1 files changed, 330 insertions, 0 deletions
diff --git a/busybox/coreutils/tail.c b/busybox/coreutils/tail.c
new file mode 100644
index 0000000..e3f89d2
--- /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;
+}