267 lines
6.5 KiB
C
267 lines
6.5 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Edward Sze-Tyan Wang.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef lint
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static char sccsid[] = "@(#)reverse.c 8.1 (Berkeley) 6/6/93";
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#endif /* not lint */
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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#include <limits.h>
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#include <errno.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <err.h>
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#include "extern.h"
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static void r_buf __P((FILE *));
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static void r_reg __P((FILE *, enum STYLE, long, struct stat *));
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/*
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* reverse -- display input in reverse order by line.
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*
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* There are six separate cases for this -- regular and non-regular
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* files by bytes, lines or the whole file.
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*
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* BYTES display N bytes
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* REG mmap the file and display the lines
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* NOREG cyclically read characters into a wrap-around buffer
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*
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* LINES display N lines
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* REG mmap the file and display the lines
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* NOREG cyclically read lines into a wrap-around array of buffers
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*
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* FILE display the entire file
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* REG mmap the file and display the lines
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* NOREG cyclically read input into a linked list of buffers
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*/
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void
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reverse(fp, style, off, sbp)
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FILE *fp;
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enum STYLE style;
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long off;
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struct stat *sbp;
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{
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if (style != REVERSE && off == 0)
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return;
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if (S_ISREG(sbp->st_mode))
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r_reg(fp, style, off, sbp);
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else
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switch(style) {
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case FBYTES:
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case RBYTES:
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bytes(fp, off);
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break;
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case FLINES:
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case RLINES:
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lines(fp, off);
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break;
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case REVERSE:
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r_buf(fp);
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break;
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}
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}
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/*
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* r_reg -- display a regular file in reverse order by line.
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*/
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static void
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r_reg(fp, style, off, sbp)
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FILE *fp;
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register enum STYLE style;
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long off;
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struct stat *sbp;
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{
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register off_t size;
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register int llen;
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register char *p;
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char *start;
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if (!(size = sbp->st_size))
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return;
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if (size > SIZE_T_MAX) {
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errno = EFBIG;
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err(0, "%s", fname);
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return;
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}
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if ((start = mmap(NULL, (size_t)size,
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PROT_READ, 0, fileno(fp), (off_t)0)) == (caddr_t)-1) {
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err(0, "%s", fname);
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return;
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}
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p = start + size - 1;
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if (style == RBYTES && off < size)
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size = off;
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/* Last char is special, ignore whether newline or not. */
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for (llen = 1; --size; ++llen)
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if (*--p == '\n') {
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WR(p + 1, llen);
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llen = 0;
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if (style == RLINES && !--off) {
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++p;
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break;
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}
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}
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if (llen)
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WR(p, llen);
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if (munmap(start, (size_t)sbp->st_size))
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err(0, "%s", fname);
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}
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typedef struct bf {
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struct bf *next;
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struct bf *prev;
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int len;
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char *l;
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} BF;
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/*
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* r_buf -- display a non-regular file in reverse order by line.
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*
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* This is the function that saves the entire input, storing the data in a
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* doubly linked list of buffers and then displays them in reverse order.
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* It has the usual nastiness of trying to find the newlines, as there's no
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* guarantee that a newline occurs anywhere in the file, let alone in any
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* particular buffer. If we run out of memory, input is discarded (and the
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* user warned).
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*/
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static void
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r_buf(fp)
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FILE *fp;
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{
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register BF *mark, *tl, *tr;
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register int ch, len, llen;
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register char *p;
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off_t enomem;
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#define BSZ (128 * 1024)
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for (mark = NULL, enomem = 0;;) {
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/*
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* Allocate a new block and link it into place in a doubly
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* linked list. If out of memory, toss the LRU block and
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* keep going.
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*/
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if (enomem || (tl = malloc(sizeof(BF))) == NULL ||
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(tl->l = malloc(BSZ)) == NULL) {
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if (!mark)
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err(1, "malloc");
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tl = enomem ? tl->next : mark;
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enomem += tl->len;
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} else if (mark) {
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tl->next = mark;
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tl->prev = mark->prev;
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mark->prev->next = tl;
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mark->prev = tl;
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} else
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mark->next = mark->prev = (mark = tl);
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/* Fill the block with input data. */
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for (p = tl->l, len = 0;
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len < BSZ && (ch = getc(fp)) != EOF; ++len)
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*p++ = ch;
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if (ferror(fp)) {
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ierr();
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return;
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}
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/*
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* If no input data for this block and we tossed some data,
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* recover it.
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*/
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if (!len) {
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if (enomem)
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enomem -= tl->len;
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tl = tl->prev;
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break;
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}
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tl->len = len;
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if (ch == EOF)
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break;
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}
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if (enomem) {
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(void)fprintf(stderr,
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"tail: warning: %ld bytes discarded\n", enomem);
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rval = 1;
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}
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/*
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* Step through the blocks in the reverse order read. The last char
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* is special, ignore whether newline or not.
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*/
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for (mark = tl;;) {
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for (p = tl->l + (len = tl->len) - 1, llen = 0; len--;
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--p, ++llen)
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if (*p == '\n') {
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if (llen) {
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WR(p + 1, llen);
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llen = 0;
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}
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if (tl == mark)
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continue;
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for (tr = tl->next; tr->len; tr = tr->next) {
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WR(tr->l, tr->len);
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tr->len = 0;
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if (tr == mark)
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break;
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}
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}
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tl->len = llen;
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if ((tl = tl->prev) == mark)
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break;
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}
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tl = tl->next;
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if (tl->len) {
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WR(tl->l, tl->len);
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tl->len = 0;
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}
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while ((tl = tl->next)->len) {
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WR(tl->l, tl->len);
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tl->len = 0;
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}
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}
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