Commit the rewrite of tail by Allen Soard

<esp-software@mail.hypermart.net>.  Thanks Allen for
you work at getting this into shape,
 -Erik

1 files changed, 245 insertions, 1119 deletions

diff --git a/coreutils/tail.c b/coreutils/tail.c
index 2746af83b..4a1aa8436 100644
--- a/coreutils/tail.c
+++ b/coreutils/tail.c
@@ -1,15 +1,4 @@
 /* vi: set sw=4 ts=4: */
-#include "internal.h"
-
-/* This file contains _two_ implementations of tail.  One is
- * a bit more full featured, but costs 6k.  The other (i.e. the
- * SIMPLE_TAIL one) is less capable, but is good enough for about
- * 99% of the things folks want to use tail for, and only costs 2k.
- */
-
-
-#ifdef BB_FEATURE_SIMPLE_TAIL
-
 /* tail -- output the last part of file(s)
    Copyright (C) 89, 90, 91, 95, 1996 Free Software Foundation, Inc.
 
@@ -32,1163 +21,300 @@
    tail -f for multiple files by Ian Lance Taylor <ian@airs.com>.  
 
    Rewrote the option parser, removed locales support,
-    and generally busyboxed, Erik Andersen <andersen@lineo.com>
+   and generally busyboxed, Erik Andersen <andersen@lineo.com>
 
    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>.
 
- */
-
+   Compleate Rewrite to correctly support "-NUM", "+NUM", and "-s" by
+   E.Allen Soard (esp@espsw.net).
 
-#include <stdio.h>
-#include <stdarg.h>
+ */
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
-#include <ctype.h>
-#define BB_DECLARE_EXTERN
-#define bb_need_help
-#include "messages.c"
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <getopt.h>
+#include "internal.h"
 
+#define STDIN "standard input"
+#define LINES 0
+#define BYTES 1
 
-#define XWRITE(fd, buffer, n_bytes)					\
-  do {									\
-      if (n_bytes > 0 && fwrite ((buffer), 1, (n_bytes), stdout) == 0)	\
-	  errorMsg("write error");					\
-  } while (0)
+static int n_files = 0;
+static char **files = NULL;
 
-/* Number of items to tail.  */
-#define DEFAULT_N_LINES 10
+static char follow=0;
 
-/* Size of atomic reads.  */
-#ifndef BUFSIZ
-#define BUFSIZ (512 * 8)
+#ifdef BB_FEATURE_SIMPLE_TAIL
+static const char unit_type=LINES;
+static const char sleep_int=1;
+#else
+static char unit_type=LINES;
+static int sleep_int=1;
+static char verbose = 0;
 #endif
 
-/* If nonzero, read from the end of one file until killed.  */
-static int forever;
-
-/* If nonzero, print filename headers.  */
-static int print_headers;
+//static off_t units=-11;
+static off_t units=0;
 
