/* 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 <fcntl.h> #include <getopt.h> #include <string.h> #include <stdlib.h> #include <unistd.h> #include <sys/types.h> #include "busybox.h" static const struct suffix_mult tail_suffixes[] = { { "b", 512 }, { "k", 1024 }, { "m", 1048576 }, { NULL, 0 } }; static const int BYTES = 0; static const int LINES = 1; static char *tailbuf; static int taillen; static int newline; static void tailbuf_append(char *buf, int len) { tailbuf = xrealloc(tailbuf, taillen + len); memcpy(tailbuf + taillen, buf, len); taillen += len; } static 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, 0); break; case 'v': show_headers = 1; break; #endif default: show_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; }