/* vi: set sw=4 ts=4: */
-/* tail -- output the last part of file(s)
- Copyright (C) 89, 90, 91, 95, 1996 Free Software Foundation, Inc.
-
- 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, 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.
+/*
+ * Mini tail implementation for busybox
+ *
+ * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
- 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.
+/* 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 */
- Original version by Paul Rubin <phr@ocf.berkeley.edu>.
- Extensions by David MacKenzie <djm@gnu.ai.mit.edu>.
- tail -f for multiple files by Ian Lance Taylor <ian@airs.com>.
+/* 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)
+ */
- Rewrote the option parser, removed locales support,
- and generally busyboxed, Erik Andersen <andersen@lineo.com>
+//kbuild:lib-$(CONFIG_TAIL) += tail.o
- Removed superfluous options and associated code ("-c", "-n", "-q").
- Removed "tail -f" support for multiple files.
- Both changes by Friedrich Vedder <fwv@myrtle.lahn.de>.
+//usage:#define tail_trivial_usage
+//usage: "[OPTIONS] [FILE]..."
+//usage:#define tail_full_usage "\n\n"
+//usage: "Print last 10 lines of each FILE (or stdin) to stdout.\n"
+//usage: "With more than one FILE, precede each with a filename header.\n"
+//usage: "\n -f Print data as file grows"
+//usage: IF_FEATURE_FANCY_TAIL(
+//usage: "\n -s SECONDS Wait SECONDS between reads with -f"
+//usage: )
+//usage: "\n -n N[kbm] Print last N lines"
+//usage: "\n -n +N[kbm] Start on Nth line and print the rest"
+//usage: IF_FEATURE_FANCY_TAIL(
+//usage: "\n -c [+]N[kbm] Print last N bytes"
+//usage: "\n -q Never print headers"
+//usage: "\n -v Always print headers"
+//usage: "\n"
+//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
+//usage: )
+//usage:
+//usage:#define tail_example_usage
+//usage: "$ tail -n 1 /etc/resolv.conf\n"
+//usage: "nameserver 10.0.0.1\n"
- Compleate Rewrite to correctly support "-NUM", "+NUM", and "-s" by
- E.Allen Soard (esp@espsw.net).
+#include "libbb.h"
- */
-#include <sys/types.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <getopt.h>
-#include "busybox.h"
-
-#define STDIN "standard input"
-#define LINES 0
-#define BYTES 1
-
-static int n_files = 0;
-static char **files = NULL;
-static char * buffer;
-static ssize_t bytes_read=0;
-static ssize_t bs;
-static ssize_t filelocation=0;
-static char pip;
-
-#ifdef BB_FEATURE_SIMPLE_TAIL
-static const char unit_type=LINES;
-#else
-static char unit_type=LINES;
-static char verbose = 0;
-#endif
+struct globals {
+ bool from_top;
+ bool exitcode;
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define INIT_G() do { } while (0)
-static off_t units=0;
+static void tail_xprint_header(const char *fmt, const char *filename)
+{
+ if (fdprintf(STDOUT_FILENO, fmt, filename) < 0)
+ bb_perror_nomsg_and_die();
+}
-static int tail_stream(int fd)
+static ssize_t tail_read(int fd, char *buf, size_t count)
{
- ssize_t startpoint;
- ssize_t endpoint=0;
- ssize_t count=0;
- ssize_t filesize=0;
- int direction=1;
-
- filelocation=0;
- startpoint=bs=BUFSIZ;
-
- filesize=lseek(fd, -1, SEEK_END)+1;
- pip=(filesize<=0);
-
- if(units>=0)
- lseek(fd,0,SEEK_SET);
- else {
- direction=-1;
- count=1;
- }
- while(units != 0) {
- if (pip) {
- char * line;
- ssize_t f_size=0;
-
- bs=BUFSIZ;
- line=xmalloc(bs);
- while(1) {
- bytes_read=read(fd,line,bs);
- if(bytes_read<=0)
- break;
- buffer=xrealloc(buffer,f_size+bytes_read);
- memcpy(&buffer[f_size],line,bytes_read);
- filelocation=f_size+=bytes_read;
- }
- bs=f_size;
- if(direction<0)
- bs--;
- if (line)
- free(line);
- } else {
- filelocation = lseek(fd, 0, SEEK_CUR);
- if(direction<0) {
- if(filelocation<bs)
- bs=filelocation;
- filelocation = lseek(fd, -bs, SEEK_CUR);
- }
- bytes_read = read(fd, buffer, bs);
- if (bytes_read <= 0)
- break;
- bs=bytes_read;
- }
- startpoint=bs;
- if(direction>0) {
- endpoint=startpoint;
- startpoint=0;
- }
- for(;startpoint!=endpoint;startpoint+=direction) {
-#ifndef BB_FEATURE_SIMPLE_TAIL
- if(unit_type==BYTES)
- count++;
- else
-#endif
- if(buffer[startpoint-1]=='\n')
- count++;
- if (!pip)
- filelocation=lseek(fd,0,SEEK_CUR);
- if(count==units*direction)
- break;
- }
- if((count==units*direction) | pip)
- break;
- if(direction<0){
- filelocation = lseek(fd, -bytes_read, SEEK_CUR);
- if(filelocation==0)
- break;
- }
+ ssize_t r;
+
+ r = full_read(fd, buf, count);
+ if (r < 0) {
+ bb_perror_msg(bb_msg_read_error);
+ G.exitcode = EXIT_FAILURE;
}
- if(pip && (direction<0))
- bs++;
- bytes_read=bs-startpoint;
- memcpy(&buffer[0],&buffer[startpoint],bytes_read);
- return 0;
+ return r;
}
-void add_file(char *name)
+#define header_fmt_str "\n==> %s <==\n"
+
+static unsigned eat_num(const char *p)