-static void write_header(const char *filename)
+int tail_stream(int file_id)
 {
-	static int first_file = 1;
-
-	printf("%s==> %s <==\n", (first_file ? "" : "\n"), filename);
-	first_file = 0;
-}
-
-/* Print the last N_LINES lines from the end of file FD.
-   Go backward through the file, reading `BUFSIZ' bytes at a time (except
-   probably the first), until we hit the start of the file or have
-   read NUMBER newlines.
-   POS starts out as the length of the file (the offset of the last
-   byte of the file + 1).
-   Return 0 if successful, 1 if an error occurred.  */
-
-static int
-file_lines(int fd, long int n_lines, off_t pos)
-{
-	char buffer[BUFSIZ];
-	int bytes_read;
-	int i;						/* Index into `buffer' for scanning.  */
-
-	if (n_lines == 0)
-		return 0;
-
-	/* Set `bytes_read' to the size of the last, probably partial, buffer;
-	   0 < `bytes_read' <= `BUFSIZ'.  */
-	bytes_read = pos % BUFSIZ;
-	if (bytes_read == 0)
-		bytes_read = BUFSIZ;
-	/* Make `pos' a multiple of `BUFSIZ' (0 if the file is short), so that all
-	   reads will be on block boundaries, which might increase efficiency.  */
-	pos -= bytes_read;
-	lseek(fd, pos, SEEK_SET);
-	bytes_read = fullRead(fd, buffer, bytes_read);
-	if (bytes_read == -1)
-		errorMsg("read error");
-
-	/* Count the incomplete line on files that don't end with a newline.  */
-	if (bytes_read && buffer[bytes_read - 1] != '\n')
-		--n_lines;
-
-	do {
-		/* Scan backward, counting the newlines in this bufferfull.  */
-		for (i = bytes_read - 1; i >= 0; i--) {
-			/* Have we counted the requested number of newlines yet?  */
-			if (buffer[i] == '\n' && n_lines-- == 0) {
-				/* If this newline wasn't the last character in the buffer,
-				   print the text after it.  */
-				if (i != bytes_read - 1)
-					XWRITE(STDOUT_FILENO, &buffer[i + 1],
-						   bytes_read - (i + 1));
-				return 0;
+	int fd;
+	ssize_t bytes_read=0;
+	ssize_t bs=BUFSIZ;
+	ssize_t startpoint=bs;
+	ssize_t endpoint=0;
+	ssize_t count=0;
+	ssize_t filesize=0;
+	ssize_t filelocation=0;
+	char direction=1;
+	char * buffer;
+	char pipe;
+
+
+	if (!strcmp(files[file_id], STDIN))
+		fd = 0;
+	else
+		fd = open(files[file_id], O_RDONLY);
+	if (fd == -1)
+		fatalError("Unable to open file %s.\n", files[file_id]);
+
+	buffer=malloc(bs);
+
+	filesize=lseek(fd, -1, SEEK_END)+1;
+	pipe=(filesize<=0);
+
+	if(units>=0)
+		lseek(fd,0,SEEK_SET);
+	else {
+		direction=-1;
+		count=1;
+	}
+	while(units != 0) {
+		if (pipe) {
+			char * line;
+			ssize_t f_size=0;
+
+			bs=BUFSIZ;
+			line=malloc(bs);
+			while(1) {
+				bytes_read=read(fd,line,bs);
+				if(bytes_read<=0)
+					break;
+				buffer=realloc(buffer,f_size+bytes_read);
+				memcpy(&buffer[f_size],line,bytes_read);
+				filelocation=f_size+=bytes_read;
 			}
-		}
-		/* Not enough newlines in that bufferfull.  */
-		if (pos == 0) {
-			/* Not enough lines in the file; print the entire file.  */
-			lseek(fd, (off_t) 0, SEEK_SET);
-			return 0;
-		}
-		pos -= BUFSIZ;
-		lseek(fd, pos, SEEK_SET);
-	}
-	while ((bytes_read = fullRead(fd, buffer, BUFSIZ)) > 0);
-	if (bytes_read == -1)
-		errorMsg("read error");
-
-	return 0;
-}
-
-/* Print the last N_LINES lines from the end of the standard input,
-   open for reading as pipe FD.
-   Buffer the text as a linked list of LBUFFERs, adding them as needed.
-   Return 0 if successful, 1 if an error occured.  */
-
-static int pipe_lines(int fd, long int n_lines)
-{
-	struct linebuffer {
-		int nbytes, nlines;
-		char buffer[BUFSIZ];
-		struct linebuffer *next;
-	};
-	typedef struct linebuffer LBUFFER;
-	LBUFFER *first, *last, *tmp;
-	int i;						/* Index into buffers.  */
-	int total_lines = 0;		/* Total number of newlines in all buffers.  */
-	int errors = 0;
-
-	first = last = (LBUFFER *) xmalloc(sizeof(LBUFFER));
-	first->nbytes = first->nlines = 0;
-	first->next = NULL;
-	tmp = (LBUFFER *) xmalloc(sizeof(LBUFFER));
-
-	/* Input is always read into a fresh buffer.  */
-	while ((tmp->nbytes = fullRead(fd, tmp->buffer, BUFSIZ)) > 0) {
-		tmp->nlines = 0;
-		tmp->next = NULL;
-
-		/* Count the number of newlines just read.  */
-		for (i = 0; i < tmp->nbytes; i++)
-			if (tmp->buffer[i] == '\n')
-				++tmp->nlines;
-		total_lines += tmp->nlines;
-
-		/* If there is enough room in the last buffer read, just append the new
-		   one to it.  This is because when reading from a pipe, `nbytes' can
-		   often be very small.  */
-		if (tmp->nbytes + last->nbytes < BUFSIZ) {
-			memcpy(&last->buffer[last->nbytes], tmp->buffer, tmp->nbytes);
-			last->nbytes += tmp->nbytes;
-			last->nlines += tmp->nlines;
+			bs=f_size;
+			if(direction<0)
+				bs--;
+			if (line)
+				free(line);
 		} else {
-			/* If there's not enough room, link the new buffer onto the end of
-			   the list, then either free up the oldest buffer for the next
-			   read if that would leave enough lines, or else malloc a new one.
-			   Some compaction mechanism is possible but probably not
-			   worthwhile.  */
-			last = last->next = tmp;
-			if (total_lines - first->nlines > n_lines) {
-				tmp = first;
-				total_lines -= first->nlines;
-				first = first->next;
-			} else
-				tmp = (LBUFFER *) xmalloc(sizeof(LBUFFER));
-		}
-	}
-	if (tmp->nbytes == -1)
-		errorMsg("read error");
-
-	free((char *) tmp);
-
-	/* This prevents a core dump when the pipe contains no newlines.  */
-	if (n_lines == 0)
-		goto free_lbuffers;
-
-	/* Count the incomplete line on files that don't end with a newline.  */
-	if (last->buffer[last->nbytes - 1] != '\n') {
-		++last->nlines;
-		++total_lines;
-	}
-
-	/* Run through the list, printing lines.  First, skip over unneeded
-	   buffers.  */
-	for (tmp = first; total_lines - tmp->nlines > n_lines; tmp = tmp->next)
-		total_lines -= tmp->nlines;
-
-	/* Find the correct beginning, then print the rest of the file.  */
-	if (total_lines > n_lines) {
-		char *cp;
-
-		/* Skip `total_lines' - `n_lines' newlines.  We made sure that
-		   `total_lines' - `n_lines' <= `tmp->nlines'.  */
-		cp = tmp->buffer;
-		for (i = total_lines - n_lines; i; --i)
-			while (*cp++ != '\n')
-				/* Do nothing.  */ ;
-		i = cp - tmp->buffer;
-	} else
-		i = 0;
-	XWRITE(STDOUT_FILENO, &tmp->buffer[i], tmp->nbytes - i);
-
-	for (tmp = tmp->next; tmp; tmp = tmp->next)
-		XWRITE(STDOUT_FILENO, tmp->buffer, tmp->nbytes);
-
-  free_lbuffers:
-	while (first) {
-		tmp = first->next;
-		free((char *) first);
-		first = tmp;
-	}
-	return errors;
-}
-
-/* Display file FILENAME from the current position in FD to the end.
-   If `forever' is nonzero, keep reading from the end of the file
-   until killed.  Return the number of bytes read from the file.  */
-
-static long dump_remainder(int fd)
-{
-	char buffer[BUFSIZ];
-	int bytes_read;
-	long total;
-
-	total = 0;
-  output:
-	while ((bytes_read = fullRead(fd, buffer, BUFSIZ)) > 0) {
-		XWRITE(STDOUT_FILENO, buffer, bytes_read);
-		total += bytes_read;
-	}
-	if (bytes_read == -1)
-		errorMsg("read error");
-	if (forever) {
-		fflush(stdout);
-		sleep(1);
-		goto output;
-	}
-
-	return total;
-}
-
-/* Output the last N_LINES lines of file FILENAME open for reading in FD.
-   Return 0 if successful, 1 if an error occurred.  */
-
-static int tail_lines(const char *filename, int fd, long int n_lines)
-{
-	struct stat stats;
-	off_t length;
-
-	if (print_headers)
-		write_header(filename);
-
-	if (fstat(fd, &stats))
-		errorMsg("fstat error");
-
-	/* Use file_lines only if FD refers to a regular file with
-	   its file pointer positioned at beginning of file.  */
-	/* FIXME: adding the lseek conjunct is a kludge.
-	   Once there's a reasonable test suite, fix the true culprit:
-	   file_lines.  file_lines shouldn't presume that the input
-	   file pointer is initially positioned to beginning of file.  */
-	if (S_ISREG(stats.st_mode)
-		&& lseek(fd, (off_t) 0, SEEK_CUR) == (off_t) 0) {
-		length = lseek(fd, (off_t) 0, SEEK_END);
-		if (length != 0 && file_lines(fd, n_lines, length))
-			return 1;
-		dump_remainder(fd);
-	} else
-		return pipe_lines(fd, n_lines);
-
-	return 0;
-}
-
-/* Display the last N_UNITS lines of file FILENAME.
-   "-" for FILENAME means the standard input.
-   Return 0 if successful, 1 if an error occurred.  */
-
-static int tail_file(const char *filename, off_t n_units)
-{
-	int fd, errors;
-
-	if (!strcmp(filename, "-")) {
-		filename = "standard input";
-		errors = tail_lines(filename, 0, (long) n_units);
-	} else {
-		/* Not standard input.  */
-		fd = open(filename, O_RDONLY);
-		if (fd == -1)
-			perror(filename);
-
-		errors = tail_lines(filename, fd, (long) n_units);
-		close(fd);
-	}
-
-	return errors;
-}
-
-extern int tail_main(int argc, char **argv)
-{
-	int exit_status = 0;
-	int n_units = DEFAULT_N_LINES;
-	int n_tmp, i;
-	char opt;
-
-	forever = print_headers = 0;
-
-	/* parse argv[] */
-	for (i = 1; i < argc; i++) {
-		if (argv[i][0] == '-') {
-			opt = argv[i][1];
-			switch (opt) {
-			case 'f':
-				forever = 1;
