position.c revision 51249
11556Srgrimes/*- 21556Srgrimes * Copyright (c) 1991, 1993, 1994 31556Srgrimes * The Regents of the University of California. All rights reserved. 41556Srgrimes * 51556Srgrimes * This code is derived from software contributed to Berkeley by 61556Srgrimes * Keith Muller of the University of California, San Diego and Lance 71556Srgrimes * Visser of Convex Computer Corporation. 81556Srgrimes * 91556Srgrimes * Redistribution and use in source and binary forms, with or without 101556Srgrimes * modification, are permitted provided that the following conditions 111556Srgrimes * are met: 121556Srgrimes * 1. Redistributions of source code must retain the above copyright 131556Srgrimes * notice, this list of conditions and the following disclaimer. 141556Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 151556Srgrimes * notice, this list of conditions and the following disclaimer in the 161556Srgrimes * documentation and/or other materials provided with the distribution. 171556Srgrimes * 3. All advertising materials mentioning features or use of this software 181556Srgrimes * must display the following acknowledgement: 191556Srgrimes * This product includes software developed by the University of 201556Srgrimes * California, Berkeley and its contributors. 211556Srgrimes * 4. Neither the name of the University nor the names of its contributors 221556Srgrimes * may be used to endorse or promote products derived from this software 231556Srgrimes * without specific prior written permission. 241556Srgrimes * 251556Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 261556Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 271556Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 281556Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 291556Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 301556Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 311556Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 321556Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 331556Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 341556Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 351556Srgrimes * SUCH DAMAGE. 361556Srgrimes */ 371556Srgrimes 381556Srgrimes#ifndef lint 3935773Scharnier#if 0 4036007Scharnierstatic char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94"; 4135773Scharnier#endif 4235773Scharnierstatic const char rcsid[] = 4350471Speter "$FreeBSD: head/bin/dd/position.c 51249 1999-09-13 21:47:10Z green $"; 441556Srgrimes#endif /* not lint */ 451556Srgrimes 4636007Scharnier#include <sys/types.h> 471556Srgrimes#include <sys/mtio.h> 481556Srgrimes 491556Srgrimes#include <err.h> 5051137Sgreen#include <errno.h> 511556Srgrimes#include <unistd.h> 521556Srgrimes 531556Srgrimes#include "dd.h" 541556Srgrimes#include "extern.h" 551556Srgrimes 561556Srgrimes/* 571556Srgrimes * Position input/output data streams before starting the copy. Device type 581556Srgrimes * dependent. Seekable devices use lseek, and the rest position by reading. 591556Srgrimes * Seeking past the end of file can cause null blocks to be written to the 601556Srgrimes * output. 611556Srgrimes */ 621556Srgrimesvoid 631556Srgrimespos_in() 641556Srgrimes{ 6551208Sgreen off_t cnt; 6651208Sgreen int warned; 6748026Sgreen ssize_t nr; 6851208Sgreen size_t bcnt; 691556Srgrimes 7051249Sgreen /* If known to be seekable, try to seek on it. */ 7151249Sgreen if (in.flags & ISSEEK) { 7251137Sgreen errno = 0; 7351208Sgreen if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1 && 7451208Sgreen errno != 0) 751556Srgrimes err(1, "%s", in.name); 761556Srgrimes return; 771556Srgrimes } 781556Srgrimes 791556Srgrimes /* 801556Srgrimes * Read the data. If a pipe, read until satisfy the number of bytes 811556Srgrimes * being skipped. No differentiation for reading complete and partial 821556Srgrimes * blocks for other devices. 831556Srgrimes */ 841556Srgrimes for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { 851556Srgrimes if ((nr = read(in.fd, in.db, bcnt)) > 0) { 861556Srgrimes if (in.flags & ISPIPE) { 871556Srgrimes if (!(bcnt -= nr)) { 881556Srgrimes bcnt = in.dbsz; 891556Srgrimes --cnt; 901556Srgrimes } 911556Srgrimes } else 921556Srgrimes --cnt; 931556Srgrimes continue; 941556Srgrimes } 951556Srgrimes 961556Srgrimes if (nr == 0) { 971556Srgrimes if (files_cnt > 1) { 981556Srgrimes --files_cnt; 991556Srgrimes continue; 1001556Srgrimes } 1011556Srgrimes errx(1, "skip reached end of input"); 1021556Srgrimes } 1031556Srgrimes 1041556Srgrimes /* 1051556Srgrimes * Input error -- either EOF with no more files, or I/O error. 1061556Srgrimes * If noerror not set die. POSIX requires that the warning 1071556Srgrimes * message be followed by an I/O display. 1081556Srgrimes */ 1091556Srgrimes if (ddflags & C_NOERROR) { 1101556Srgrimes if (!warned) { 1111556Srgrimes warn("%s", in.name); 1121556Srgrimes warned = 1; 1131556Srgrimes summary(); 1141556Srgrimes } 1151556Srgrimes continue; 1161556Srgrimes } 1171556Srgrimes err(1, "%s", in.name); 1181556Srgrimes } 1191556Srgrimes} 1201556Srgrimes 1211556Srgrimesvoid 1221556Srgrimespos_out() 1231556Srgrimes{ 1241556Srgrimes struct mtop t_op; 12548026Sgreen off_t cnt; 12648026Sgreen ssize_t n; 1271556Srgrimes 12851249Sgreen /* 12951249Sgreen * If not a tape, try seeking on the file. Seeking on a pipe is 13051249Sgreen * going to fail, but don't protect the user -- they shouldn't 13151249Sgreen * have specified the seek operand. 13251249Sgreen */ 13351249Sgreen if (!(out.flags & ISTAPE)) { 13451137Sgreen errno = 0; 13551137Sgreen if (lseek(out.fd, out.offset * out.dbsz, SEEK_SET) == -1 && 13651208Sgreen errno != 0) 1371556Srgrimes err(1, "%s", out.name); 1381556Srgrimes return; 1391556Srgrimes } 1401556Srgrimes 1411556Srgrimes /* If no read access, try using mtio. */ 1421556Srgrimes if (out.flags & NOREAD) { 1431556Srgrimes t_op.mt_op = MTFSR; 1441556Srgrimes t_op.mt_count = out.offset; 1451556Srgrimes 14648026Sgreen if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 1471556Srgrimes err(1, "%s", out.name); 1481556Srgrimes return; 1491556Srgrimes } 1501556Srgrimes 1511556Srgrimes /* Read it. */ 1521556Srgrimes for (cnt = 0; cnt < out.offset; ++cnt) { 1531556Srgrimes if ((n = read(out.fd, out.db, out.dbsz)) > 0) 1541556Srgrimes continue; 1551556Srgrimes 15648026Sgreen if (n == -1) 1571556Srgrimes err(1, "%s", out.name); 1581556Srgrimes 1591556Srgrimes /* 1601556Srgrimes * If reach EOF, fill with NUL characters; first, back up over 1611556Srgrimes * the EOF mark. Note, cnt has not yet been incremented, so 1621556Srgrimes * the EOF read does not count as a seek'd block. 1631556Srgrimes */ 1641556Srgrimes t_op.mt_op = MTBSR; 1651556Srgrimes t_op.mt_count = 1; 1661556Srgrimes if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) 1671556Srgrimes err(1, "%s", out.name); 1681556Srgrimes 1691556Srgrimes while (cnt++ < out.offset) 1701556Srgrimes if ((n = write(out.fd, out.db, out.dbsz)) != out.dbsz) 1711556Srgrimes err(1, "%s", out.name); 1721556Srgrimes break; 1731556Srgrimes } 1741556Srgrimes} 175