X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=tail.c;h=90cc2a6efad9e5d9e09ce90296953768eba99544;hb=95b520110dc1ee6ee670817fdd6312a8565cf34c;hp=7a64c4ca3734618f2ca7a8de63e424bc82fc3765;hpb=1792f8c48926450501e19d32e78e140bcb9661c6;p=oweals%2Fbusybox.git diff --git a/tail.c b/tail.c index 7a64c4ca3..90cc2a6ef 100644 --- a/tail.c +++ b/tail.c @@ -1,909 +1,251 @@ -/* 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 . - Extensions by David MacKenzie . - tail -f for multiple files by Ian Lance Taylor . - - Rewrote the option parser, removed locales support, - and generally busyboxed, Erik Andersen - +/* vi: set sw=4 ts=4: */ +/* + * Mini tail implementation for busybox + * + * + * Copyright (C) 2001 by Matt Kraai + * + * 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 + * */ -#include "internal.h" -#include -#include -#include -#include -#include -#include #include -#include - - - -/* Disable assertions. Some systems have broken assert macros. */ -#define NDEBUG 1 - - -static void 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) \ - 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) -#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; +#include +#include +#include +#include +#include +#include "busybox.h" -/* When to print the filename banners. */ -enum header_mode -{ - multiple_files, always, never +static const struct suffix_mult tail_suffixes[] = { + { "b", 512 }, + { "k", 1024 }, + { "m", 1048576 }, + { NULL, 0 } }; -char *xmalloc (); +static const int BYTES = 0; +static const int LINES = 1; -/* The name this program was run with. */ -char *program_name; +static char *tailbuf; +static int taillen; +static int newline; -/* Nonzero if we have ever read standard input. */ -static int have_read_stdin; - - -static const char tail_usage[] = -"tail [OPTION]... [FILE]...\n\ -\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=N[kbm] output the last N bytes\n\ - -f output appended data as the file grows\n\ - -n=N output the last N lines, instead of last 10\n\ - -q never output headers giving file names\n\ - -v always output headers giving file names\n\ - --help display this help and exit\n\ -\n\ -If the first character of N (bytes or lines) is a `+', output begins with \n\ -the Nth item from the start of each file, otherwise, print the last N items\n\ -in the file. N bytes may be suffixed by k (x1024), b (x512), or m (1024^2).\n\n"; - -static void -write_header (const char *filename, const char *comment) +static void tailbuf_append(char *buf, int len) { - static int first_file = 1; - - printf ("%s==> %s%s%s <==\n", (first_file ? "" : "\n"), filename, - (comment ? ": " : ""), - (comment ? comment : "")); - first_file = 0; + tailbuf = xrealloc(tailbuf, taillen + len); + memcpy(tailbuf + taillen, buf, len); + taillen += len; } -/* 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) +static void tailbuf_trunc() { - 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) - { - 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 = fullRead (fd, buffer, BUFSIZ)) > 0); - if (bytes_read == -1) - { - error (0, errno, "%s", filename); - return 1; - } - return 0; + char *s; + s = memchr(tailbuf, '\n', taillen); + memmove(tailbuf, s + 1, taillen - ((s + 1) - tailbuf)); + taillen -= (s + 1) - tailbuf; + newline = 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) +int tail_main(int argc, char **argv) { - 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 (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 = 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)); - } - } - } - 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 = fullRead (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 = fullRead (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 = fullRead (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); + int from_top = 0, units = LINES, count = 10, sleep_period = 1; + int show_headers = 0, hide_headers = 0, follow = 0; + int *fds, nfiles = 0, status = EXIT_SUCCESS, nread, nwrite, seen = 0; + char *s, *start, *end, buf[BUFSIZ]; + int i, opt; + + while ((opt = getopt(argc, argv, "c:fhn:q:s:v")) > 0) { + switch (opt) { + case 'f': + follow = 1; + break; +#ifdef BB_FEATURE_FANCY_TAIL + case 'c': + units = BYTES; + /* FALLS THROUGH */ +#endif + case 'n': + count = parse_number(optarg, tail_suffixes); + if (count < 0) + count = -count; + if (optarg[0] == '+') + from_top = 1; + break; +#ifdef