| /* 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 |
| * |
| */ |
| |
| #include "busybox.h" |
| |
| #include <fcntl.h> |
| #include <getopt.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| #include <sys/types.h> |
| |
| static const struct suffix_mult tail_suffixes[] = { |
| { "b", 512 }, |
| { "k", 1024 }, |
| { "m", 1048576 }, |
| { NULL, 0 } |
| }; |
| |
| #ifndef BB_FEATURE_SIMPLE_TAIL |
| static const struct suffix_mult null_suffixes[] = { |
| { NULL, 0 } |
| }; |
| #endif |
| |
| static const int BYTES = 0; |
| static const int LINES = 1; |
| |
| static char *tailbuf; |
| static int taillen; |
| static int newline; |
| |
| void tailbuf_append(char *buf, int len) |
| { |
| tailbuf = xrealloc(tailbuf, taillen + len); |
| memcpy(tailbuf + taillen, buf, len); |
| taillen += len; |
| } |
| |
| void tailbuf_trunc() |
| { |
| char *s; |
| s = memchr(tailbuf, '\n', taillen); |
| memmove(tailbuf, s + 1, taillen - ((s + 1) - tailbuf)); |
| taillen -= (s + 1) - tailbuf; |
| newline = 0; |
| } |
| |
| int tail_main(int argc, char **argv) |
| { |
| 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; |
| #ifndef BB_FEATURE_SIMPLE_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; |
| #ifndef BB_FEATURE_SIMPLE_TAIL |
| case 'q': |
| hide_headers = 1; |
| break; |
| case 's': |
| sleep_period = parse_number(optarg, null_suffixes); |
| break; |
| case 'v': |
| show_headers = 1; |
| break; |
| #endif |
| default: |
| usage(tail_usage); |
| } |
| } |
| |
| /* 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; |
| } |
| } |
| } |
| |
| #ifndef BB_FEATURE_SIMPLE_TAIL |
| /* tail the files */ |
| if (!from_top && units == BYTES) |
| tailbuf = xmalloc(count); |
| #endif |
| |
| for (i = 0; i < nfiles; i++) { |
| if (fds[i] == -1) |
| continue; |
| 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) { |
| #ifndef BB_FEATURE_SIMPLE_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 { |
| #ifndef BB_FEATURE_SIMPLE_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)); |
| } |
| } |
| } |
| |
| if (nread < 0) { |
| perror_msg("read"); |
| status = EXIT_FAILURE; |
| } |
| |
| #ifndef BB_FEATURE_SIMPLE_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 |
| |
| if (!from_top && units == LINES) { |
| if (full_write(STDOUT_FILENO, tailbuf, taillen) < 0) { |
| perror_msg("write"); |
| status = EXIT_FAILURE; |
| } |
| } |
| |
| taillen = 0; |
| } |
| |
| while (follow) { |
| sleep(sleep_period); |
| |
| for (i = 0; i < nfiles; i++) { |
| if (fds[i] == -1) |
| continue; |
| |
| if ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) { |
| if (show_headers || (!hide_headers && nfiles > 1)) |
| printf("\n==> %s <==\n", argv[optind + i]); |
| |
| do { |
| full_write(STDOUT_FILENO, buf, nread); |
| } while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0); |
| } |
| |
| if (nread < 0) { |
| perror_msg("read"); |
| status = EXIT_FAILURE; |
| } |
| } |
| } |
| |
| return status; |
| } |