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Diffstat (limited to 'bin/dd/position.c')
| -rw-r--r-- | bin/dd/position.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/bin/dd/position.c b/bin/dd/position.c new file mode 100644 index 0000000..57bfde5 --- /dev/null +++ b/bin/dd/position.c @@ -0,0 +1,186 @@ +/*- + * 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. + * 4. 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. + */ + +#ifndef lint +#if 0 +static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94"; +#endif +#endif /* not lint */ +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/types.h> +#include <sys/mtio.h> + +#include <err.h> +#include <errno.h> +#include <inttypes.h> +#include <signal.h> +#include <unistd.h> + +#include "dd.h" +#include "extern.h" + +/* + * 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, in.offset * in.dbsz, 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(); + 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, out.offset * out.dbsz, 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) { + if ((n = read(out.fd, out.db, out.dbsz)) > 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) { + n = write(out.fd, out.db, out.dbsz); + if (n == -1) + err(1, "%s", out.name); + if ((size_t)n != out.dbsz) + errx(1, "%s: write failure", out.name); + } + break; + } +} |
