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Diffstat (limited to 'usr.bin/tail/read.c')
| -rw-r--r-- | usr.bin/tail/read.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/usr.bin/tail/read.c b/usr.bin/tail/read.c new file mode 100644 index 0000000..4e9374d --- /dev/null +++ b/usr.bin/tail/read.c @@ -0,0 +1,210 @@ +/* $NetBSD: read.c,v 1.17 2011/09/03 10:59:10 christos 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/cdefs.h> +#ifndef lint +#if 0 +static char sccsid[] = "@(#)read.c 8.1 (Berkeley) 6/6/93"; +#endif +__RCSID("$NetBSD: read.c,v 1.17 2011/09/03 10:59:10 christos Exp $"); +#endif /* not lint */ + +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <errno.h> +#include <unistd.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include "extern.h" + +/* + * displaybytes -- 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. + * + * Non-zero return means than a (non-fatal) error occurred. + */ +int +displaybytes(FILE *fp, off_t off) +{ + int ch, len, tlen; + char *ep, *p, *t; + int wrap; + char *sp; + + if ((sp = p = malloc(off)) == NULL) + xerr(1, "malloc"); + + for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) { + *p = ch; + if (++p == ep) { + wrap = 1; + p = sp; + } + } + if (ferror(fp)) { + ierr(); + 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) != 0) + WR(sp, len); + } + return 0; +} + +/* + * displaylines -- 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. + * + * Non-zero return means than a (non-fatal) error occurred. + */ +int +displaylines(FILE *fp, off_t off) +{ + struct { + int blen; + int len; + char *l; + } *lines; + int ch; + char *p; + int blen, cnt, recno, wrap; + char *sp, *n; + + p = NULL; + if ((lines = malloc(off * sizeof(*lines))) == NULL) + xerr(1, "malloc"); + + memset(lines, 0, sizeof(*lines) * off); + + sp = NULL; + blen = cnt = recno = wrap = 0; + + while ((ch = getc(fp)) != EOF) { + if (++cnt > blen) { + if ((n = realloc(sp, blen + 1024)) == NULL) + xerr(1, "realloc"); + sp = n; + blen += 1024; + p = sp + cnt - 1; + } + *p++ = ch; + if (ch == '\n') { + if (lines[recno].blen < cnt) { + if ((n = realloc(lines[recno].l, + cnt + 256)) == NULL) + xerr(1, "realloc"); + lines[recno].l = n; + lines[recno].blen = cnt + 256; + } + memmove(lines[recno].l, sp, lines[recno].len = cnt); + cnt = 0; + p = sp; + if (++recno == off) { + wrap = 1; + recno = 0; + } + } + } + if (ferror(fp)) { + free(lines); + ierr(); + return 1; + } + if (cnt) { + lines[recno].l = sp; + lines[recno].len = cnt; + if (++recno == off) { + wrap = 1; + recno = 0; + } + } + + if (rflag) { + for (cnt = recno - 1; cnt >= 0; --cnt) + WR(lines[cnt].l, lines[cnt].len); + if (wrap) + for (cnt = off - 1; cnt >= recno; --cnt) + WR(lines[cnt].l, lines[cnt].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); + } + free(lines); + return 0; +} |