-				break;
-			case 'n':
-				n_tmp = 0;
-				if (++i < argc)
-					n_tmp = atoi(argv[i]);
-				if (n_tmp < 1)
-					usage(tail_usage);
-				n_units = n_tmp;
-				break;
-			case '-':
-			case 'h':
-				usage(tail_usage);
-			default:
-				if ((n_units = atoi(&argv[i][1])) < 1) {
-					errorMsg("invalid option -- %c\n", opt);
-					usage(tail_usage);
-				}
+			filelocation = lseek(fd, 0, SEEK_CUR);
+			if(direction<0) {
+				if(filelocation<bs)
+					bs=filelocation;
+				filelocation = lseek(fd, -bs, SEEK_CUR);
 			}
-		} else {
-			break;
+			bytes_read = read(fd, buffer, bs);
+			if (bytes_read <= 0)
+				break;
+			bs=bytes_read;
 		}
-	}
-
-	if (i + 1 < argc) {
-		if (forever) {
-			errorMsg("option -f is invalid with multiple files\n");
-			usage(tail_usage);
+		startpoint=bs;
+		if(direction>0) {
+			endpoint=startpoint;
+			startpoint=0;
 		}
-		print_headers = 1;
-	}
-
-	if (i >= argc) {
-		exit_status |= tail_file("-", n_units);
-	} else {
-		for (; i < argc; i++)
-			exit_status |= tail_file(argv[i], n_units);
-	}
-
-	return(exit_status == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
-}
-
-
-#else
-// Here follows the code for the full featured tail code
-
-
-/* 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.
-
-   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.
-
-   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>.  
-
-   Rewrote the option parser, removed locales support,
-    and generally busyboxed, Erik Andersen <andersen@lineo.com>
- 
- */
-
-#include "internal.h"
-
-#include <stdio.h>
-#include <stdarg.h>
-#include <assert.h>
-#include <errno.h>
-#include <sys/types.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <ctype.h>
-
-
-
-/* Disable assertions.  Some systems have broken assert macros.  */
-#define NDEBUG 1
-
-
-static void detailed_error(int i, int errnum, char *fmt, ...)
-			  __attribute__ ((format (printf, 3, 4)));
-static void detailed_error(int i, int errnum, char *fmt, ...)
-{
-	va_list arguments;
-
-	va_start(arguments, fmt);
-	vfprintf(stderr, fmt, arguments);
-	fprintf(stderr, "\n%s\n", strerror(errnum));
-	va_end(arguments);
-	exit(i);
-}
-
-
-#define XWRITE(fd, buffer, n_bytes)					\
-  do									\
-    {									\
-      assert ((fd) == 1);						\
-      assert ((n_bytes) >= 0);						\
-      if (n_bytes > 0 && fwrite ((buffer), 1, (n_bytes), stdout) == 0)	\
-	detailed_error (EXIT_FAILURE, errno, "write error");			\
-    }									\
-  while (0)
-
-/* Number of items to tail.  */
-#define DEFAULT_N_LINES 10
-
-/* Size of atomic reads.  */
-#ifndef BUFSIZ
-#define BUFSIZ (512 * 8)
+		for(;startpoint!=endpoint;startpoint+=direction) {
+#ifndef BB_FEATURE_SIMPLE_TAIL
+			if(unit_type==BYTES)
+				count++;
+			else
 #endif
-
-/* If nonzero, interpret the numeric argument as the number of lines.
-   Otherwise, interpret it as the number of bytes.  */
-static int count_lines;
-
-/* If nonzero, read from the end of one file until killed.  */
-static int forever;
-
-/* If nonzero, read from the end of multiple files until killed.  */
-static int forever_multiple;
-
-/* Array of file descriptors if forever_multiple is 1.  */
-static int *file_descs;
-
-/* Array of file sizes if forever_multiple is 1.  */
-static off_t *file_sizes;
-
-/* If nonzero, count from start of file instead of end.  */
-static int from_start;
-
-/* If nonzero, print filename headers.  */
-static int print_headers;
-
-/* When to print the filename banners.  */
-enum header_mode {
-	multiple_files, always, never
-};
-
-/* The name this program was run with.  */
-char *program_name;
-
-/* Nonzero if we have ever read standard input.  */
-static int have_read_stdin;
-
-static void write_header(const char *filename, const char *comment)
-{
-	static int first_file = 1;
-
-	printf("%s==> %s%s%s <==\n", (first_file ? "" : "\n"), filename,
-		   (comment ? ": " : ""), (comment ? comment : ""));
-	first_file = 0;
-}
-
-/* Print the last N_LINES lines from the end of file FD.
-   Go backward through the file, reading `BUFSIZ' bytes at a time (except
-   probably the first), until we hit the start of the file or have
-   read NUMBER newlines.
-   POS starts out as the length of the file (the offset of the last
-   byte of the file + 1).
-   Return 0 if successful, 1 if an error occurred.  */
-
-static int
-file_lines(const char *filename, int fd, long int n_lines, off_t pos)
-{
-	char buffer[BUFSIZ];
-	int bytes_read;
-	int i;						/* Index into `buffer' for scanning.  */
-
-	if (n_lines == 0)
-		return 0;
-
-	/* Set `bytes_read' to the size of the last, probably partial, buffer;
-	   0 < `bytes_read' <= `BUFSIZ'.  */
-	bytes_read = pos % BUFSIZ;
-	if (bytes_read == 0)
-		bytes_read = BUFSIZ;
-	/* Make `pos' a multiple of `BUFSIZ' (0 if the file is short), so that all
-	   reads will be on block boundaries, which might increase efficiency.  */
-	pos -= bytes_read;
-	lseek(fd, pos, SEEK_SET);
-	bytes_read = fullRead(fd, buffer, bytes_read);
-	if (bytes_read == -1) {
-		detailed_error(0, errno, "%s", filename);
-		return 1;
-	}
-
-	/* Count the incomplete line on files that don't end with a newline.  */
-	if (bytes_read && buffer[bytes_read - 1] != '\n')
-		--n_lines;
-
-	do {
-		/* Scan backward, counting the newlines in this bufferfull.  */
-		for (i = bytes_read - 1; i >= 0; i--) {
-			/* Have we counted the requested number of newlines yet?  */
-			if (buffer[i] == '\n' && n_lines-- == 0) {
-				/* If this newline wasn't the last character in the buffer,
-				   print the text after it.  */
-				if (i != bytes_read - 1)
-					XWRITE(STDOUT_FILENO, &buffer[i + 1],
-						   bytes_read - (i + 1));
-				return 0;
-			}
-		}
-		/* Not enough newlines in that bufferfull.  */
-		if (pos == 0) {
-			/* Not enough lines in the file; print the entire file.  */
-			lseek(fd, (off_t) 0, SEEK_SET);
-			return 0;
+				if(buffer[startpoint-1]=='\n')
+					count++;
+			if (!pipe)
+				filelocation=lseek(fd,0,SEEK_CUR);
+			if(count==abs(units))
+				break;
 		}
-		pos -= BUFSIZ;
-		lseek(fd, pos, SEEK_SET);
-	}
-	while ((bytes_read = fullRead(fd, buffer, BUFSIZ)) > 0);
-	if (bytes_read == -1) {
-		detailed_error(0, errno, "%s", filename);
-		return 1;
-	}
-	return 0;
-}
-
-/* Print the last N_LINES lines from the end of the standard input,
-   open for reading as pipe FD.
-   Buffer the text as a linked list of LBUFFERs, adding them as needed.
-   Return 0 if successful, 1 if an error occured.  */
-
-static int pipe_lines(const char *filename, int fd, long int n_lines)
-{
-	struct linebuffer {
-		int nbytes, nlines;
-		char buffer[BUFSIZ];
-		struct linebuffer *next;
-	};
-	typedef struct linebuffer LBUFFER;
-	LBUFFER *first, *last, *tmp;
-	int i;						/* Index into buffers.  */
-	int total_lines = 0;		/* Total number of newlines in all buffers.  */
-	int errors = 0;
-
-	first = last = (LBUFFER *) xmalloc(sizeof(LBUFFER));
-	first->nbytes = first->nlines = 0;
-	first->next = NULL;
-	tmp = (LBUFFER *) xmalloc(sizeof(LBUFFER));
-
-	/* Input is always read into a fresh buffer.  */
-	while ((tmp->nbytes = fullRead(fd, tmp->buffer, BUFSIZ)) > 0) {
-		tmp->nlines = 0;
-		tmp->next = NULL;
-
-		/* Count the number of newlines just read.  */
-		for (i = 0; i < tmp->nbytes; i++)
-			if (tmp->buffer[i] == '\n')
-				++tmp->nlines;
-		total_lines += tmp->nlines;
-
-		/* If there is enough room in the last buffer read, just append the new
-		   one to it.  This is because when reading from a pipe, `nbytes' can
-		   often be very small.  */
-		if (tmp->nbytes + last->nbytes < BUFSIZ) {
-			memcpy(&last->buffer[last->nbytes], tmp->buffer, tmp->nbytes);
-			last->nbytes += tmp->nbytes;
-			last->nlines += tmp->nlines;
-		} else {
-			/* If there's not enough room, link the new buffer onto the end of
-			   the list, then either free up the oldest buffer for the next
-			   read if that would leave enough lines, or else malloc a new one.
-			   Some compaction mechanism is possible but probably not
-			   worthwhile.  */
-			last = last->next = tmp;
-			if (total_lines - first->nlines > n_lines) {
-				tmp = first;
-				total_lines -= first->nlines;
-				first = first->next;
-			} else
-				tmp = (LBUFFER *) xmalloc(sizeof(LBUFFER));
+		if((count==abs(units)) | pipe)
+			break;
+		if(direction<0){
+			filelocation = lseek(fd, -bytes_read, SEEK_CUR);
+			if(filelocation==0)
+				break;
 		}
 	}
-	if (tmp->nbytes == -1) {
-		detailed_error(0, errno, "%s", filename);
-		errors = 1;
-		free((char *) tmp);
-		goto free_lbuffers;
-	}
-
-	free((char *) tmp);
-
-	/* This prevents a core dump when the pipe contains no newlines.  */
-	if (n_lines == 0)
-		goto free_lbuffers;
-
-	/* Count the incomplete line on files that don't end with a newline.  */
-	if (last->buffer[last->nbytes - 1] != '\n') {
-		++last->nlines;
-		++total_lines;
-	}
+	if(pipe && (direction<0))
+		bs++;
+	bytes_read=bs-startpoint;
+	memcpy(&buffer[0],&buffer[startpoint],bytes_read);
 
