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author | Cameron Katri <me@cameronkatri.com> | 2021-05-09 14:20:58 -0400 |
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committer | Cameron Katri <me@cameronkatri.com> | 2021-05-09 14:20:58 -0400 |
commit | 5fd83771641d15c418f747bd343ba6738d3875f7 (patch) | |
tree | 5abf0f78f680d9837dbd93d4d4c3933bb7509599 /text_cmds/tail/forward.c | |
download | apple_cmds-5fd83771641d15c418f747bd343ba6738d3875f7.tar.gz apple_cmds-5fd83771641d15c418f747bd343ba6738d3875f7.tar.zst apple_cmds-5fd83771641d15c418f747bd343ba6738d3875f7.zip |
Import macOS userland
adv_cmds-176
basic_cmds-55
bootstrap_cmds-116.100.1
developer_cmds-66
diskdev_cmds-667.40.1
doc_cmds-53.60.1
file_cmds-321.40.3
mail_cmds-35
misc_cmds-34
network_cmds-606.40.1
patch_cmds-17
remote_cmds-63
shell_cmds-216.60.1
system_cmds-880.60.2
text_cmds-106
Diffstat (limited to 'text_cmds/tail/forward.c')
-rw-r--r-- | text_cmds/tail/forward.c | 520 |
1 files changed, 520 insertions, 0 deletions
diff --git a/text_cmds/tail/forward.c b/text_cmds/tail/forward.c new file mode 100644 index 0000000..172898a --- /dev/null +++ b/text_cmds/tail/forward.c @@ -0,0 +1,520 @@ +/*- + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. 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. + */ + +#include <sys/cdefs.h> + +__FBSDID("$FreeBSD$"); + +#ifndef lint +static const char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93"; +#endif + +#include <sys/param.h> +#include <sys/mount.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/time.h> +#include <sys/mman.h> +#include <sys/event.h> + +#include <err.h> +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "extern.h" + +static void rlines(FILE *, off_t, struct stat *); +static void show(file_info_t *); +static void set_events(file_info_t *files); + +/* defines for inner loop actions */ +#define USE_SLEEP 0 +#define USE_KQUEUE 1 +#define ADD_EVENTS 2 + +struct kevent *ev; +int action = USE_SLEEP; +int kq; + +static const file_info_t *last; + +/* + * 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 (bytes(fp, off)) + return; + break; + case RLINES: + if (S_ISREG(sbp->st_mode)) + 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 (lines(fp, off)) + return; + break; + default: + break; + } + + while ((ch = getc(fp)) != EOF) + if (putchar(ch) == EOF) + oerr(); + if (ferror(fp)) { + ierr(); + return; + } + (void)fflush(stdout); +} + +/* + * rlines -- display the last offset lines of the file. + */ +static void +rlines(fp, off, sbp) + FILE *fp; + off_t off; + struct stat *sbp; +{ +#ifdef __APPLE__ + /* Using mmap on network filesystems can frequently lead + to distress, and even on local file systems other processes + truncating the file can also lead to upset. */ + + /* Seek to sbp->st_blksize before the end of the file, find + all the newlines. If there are enough, print the last off + lines. Otherwise go back another sbp->st_blksize bytes, + and count newlines. Avoid re-reading blocks when possible. */ + + // +1 because we capture line ends and we want off line _starts_, + // +1 because the first line might be partial when try_at != 0 + off_t search_for = off +2; + off_t try_at = sbp->st_size; + off_t last_try = sbp->st_size; + off_t found_this_pass = 0; + off_t found_total = 0; + off_t *found_at = calloc(search_for, sizeof(off_t)); + + flockfile(fp); + + if (found_at == NULL) { + ierr(); + goto done; + } + + if (off == 0 || sbp->st_size == 0) { + goto done; + } + + /* The last character is special. Check to make sure that it is a \n, + * and if not, subtract one from the number of \n we need to search for. + */ + if (0 != fseeko(fp, sbp->st_size - 1, SEEK_SET)) { + ierr(); + goto done; + } + if ('\n' != getc_unlocked(fp)) { + search_for--; + } + + while(try_at != 0) { + found_this_pass = 0; + + if (try_at < sbp->st_blksize) { + found_at[found_this_pass++] = 0; + try_at = 0; + } else { + last_try = try_at; + try_at -= sbp->st_blksize; + } + + if (0 != fseeko(fp, try_at, SEEK_SET)) { + ierr(); + goto done; + } + + char ch; + while(EOF != (ch = getc_unlocked(fp))) { + if (ch == '\n') { + found_at[found_this_pass++ % search_for] = ftello(fp); + found_total++; + } + if (ftello(fp) == last_try && found_total < search_for) { + // We just reached the last block we scanned, + // and we know there arn't enough lines found + // so far to be happy, so we don't have to + // read it again. + break; + } + } + + if (found_this_pass >= search_for || try_at == 0) { + off_t min = found_at[0]; + int min_i = 0; + int i; + int lim = (found_this_pass < search_for) ? found_this_pass : search_for; + for(i = 1; i < lim; i++) { + if (found_at[i] < min) { + min = found_at[i]; + min_i = i; + } + } + + off_t target = min; + + if (found_this_pass >= search_for) { + // min_i might be a partial line (unless + // try_at is 0). If we found search_for + // lines, min_i+1 is the first known full line + // _and_ because we look for an extra line we + // don't need to show it. + target = found_at[(min_i + 1) % search_for]; + } + + if (0 != fseeko(fp, target, SEEK_SET)) { + ierr(); + goto done; + } + + flockfile(stdout); + while(EOF != (ch = getc_unlocked(fp))) { + if (EOF == putchar_unlocked(ch)) { + funlockfile(stdout); + oerr(); + goto done; + } + } + funlockfile(stdout); + goto done; + } + } + +done: + funlockfile(fp); + free(found_at); + return; +#else + 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; + } +#endif +} + +static void +show(file_info_t *file) +{ + int ch; + + while ((ch = getc(file->fp)) != EOF) { + if (last != file && no_files > 1) { + if (!qflag) + (void)printf("\n==> %s <==\n", file->file_name); + last = file; + } + if (putchar(ch) == EOF) + oerr(); + } + (void)fflush(stdout); + if (ferror(file->fp)) { + file->fp = NULL; + fname = file->file_name; + ierr(); + fname = NULL; + } else + clearerr(file->fp); +} + +static void +set_events(file_info_t *files) +{ + int i, n = 0; + file_info_t *file; + struct timespec ts; + struct statfs sf; + + ts.tv_sec = 0; + ts.tv_nsec = 0; + + action = USE_KQUEUE; + for (i = 0, file = files; i < no_files; i++, file++) { + if (! file->fp) + continue; + + if (fstatfs(fileno(file->fp), &sf) == 0 && + (sf.f_flags & MNT_LOCAL) == 0) { + action = USE_SLEEP; + return; + } + + 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; + } +} + +/* + * follow -- display the file, from an offset, forward. + * + */ +void +follow(file_info_t *files, enum STYLE style, off_t off) +{ + int active, i, n = -1; + struct stat sb2; + file_info_t *file; + 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 && !qflag) + (void)printf("\n==> %s <==\n", file->file_name); + fname = file->file_name; + forward(file->fp, style, off, &file->st); + fname = NULL; + if (Fflag && fileno(file->fp) != STDIN_FILENO) + n++; + } + } + if (! active) + return; + + last = --file; + + kq = kqueue(); + if (kq < 0) + err(1, "kqueue"); + ev = malloc(n * sizeof(struct kevent)); + if (! ev) + 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) + continue; + if (Fflag && file->fp && fileno(file->fp) != STDIN_FILENO) { + if (stat(file->file_name, &sb2) == 0 && + (sb2.st_ino != file->st.st_ino || + sb2.st_dev != file->st.st_dev || + sb2.st_nlink == 0)) { + show(file); + 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); + } + + 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 < 0) + 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, (off_t)0, SEEK_END) == -1) { + ierr(); + continue; + } + } + break; + + case USE_SLEEP: + (void) usleep(250000); + break; + } + } +} |