diff options
| -rw-r--r-- | NEWS | 5 | ||||
| -rw-r--r-- | doc/coreutils.texi | 50 | ||||
| -rw-r--r-- | src/dd.c | 204 | ||||
| -rw-r--r-- | tests/Makefile.am | 1 | ||||
| -rwxr-xr-x | tests/dd/bytes | 57 |
5 files changed, 253 insertions, 64 deletions
@@ -2,6 +2,11 @@ GNU coreutils NEWS -*- outline -*- * Noteworthy changes in release ?.? (????-??-??) [?] +** New features + + dd now accepts the count_bytes, skip_bytes iflags and the count_bytes + oflag, to more easily allow processing portions of a file. + ** Bug fixes mv now lets you move a symlink onto a same-inode destination file that diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 52838e747..02c3a2a5d 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -8057,18 +8057,24 @@ When converting variable-length records to fixed-length ones (@option{conv=block}) or the reverse (@option{conv=unblock}), use @var{bytes} as the fixed record length. -@item skip=@var{blocks} +@item skip=@var{n} @opindex skip -Skip @var{blocks} @samp{ibs}-byte blocks in the input file before copying. +Skip @var{n} @samp{ibs}-byte blocks in the input file before copying. +If @samp{iflag=skip_bytes} is specified, @var{n} is interpreted +as a byte count rather than a block count. -@item seek=@var{blocks} +@item seek=@var{n} @opindex seek -Skip @var{blocks} @samp{obs}-byte blocks in the output file before copying. +Skip @var{n} @samp{obs}-byte blocks in the output file before copying. +if @samp{oflag=seek_bytes} is specified, @var{n} is interpreted +as a byte count rather than a block count. -@item count=@var{blocks} +@item count=@var{n} @opindex count -Copy @var{blocks} @samp{ibs}-byte blocks from the input file, instead +Copy @var{n} @samp{ibs}-byte blocks from the input file, instead of everything until the end of the file. +if @samp{iflag=count_bytes} is specified, @var{n} is interpreted +as a byte count rather than a block count. @item status=noxfer @opindex status @@ -8321,6 +8327,27 @@ When that happens, continue calling @code{read} to fill the remainder of the block. This flag can be used only with @code{iflag}. +@item count_bytes +@opindex count_bytes +Interpret the @samp{count=} operand as a byte count, +rather than a block count, which allows specifying +a length that is not a multiple of the I/O block size. +This flag can be used only with @code{iflag}. + +@item skip_bytes +@opindex skip_bytes +Interpret the @samp{skip=} operand as a byte count, +rather than a block count, which allows specifying +an offset that is not a multiple of the I/O block size. +This flag can be used only with @code{iflag}. + +@item seek_bytes +@opindex seek_bytes +Interpret the @samp{seek=} operand as a byte count, +rather than a block count, which allows specifying +an offset that is not a multiple of the I/O block size. +This flag can be used only with @code{oflag}. + @end table These flags are not supported on all systems, and @samp{dd} rejects @@ -8343,10 +8370,13 @@ should not be too large---values larger than a few megabytes are generally wasteful or (as in the gigabyte..exabyte case) downright counterproductive or error-inducing. -Use different @command{dd} invocations to use different block sizes for -skipping and I/O@. For example, the following shell