1 files changed, 330 insertions, 0 deletions

diff --git a/busybox/coreutils/tail.c b/busybox/coreutils/tail.c
new file mode 100644
index 000000000..e3f89d2ee
--- /dev/null
+++ b/busybox/coreutils/tail.c
@@ -0,0 +1,330 @@
+/* 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
+ *
+ */
+
+/* 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 */
+
+/* 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)
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include "busybox.h"
+
+static const struct suffix_mult tail_suffixes[] = {
+        { "b", 512 },
+        { "k", 1024 },
+        { "m", 1048576 },
+        { NULL, 0 }
+};
+
+static int status
+#if EXIT_SUCCESS != 0
+        = EXIT_SUCCESS  /* If it is 0 (paranoid check), let bss initialize it. */
+#endif
+        ;
+
+static void tail_xprint_header(const char *fmt, const char *filename)
+{
+        /* If we get an output error, there is really no sense in continuing. */
+        if (dprintf(STDOUT_FILENO, fmt, filename) < 0) {
+                bb_perror_nomsg_and_die();
+        }
+}
+
+/* len should probably be size_t */
+static void tail_xbb_full_write(const char *buf, size_t len)
+{
+        /* If we get a write error, there is really no sense in continuing. */
+        if (bb_full_write(STDOUT_FILENO, buf, len) < 0) {
+                bb_perror_nomsg_and_die();
+        }
+}
+
+static ssize_t tail_read(int fd, char *buf, size_t count)
+{
+        ssize_t r;
+
+        if ((r = safe_read(fd, buf, count)) < 0) {
+                bb_perror_msg("read");
+                status = EXIT_FAILURE;
+        }
+
+        return r;
+}
+
+static const char tail_opts[] =
+        "fn:c:"
+#ifdef CONFIG_FEATURE_FANCY_TAIL
+        "qs:v"
+#endif
+        ;
+
+static const char header_fmt[] = "\n==> %s <==\n";
+
+int tail_main(int argc, char **argv)
+{
+        long count = 10;
+        unsigned int sleep_period = 1;
+        int from_top = 0;
+        int follow = 0;
+        int header_threshhold = 1;
+        int count_bytes = 0;
+
+        char *tailbuf;
+        size_t tailbufsize;
+        int taillen = 0;
+        int newline = 0;
+
+        int *fds, nfiles, nread, nwrite, seen, i, opt;
+        char *s, *buf;
+        const char *fmt;
+
+        /* Allow legacy syntax of an initial numeric option without -n. */
+        if (argc >=2 && ((argv[1][0] == '+') || ((argv[1][0] == '-')
+                        /* && (isdigit)(argv[1][1]) */
+                        && (((unsigned int)(argv[1][1] - '0')) <= 9))))
+        {
+                optind = 2;
+                optarg = argv[1];
+                goto GET_COUNT;
+        }
+
+        while ((opt = getopt(argc, argv, tail_opts)) > 0) {
+                switch (opt) {
+                        case 'f':
+                                follow = 1;
+                                break;
+                        case 'c':
+                                count_bytes = 1;
+                                /* FALLS THROUGH */
+                        case 'n':
+                        GET_COUNT:
+                                count = bb_xgetlarg10_sfx(optarg, tail_suffixes);
+                                /* Note: Leading whitespace is an error trapped above. */
+                                if (*optarg == '+') {
+                                        from_top = 1;
+                                } else {
+                                        from_top = 0;
+                                }
+                                if (count < 0) {
+                                        count = -count;
+                                }
+                                break;
+#ifdef CONFIG_FEATURE_FANCY_TAIL
+                        case 'q':
+                                header_threshhold = INT_MAX;
+                                break;
+                        case 's':
+                                sleep_period =bb_xgetularg10_bnd(optarg, 0, UINT_MAX);
+                                break;
+                        case 'v':
+                                header_threshhold = 0;
+                                break;
+#endif
+                        default:
+                                bb_show_usage();
+                }
+        }
+
+        /* open all the files */
+        fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1));
+
+        argv += optind;
+        nfiles = i = 0;
+
+        if ((argc -= optind) == 0) {
+                struct stat statbuf;
+
+                if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) {
+                        follow = 0;
+                }
+                /* --argv; */
+                *argv = (char *) bb_msg_standard_input;
+                goto DO_STDIN;
+        }
+
+        do {
+                if ((argv[i][0] == '-') && !argv[i][1]) {
+                DO_STDIN:
+                        fds[nfiles] = STDIN_FILENO;
+                } else if ((fds[nfiles] = open(argv[i], O_RDONLY)) < 0) {
+                        bb_perror_msg("%s", argv[i]);
+                        status = EXIT_FAILURE;
+                        continue;
+                }
+                argv[nfiles] = argv[i];
+                ++nfiles;
+        } while (++i < argc);
+
+        if (!nfiles) {
+                bb_error_msg_and_die("no files");
+        }
+
+        tailbufsize = BUFSIZ;
+
+        /* tail the files */
+        if (from_top < count_bytes) {   /* Each is 0 or 1, so true iff 0 < 1. */
+                /* Hence, !from_top && count_bytes */
+                if (tailbufsize < count) {
+                        tailbufsize = count + BUFSIZ;
+                }
+        }
+
+        buf = tailbuf = xmalloc(tailbufsize);
+
+        fmt = header_fmt + 1;   /* Skip header leading newline on first output. */
+        i = 0;
+        do {
+                /* Be careful.  It would be possible to optimize the count-bytes
+                 * case if the file is seekable.  If you do though, remember that
+                 * starting file position may not be the beginning of the file.