-	/* Run through the list, printing lines.  First, skip over unneeded
-	   buffers.  */
-	for (tmp = first; total_lines - tmp->nlines > n_lines; tmp = tmp->next)
-		total_lines -= tmp->nlines;
-
-	/* Find the correct beginning, then print the rest of the file.  */
-	if (total_lines > n_lines) {
-		char *cp;
-
-		/* Skip `total_lines' - `n_lines' newlines.  We made sure that
-		   `total_lines' - `n_lines' <= `tmp->nlines'.  */
-		cp = tmp->buffer;
-		for (i = total_lines - n_lines; i; --i)
-			while (*cp++ != '\n')
-				/* Do nothing.  */ ;
-		i = cp - tmp->buffer;
-	} else
-		i = 0;
-	XWRITE(STDOUT_FILENO, &tmp->buffer[i], tmp->nbytes - i);
-
-	for (tmp = tmp->next; tmp; tmp = tmp->next)
-		XWRITE(STDOUT_FILENO, tmp->buffer, tmp->nbytes);
-
-  free_lbuffers:
-	while (first) {
-		tmp = first->next;
-		free((char *) first);
-		first = tmp;
-	}
-	return errors;
-}
-
-/* Print the last N_BYTES characters from the end of pipe FD.
-   This is a stripped down version of pipe_lines.
-   Return 0 if successful, 1 if an error occurred.  */
-
-static int pipe_bytes(const char *filename, int fd, off_t n_bytes)
-{
-	struct charbuffer {
-		int nbytes;
-		char buffer[BUFSIZ];
-		struct charbuffer *next;
-	};
-	typedef struct charbuffer CBUFFER;
-	CBUFFER *first, *last, *tmp;
-	int i;						/* Index into buffers.  */
-	int total_bytes = 0;		/* Total characters in all buffers.  */
-	int errors = 0;
-
-	first = last = (CBUFFER *) xmalloc(sizeof(CBUFFER));
-	first->nbytes = 0;
-	first->next = NULL;
-	tmp = (CBUFFER *) xmalloc(sizeof(CBUFFER));
-
-	/* Input is always read into a fresh buffer.  */
-	while ((tmp->nbytes = fullRead(fd, tmp->buffer, BUFSIZ)) > 0) {
-		tmp->next = NULL;
-
-		total_bytes += tmp->nbytes;
-		/* If there is enough room in the last buffer read, just append the new
-		   one to it.  This is because when reading from a pipe, `nbytes' can
-		   often be very small.  */
-		if (tmp->nbytes + last->nbytes < BUFSIZ) {
-			memcpy(&last->buffer[last->nbytes], tmp->buffer, tmp->nbytes);
-			last->nbytes += tmp->nbytes;
-		} else {
-			/* If there's not enough room, link the new buffer onto the end of
-			   the list, then either free up the oldest buffer for the next
-			   read if that would leave enough characters, or else malloc a new
-			   one.  Some compaction mechanism is possible but probably not
-			   worthwhile.  */
-			last = last->next = tmp;
-			if (total_bytes - first->nbytes > n_bytes) {
-				tmp = first;
-				total_bytes -= first->nbytes;
-				first = first->next;
-			} else {
-				tmp = (CBUFFER *) xmalloc(sizeof(CBUFFER));
-			}
+	bs=BUFSIZ;
+	while (1) {
+		if((filelocation>0 || pipe)){
+			write(1,buffer,bytes_read);
 		}
-	}
-	if (tmp->nbytes == -1) {
-		detailed_error(0, errno, "%s", filename);
-		errors = 1;
-		free((char *) tmp);
-		goto free_cbuffers;
-	}
-
-	free((char *) tmp);
-
-	/* Run through the list, printing characters.  First, skip over unneeded
-	   buffers.  */
-	for (tmp = first; total_bytes - tmp->nbytes > n_bytes; tmp = tmp->next)
-		total_bytes -= tmp->nbytes;
-
-	/* Find the correct beginning, then print the rest of the file.
-	   We made sure that `total_bytes' - `n_bytes' <= `tmp->nbytes'.  */
-	if (total_bytes > n_bytes)
-		i = total_bytes - n_bytes;
-	else
-		i = 0;
-	XWRITE(STDOUT_FILENO, &tmp->buffer[i], tmp->nbytes - i);
-
-	for (tmp = tmp->next; tmp; tmp = tmp->next)
-		XWRITE(STDOUT_FILENO, tmp->buffer, tmp->nbytes);
-
-  free_cbuffers:
-	while (first) {
-		tmp = first->next;
-		free((char *) first);
-		first = tmp;
-	}
-	return errors;
-}
-
-/* Skip N_BYTES characters from the start of pipe FD, and print
-   any extra characters that were read beyond that.
-   Return 1 on error, 0 if ok.  */
-
-static int start_bytes(const char *filename, int fd, off_t n_bytes)
-{
-	char buffer[BUFSIZ];
-	int bytes_read = 0;
-
-	while (n_bytes > 0 && (bytes_read = fullRead(fd, buffer, BUFSIZ)) > 0)
-		n_bytes -= bytes_read;
-	if (bytes_read == -1) {
-		detailed_error(0, errno, "%s", filename);
-		return 1;
-	} else if (n_bytes < 0)
-		XWRITE(STDOUT_FILENO, &buffer[bytes_read + n_bytes], -n_bytes);
-	return 0;
-}
-
-/* Skip N_LINES lines at the start of file or pipe FD, and print
-   any extra characters that were read beyond that.
-   Return 1 on error, 0 if ok.  */
-
-static int start_lines(const char *filename, int fd, long int n_lines)
-{
-	char buffer[BUFSIZ];
-	int bytes_read = 0;
-	int bytes_to_skip = 0;
-
-	while (n_lines && (bytes_read = fullRead(fd, buffer, BUFSIZ)) > 0) {
-		bytes_to_skip = 0;
-		while (bytes_to_skip < bytes_read)
-			if (buffer[bytes_to_skip++] == '\n' && --n_lines == 0)
+		bytes_read = read(fd, buffer, bs);
+		filelocation+=bytes_read;
+		if (bytes_read <= 0) {
+			if (!follow) {
+				close(fd);
 				break;
-	}
-	if (bytes_read == -1) {
-		detailed_error(0, errno, "%s", filename);
-		return 1;
-	} else if (bytes_to_skip < bytes_read) {
-		XWRITE(STDOUT_FILENO, &buffer[bytes_to_skip],
-			   bytes_read - bytes_to_skip);
-	}
-	return 0;
-}
-
-/* Display file FILENAME from the current position in FD to the end.
-   If `forever' is nonzero, keep reading from the end of the file
-   until killed.  Return the number of bytes read from the file.  */
-
-static long dump_remainder(const char *filename, int fd)
-{
-	char buffer[BUFSIZ];
-	int bytes_read;
-	long total;
-
-	total = 0;
-  output:
-	while ((bytes_read = fullRead(fd, buffer, BUFSIZ)) > 0) {
-		XWRITE(STDOUT_FILENO, buffer, bytes_read);
-		total += bytes_read;
-	}
-	if (bytes_read == -1)
-		detailed_error(EXIT_FAILURE, errno, "%s", filename);
-	if (forever) {
-		fflush(stdout);
-		sleep(1);
-		goto output;
-	} else {
-		if (forever_multiple)
-			fflush(stdout);
-	}
-
-	return total;
-}
-
-/* Tail NFILES (>1) files forever until killed.  The file names are in
-   NAMES.  The open file descriptors are in `file_descs', and the size
-   at which we stopped tailing them is in `file_sizes'.  We loop over
-   each of them, doing an fstat to see if they have changed size.  If
-   none of them have changed size in one iteration, we sleep for a
-   second and try again.  We do this until the user interrupts us.  */
-
-static void tail_forever(char **names, int nfiles)
-{
-	int last;
-
-	last = -1;
-
-	while (1) {
-		int i;
-		int changed;
-
-		changed = 0;
-		for (i = 0; i < nfiles; i++) {
-			struct stat stats;
-
-			if (file_descs[i] < 0)
-				continue;
-			if (fstat(file_descs[i], &stats) < 0) {
-				detailed_error(0, errno, "%s", names[i]);
-				file_descs[i] = -1;
-				continue;
-			}
-			if (stats.st_size == file_sizes[i])
-				continue;
-
-			/* This file has changed size.  Print out what we can, and
-			   then keep looping.  */
-
-			changed = 1;
-
-			if (stats.st_size < file_sizes[i]) {
-				write_header(names[i], "file truncated");
-				last = i;
-				lseek(file_descs[i], stats.st_size, SEEK_SET);
-				file_sizes[i] = stats.st_size;
-				continue;
-			}
-
-			if (i != last) {
-				if (print_headers)
-					write_header(names[i], NULL);
-				last = i;
 			}
-			file_sizes[i] += dump_remainder(names[i], file_descs[i]);
+			sleep(sleep_int);
 		}
-
-		/* If none of the files changed size, sleep.  */
-		if (!changed)
-			sleep(1);
-	}
-}
-
-/* Output the last N_BYTES bytes of file FILENAME open for reading in FD.
-   Return 0 if successful, 1 if an error occurred.  */
-
-static int tail_bytes(const char *filename, int fd, off_t n_bytes)
-{
-	struct stat stats;
-
-	/* FIXME: resolve this like in dd.c.  */
-	/* Use fstat instead of checking for errno == ESPIPE because
-	   lseek doesn't work on some special files but doesn't return an
-	   error, either.  */
-	if (fstat(fd, &stats)) {
-		detailed_error(0, errno, "%s", filename);
-		return 1;
-	}
-
-	if (from_start) {
-		if (S_ISREG(stats.st_mode))
-			lseek(fd, n_bytes, SEEK_CUR);
-		else if (start_bytes(filename, fd, n_bytes))
-			return 1;
-		dump_remainder(filename, fd);
-	} else {
-		if (S_ISREG(stats.st_mode)) {
-			off_t current_pos, end_pos;
-			size_t bytes_remaining;
-
-			if ((current_pos = lseek(fd, (off_t) 0, SEEK_CUR)) != -1
-				&& (end_pos = lseek(fd, (off_t) 0, SEEK_END)) != -1) {
-				off_t diff;
-
-				/* Be careful here.  The current position may actually be
-				   beyond the end of the file.  */
-				bytes_remaining = (diff =
-								   end_pos - current_pos) < 0 ? 0 : diff;
-			} else {
-				detailed_error(0, errno, "%s", filename);
-				return 1;
-			}
-
-			if (bytes_remaining <= n_bytes) {
-				/* From the current position to end of file, there are no
-				   more bytes than have been requested.  So reposition the
-				   file pointer to the incoming current position and print
-				   everything after that.  */
-				lseek(fd, current_pos, SEEK_SET);
-			} else {
-				/* There are more bytes remaining than were requested.
-				   Back up.  */
-				lseek(fd, -n_bytes, SEEK_END);
-			}
-			dump_remainder(filename, fd);
-		} else
-			return pipe_bytes(filename, fd, n_bytes);
+		usleep(sleep_int * 1000);
 	}
+	if (buffer)
+		free(buffer);
 	return 0;
 }
 
