diff options
author | joerg <joerg@FreeBSD.org> | 1997-10-11 20:09:05 +0000 |
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committer | joerg <joerg@FreeBSD.org> | 1997-10-11 20:09:05 +0000 |
commit | 4841b45bbe197e54bb7732317930e8591d51362c (patch) | |
tree | 2bbaeb532cca6a0c260f5fc674f9d1d0ce9b10cb /bin/dd | |
parent | 11466e2a6f0898af142d8fbff4ead6b7078c6e04 (diff) | |
download | FreeBSD-src-4841b45bbe197e54bb7732317930e8591d51362c.zip FreeBSD-src-4841b45bbe197e54bb7732317930e8591d51362c.tar.gz |
Teach dd(1) about an option to write sparse files. Can be useful for
things like diskless clients' swap files etc.
Submitted by: pascal@zuo.dec.com (Pascal Pederiva) (ages ago, with many
stylistic changes by me)
Diffstat (limited to 'bin/dd')
-rw-r--r-- | bin/dd/args.c | 3 | ||||
-rw-r--r-- | bin/dd/dd.1 | 9 | ||||
-rw-r--r-- | bin/dd/dd.c | 37 | ||||
-rw-r--r-- | bin/dd/dd.h | 3 |
4 files changed, 45 insertions, 7 deletions
diff --git a/bin/dd/args.c b/bin/dd/args.c index c5a14f7..f1e556a 100644 --- a/bin/dd/args.c +++ b/bin/dd/args.c @@ -34,7 +34,7 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * $Id: args.c,v 1.8 1997/02/22 14:02:41 peter Exp $ + * $Id: args.c,v 1.9 1997/10/08 12:10:33 eivind Exp $ */ #ifndef lint @@ -283,6 +283,7 @@ static struct conv { { "oldascii", C_ASCII, C_EBCDIC, e2a_32V }, { "oldebcdic", C_EBCDIC, C_ASCII, a2e_32V }, { "oldibm", C_EBCDIC, C_ASCII, a2ibm_32V }, + { "sparse", C_SPARSE, 0, NULL }, { "osync", C_OSYNC, C_BS, NULL }, { "swab", C_SWAB, 0, NULL }, { "sync", C_SYNC, 0, NULL }, diff --git a/bin/dd/dd.1 b/bin/dd/dd.1 index 157e52e..85aca7b 100644 --- a/bin/dd/dd.1 +++ b/bin/dd/dd.1 @@ -33,7 +33,7 @@ .\" SUCH DAMAGE. .\" .\" @(#)dd.1 8.2 (Berkeley) 1/13/94 -.\" $Id: dd.1,v 1.4 1997/02/22 14:02:43 peter Exp $ +.\" $Id: dd.1,v 1.5 1997/04/28 04:07:29 steve Exp $ .\" .Dd January 13, 1994 .Dt DD 1 @@ -250,6 +250,13 @@ regularly sized blocks to be written. This option is incompatible with use of the .Cm bs= Ns Ar n block size specification. +.It Cm sparse +If one or more output blocks would consist solely of +.Tn NUL +bytes, try to seek the output file by the required space instead of +filling them with +.Tn NULs , +resulting in a sparse file. .It Cm swab Swap every pair of input bytes. If an input buffer has an odd number of bytes, the last byte will be diff --git a/bin/dd/dd.c b/bin/dd/dd.c index 60d7e67..bf14e16 100644 --- a/bin/dd/dd.c +++ b/bin/dd/dd.c @@ -34,7 +34,7 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * $Id: dd.c,v 1.10 1997/02/22 14:02:44 peter Exp $ + * $Id: dd.c,v 1.11 1997/08/19 19:46:18 jlemon Exp $ */ #ifndef lint @@ -75,6 +75,7 @@ IO in, out; /* input/output state */ STAT st; /* statistics */ void (*cfunc) __P((void)); /* conversion function */ u_long cpy_cnt; /* # of blocks to copy */ +u_long pending = 0; /* pending seek if sparse */ u_int ddflags; /* conversion options */ u_int cbsz; /* conversion block size */ u_int files_cnt = 1; /* # of files to copy */ @@ -347,7 +348,7 @@ dd_close() memset(out.dbp, 0, out.dbsz - out.dbcnt); out.dbcnt = out.dbsz; } - if (out.dbcnt) + if (out.dbcnt || pending) dd_out(1); } @@ -356,7 +357,7 @@ dd_out(force) int force; { static int warned; - int cnt, n, nw; + int cnt, n, nw, i, sparse; u_char *outp; /* @@ -378,7 +379,35 @@ dd_out(force) outp = out.db; for (n = force ? out.dbcnt : out.dbsz;; n = out.dbsz) { for (cnt = n;; cnt -= nw) { - nw = write(out.fd, outp, cnt); + sparse = 0; + if (ddflags & C_SPARSE) { + sparse = 1; /* Is buffer sparse? */ + for (i = 0; i < cnt; i++) + if (outp[i] != 0) { + sparse = 0; + break; + } + } + if (sparse && !force) { + pending += cnt; + nw = cnt; + } else { + if (pending != 0) { + if (force) + pending--; + if (lseek (out.fd, pending, SEEK_CUR) == -1) + err(2, "%s: seek error creating sparse file", + out.name); + if (force) + write(out.fd, outp, 1); + pending = 0; + } + if (cnt) + nw = write(out.fd, outp, cnt); + else + return; + } + if (nw <= 0) { if (nw == 0) errx(1, "%s: end of device", out.name); diff --git a/bin/dd/dd.h b/bin/dd/dd.h index 30904d9..477f444 100644 --- a/bin/dd/dd.h +++ b/bin/dd/dd.h @@ -35,7 +35,7 @@ * SUCH DAMAGE. * * @(#)dd.h 8.3 (Berkeley) 4/2/94 - * $Id$ + * $Id: dd.h,v 1.6 1997/02/22 14:02:45 peter Exp $ */ /* Input/output stream state. */ @@ -95,3 +95,4 @@ typedef struct { #define C_UCASE 0x40000 #define C_UNBLOCK 0x80000 #define C_OSYNC 0x100000 +#define C_SPARSE 0x200000 |