+                 * Beware of backing up too far.  See example in wc.c.
+                 */
+                if ((!(count|from_top)) && (lseek(fds[i], 0, SEEK_END) >= 0)) {
+                        continue;
+                }
+
+                if (nfiles > header_threshhold) {
+                        tail_xprint_header(fmt, argv[i]);
+                        fmt = header_fmt;
+                }
+
+                buf = tailbuf;
+                taillen = 0;
+                seen = 1;
+                newline = 0;
+
+                while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) {
+                        if (from_top) {
+                                nwrite = nread;
+                                if (seen < count) {
+                                        if (count_bytes) {
+                                                nwrite -= (count - seen);
+                                                seen = count;
+                                        } else {
+                                                s = buf;
+                                                do {
+                                                        --nwrite;
+                                                        if ((*s++ == '\n') && (++seen == count)) {
+                                                                break;
+                                                        }
+                                                } while (nwrite);
+                                        }
+                                }
+                                tail_xbb_full_write(buf + nread - nwrite, nwrite);
+                        } else if (count) {
+                                if (count_bytes) {
+                                        taillen += nread;
+                                        if (taillen > count) {
+                                                memmove(tailbuf, tailbuf + taillen - count, count);
+                                                taillen = count;
+                                        }
+                                } else {
+                                        int k = nread;
+                                        int nbuf = 0;
+
+                                        while (k) {
+                                                --k;
+                                                if (buf[k] == '\n') {
+                                                        ++nbuf;
+                                                }
+                                        }
+
+                                        if (newline + nbuf < count) {
+                                                newline += nbuf;
+                                                taillen += nread;
+
+                                        } else {
+                                                int extra = 0;
+                                                if (buf[nread-1] != '\n') {
+                                                        extra = 1;
+                                                }
+
+                                                k = newline + nbuf + extra - count;
+                                                s = tailbuf;
+                                                while (k) {
+                                                        if (*s == '\n') {
+                                                                --k;
+                                                        }
+                                                        ++s;
+                                                }
+
+                                                taillen += nread - (s - tailbuf);
+                                                memmove(tailbuf, s, taillen);
+                                                newline = count - extra;
+                                        }
+                                        if (tailbufsize < taillen + BUFSIZ) {
+                                                tailbufsize = taillen + BUFSIZ;
+                                                tailbuf = xrealloc(tailbuf, tailbufsize);
+                                        }
+                                }
+                                buf = tailbuf + taillen;
+                        }
+                }
+
+                if (!from_top) {
+                        tail_xbb_full_write(tailbuf, taillen);
+                }
+
+                taillen = 0;
+        } while (++i < nfiles);
+
+        buf = xrealloc(tailbuf, BUFSIZ);
+
+        fmt = NULL;
+
+        while (follow) {
+                sleep(sleep_period);
+                i = 0;
+                do {
+                        if (nfiles > header_threshhold) {
+                                fmt = header_fmt;
+                        }
+                        while ((nread = tail_read(fds[i], buf, sizeof(buf))) > 0) {
+                                if (fmt) {
+                                        tail_xprint_header(fmt, argv[i]);
+                                        fmt = NULL;
+                                }
+                                tail_xbb_full_write(buf, nread);
+                        }
+                } while (++i < nfiles);
+        }
+
+        return status;
+}