-/* Output the last N_LINES lines of file FILENAME open for reading in FD.
-   Return 0 if successful, 1 if an error occurred.  */
-
-static int tail_lines(const char *filename, int fd, long int n_lines)
+void add_file(char *name)
 {
-	struct stat stats;
-	off_t length;
-
-	if (fstat(fd, &stats)) {
-		detailed_error(0, errno, "%s", filename);
-		return 1;
-	}
-
-	if (from_start) {
-		if (start_lines(filename, fd, n_lines))
-			return 1;
-		dump_remainder(filename, fd);
-	} else {
-		/* Use file_lines only if FD refers to a regular file with
-		   its file pointer positioned at beginning of file.  */
-		/* FIXME: adding the lseek conjunct is a kludge.
-		   Once there's a reasonable test suite, fix the true culprit:
-		   file_lines.  file_lines shouldn't presume that the input
-		   file pointer is initially positioned to beginning of file.  */
-		if (S_ISREG(stats.st_mode)
-			&& lseek(fd, (off_t) 0, SEEK_CUR) == (off_t) 0) {
-			length = lseek(fd, (off_t) 0, SEEK_END);
-			if (length != 0 && file_lines(filename, fd, n_lines, length))
-				return 1;
-			dump_remainder(filename, fd);
-		} else
-			return pipe_lines(filename, fd, n_lines);
-	}
-	return 0;
+	++n_files;
+	files = realloc(files, n_files);
+	files[n_files - 1] = (char *) malloc(strlen(name) + 1);
+	strcpy(files[n_files - 1], name);
 }
 