BB_FEATURE_FANCY_TAIL + case 'q': + hide_headers = 1; + break; + case 's': + sleep_period = parse_number(optarg, 0); + break; + case 'v': + show_headers = 1; + break; +#endif + default: + show_usage(); + } } - 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); + /* open all the files */ + fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1)); + if (argc == optind) { + fds[nfiles++] = STDIN_FILENO; + argv[optind] = "standard input"; + } else { + for (i = optind; i < argc; i++) { + if (strcmp(argv[i], "-") == 0) { + fds[nfiles++] = STDIN_FILENO; + argv[i] = "standard input"; + } else if ((fds[nfiles++] = open(argv[i], O_RDONLY)) < 0) { + perror_msg("%s", argv[i]); + status = EXIT_FAILURE; + } + } } - 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; + +#ifdef BB_FEATURE_FANCY_TAIL + /* tail the files */ + if (!from_top && units == BYTES) + tailbuf = xmalloc(count); +#endif - 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; + for (i = 0; i < nfiles; i++) { + if (fds[i] == -1) + continue; + if (!count) { + lseek(fds[i], 0, SEEK_END); + continue; } - 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; + seen = 0; + if (show_headers || (!hide_headers && nfiles > 1)) + printf("%s==> %s <==\n", i == 0 ? "" : "\n", argv[optind + i]); + while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) { + if (from_top) { +#ifdef BB_FEATURE_FANCY_TAIL + if (units == BYTES) { + if (count - 1 <= seen) + nwrite = nread; + else if (count - 1 <= seen + nread) + nwrite = nread + seen - (count - 1); + else + nwrite = 0; + seen += nread; + } else { +#else + { +#endif + if (count - 1 <= seen) + nwrite = nread; + else { + nwrite = 0; + for (s = memchr(buf, '\n', nread); s != NULL; + s = memchr(s+1, '\n', nread - (s + 1 - buf))) { + if (count - 1 <= ++seen) { + nwrite = nread - (s + 1 - buf); + break; + } + } + } + } + if (full_write(STDOUT_FILENO, buf + nread - nwrite, + nwrite) < 0) { + perror_msg("write"); + status = EXIT_FAILURE; + break; + } + } else { +#ifdef BB_FEATURE_FANCY_TAIL + if (units == BYTES) { + if (nread < count) { + memmove(tailbuf, tailbuf + nread, count - nread); + memcpy(tailbuf + count - nread, buf, nread); + } else { + memcpy(tailbuf, buf + nread - count, count); + } + seen += nread; + } else { +#else + { +#endif + for (start = buf, end = memchr(buf, '\n', nread); + end != NULL; start = end+1, + end = memchr(start, '\n', nread - (start - buf))) { + if (newline && count <= seen) + tailbuf_trunc(); + tailbuf_append(start, end - start + 1); + seen++; + newline = 1; + } + if (newline && count <= seen && nread - (start - buf) > 0) + tailbuf_trunc(); + tailbuf_append(start, nread - (start - buf)); + } + } } - } - else - { - if (close (fd)) - { - error (0, errno, "%s", filename); - errors = 1; + + if (nread < 0) { + perror_msg("read"); + status = EXIT_FAILURE; } - } - } - } - return errors; -} +#ifdef BB_FEATURE_FANCY_TAIL + if (!from_top && units == BYTES) { + if (count < seen) + seen = count; + if (full_write(STDOUT_FILENO, tailbuf + count - seen, seen) < 0) { + perror_msg("write"); + status = EXIT_FAILURE; + } + } +#endif -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; + if (!from_top && units == LINES) { + if (full_write(STDOUT_FILENO, tailbuf, taillen) < 0) { + perror_msg("write"); + status = EXIT_FAILURE; + } + } - 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; + taillen = 0; } - 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; - case 'n': - count_lines = 1; + while (follow) { + sleep(sleep_period); - if (--argc < 1) { - usage(tail_usage); - } - n_units = atol(*(++argv)); - stopit = 1; - break; + for (i = 0; i < nfiles; i++) { + if (fds[i] == -1) + continue; - case 'q': - header_mode = never; - break; + if ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) { + if (show_headers || (!hide_headers && nfiles > 1)) + printf("\n==> %s <==\n", argv[optind + i]); - case 'v': - header_mode = always; - break; + do { + full_write(STDOUT_FILENO, buf, nread); + } while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0); + } - default: - usage (tail_usage); - } + if (nread < 0) { + perror_msg("read"); + status = EXIT_FAILURE; + } + } } - } - - - 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) - error (EXIT_FAILURE, errno, "-"); - if (fclose (stdout) == EOF) - error (EXIT_FAILURE, errno, "write error"); - exit (exit_status == 0 ? EXIT_SUCCESS : EXIT_FAILURE); + return status; }