/*- * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Edward Sze-Tyan Wang. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)forward.c 8.1 (Berkeley) 6/6/93 * $FreeBSD: src/usr.bin/tail/forward.c,v 1.11.6.7 2003/01/07 05:26:22 tjr Exp $ */ #include #include #include #include #ifndef BOOTSTRAPPING #include #endif #include #include #include #include #include #include #include #include #include "extern.h" static void rlines(FILE *, off_t, struct stat *); /* defines for inner loop actions */ #define USE_SLEEP 0 #ifndef BOOTSTRAPPING #define USE_KQUEUE 1 #define ADD_EVENTS 2 struct kevent *ev; #endif int action = USE_SLEEP; int kq; /* * forward -- display the file, from an offset, forward. * * There are eight separate cases for this -- regular and non-regular * files, by bytes or lines and from the beginning or end of the file. * * FBYTES byte offset from the beginning of the file * REG seek * NOREG read, counting bytes * * FLINES line offset from the beginning of the file * REG read, counting lines * NOREG read, counting lines * * RBYTES byte offset from the end of the file * REG seek * NOREG cyclically read characters into a wrap-around buffer * * RLINES * REG mmap the file and step back until reach the correct offset. * NOREG cyclically read lines into a wrap-around array of buffers */ void forward(FILE *fp, enum STYLE style, off_t off, struct stat *sbp) { int ch; switch(style) { case FBYTES: if (off == 0) break; if (S_ISREG(sbp->st_mode)) { if (sbp->st_size < off) off = sbp->st_size; if (fseeko(fp, off, SEEK_SET) == -1) { ierr(); return; } } else while (off--) if ((ch = getc(fp)) == EOF) { if (ferror(fp)) { ierr(); return; } break; } break; case FLINES: if (off == 0) break; for (;;) { if ((ch = getc(fp)) == EOF) { if (ferror(fp)) { ierr(); return; } break; } if (ch == '\n' && !--off) break; } break; case RBYTES: if (S_ISREG(sbp->st_mode)) { if (sbp->st_size >= off && fseeko(fp, -off, SEEK_END) == -1) { ierr(); return; } } else if (off == 0) { while (getc(fp) != EOF); if (ferror(fp)) { ierr(); return; } } else if (display_bytes(fp, off)) return; break; case RLINES: if (S_ISREG(sbp->st_mode) && sbp->st_size != 0) if (!off) { if (fseeko(fp, (off_t)0, SEEK_END) == -1) { ierr(); return; } } else rlines(fp, off, sbp); else if (off == 0) { while (getc(fp) != EOF); if (ferror(fp)) { ierr(); return; } } else if (display_lines(fp, off)) return; break; case REVERSE: errx(1, "internal error: forward style cannot be REVERSE"); /* NOTREACHED */ } while ((ch = getc(fp)) != EOF) { if (putchar(ch) == EOF) oerr(); } if (ferror(fp)) { ierr(); return; } fflush(stdout); } /* * rlines -- display the last offset lines of the file. */ static void rlines(FILE *fp, off_t off, struct stat *sbp) { struct mapinfo map; off_t curoff, size; int i; if (!(size = sbp->st_size)) return; map.start = NULL; map.fd = fileno(fp); map.mapoff = map.maxoff = size; /* * Last char is special, ignore whether newline or not. Note that * size == 0 is dealt with above, and size == 1 sets curoff to -1. */ curoff = size - 2; while (curoff >= 0) { if (curoff < map.mapoff && maparound(&map, curoff) != 0) { ierr(); return; } for (i = curoff - map.mapoff; i >= 0; i--) if (map.start[i] == '\n' && --off == 0) break; /* `i' is either the map offset of a '\n', or -1. */ curoff = map.mapoff + i; if (i >= 0) break; } curoff++; if (mapprint(&map, curoff, size - curoff) != 0) { ierr(); exit(1); } /* Set the file pointer to reflect the length displayed. */ if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) { ierr(); return; } if (map.start != NULL && munmap(map.start, map.maplen)) { ierr(); return; } } /* * follow -- display the file, from an offset, forward. */ #ifndef BOOTSTRAPPING static void show(file_info_t *file, int at_index) { int ch, first; first = 1; while ((ch = getc(file->fp)) != EOF) { if (first && no_files > 1) { showfilename(at_index, file->file_name); first = 0; } if (putchar(ch) == EOF) oerr(); } fflush(stdout); if (ferror(file->fp)) { file->fp = NULL; ierr(); } else { clearerr(file->fp); } } #endif void showfilename(int at_index, const char *filename) { static int last_index = -1; static int continuing = 0; if (last_index == at_index) return; if (!qflag) { if (continuing) printf("\n"); printf("==> %s <==\n", filename); } continuing = 1; last_index = at_index; } #ifndef BOOTSTRAPPING static void set_events(file_info_t *files) { int i, n; file_info_t *file; struct timespec ts; ts.tv_sec = 0; ts.tv_nsec = 0; n = 0; action = USE_KQUEUE; for (i = 0, file = files; i < no_files; i++, file++) { if (file->fp == NULL) continue; if (Fflag && fileno(file->fp) != STDIN_FILENO) { EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_CLEAR, NOTE_DELETE | NOTE_RENAME, 0, 0); n++; } EV_SET(&ev[n], fileno(file->fp), EVFILT_READ, EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0); n++; } if (kevent(kq, ev, n, NULL, 0, &ts) < 0) action = USE_SLEEP; } void follow(file_info_t *files, enum STYLE style, off_t off) { int active, i, n; file_info_t *file; struct stat sb2; struct timespec ts; /* Position each of the files */ file = files; active = 0; n = 0; for (i = 0; i < no_files; i++, file++) { if (file->fp) { active = 1; n++; if (no_files > 1) showfilename(i, file->file_name); forward(file->fp, style, off, &file->st); if (Fflag && fileno(file->fp) != STDIN_FILENO) n++; } } if (!active) return; kq = kqueue(); if (kq == -1) err(1, "kqueue"); ev = malloc(n * sizeof(struct kevent)); if (ev == NULL) err(1, "Couldn't allocate memory for kevents."); set_events(files); for (;;) { for (i = 0, file = files; i < no_files; i++, file++) { if (file->fp == NULL) continue; if (Fflag && fileno(file->fp) != STDIN_FILENO) { if (stat(file->file_name, &sb2) == -1) { /* * file was rotated, skip it until it * reappears. */ continue; } if (sb2.st_ino != file->st.st_ino || sb2.st_dev != file->st.st_dev || sb2.st_nlink == 0) { file->fp = freopen(file->file_name, "r", file->fp); if (file->fp == NULL) { ierr(); continue; } else { memcpy(&file->st, &sb2, sizeof(struct stat)); set_events(files); } } } show(file, i); } switch (action) { case USE_KQUEUE: ts.tv_sec = 1; ts.tv_nsec = 0; /* * In the -F case, we set a timeout to ensure that * we re-stat the file at least once every second. */ n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL); if (n == -1) err(1, "kevent"); if (n == 0) { /* timeout */ break; } else if (ev->filter == EVFILT_READ && ev->data < 0) { /* file shrank, reposition to end */ if (lseek(ev->ident, 0, SEEK_END) == -1) { ierr(); continue; } } break; case USE_SLEEP: usleep(250000); break; } } } #endif