-/* Display the last N_UNITS units of file FILENAME, open for reading
-   in FD.
-   Return 0 if successful, 1 if an error occurred.  */
 
-static int tail(const char *filename, int fd, off_t n_units)
+int tail_main(int argc, char **argv)
 {
-	if (count_lines)
-		return tail_lines(filename, fd, (long) n_units);
-	else
-		return tail_bytes(filename, fd, n_units);
-}
-
-/* Display the last N_UNITS units of file FILENAME.
-   "-" for FILENAME means the standard input.
-   FILENUM is this file's index in the list of files the user gave.
-   Return 0 if successful, 1 if an error occurred.  */
-
-static int tail_file(const char *filename, off_t n_units, int filenum)
-{
-	int fd, errors;
-	struct stat stats;
-
-	if (!strcmp(filename, "-")) {
-		have_read_stdin = 1;
-		filename = "standard input";
-		if (print_headers)
-			write_header(filename, NULL);
-		errors = tail(filename, 0, n_units);
-		if (forever_multiple) {
-			if (fstat(0, &stats) < 0) {
-				detailed_error(0, errno, "standard input");
-				errors = 1;
-			} else if (!S_ISREG(stats.st_mode)) {
-				detailed_error(0, 0,
-							   "standard input: cannot follow end of non-regular file");
-				errors = 1;
-			}
-			if (errors)
-				file_descs[filenum] = -1;
-			else {
-				file_descs[filenum] = 0;
-				file_sizes[filenum] = stats.st_size;
-			}
-		}
-	} else {
-		/* Not standard input.  */
-		fd = open(filename, O_RDONLY);
-		if (fd == -1) {
-			if (forever_multiple)
-				file_descs[filenum] = -1;
-			detailed_error(0, errno, "%s", filename);
-			errors = 1;
-		} else {
-			if (print_headers)
-				write_header(filename, NULL);
-			errors = tail(filename, fd, n_units);
-			if (forever_multiple) {
-				if (fstat(fd, &stats) < 0) {
-					detailed_error(0, errno, "%s", filename);
-					errors = 1;
-				} else if (!S_ISREG(stats.st_mode)) {
-					detailed_error(0, 0,
-								   "%s: cannot follow end of non-regular file",
-								   filename);
-					errors = 1;
-				}
-				if (errors) {
-					close(fd);
-					file_descs[filenum] = -1;
-				} else {
-					file_descs[filenum] = fd;
-					file_sizes[filenum] = stats.st_size;
-				}
-			} else {
-				if (close(fd)) {
-					detailed_error(0, errno, "%s", filename);
-					errors = 1;
-				}
-			}
+	int show_headers = 1;
+	int test;
+	int c;
+	int nargs=0;
+	char **argn=NULL;
+
+	opterr = 0;
+	
+	for(c=0;c<argc;c++){
+		test=atoi(argv[c]);
+		if(test){
+			units=test;
+			if(units<0)
+				units=units-1;
+		}else{
+			nargs++;
+			argn = realloc(argn, nargs);
+			argn[nargs - 1] = (char *) malloc(strlen(argv[c]) + 1);
+			strcpy(argn[nargs - 1], argv[c]);
 		}
 	}
+	while (1) {
+		int opt_index = 0;
 
