0.3.6.1/experiments/cp_removeblocks.c

/*
 *  Copyright (C) 2004  Anders Gavare.  All rights reserved.
 *
 *  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. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 *
 *  $Id: cp_removeblocks.c,v 1.11 2005/01/09 01:55:27 debug Exp $
 *
 *  This program copies a file, but only those blocks that are not zero-
 *  filled.  Typical usage would be if you have a harddisk image stored
 *  as a file, which has all its zeroed blocks explicitly saved on disk,
 *  and would like to save space.
 *
 *  Example:  You download a file called diskimage.gz from somewhere,
 *            run gunzip on it, and the resulting file diskimage is
 *            1 GB large.  ls -l reports the file size as 1 GB, and
 *            so does 'du -k diskimage'.  If a lot of the space used
 *            by diskimage is actually zeroes, those parts do not need
 *            to actually be saved. By running this program on diskimage:
 *
 *                ./cp_removeblocks diskimage diskimage_compact
 *
 *            you will get a file with the same functionality, but possibly
 *            using less disk space.  ('ls -l diskimage_compact' should
 *            return the same size as for diskimage, but 'du -k' will
 *            print only how many kb the file takes up on your disk.)
 *
 *            You don't even need to gunzip the file to be 1 GB first,
 *            you can pipe it through cp_removeblocks directly.
 *
 *                gunzip -c file.img.gz | ./cp_removeblocks - file.img
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

#define BSIZE   512


int main(int argc, char *argv[])
{
        FILE *f1, *f2;
        unsigned char buf[BSIZE];
        off_t len;
        off_t in_pos = 0;
        int i, res, wrote_last = 0;

        if (argc != 3) {
                fprintf(stderr, "usage: %s infile outfile\n", argv[0]);
                fprintf(stderr, "if infile is \"-\", then stdin is used.\n");
                fprintf(stderr, "if outfile is \"-\", then stdout is used.\n");
                exit(1);
        }

        if (strcmp(argv[1], "-") == 0)
                f1 = stdin;
        else
                f1 = fopen(argv[1], "r");

        if (f1 == NULL) {
                perror(argv[1]);
                exit(1);
        }

        if (strcmp(argv[2], "-") == 0)
                f2 = stdout;
        else
                f2 = fopen(argv[2], "w");

        if (f2 == NULL) {
                perror(argv[2]);
                exit(1);
        }

        while (!feof(f1)) {
                len = fread(buf, 1, BSIZE, f1);

                if (len > 0) {
                        /*  Check for data in buf:  */
                        for (i=0; i<len; i++)
                                if (buf[i])
                                        break;

                        if (i < len) {
                                fseeko(f2, in_pos, SEEK_SET);
                                fwrite(buf, 1, len, f2);
                                wrote_last = 1;
                        } else
                                wrote_last = 0;

                        in_pos += len;
                }
        }

        /*
         *  Copy the last byte explicitly, if necessary.
         *  (This causes f2 to get the correct file size.)
         */
        if (!wrote_last && in_pos > 0) {
                res = fseeko(f2, in_pos - 1, SEEK_SET);
                if (res != 0)
                        perror("fseeko(f2)");

                buf[0] = '\0';
                fwrite(&buf[0], 1, 1, f2);
        }

        fclose(f1);
        fclose(f2);

        return 0;
}

1	dpavlin	2	/*
2			* Copyright (C) 2004 Anders Gavare. All rights reserved.
3			*
4			* Redistribution and use in source and binary forms, with or without
5			* modification, are permitted provided that the following conditions are met:
6			*
7			* 1. Redistributions of source code must retain the above copyright
8			* notice, this list of conditions and the following disclaimer.
9			* 2. Redistributions in binary form must reproduce the above copyright
10			* notice, this list of conditions and the following disclaimer in the
11			* documentation and/or other materials provided with the distribution.
12			* 3. The name of the author may not be used to endorse or promote products
13			* derived from this software without specific prior written permission.
14			*
15			* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18			* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25			* SUCH DAMAGE.
26			*
27			*
28			* $Id: cp_removeblocks.c,v 1.11 2005/01/09 01:55:27 debug Exp $
29			*
30			* This program copies a file, but only those blocks that are not zero-
31			* filled. Typical usage would be if you have a harddisk image stored
32			* as a file, which has all its zeroed blocks explicitly saved on disk,
33			* and would like to save space.
34			*
35			* Example: You download a file called diskimage.gz from somewhere,
36			* run gunzip on it, and the resulting file diskimage is
37			* 1 GB large. ls -l reports the file size as 1 GB, and
38			* so does 'du -k diskimage'. If a lot of the space used
39			* by diskimage is actually zeroes, those parts do not need
40			* to actually be saved. By running this program on diskimage:
41			*
42			* ./cp_removeblocks diskimage diskimage_compact
43			*
44			* you will get a file with the same functionality, but possibly
45			* using less disk space. ('ls -l diskimage_compact' should
46			* return the same size as for diskimage, but 'du -k' will
47			* print only how many kb the file takes up on your disk.)
48			*
49			* You don't even need to gunzip the file to be 1 GB first,
50			* you can pipe it through cp_removeblocks directly.
51			*
52			* gunzip -c file.img.gz \| ./cp_removeblocks - file.img
53			*/
54
55			#include <stdio.h>
56			#include <stdlib.h>
57			#include <string.h>
58			#include <sys/types.h>
59
60			#define BSIZE 512
61
62
63			int main(int argc, char *argv[])
64			{
65			FILE f1, f2;
66			unsigned char buf[BSIZE];
67			off_t len;
68			off_t in_pos = 0;
69			int i, res, wrote_last = 0;
70
71			if (argc != 3) {
72			fprintf(stderr, "usage: %s infile outfile\n", argv[0]);
73			fprintf(stderr, "if infile is \"-\", then stdin is used.\n");
74			fprintf(stderr, "if outfile is \"-\", then stdout is used.\n");
75			exit(1);
76			}
77
78			if (strcmp(argv[1], "-") == 0)
79			f1 = stdin;
80			else
81			f1 = fopen(argv[1], "r");
82
83			if (f1 == NULL) {
84			perror(argv[1]);
85			exit(1);
86			}
87
88			if (strcmp(argv[2], "-") == 0)
89			f2 = stdout;
90			else
91			f2 = fopen(argv[2], "w");
92
93			if (f2 == NULL) {
94			perror(argv[2]);
95			exit(1);
96			}
97
98			while (!feof(f1)) {
99			len = fread(buf, 1, BSIZE, f1);
100
101			if (len > 0) {
102			/* Check for data in buf: */
103			for (i=0; i<len; i++)
104			if (buf[i])
105			break;
106
107			if (i < len) {
108			fseeko(f2, in_pos, SEEK_SET);
109			fwrite(buf, 1, len, f2);
110			wrote_last = 1;
111			} else
112			wrote_last = 0;
113
114			in_pos += len;
115			}
116			}
117
118			/*
119			* Copy the last byte explicitly, if necessary.
120			* (This causes f2 to get the correct file size.)
121			*/
122			if (!wrote_last && in_pos > 0) {
123			res = fseeko(f2, in_pos - 1, SEEK_SET);
124			if (res != 0)
125			perror("fseeko(f2)");
126
127			buf[0] = '\0';
128			fwrite(&buf[0], 1, 1, f2);
129			}
130
131			fclose(f1);
132			fclose(f2);
133
134			return 0;
135			}
136