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IABSD.fr/src/usr.bin/tail/read.c
martijn
- usr.bin/tail/read.c
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/* $OpenBSD: read.c,v 1.20 2017/03/26 19:55:07 martijn Exp $ */ /* $NetBSD: read.c,v 1.4 1994/11/23 07:42:07 jtc Exp $ */ /*- * 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. */ #include <sys/types.h> #include <sys/stat.h> #include <err.h> #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include "extern.h" /* * bytes -- read bytes to an offset from the end and display. * * This is the function that reads to a byte offset from the end of the input, * storing the data in a wrap-around buffer which is then displayed. If the * rflag is set, the data is displayed in lines in reverse order, and this * routine has the usual nastiness of trying to find the newlines. Otherwise, * it is displayed from the character closest to the beginning of the input to * the end. * * A non-zero return means an (non-fatal) error occurred. * */ int bytes(struct tailfile *tf, off_t off) { int ch; size_t len, tlen; char *ep, *p, *t; int wrap; char *sp; if (off > SIZE_MAX) errx(1, "offset too large"); if ((sp = p = malloc(off)) == NULL) err(1, NULL); for (wrap = 0, ep = p + off; (ch = getc(tf->fp)) != EOF;) { *p = ch; if (++p == ep) { wrap = 1; p = sp; } } if (ferror(tf->fp)) { ierr(tf->fname); free(sp); return(1); } if (rflag) { for (t = p - 1, len = 0; t >= sp; --t, ++len) if (*t == '\n' && len) { WR(t + 1, len); len = 0; } if (wrap) { tlen = len; for (t = ep - 1, len = 0; t >= p; --t, ++len) if (*t == '\n') { if (len) { WR(t + 1, len); len = 0; } if (tlen) { WR(sp, tlen); tlen = 0; } } if (len) WR(t + 1, len); if (tlen) WR(sp, tlen); } } else { if (wrap && (len = ep - p)) WR(p, len); if ((len = p - sp)) WR(sp, len); } free(sp); return(0); } /* * lines -- read lines to an offset from the end and display. * * This is the function that reads to a line offset from the end of the input, * storing the data in an array of buffers which is then displayed. If the * rflag is set, the data is displayed in lines in reverse order, and this * routine has the usual nastiness of trying to find the newlines. Otherwise, * it is displayed from the line closest to the beginning of the input to * the end. * * A non-zero return means an (non-fatal) error occurred. * */ int lines(struct tailfile *tf, off_t off) { struct { size_t blen; size_t len; char *l; } *lines = NULL; int ch, rc = 0; char *p = NULL; int wrap; size_t cnt, lineno, nlineno, recno, blen, newsize; char *sp = NULL, *newp = NULL; if (off > SIZE_MAX) errx(1, "offset too large"); lineno = blen = cnt = recno = wrap = 0; while ((ch = getc(tf->fp)) != EOF) { if (++cnt > blen) { newsize = blen + 1024; if ((newp = realloc(sp, newsize)) == NULL) err(1, NULL); sp = newp; blen = newsize; p = sp + cnt - 1; } *p++ = ch; if (recno >= lineno) { nlineno = (lineno + 1024) > off ? (size_t) off : lineno + 1024; if ((lines = recallocarray(lines, lineno, nlineno, sizeof(*lines))) == NULL) err(1, NULL); lineno = nlineno; } if (ch == '\n') { if (lines[recno].blen < cnt) { newsize = cnt + 256; if ((newp = realloc(lines[recno].l, newsize)) == NULL) err(1, NULL); lines[recno].l = newp; lines[recno].blen = newsize; } memcpy(lines[recno].l, sp, (lines[recno].len = cnt)); cnt = 0; p = sp; if (++recno == off) { wrap = 1; recno = 0; } } } if (ferror(tf->fp)) { ierr(tf->fname); rc = 1; goto done; } if (cnt) { lines[recno].l = sp; lines[recno].len = cnt; sp = NULL; if (++recno == off) { wrap = 1; recno = 0; } } if (rflag) { for (cnt = recno; cnt > 0; --cnt) WR(lines[cnt - 1].l, lines[cnt - 1].len); if (wrap) for (cnt = off; cnt > recno; --cnt) WR(lines[cnt - 1].l, lines[cnt - 1].len); } else { if (wrap) for (cnt = recno; cnt < off; ++cnt) WR(lines[cnt].l, lines[cnt].len); for (cnt = 0; cnt < recno; ++cnt) WR(lines[cnt].l, lines[cnt].len); } done: for (cnt = 0; cnt < lineno; cnt++) free(lines[cnt].l); free(sp); free(lines); return(rc); }