Subject: bug#9157: [PATCH] dd: sparse conv flag

From: Glenn Morris <[email-masked]>
Date: Sat, 06 Aug 2011 16:52:46 -0400

This bug was reported via bcc. Because of this, the bug tracking system
did not know which package it was associated with and assigned it to
debbugs.gnu.org. I have reassigned it to the coreutils package and am
sending this so that the bug-coreutils mailing list sees the report.

See the complete report at http://debbugs.gnu.org/cgi/bugreport.cgi?bug=9157

Roman Rybalko wrote:

> ---
>  doc/coreutils.texi |    4 +++
>  src/dd.c           |   22 +++++++++++++++-
>  tests/Makefile.am  |    1 +
>  tests/dd/sparse    |   70 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 96 insertions(+), 1 deletions(-)
>  create mode 100755 tests/dd/sparse
>
> diff --git a/doc/coreutils.texi b/doc/coreutils.texi
> index 424446c..761c698 100644
> --- a/doc/coreutils.texi
> +++ b/doc/coreutils.texi
> @@ -8127,6 +8127,10 @@ Pad every input block to size of @samp{ibs} with trailing zero bytes.
>  When used with @samp{block} or @samp{unblock}, pad with spaces instead of
>  zero bytes.
>  
> +@item sparse
> +@opindex sparse
> +Make sparse output file.
> +
>  @end table
>  
>  The following ``conversions'' are really file flags
> diff --git a/src/dd.c b/src/dd.c
> index 0824f6c..0393740 100644
> --- a/src/dd.c
> +++ b/src/dd.c
> @@ -126,7 +126,8 @@ enum
>      C_NOCREAT = 010000,
>      C_EXCL = 020000,
>      C_FDATASYNC = 040000,
> -    C_FSYNC = 0100000
> +    C_FSYNC = 0100000,
> +    C_SPARSE = 0200000
>    };
>  
>  /* Status bit masks.  */
> @@ -268,6 +269,7 @@ static struct symbol_value const conversions[] =
>    {"sync", C_SYNC},		/* Pad input records to ibs with NULs. */
>    {"fdatasync", C_FDATASYNC},	/* Synchronize output data before finishing.  */
>    {"fsync", C_FSYNC},		/* Also synchronize output metadata.  */
> +  {"sparse", C_SPARSE},		/* Make sparse output file. */
>    {"", 0}
>  };
>  
> @@ -533,6 +535,9 @@ Each CONV symbol may be:\n\
>    fsync     likewise, but also write metadata\n\
>  "), stdout);
>        fputs (_("\
> +  sparse    make sparse output file\n\
> +"), stdout);
> +      fputs (_("\
>  \n\
>  Each FLAG symbol may be:\n\
>  \n\
> @@ -985,6 +990,21 @@ iwrite (int fd, char const *buf, size_t size)
>      {
>        ssize_t nwritten;
>        process_signals ();
> +      if (conversions_mask & C_SPARSE)
> +        {
> +          off_t seek_size = 0;
> +          while (total_written + seek_size < size && buf[total_written + seek_size] == 0)
> +            ++seek_size;
> +          if (seek_size)
> +            {
> +              off_t cur_off = 0;
> +              cur_off = lseek(fd, seek_size, SEEK_CUR);
> +              if (cur_off < 0)
> +                break;
> +              total_written += seek_size;
> +              continue;
> +            }
> +        }
>        nwritten = write (fd, buf + total_written, size - total_written);
>        if (nwritten < 0)
>          {
> diff --git a/tests/Makefile.am b/tests/Makefile.am
> index ebd1b11..0f1376a 100644
> --- a/tests/Makefile.am
> +++ b/tests/Makefile.am
> @@ -364,6 +364,7 @@ TESTS =						\
>    dd/skip-seek					\
>    dd/skip-seek2					\
>    dd/skip-seek-past-file			\
> +  dd/sparse                                     \
>    dd/stderr					\
>    dd/unblock					\
>    dd/unblock-sync				\
> diff --git a/tests/dd/sparse b/tests/dd/sparse
> new file mode 100755
> index 0000000..f0e0806
> --- /dev/null
> +++ b/tests/dd/sparse
> @@ -0,0 +1,70 @@
> +#!/bin/sh
> +# Ensure that dd conv=sparse works.
> +
> +# Copyright (C) 2003, 2005-2011 Free Software Foundation, Inc.
> +
> +# This program is free software: you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation, either version 3 of the License, or
> +# (at your option) any later version.
> +
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +. "${srcdir=.}/init.sh"; path_prepend_ ../src
> +print_ver_ dd
> +
> +# sometimes we may read less than 1M
> +dd if=/dev/zero of=sample0 count=1 bs=1M 2> /dev/null || fail=1
> +[ "`stat -c %s sample0`" = "1048576" ] || fail=1
> +dd if=/dev/urandom of=sample1 count=1 bs=1M 2> /dev/null || fail=1
> +[ "`stat -c %s sample1`" = "1048576" ] || fail=1
> +
> +# test 1
> +dd if=sample1 of=test1 seek=0 bs=1M 2> /dev/null || fail=1
> +dd if=sample0 of=test1 seek=1 bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=test1 seek=2 bs=1M 2> /dev/null || fail=1
> +
> +# test 1-1
> +dd if=test1 of=out1-1 conv=sparse bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=out1-1-check bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=out1-1-check seek=2 bs=1M 2> /dev/null || fail=1
> +[ "`stat -c '%s %b %B' out1-1`" = "`stat -c '%s %b %B' out1-1-check`" ] || fail=1
> +
> +# test 1-2
> +dd if=test1 of=out1-2 seek=1 conv=sparse bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=out1-2-check seek=1 bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=out1-2-check seek=3 bs=1M 2> /dev/null || fail=1
> +[ "`stat -c '%s %b %B' out1-2`" = "`stat -c '%s %b %B' out1-2-check`" ] || fail=1
> +
> +# test 1-3
> +dd if=test1 of=out1-3 seek=1 skip=1 conv=sparse bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=out1-3-check seek=2 bs=1M 2> /dev/null || fail=1
> +[ "`stat -c '%s %b %B' out1-3`" = "`stat -c '%s %b %B' out1-3-check`" ] || fail=1
> +
> +# test 2
> +dd if=sample0 of=test2 seek=0 bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=test2 seek=1 bs=1M 2> /dev/null || fail=1
> +dd if=sample0 of=test2 seek=2 bs=1M 2> /dev/null || fail=1
> +
> +# test 2-1
> +dd if=test2 of=out2-1 conv=sparse bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=out2-1-check seek=1 bs=1M 2> /dev/null || fail=1
> +[ "`stat -c '%s %b %B' out2-1`" = "`stat -c '%s %b %B' out2-1-check`" ] || fail=1
> +
> +# test 2-2
> +dd if=test2 of=out2-2 seek=1 conv=sparse bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=out2-2-check seek=2 bs=1M 2> /dev/null || fail=1
> +[ "`stat -c '%s %b %B' out2-2`" = "`stat -c '%s %b %B' out2-2-check`" ] || fail=1
> +
> +# test 2-3
> +dd if=test2 of=out2-3 seek=1 skip=1 conv=sparse bs=1M 2> /dev/null || fail=1
> +dd if=sample1 of=out2-3-check seek=1 bs=1M 2> /dev/null || fail=1
> +[ "`stat -c '%s %b %B' out2-3`" = "`stat -c '%s %b %B' out2-3-check`" ] || fail=1
> +
> +Exit $fail