commands copy data -in 512 KiB blocks between a disk and a tape, but do not save or restore a -4 KiB label at the start of the disk: +To process data that is at an offset or size that is not a +multiple of the I/O@ block size, you can use the @samp{skip_bytes}, +@samp{seek_bytes} and @samp{count_bytes} flags. Alternatively +the traditional method of separate @command{dd} invocations can be used. +For example, the following shell commands copy data +in 512 KiB blocks between a disk and a tape, but do not save +or restore a 4 KiB label at the start of the disk: @example disk=/dev/rdsk/c0t1d0s2 @@ -156,12 +156,23 @@ static size_t conversion_blocksize = 0; /* Skip this many records of 'input_blocksize' bytes before input. */ static uintmax_t skip_records = 0; +/* Skip this many bytes before input in addition of 'skip_records' + records. */ +static size_t skip_bytes = 0; + /* Skip this many records of 'output_blocksize' bytes before output. */ static uintmax_t seek_records = 0; +/* Skip this many bytes in addition to 'seek_records' records before + output. */ +static uintmax_t seek_bytes = 0; + /* Copy only this many records. The default is effectively infinity. */ static uintmax_t max_records = (uintmax_t) -1; +/* Copy this many bytes in addition to 'max_records' records. */ +static size_t max_bytes = 0; + /* Bit vector of conversions to apply. */ static int conversions_mask = 0; @@ -241,7 +252,7 @@ static bool i_nocache, o_nocache; static ssize_t (*iread_fnc) (int fd, char *buf, size_t size); /* A longest symbol in the struct symbol_values tables below. */ -#define LONGEST_SYMBOL "fdatasync" +#define LONGEST_SYMBOL "count_bytes" /* A symbol and the corresponding integer value. */ struct symbol_value @@ -296,37 +307,55 @@ enum O_FULLBLOCK = FFS_MASK (v), v2 = v ^ O_FULLBLOCK, - O_NOCACHE = FFS_MASK (v2) + O_NOCACHE = FFS_MASK (v2), + v3 = v2 ^ O_NOCACHE, + + O_COUNT_BYTES = FFS_MASK (v3), + v4 = v3 ^ O_COUNT_BYTES, + + O_SKIP_BYTES = FFS_MASK (v4), + v5 = v4 ^ O_SKIP_BYTES, + + O_SEEK_BYTES = FFS_MASK (v5) }; /* Ensure that we got something. */ verify (O_FULLBLOCK != 0); verify (O_NOCACHE != 0); +verify (O_COUNT_BYTES != 0); +verify (O_SKIP_BYTES != 0); +verify (O_SEEK_BYTES != 0); #define MULTIPLE_BITS_SET(i) (((i) & ((i) - 1)) != 0) /* Ensure that this is a single-bit value. */ verify ( ! MULTIPLE_BITS_SET (O_FULLBLOCK)); verify ( ! MULTIPLE_BITS_SET (O_NOCACHE)); +verify ( ! MULTIPLE_BITS_SET (O_COUNT_BYTES)); +verify ( ! MULTIPLE_BITS_SET (O_SKIP_BYTES)); +verify ( ! MULTIPLE_BITS_SET (O_SEEK_BYTES)); /* Flags, for iflag="..." and oflag="...". */ static struct symbol_value const flags[] = { - {"append", O_APPEND}, - {"binary", O_BINARY}, - {"cio", O_CIO}, - {"direct", O_DIRECT}, - {"directory", O_DIRECTORY}, - {"dsync", O_DSYNC}, - {"noatime", O_NOATIME}, - {"nocache", O_NOCACHE}, /* Discard cache. */ - {"noctty", O_NOCTTY}, - {"nofollow", HAVE_WORKING_O_NOFOLLOW ? O_NOFOLLOW : 0}, - {"nolinks", O_NOLINKS}, - {"nonblock", O_NONBLOCK}, - {"sync", O_SYNC}, - {"text", O_TEXT}, - {"fullblock", O_FULLBLOCK}, /* Accumulate full blocks from input. */ + {"append", O_APPEND}, + {"binary", O_BINARY}, + {"cio", O_CIO}, + {"direct", O_DIRECT}, + {"directory", O_DIRECTORY}, + {"dsync", O_DSYNC}, + {"noatime", O_NOATIME}, + {"nocache", O_NOCACHE}, /* Discard