-	return errors;
-}
-
-extern int tail_main(int argc, char **argv)
-{
-	int stopit = 0;
-	enum header_mode header_mode = multiple_files;
-	int exit_status = 0;
-
-	/* If from_start, the number of items to skip before printing; otherwise,
-	   the number of items at the end of the file to print.  Initially, -1
-	   means the value has not been set.  */
-	off_t n_units = -1;
-	int n_files;
-	char **file;
-
-	program_name = argv[0];
-	have_read_stdin = 0;
-	count_lines = 1;
-	forever = forever_multiple = from_start = print_headers = 0;
-
-	/* Parse any options */
-	//fprintf(stderr, "argc=%d, argv=%s\n", argc, *argv);
-	while (--argc > 0 && (**(++argv) == '-' || **argv == '+')) {
-		if (**argv == '+') {
-			from_start = 1;
-		}
-		stopit = 0;
-		while (stopit == 0 && *(++(*argv))) {
-			switch (**argv) {
-			case 'c':
-				count_lines = 0;
-
-				if (--argc < 1) {
-					usage(tail_usage);
-				}
-				n_units = getNum(*(++argv));
-				stopit = 1;
-				break;
-
-			case 'f':
-				forever = 1;
-				break;
+		c = getopt_long_only(nargs, argn,
+			"c:fhn:s:qv", NULL, &opt_index);
+		if (c == -1)
+			break;
+		switch (c) {
 
