Latest and greatest
diff --git a/tail.c b/tail.c
new file mode 100644
index 0000000..058d462
--- /dev/null
+++ b/tail.c
@@ -0,0 +1,955 @@
+/* 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. */
+
+/* Can display any amount of data, unlike the Unix version, which uses
+ a fixed size buffer and therefore can only deliver a limited number
+ of lines.
+
+ Options:
+ -b Tail by N 512-byte blocks.
+ -c, --bytes=N[bkm] Tail by N bytes
+ [or 512-byte blocks, kilobytes, or megabytes].
+ -f, --follow Loop forever trying to read more characters at the
+ end of the file, on the assumption that the file
+ is growing. Ignored if reading from a pipe.
+ -n, --lines=N Tail by N lines.
+ -q, --quiet, --silent Never print filename headers.
+ -v, --verbose Always print filename headers.
+
+ If a number (N) starts with a `+', begin printing with the Nth item
+ from the start of each file, instead of from the end.
+
+ Reads from standard input if no files are given or when a filename of
+ ``-'' is encountered.
+ By default, filename headers are printed only more than one file
+ is given.
+ By default, prints the last 10 lines (tail -n 10).
+
+ 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>. */
+
+#include "internal.h"
+
+#include <stdio.h>
+#include <assert.h>
+#include <errno.h>
+#include <sys/types.h>
+
+
+/* Disable assertions. Some systems have broken assert macros. */
+#define NDEBUG 1
+
+
+static void error(int i, int errnum, char* fmt, const char *msg)
+{
+ fprintf(stderr, fmt, msg);
+ perror( errnum);
+ 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) \
+ error (EXIT_FAILURE, errno, "write error", NULL); \
+ } \
+ while (0)
+
+/* Number of items to tail. */
+#define DEFAULT_N_LINES 10
+
+/* Size of atomic reads. */
+#ifndef BUFSIZ
+#define BUFSIZ (512 * 8)
+#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
+};
+
+char *xmalloc ();
+int safe_read ();
+
+/* The name this program was run with. */
+char *program_name;
+
+/* Nonzero if we have ever read standard input. */
+static int have_read_stdin;
+
+/* If nonzero, display usage information and exit. */
+static int show_help;
+
+/* If nonzero, print the version on standard output then exit. */
+static int show_version;
+
+static const char tail_usage[] =
+"tail [OPTION]... [FILE]...\n\
+Print last 10 lines of each FILE to standard output.\n\
+With more than one FILE, precede each with a header giving the file name.\n\
+With no FILE, or when FILE is -, read standard input.\n\
+\n\
+ -c, --bytes=N output the last N bytes\n\
+ -f, --follow output appended data as the file grows\n\
+ -n, --lines=N output the last N lines, instead of last 10\n\
+ -q, --quiet, --silent never output headers giving file names\n\
+ -v, --verbose always output headers giving file names\n\
+ --help display this help and exit\n\
+ --version output version information and exit\n\
+\n\
+If the first character of N (the number of bytes or lines) is a `+',\n\
+print beginning with the Nth item from the start of each file, otherwise,\n\
+print the last N items in the file. N may have a multiplier suffix:\n\
+b for 512, k for 1024, m for 1048576 (1 Meg). A first OPTION of -VALUE\n\
+or +VALUE is treated like -n VALUE or -n +VALUE unless VALUE has one of\n\
+the [bkm] suffix multipliers, in which case it is treated like -c VALUE\n\
+or -c +VALUE.\n";
+
+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 = safe_read (fd, buffer, bytes_read);
+ if (bytes_read == -1)
+ {
+ 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;
+ }
+ pos -= BUFSIZ;
+ lseek (fd, pos, SEEK_SET);
+ }
+ while ((bytes_read = safe_read (fd, buffer, BUFSIZ)) > 0);
+ if (bytes_read == -1)
+ {
+ 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 = safe_read (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 (tmp->nbytes == -1)
+ {
+ 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;
+ }
+
