0x2) count = eat_num(str_c); // -c
+ if (opt & 0x4) count = eat_num(str_n); // -n
+#if ENABLE_FEATURE_FANCY_TAIL
+ /* q: make it impossible for nfiles to be > header_threshhold */
+ if (opt & 0x8) header_threshhold = UINT_MAX; // -q
+ //if (opt & 0x10) // -s
+ if (opt & 0x20) header_threshhold = 0; // -v
+# define FOLLOW_RETRY (opt & 0x40)
+#else
+# define FOLLOW_RETRY 0
#endif
- default:
- show_usage();
+ argc -= optind;
+ argv += optind;
+
+ /* open all the files */
+ fds = xmalloc(sizeof(fds[0]) * (argc + 1));
+ if (!argv[0]) {
+ struct stat statbuf;
+
+ if (fstat(STDIN_FILENO, &statbuf) == 0
+ && S_ISFIFO(statbuf.st_mode)
+ ) {
+ opt &= ~1; /* clear FOLLOW */
}
+ argv[0] = (char *) bb_msg_standard_input;
}
+ nfiles = i = 0;
+ do {
+ int fd = open_or_warn_stdin(argv[i]);
+ if (fd < 0 && !FOLLOW_RETRY) {
+ G.exitcode = EXIT_FAILURE;
+ continue;
+ }
+ fds[nfiles] = fd;
+ argv[nfiles++] = argv[i];
+ } while (++i < argc);
- /* 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;
- }
+ if (!nfiles)
+ bb_error_msg_and_die("no files");
+
+ /* prepare the buffer */
+ tailbufsize = BUFSIZ;
+ if (!G.from_top && COUNT_BYTES) {
+ if (tailbufsize < count + BUFSIZ) {
+ tailbufsize = count + BUFSIZ;
}
}
-
-#ifdef BB_FEATURE_FANCY_TAIL
+ /* tail -c1024m REGULAR_FILE doesn't really need 1G mem block.
+ * (In fact, it doesn't need ANY memory). So delay allocation.
+ */
+ tailbuf = NULL;
+
/* tail the files */
- if (!from_top && units == BYTES)
- tailbuf = xmalloc(count);
-#endif
- for (i = 0; i < nfiles; i++) {
- if (fds[i] == -1)
- continue;
- if (!count) {
- lseek(fds[i], 0, SEEK_END);
- continue;
+ fmt = header_fmt_str + 1; /* skip leading newline in the header on the first output */
+ i = 0;
+ do {
+ char *buf;
+ int taillen;
+ int newlines_seen;
+ unsigned seen;
+ int nread;
+ int fd = fds[i];
+
+ if (ENABLE_FEATURE_FANCY_TAIL && fd < 0)
+ continue; /* may happen with -F */
+
+ if (nfiles > header_threshhold) {
+ tail_xprint_header(fmt, argv[i]);
+ fmt = header_fmt_str;
}
- 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) {
-#ifdef BB_FEATURE_FANCY_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
- {
+
+ if (!G.from_top) {
+ off_t current = lseek(fd, 0, SEEK_END);
+ if (current > 0) {
+ unsigned off;
+ if (COUNT_BYTES) {
+ /* Optimizing count-bytes case if the file is seekable.
+ * Beware of backing up too far.
+ * Also we exclude files with size 0 (because of /proc/xxx) */
+ if (count == 0)
+ continue; /* showing zero bytes is easy :) */
+ current -= count;
+ if (current < 0)
+ current = 0;
+ xlseek(fd, current, SEEK_SET);
+ bb_copyfd_size(fd, STDOUT_FILENO, count);
+ continue;
+ }
+#if 1 /* This is technically incorrect for *LONG* strings, but very useful */
+ /* Optimizing count-lines case if the file is seekable.
+ * We assume the lines are <64k.
+ * (Users complain that tail takes too long
+ * on multi-gigabyte files) */
+ off = (count | 0xf); /* for small counts, be more paranoid */
+ if (off > (INT_MAX / (64*1024)))
+ off = (INT_MAX / (64*1024));
+ current -= off * (64*1024);
+ if (current < 0)
+ current = 0;
+ xlseek(fd, current, SEEK_SET);
#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);
+ }
+ }
+
+ if (!tailbuf)
+ tailbuf = xmalloc(tailbufsize);
+
+ buf = tailbuf;
+ taillen = 0;
+ /* "We saw 1st line/byte".