{
- ++n_files;
- files = xrealloc(files, n_files);
- files[n_files - 1] = (char *) xmalloc(strlen(name) + 1);
- strcpy(files[n_files - 1], name);
+ 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 show_headers = 1;
- int test;
- int opt;
- char follow=0;
- int sleep_int=1;
- int *fd;
-
- opterr = 0;
-
- while ((opt=getopt(argc,argv,"c:fhn:s:q:v")) >0) {
-
- switch (opt) {
-#ifndef BB_FEATURE_SIMPLE_TAIL
- case 'c':
- unit_type = BYTES;
- test = atoi(optarg);
- if(test==0)
- usage(tail_usage);
- if(optarg[strlen(optarg)-1]>'9') {
- switch (optarg[strlen(optarg)-1]) {
- case 'b':
- test *= 512;
- break;
- case 'k':
- test *= 1024;
- break;
- case 'm':
- test *= (1024 * 1024);
- break;
- default:
- fprintf(stderr,"Size must be b,k, or m.");
- usage(tail_usage);
- }
- }
- if(optarg[0]=='+')
- units=test+1;
- else
- units=-(test+1);
- break;
- case 'q':
- show_headers = 0;
- break;
- case 's':
- sleep_int = atoi(optarg);
- if(sleep_int<1)
- sleep_int=1;
- break;
- case 'v':
- verbose = 1;
- break;
+ 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;
+
+ 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 'f':
- follow = 1;
- break;
- case 'h':
- usage(tail_usage);
- break;
- case 'n':
- test = atoi(optarg);
- if (test) {
- if (optarg[0] == '+')
- units = test;
- else
- units = -(test+1);
- } else
- usage(tail_usage);
- break;
- default:
- errorMsg("\nUnknown arg: %c.\n\n",optopt);
- usage(tail_usage);
+
+ /* -s NUM, -F imlies -f */
+ IF_FEATURE_FANCY_TAIL(opt_complementary = "s+: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
+ 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;
}
- while (optind <= argc) {
- if(optind==argc) {
- if (n_files==0)
- add_file(STDIN);
- else
- break;
- }else {
- if (!strcmp(argv[optind], "-")) {
- add_file(STDIN);
- } else {
- add_file(argv[optind]);
- }
- optind++;
+ 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);
+
+ 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;
}
}
- if(units==0)
- units=-11;
- if(units>0)
- units--;
- fd=xmalloc(sizeof(int)*n_files);
- if (n_files == 1)
-#ifndef BB_FEATURE_SIMPLE_TAIL
- if (!verbose)
+ /* 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 */
+
+ 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;
+ }
+
+ 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
- show_headers = 0;
- buffer=xmalloc(BUFSIZ);
- for (test = 0; test < n_files; test++) {
- if (show_headers)
- printf("==> %s <==\n", files[test]);
- if (!strcmp(files[test], STDIN))
- fd[test] = 0;
- else
- fd[test] = open(files[test], O_RDONLY);
- if (fd[test] == -1)
- fatalError("Unable to open file %s.\n", files[test]);
- tail_stream(fd[test]);
-
- bs=BUFSIZ;
- while (1) {
- if((filelocation>0 || pip)){
- write(1,buffer,bytes_read);
}
- bytes_read = read(fd[test], buffer, bs);
- filelocation+=bytes_read;
- if (bytes_read <= 0) {
- break;
+ }
+
+ 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 (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;
+ }
+ } else {
+ int k = nread;
+ int newlines_in_buf = 0;
+
+ do { /* count '\n' in last read */
+ k--;
+ if (buf[k] == '\n') {
+ newlines_in_buf++;
+ }
+ } while (k);
+
+ if (newlines_seen + newlines_in_buf < (int)count) {
+ newlines_seen += newlines_in_buf;
+ taillen += nread;
+ } else {
+ int extra = (buf[nread-1] != '\n');
+ char *s;
+
+ 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;
}
- usleep(sleep_int * 1000);
+ } /* while (tail_read() > 0) */
+ if (!G.from_top) {
+ xwrite(STDOUT_FILENO, tailbuf, taillen);
}
- if(n_files>1)
- printf("\n");
- }
- while(1){
- for (test = 0; test < n_files; test++) {
- if(!follow){
- close(fd[test]);
+ } while (++i < nfiles);
+ prev_fd = fds[i-1];
+
+ tailbuf = xrealloc(tailbuf, BUFSIZ);
+
+ fmt = NULL;
+
+ if (FOLLOW) while (1) {
+ sleep(sleep_period);
+
+ i = 0;
+ do {
+ int nread;
+ const char *filename = argv[i];
+ int fd = fds[i];
+
+ if (FOLLOW_RETRY) {
+ struct stat sbuf, fsbuf;
+
+ 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;
- } else {
- sleep(sleep_int);
- bytes_read = read(fd[test], buffer, bs);
- if(bytes_read>0) {
- if (show_headers)
- printf("==> %s <==\n", files[test]);
- write(1,buffer,bytes_read);
- if(n_files>1)
- printf("\n");
+ 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);
+ }
+
+ 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);
}
- }
- if(!follow)
- break;
+ } while (++i < nfiles);
+ } /* while (1) */
+
+ if (ENABLE_FEATURE_CLEAN_UP) {
+ free(fds);
+ free(tailbuf);
}
- if (fd)
- free(fd);
- if (buffer)
- free(buffer);
- if(files)
- free(files);
- return 0;
+ return G.exitcode;
}
-
-/*
-Local Variables:
-c-file-style: "linux"
-c-basic-offset: 4
-tab-width: 4
-End:
-*/
projects / platform / upstream / busybox.git / blobdiff