bin/dd/position.c

/*-
 * 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: src/bin/dd/position.c,v 1.23 2004/04/06 20:06:46 markm Exp $");

#include <sys/types.h>
#include <sys/mtio.h>

#include <err.h>
#include <errno.h>
#include <inttypes.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;
                        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;
        }
}
Revision:	2
Committed:	Sat Feb 25 02:29:52 2006 UTC (18 years, 2 months ago) by laffer1
Content type:	text/plain
Original Path:	*branches/MidnightBSD/bin/dd/position.c*
File size:	5127 byte(s)
Log Message:	Imported from FreeBSD 6.0 sources
#	User	Rev	Content
1	laffer1	2	/*-
2			* Copyright (c) 1991, 1993, 1994
3			* The Regents of the University of California. All rights reserved.
4			*
5			* This code is derived from software contributed to Berkeley by
6			* Keith Muller of the University of California, San Diego and Lance
7			* Visser of Convex Computer Corporation.
8			*
9			* Redistribution and use in source and binary forms, with or without
10			* modification, are permitted provided that the following conditions
11			* are met:
12			* 1. Redistributions of source code must retain the above copyright
13			* notice, this list of conditions and the following disclaimer.
14			* 2. Redistributions in binary form must reproduce the above copyright
15			* notice, this list of conditions and the following disclaimer in the
16			* documentation and/or other materials provided with the distribution.
17			* 4. Neither the name of the University nor the names of its contributors
18			* may be used to endorse or promote products derived from this software
19			* without specific prior written permission.
20			*
21			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24			* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31			* SUCH DAMAGE.
32			*/
33
34			#ifndef lint
35			#if 0
36			static char sccsid[] = "@(#)position.c 8.3 (Berkeley) 4/2/94";
37			#endif
38			#endif /* not lint */
39			#include <sys/cdefs.h>
40			__FBSDID("$FreeBSD: src/bin/dd/position.c,v 1.23 2004/04/06 20:06:46 markm Exp $");
41
42			#include <sys/types.h>
43			#include <sys/mtio.h>
44
45			#include <err.h>
46			#include <errno.h>
47			#include <inttypes.h>
48			#include <unistd.h>
49
50			#include "dd.h"
51			#include "extern.h"
52
53			/*
54			* Position input/output data streams before starting the copy. Device type
55			* dependent. Seekable devices use lseek, and the rest position by reading.
56			* Seeking past the end of file can cause null blocks to be written to the
57			* output.
58			*/
59			void
60			pos_in(void)
61			{
62			off_t cnt;
63			int warned;
64			ssize_t nr;
65			size_t bcnt;
66
67			/* If known to be seekable, try to seek on it. */
68			if (in.flags & ISSEEK) {
69			errno = 0;
70			if (lseek(in.fd, in.offset * in.dbsz, SEEK_CUR) == -1 &&
71			errno != 0)
72			err(1, "%s", in.name);
73			return;
74			}
75
76			/* Don't try to read a really weird amount (like negative). */
77			if (in.offset < 0)
78			errx(1, "%s: illegal offset", "iseek/skip");
79
80			/*
81			* Read the data. If a pipe, read until satisfy the number of bytes
82			* being skipped. No differentiation for reading complete and partial
83			* blocks for other devices.
84			*/
85			for (bcnt = in.dbsz, cnt = in.offset, warned = 0; cnt;) {
86			if ((nr = read(in.fd, in.db, bcnt)) > 0) {
87			if (in.flags & ISPIPE) {
88			if (!(bcnt -= nr)) {
89			bcnt = in.dbsz;
90			--cnt;
91			}
92			} else
93			--cnt;
94			continue;
95			}
96
97			if (nr == 0) {
98			if (files_cnt > 1) {
99			--files_cnt;
100			continue;
101			}
102			errx(1, "skip reached end of input");
103			}
104
105			/*
106			* Input error -- either EOF with no more files, or I/O error.
107			* If noerror not set die. POSIX requires that the warning
108			* message be followed by an I/O display.
109			*/
110			if (ddflags & C_NOERROR) {
111			if (!warned) {
112			warn("%s", in.name);
113			warned = 1;
114			summary();
115			}
116			continue;
117			}
118			err(1, "%s", in.name);
119			}
120			}
121
122			void
123			pos_out(void)
124			{
125			struct mtop t_op;
126			off_t cnt;
127			ssize_t n;
128
129			/*
130			* If not a tape, try seeking on the file. Seeking on a pipe is
131			* going to fail, but don't protect the user -- they shouldn't
132			* have specified the seek operand.
133			*/
134			if (out.flags & (ISSEEK \| ISPIPE)) {
135			errno = 0;
136			if (lseek(out.fd, out.offset * out.dbsz, SEEK_CUR) == -1 &&
137			errno != 0)
138			err(1, "%s", out.name);
139			return;
140			}
141
142			/* Don't try to read a really weird amount (like negative). */
143			if (out.offset < 0)
144			errx(1, "%s: illegal offset", "oseek/seek");
145
146			/* If no read access, try using mtio. */
147			if (out.flags & NOREAD) {
148			t_op.mt_op = MTFSR;
149			t_op.mt_count = out.offset;
150
151			if (ioctl(out.fd, MTIOCTOP, &t_op) == -1)
152			err(1, "%s", out.name);
153			return;
154			}
155
156			/* Read it. */
157			for (cnt = 0; cnt < out.offset; ++cnt) {
158			if ((n = read(out.fd, out.db, out.dbsz)) > 0)
159			continue;
160
161			if (n == -1)
162			err(1, "%s", out.name);
163
164			/*
165			* If reach EOF, fill with NUL characters; first, back up over
166			* the EOF mark. Note, cnt has not yet been incremented, so
167			* the EOF read does not count as a seek'd block.
168			*/
169			t_op.mt_op = MTBSR;
170			t_op.mt_count = 1;
171			if (ioctl(out.fd, MTIOCTOP, &t_op) == -1)
172			err(1, "%s", out.name);
173
174			while (cnt++ < out.offset) {
175			n = write(out.fd, out.db, out.dbsz);
176			if (n == -1)
177			err(1, "%s", out.name);
178			if ((size_t)n != out.dbsz)
179			errx(1, "%s: write failure", out.name);
180			}
181			break;
182			}
183			}