+ * Used only by +N code ("start from Nth", 1-based): */
+ seen = 1;
+ newlines_seen = 0;
+ while ((nread = tail_read(fd, buf, tailbufsize - taillen)) > 0) {
+ if (G.from_top) {
+ int nwrite = nread;
+ if (seen < count) {
+ /* We need to skip a few more bytes/lines */
+ if (COUNT_BYTES) {
+ nwrite -= (count - seen);
+ seen += nread;
+ } else {
+ char *s = buf;
+ do {
+ --nwrite;
+ if (*s++ == '\n' && ++seen == count) {
break;
}
- }
+ } while (nwrite);
}
}
- if (full_write(STDOUT_FILENO, buf + nread - nwrite,
- nwrite) < 0) {
- perror_msg("write");
- status = EXIT_FAILURE;
- break;
- }
- } else {
-#ifdef BB_FEATURE_FANCY_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);
+ if (nwrite > 0)
+ xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
+ } else if (count) {
+ if (COUNT_BYTES) {
+ taillen += nread;
+ if (taillen > (int)count) {
+ memmove(tailbuf, tailbuf + taillen - count, count);
+ taillen = 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));
- }
- }
- }
+ int k = nread;
+ int newlines_in_buf = 0;
- if (nread < 0) {
- perror_msg("read");
- status = EXIT_FAILURE;
- }
+ do { /* count '\n' in last read */
+ k--;
+ if (buf[k] == '\n') {
+ newlines_in_buf++;
+ }
+ } while (k);
-#ifdef BB_FEATURE_FANCY_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 (newlines_seen + newlines_in_buf < (int)count) {
+ newlines_seen += newlines_in_buf;
+ taillen += nread;
+ } else {
+ int extra = (buf[nread-1] != '\n');
+ char *s;
- if (!from_top && units == LINES) {
- if (full_write(STDOUT_FILENO, tailbuf, taillen) < 0) {
- perror_msg("write");
- status = EXIT_FAILURE;
+ k = newlines_seen + newlines_in_buf + extra - count;
+ s = tailbuf;
+ while (k) {
+ if (*s == '\n') {
+ k--;
+ }
+ s++;
+ }
+ taillen += nread - (s - tailbuf);
+ memmove(tailbuf, s, taillen);
+ newlines_seen = count - extra;
+ }
+ if (tailbufsize < (size_t)taillen + BUFSIZ) {
+ tailbufsize = taillen + BUFSIZ;
+ tailbuf = xrealloc(tailbuf, tailbufsize);
+ }
+ }
+ buf = tailbuf + taillen;
}
+ } /* while (tail_read() > 0) */
+ if (!G.from_top) {
+ xwrite(STDOUT_FILENO, tailbuf, taillen);
}
+ } while (++i < nfiles);
+ prev_fd = fds[i-1];
- taillen = 0;
- }
+ tailbuf = xrealloc(tailbuf, BUFSIZ);
+
+ fmt = NULL;
- while (follow) {
+ if (FOLLOW) while (1) {
sleep(sleep_period);
- for (i = 0; i < nfiles; i++) {
- if (fds[i] == -1)
- continue;
+ i = 0;
+ do {
+ int nread;
+ const char *filename = argv[i];
+ int fd = fds[i];
- if ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
- if (show_headers || (!hide_headers && nfiles > 1))
- printf("\n==> %s <==\n", argv[optind + i]);
+ if (FOLLOW_RETRY) {
+ struct stat sbuf, fsbuf;
- do {
- full_write(STDOUT_FILENO, buf, nread);
- } while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0);
+ if (fd < 0
+ || fstat(fd, &fsbuf) < 0
+ || stat(filename, &sbuf) < 0
+ || fsbuf.st_dev != sbuf.st_dev
+ || fsbuf.st_ino != sbuf.st_ino
+ ) {
+ int new_fd;
+
+ if (fd >= 0)
+ close(fd);
+ new_fd = open(filename, O_RDONLY);
+ if (new_fd >= 0) {
+ bb_error_msg("%s has %s; following end of new file",
+ filename, (fd < 0) ? "appeared" : "been replaced"
+ );
+ } else if (fd >= 0) {
+ bb_perror_msg("%s has become inaccessible", filename);
+ }
+ fds[i] = fd = new_fd;
+ }
+ }
+ if (ENABLE_FEATURE_FANCY_TAIL && fd < 0)
+ continue;
+ if (nfiles > header_threshhold) {
+ fmt = header_fmt_str;
}
+ for (;;) {
+ /* tail -f keeps following files even if they are truncated */
+ struct stat sbuf;
+ /* /proc files report zero st_size, don't lseek them */
+ if (fstat(fd, &sbuf) == 0 && sbuf.st_size > 0) {
+ off_t current = lseek(fd, 0, SEEK_CUR);
+ if (sbuf.st_size < current)
+ xlseek(fd, 0, SEEK_SET);
+ }
- if (nread < 0) {
- perror_msg("read");
- status = EXIT_FAILURE;
+ nread = tail_read(fd, tailbuf, BUFSIZ);
+ if (nread <= 0)
+ break;
+ if (fmt && (fd != prev_fd)) {
+ tail_xprint_header(fmt, filename);
+ fmt = NULL;
+ prev_fd = fd;
+ }
+ xwrite(STDOUT_FILENO, tailbuf, nread);
}
- }
- }
+ } while (++i < nfiles);
+ } /* while (1) */
- return status;
+ if (ENABLE_FEATURE_CLEAN_UP) {
+ free(fds);
+ free(tailbuf);
+ }
+ return G.exitcode;
}
projects / oweals / busybox.git / blobdiff