+ /* 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 = safe_read (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));
+ }
+ }
+ }
+ if (tmp->nbytes == -1)
+ {
+ 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 = safe_read (fd, buffer, BUFSIZ)) > 0)
+ n_bytes -= bytes_read;
+ if (bytes_read == -1)
+ {
+ 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 = safe_read (fd, buffer, BUFSIZ)) > 0)
+ {
+ bytes_to_skip = 0;
+ while (bytes_to_skip < bytes_read)
+ if (buffer[bytes_to_skip++] == '\n' && --n_lines == 0)
+ break;
+ }
+ if (bytes_read == -1)
+ {
+ 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 = safe_read (fd, buffer, BUFSIZ)) > 0)
+ {
+ XWRITE (STDOUT_FILENO, buffer, bytes_read);
+ total += bytes_read;
+ }
+ if (bytes_read == -1)
+ 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)
+ {
+ 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]);
+ }
+
+ /* 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))
+ {
+ 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
+ {
+ 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);
+ }
+ 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)
+{
+ struct stat stats;
+ off_t length;
+
+ if (fstat (fd, &stats))
+ {
+ 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;
+}
+
+/* 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)
+{
+ 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)
+ {
+ error (0, errno, "standard input");
+ errors = 1;
+ }
+ else if (!S_ISREG (stats.st_mode))
+ {
+ 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;
+ 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)
+ {
+ error (0, errno, "%s", filename);
+ errors = 1;
+ }
+ else if (!S_ISREG (stats.st_mode))
+ {
+ 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))
+ {
+ error (0, errno, "%s", filename);
+ errors = 1;
+ }
+ }
+ }
+ }
+
+ return errors;
+}
+
+extern int
+tai_main (int argc, char **argv)
+{
+ 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;
+ long int tmp_long;
+ int c; /* Option character. */
+ int n_files;
+ char **file;
+
+ program_name = argv[0];
+ have_read_stdin = 0;
+ count_lines = 1;
+ forever = forever_multiple = from_start = print_headers = 0;
+
+ if (argc > 1
+ && ((argv[1][0] == '-' && ISDIGIT (argv[1][1]))
+ || (argv[1][0] == '+' && (ISDIGIT (argv[1][1])
+ || argv[1][1] == 0))))
+ {
+ /* Old option syntax: a dash or plus, one or more digits (zero digits
+ are acceptable with a plus), and one or more option letters. */
+ if (argv[1][0] == '+')
+ from_start = 1;
+ if (argv[1][1] != '\0')
+ {
+ strtol_error s_err;
+ char *p;
+
+ s_err = xstrtol (++argv[1], &p, 0, &tmp_long, "bkm");
+ n_units = tmp_long;
+ if (s_err == LONGINT_OVERFLOW)
+ {
+ STRTOL_FATAL_ERROR (argv[1], "argument", s_err);
+ }
+
+ /* If a [bkm] suffix was given then count bytes, not lines. */
+ if (p[-1] == 'b' || p[-1] == 'k' || p[-1] == 'm')
+ count_lines = 0;
+
+ /* Parse any appended option letters. */
+ while (*p)
+ {
+ switch (*p)
+ {
+ case 'c':
+ /* Interpret N_UNITS as # of bytes. */
+ count_lines = 0;
+ break;
+
+ case 'f':
+ forever = 1;
+ break;
+
+ case 'l':
+ count_lines = 1;
+ break;
+
+ case 'q':
+ header_mode = never;
+ break;
+
+ case 'v':
+ header_mode = always;
+ break;
+
+ default:
+ error (0, 0, "unrecognized option '%c'", *p);
+ usage (tail_usage);
+ }
+ ++p;
+ }
+ }
+ /* Make the options we just parsed invisible to getopt. */
+ argv[1] = argv[0];
+ argv++;
+ argc--;
+ }
+
+ if (show_version)
+ {
+ printf ("tail - %s\n", PACKAGE_VERSION);
+ exit (EXIT_SUCCESS);
+ }
+
+ if (show_help)
+ 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 - optind;
+ file = argv + optind;
+
+ 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)
+ error (EXIT_FAILURE, errno, "-");
+ if (fclose (stdout) == EOF)
+ error (EXIT_FAILURE, errno, "write error");
+ exit (exit_status == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
+}