/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1991, 1993, 1994 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Keith Muller of the University of California, San Diego and Lance * Visser of Convex Computer Corporation. * * 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/mtio.h> #include <err.h> #include <errno.h> #include <inttypes.h> #include <limits.h> #include <signal.h> #include <unistd.h> #include "dd.h" #include "extern.h" static off_t seek_offset(IO *io) { off_t n; size_t sz; n = io->offset; sz = io->dbsz; _Static_assert(sizeof(io->offset) == sizeof(int64_t), "64-bit off_t"); /* * If the lseek offset will be negative, verify that this is a special * device file. Some such files (e.g. /dev/kmem) permit "negative" * offsets. * * Bail out if the calculation of a file offset would overflow. */ if ((io->flags & ISCHR) == 0 && (n < 0 || n > OFF_MAX / (ssize_t)sz)) errx(1, "seek offsets cannot be larger than %jd", (intmax_t)OFF_MAX); else if ((io->flags & ISCHR) != 0 && (uint64_t)n > UINT64_MAX / sz) errx(1, "seek offsets cannot be larger than %ju", (uintmax_t)UINT64_MAX); return ((off_t)( (uint64_t)n * sz )); } /* * Position input/output data streams before starting the copy. Device type * dependent. Seekable devices use lseek, and the rest position by reading. * Seeking past the end of file can cause null blocks to be written to the * output. */ void pos_in(void) { off_t cnt; int warned; ssize_t nr; size_t bcnt; /* If known to be seekable, try to seek on it. */ if (in.flags & ISSEEK) { errno = 0; if (lseek(in.fd, seek_offset(&in), SEEK_CUR) == -1 && errno != 0) err(1, "%s", in.name); return; } /* Don't try to read a really weird amount (like negative). */ if (in.offset < 0) errx(1, "%s: illegal offset", "iseek/skip"); /* * Read the data. If a pipe, read until satisfy the number of bytes * being skipped. No differentiation for reading complete and partial * blocks for other devices. */ for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) { if ((nr = read(in.fd, in.db, bcnt)) > 0) { if (in.flags & ISPIPE) { if (!(bcnt -= nr)) { bcnt = in.dbsz; --cnt; } } else --cnt; if (need_summary) summary(); if (need_progress) progress(); continue; } if (nr == 0) { if (files_cnt > 1) { --files_cnt; continue; } errx(1, "skip reached end of input"); } /* * Input error -- either EOF with no more files, or I/O error. * If noerror not set die. POSIX requires that the warning * message be followed by an I/O display. */ if (ddflags & C_NOERROR) { if (!warned) { warn("%s", in.name); warned = 1; summary(); } continue; } err(1, "%s", in.name); } } void pos_out(void) { struct mtop t_op; off_t cnt; ssize_t n; /* * If not a tape, try seeking on the file. Seeking on a pipe is * going to fail, but don't protect the user -- they shouldn't * have specified the seek operand. */ if (out.flags & (ISSEEK | ISPIPE)) { errno = 0; if (lseek(out.fd, seek_offset(&out), SEEK_CUR) == -1 && errno != 0) err(1, "%s", out.name); return; } /* Don't try to read a really weird amount (like negative). */ if (out.offset < 0) errx(1, "%s: illegal offset", "oseek/seek"); /* If no read access, try using mtio. */ if (out.flags & NOREAD) { t_op.mt_op = MTFSR; t_op.mt_count = out.offset; if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) err(1, "%s", out.name); return; } /* Read it. */ for (cnt = 0; cnt < out.offset; ++cnt) { before_io(); n = read(out.fd, out.db, out.dbsz); after_io(); if (n > 0) continue; if (n == -1) err(1, "%s", out.name); /* * If reach EOF, fill with NUL characters; first, back up over * the EOF mark. Note, cnt has not yet been incremented, so * the EOF read does not count as a seek'd block. */ t_op.mt_op = MTBSR; t_op.mt_count = 1; if (ioctl(out.fd, MTIOCTOP, &t_op) == -1) err(1, "%s", out.name); while (cnt++ < out.offset) { before_io(); n = write(out.fd, out.db, out.dbsz); after_io(); if (n == -1) err(1, "%s", out.name); if (n != out.dbsz) errx(1, "%s: write failure", out.name); } break; } }