cache. */ + {"noctty", O_NOCTTY}, + {"nofollow", HAVE_WORKING_O_NOFOLLOW ? O_NOFOLLOW : 0}, + {"nolinks", O_NOLINKS}, + {"nonblock", O_NONBLOCK}, + {"sync", O_SYNC}, + {"text", O_TEXT}, + {"fullblock", O_FULLBLOCK}, /* Accumulate full blocks from input. */ + {"count_bytes", O_COUNT_BYTES}, + {"skip_bytes", O_SKIP_BYTES}, + {"seek_bytes", O_SEEK_BYTES}, {"", 0} }; @@ -489,7 +518,7 @@ Copy a file, converting and formatting according to the operands.\n\ bs=BYTES read and write up to BYTES bytes at a time\n\ cbs=BYTES convert BYTES bytes at a time\n\ conv=CONVS convert the file as per the comma separated symbol list\n\ - count=BLOCKS copy only BLOCKS input blocks\n\ + count=N copy only N input blocks\n\ ibs=BYTES read up to BYTES bytes at a time (default: 512)\n\ "), stdout); fputs (_("\ @@ -498,8 +527,8 @@ Copy a file, converting and formatting according to the operands.\n\ obs=BYTES write BYTES bytes at a time (default: 512)\n\ of=FILE write to FILE instead of stdout\n\ oflag=FLAGS write as per the comma separated symbol list\n\ - seek=BLOCKS skip BLOCKS obs-sized blocks at start of output\n\ - skip=BLOCKS skip BLOCKS ibs-sized blocks at start of input\n\ + seek=N skip N obs-sized blocks at start of output\n\ + skip=N skip N ibs-sized blocks at start of input\n\ status=noxfer suppress transfer statistics\n\ "), stdout); fputs (_("\ @@ -568,6 +597,15 @@ Each FLAG symbol may be:\n\ fputs (_(" binary use binary I/O for data\n"), stdout); if (O_TEXT) fputs (_(" text use text I/O for data\n"), stdout); + if (O_COUNT_BYTES) + fputs (_(" count_bytes treat 'count=N' as a byte count (iflag only)\n\ +"), stdout); + if (O_SKIP_BYTES) + fputs (_(" skip_bytes treat 'skip=N' as a byte count (iflag only)\n\ +"), stdout); + if (O_SEEK_BYTES) + fputs (_(" seek_bytes treat 'seek=N' as a byte count (oflag only)\n\ +"), stdout); { char const *siginfo_name = (SIGINFO == SIGUSR1 ? "USR1" : "INFO"); @@ -1120,6 +1158,9 @@ scanargs (int argc, char *const *argv) { int i; size_t blocksize = 0; + uintmax_t count = (uintmax_t) -1; + uintmax_t skip = 0; + uintmax_t seek = 0; for (i = optind; i < argc; i++) { @@ -1175,11 +1216,11 @@ scanargs (int argc, char *const *argv) conversion_blocksize = n; } else if (operand_is (name, "skip")) - skip_records = n; + skip = n; else if (operand_is (name, "seek")) - seek_records = n; + seek = n; else if (operand_is (name, "count")) - max_records = n; + count = n; else { error (0, 0, _("unrecognized operand %s"), quote (name)); @@ -1216,6 +1257,43 @@ scanargs (int argc, char *const *argv) usage (EXIT_FAILURE); } + if (input_flags & O_SEEK_BYTES) + { + error (0, 0, "%s: %s", _("invalid input flag"), "'seek_bytes'"); + usage (EXIT_FAILURE); + } + + if (output_flags & (O_COUNT_BYTES | O_SKIP_BYTES)) + { + error (0, 0, "%s: %s", _("invalid output flag"), + output_flags & O_COUNT_BYTES ? "'count_bytes'" : "'skip_bytes'"); + usage (EXIT_FAILURE); + } + + if (input_flags & O_SKIP_BYTES && skip != 0) + { + skip_records = skip / input_blocksize; + skip_bytes = skip % input_blocksize; + } + else if (skip != 0) + skip_records = skip; + + if (input_flags & O_COUNT_BYTES && count != (uintmax_t) -1) + { + max_records = count / input_blocksize; + max_bytes = count % input_blocksize; + } + else if (count != (uintmax_t) -1) + max_records = count; + + if (output_flags & O_SEEK_BYTES && seek != 0) + { + seek_records = seek / output_blocksize; + seek_bytes = seek % output_blocksize; + } + else if (seek != 0) + seek_records = seek; + /* Warn about partial reads if bs=SIZE is given and iflag=fullblock is not, and if counting or skipping bytes or using direct I/O. This helps to avoid confusion with miscounts, and to avoid issues @@ -1411,18 +1489,20 @@ skip_via_lseek (char const *filename, int fdesc, off_t offset, int whence) # define skip_via_lseek(Filename, Fd, Offset, Whence) lseek (Fd, Offset, Whence) #endif -/* Throw away RECORDS blocks of BLOCKSIZE bytes on file descriptor FDESC, - which is open with read permission for FILE. Store up to BLOCKSIZE - bytes of the data at a time in BUF, if necessary. RECORDS must be - nonzero. If fdesc is STDIN_FILENO, advance the input offset. - Return the number of records remaining, i.e., that were not skipped - because EOF was reached. */ +/* Throw away RECORDS blocks of BLOCKSIZE bytes plus BYTES bytes on + file descriptor FDESC, which is open with read permission for FILE. + Store up to BLOCKSIZE bytes of the data at a time in BUF, if + necessary. RECORDS or BYTES must be nonzero. If FDESC is + STDIN_FILENO, advance the input offset. Return the number of + records remaining, i.e., that were not skipped because EOF was + reached. If FDESC is STDOUT_FILENO, on return, BYTES is the + remaining bytes in addition to the remaining records. */ static uintmax_t skip (int fdesc, char const *file, uintmax_t records, size_t blocksize, - char *buf) + size_t *bytes, char *buf) { - uintmax_t offset = records * blocksize; + uintmax_t offset = records * blocksize + *bytes; /* Try lseek and if an error indicates it was an inappropriate operation -- or if the file offset is not representable as an off_t -- @@ -1450,7 +1530,10 @@ skip (int fdesc, char const *file, uintmax_t records, size_t blocksize, advance_input_offset (offset); } else - records = 0; + { + records = 0; + *bytes = 0; + } return records; } else @@ -1491,29 +1574,30 @@ skip (int fdesc, char const *file, uintmax_t records, size_t blocksize, do { - ssize_t nread = iread_fnc (fdesc, buf, blocksize); + ssize_t nread = iread_fnc (fdesc, buf, records ? blocksize : *bytes); if (nread < 0) { if (fdesc == STDIN_FILENO) { error (0, errno, _("reading %s"), quote (file)); if (conversions_mask & C_NOERROR) - { - print_stats (); - continue; - } + print_stats (); } else error (0, lseek_errno, _("%s: cannot seek"), quote (file)); quit (EXIT_FAILURE); } - - if (nread == 0) + else if (nread == 0) break; - if (fdesc == STDIN_FILENO) + else if (fdesc == STDIN_FILENO) advance_input_offset (nread); + + if (records != 0) + records--; + else + *bytes = 0; } - while (--records != 0); + while (records || *bytes); return records; } @@ -1777,11 +1861,13 @@ dd_copy (void) obuf = ibuf; } - if (skip_records != 0) + if (skip_records != 0 || skip_bytes != 0) { - uintmax_t us_bytes = input_offset + (skip_records * input_blocksize); + uintmax_t us_bytes = input_offset + (skip_records * input_blocksize) + + skip_bytes; uintmax_t us_blocks = skip (STDIN_FILENO, input_file, - skip_records, input_blocksize, ibuf); + skip_records, input_blocksize, &skip_bytes, + ibuf); us_bytes -= input_offset; /* POSIX doesn't say what to do when dd detects it has been @@ -1797,34 +1883,41 @@ dd_copy (void) } } - if (seek_records != 0) + if (seek_records != 0 || seek_bytes != 0) { + size_t bytes = seek_bytes; uintmax_t write_records = skip (STDOUT_FILENO, output_file, - seek_records, output_blocksize, obuf); + seek_records, output_blocksize, &bytes, + obuf); - if (write_records != 0) + if (write_records != 0 || bytes != 0) { - memset (obuf, 0, output_blocksize); + memset (obuf, 0, write_records ? output_blocksize : bytes); do { - if (iwrite (STDOUT_FILENO, obuf, output_blocksize) - != output_blocksize) + size_t size = write_records ? output_blocksize : bytes; + if (iwrite (STDOUT_FILENO, obuf, size) != size) { error (0, errno, _("writing to %s"), quote (output_file)); quit (EXIT_FAILURE); } + + if (write_records != 0) + write_records--; + else + bytes = 0; } - while (--write_records != 0); + while (write_records || bytes); } } - if (max_records == 0) + if (max_records == 0 && max_bytes == 0) return exit_status; while (1) { - if (r_partial + r_full >= max_records) + if (r_partial + r_full >= max_records + (max_bytes ? 1 : 0)) break; /* Zero the buffer before reading, so that if we get a read error, @@ -1835,7 +1928,10 @@ dd_copy (void) (conversions_mask & (C_BLOCK | C_UNBLOCK)) ? ' ' : '\0', input_blocksize); - nread = iread_fnc (STDIN_FILENO, ibuf, input_blocksize); + if (r_partial + r_full >= max_records) + nread = iread_fnc (STDIN_FILENO, ibuf, max_bytes); + else + nread = iread_fnc (STDIN_FILENO, ibuf, input_blocksize); if (nread >= 0 && i_nocache) invalidate_cache (STDIN_FILENO, nread); diff --git a/tests/Makefile.am b/tests/Makefile.am index c951f69a1..7b5368195 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -369,6 +369,7 @@ TESTS = \ dd/reblock \ dd/skip-seek \ dd/skip-seek2 \ + dd/bytes \ dd/skip-seek-past-file \ dd/stderr \ dd/unblock \ diff --git a/tests/dd/bytes b/tests/dd/bytes new file mode 100755 index 000000000..603874290 --- /dev/null +++ b/tests/dd/bytes @@ -0,0 +1,57 @@ +#!/bin/sh + +# Copyright (C) 2012 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 + +# count_bytes +echo 0123456789abcdefghijklm > in || framework_failure_ +dd count=14 conv=swab iflag=count_bytes < in > out 2> /dev/null || fail=1 +case `cat out` in + 1032547698badc) ;; + *) fail=1 ;; +esac + +# skip_bytes +echo 0123456789abcdefghijklm > in || framework_failure_ +dd skip=10 iflag=skip_bytes < in > out 2> /dev/null || fail=1 +case `cat out` in + abcdefghijklm) ;; + *) fail=1 ;; +esac + +# skip records and bytes from pipe +echo 0123456789abcdefghijklm | + dd skip=10 bs=2 iflag=skip_bytes > out 2> /dev/null || fail=1 +case `cat out` in + abcdefghijklm) ;; + *) fail=1 ;; +esac + +# seek bytes +echo abcdefghijklm | + dd bs=5 seek=8 oflag=seek_bytes > out 2> /dev/null || fail=1 +echo abcdefghijklm | + dd bs=4 seek=2 > expected 2> /dev/null || fail=1 +compare expected out || fail=1 + +# seek bytes on empty file +echo abcdefghijklm | + dd bs=5 seek=8 oflag=seek_bytes > out2 2> /dev/null || fail=1 +compare expected out2 || fail=1 + +Exit $fail |