-			case 'n':
-				count_lines = 1;
+#ifndef BB_FEATURE_SIMPLE_TAIL
 
-				if (--argc < 1) {
+		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);
 				}
-				n_units = atol(*(++argv));
-				stopit = 1;
-				break;
-
-			case 'q':
-				header_mode = never;
-				break;
-
-			case 'v':
-				header_mode = always;
-				break;
-
-			default:
-				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;
+#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",c);
+			usage(tail_usage);
 		}
 	}
-
-
-	if (n_units == -1)
-		n_units = DEFAULT_N_LINES;
-
-	/* To start printing with item N_UNITS from the start of the file, skip
-	   N_UNITS - 1 items.  `tail +0' is actually meaningless, but for Unix
-	   compatibility it's treated the same as `tail +1'.  */
-	if (from_start) {
-		if (n_units)
-			--n_units;
-	}
-
-	n_files = argc;
-	file = argv;
-
-	if (n_files > 1 && forever) {
-		forever_multiple = 1;
-		forever = 0;
-		file_descs = (int *) xmalloc(n_files * sizeof(int));
-
-		file_sizes = (off_t *) xmalloc(n_files * sizeof(off_t));
-	}
-
-	if (header_mode == always
-		|| (header_mode == multiple_files && n_files > 1))
-		print_headers = 1;
-
-	if (n_files == 0) {
-		exit_status |= tail_file("-", n_units, 0);
-	} else {
-		int i;
-
-		for (i = 0; i < n_files; i++)
-			exit_status |= tail_file(file[i], n_units, i);
-
-		if (forever_multiple)
-			tail_forever(file, n_files);
-	}
-
-	if (have_read_stdin && close(0) < 0)
-		detailed_error(EXIT_FAILURE, errno, "-");
-	if (fclose(stdout) == EOF)
-		detailed_error(EXIT_FAILURE, errno, "write error");
-	exit(exit_status == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
+	while (optind < nargs) {
+		if (!strcmp(argn[optind], "-"))
+			add_file(STDIN);
+		else
+			add_file(argn[optind]);
+		optind++;
+	}
+	if(units==0)
+		units=-11;
+	if(units>0)
+		units--;
+	if (n_files == 0)
+		add_file(STDIN);
+	if (n_files == 1)
+#ifndef BB_FEATURE_SIMPLE_TAIL
+		if (!verbose)
+#endif
+			show_headers = 0;
+	for (test = 0; test < n_files; test++) {
+		if (show_headers)
+			printf("==> %s <==\n", files[test]);
+		tail_stream(test);
+	}
+	if(files)
+		free(files);
+	if(argn)
+		free(argn);
+	return 0;
 }
 
-
-#endif
+/*
+Local Variables:
+c-file-style: "linux"
+c-basic-offset: 4
+tab-width: 4
+End:
+*/