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dd: counts ending in "B" now count bytes

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This implements my suggestion in Bug#54112.
* src/dd.c (usage): Document the change.
(parse_integer, scanargs): Implement the change.
Omit some now-obsolete checks for invalid flags.
* tests/dd/bytes.sh: Test the new behavior, while retaining
checks for the now-obsolete usage.
* tests/dd/nocache_eof.sh: Avoid now-obsolete usage.
This commit is contained in:
Paul Eggert
2022-02-22 18:27:09 -08:00
parent ef694d3448
commit 97e9778296
5 changed files with 115 additions and 125 deletions
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6
NEWS
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@@ -60,6 +60,12 @@ GNU coreutils NEWS -*- outline -*-
dd now supports the aliases iseek=N for skip=N, and oseek=N for seek=N,
like FreeBSD and other operating systems.
dd now counts bytes instead of blocks if a block count ends in "B".
For example, 'dd count=100KiB' now copies 100 KiB of data, not
102,400 blocks of data. The flags count_bytes, skip_bytes and
seek_bytes are therefore obsolescent and are no longer documented,
though they still work.
timeout --foreground --kill-after=... will now exit with status 137
if the kill signal was sent, which is consistent with the behavior
when the --foreground option is not specified. This allows users to

53
doc/coreutils.texi
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@@ -9268,9 +9268,9 @@ use @var{bytes} as the fixed record length.
@opindex skip
@opindex iseek
Skip @var{n} @samp{ibs}-byte blocks in the input file before copying.
With @samp{iflag=skip_bytes}, interpret @var{n}
If @var{n} ends in the letter @samp{B}, interpret @var{n}
as a byte count rather than a block count.
(The @samp{iseek=} spelling is an extension to POSIX.)
(@samp{B} and the @samp{iseek=} spelling are GNU extensions to POSIX.)
@item seek=@var{n}
@itemx oseek=@var{n}
@@ -9278,16 +9278,17 @@ as a byte count rather than a block count.
@opindex oseek
Skip @var{n} @samp{obs}-byte blocks in the output file before
truncating or copying.
With @samp{oflag=seek_bytes}, interpret @var{n}
If @var{n} ends in the letter @samp{B}, interpret @var{n}
as a byte count rather than a block count.
(The @samp{oseek=} spelling is an extension to POSIX.)
(@samp{B} and the @samp{oseek=} spelling are GNU extensions to POSIX.)
@item count=@var{n}
@opindex count
Copy @var{n} @samp{ibs}-byte blocks from the input file, instead
of everything until the end of the file.
With @samp{iflag=count_bytes}, interpret @var{n}
as a byte count rather than a block count.
If @var{n} ends in the letter @samp{B},
interpret @var{n} as a byte count rather than a block count;
this is a GNU extension to POSIX.
If short reads occur, as could be the case
when reading from a pipe for example, @samp{iflag=fullblock}
ensures that @samp{count=} counts complete input blocks
@@ -9627,27 +9628,6 @@ as they may return short reads. In that case,
this flag is needed to ensure that a @samp{count=} argument is
interpreted as a block count rather than a count of read operations.
@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=} or @samp{iseek=} 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=} or @samp{oseek=} 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 all GNU extensions to POSIX.
@@ -9680,23 +9660,22 @@ 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.
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.
To process data with offset or size that is not a multiple of the I/O
block size, you can use a numeric string @var{n} that ends in the
letter @samp{B}.
For example, the following shell commands copy data
in 512 KiB blocks between a flash drive and a tape, but do not save
or restore a 1 MiB area at the start of the flash drive:
in 1 MiB blocks between a flash drive and a tape, but do not save
or restore a 512-byte area at the start of the flash drive:
@example
flash=/dev/sda
tape=/dev/st0
# Copy all but the initial 1 MiB from flash to tape.
(dd bs=1M skip=1 count=0 && dd bs=512k) <$flash >$tape
# Copy all but the initial 512 bytes from flash to tape.
dd if=$flash iseek=512B bs=1MiB of=$tape
# Copy from tape back to flash, leaving initial 1 MiB alone.
(dd bs=1M seek=1 count=0 && dd bs=512k) <$tape >$flash
# Copy from tape back to flash, leaving initial 512 bytes alone.
dd if=$tape bs=1MiB of=$flash oseek=512B
@end example
@cindex ddrescue

108
src/dd.c
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@@ -575,6 +575,7 @@ N and BYTES may be followed by the following multiplicative suffixes:\n\
c=1, w=2, b=512, kB=1000, K=1024, MB=1000*1000, M=1024*1024, xM=M,\n\
GB=1000*1000*1000, G=1024*1024*1024, and so on for T, P, E, Z, Y.\n\
Binary prefixes can be used, too: KiB=K, MiB=M, and so on.\n\
If N ends in 'B', it counts bytes not blocks.\n\
\n\
Each CONV symbol may be:\n\
\n\
@@ -638,15 +639,6 @@ 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);
{
printf (_("\
@@ -1419,9 +1411,8 @@ parse_symbols (char const *str, struct symbol_value const *table,
/* Return the value of STR, interpreted as a non-negative decimal integer,
optionally multiplied by various values.
If STR does not represent a number in this format,
set *INVALID to a nonzero error value and return
INTMAX_MAX if it is an overflow, an indeterminate value otherwise. */
Set *INVALID to an appropriate error value and return INTMAX_MAX if
it is an overflow, an indeterminate value if some other error occurred. */
static intmax_t
parse_integer (char const *str, strtol_error *invalid)
@@ -1430,53 +1421,57 @@ parse_integer (char const *str, strtol_error *invalid)
allow strings like " -0". Initialize N to an interminate value;
calling code should not rely on this function returning 0
when *INVALID represents a non-overflow error. */
uintmax_t n = 0;
int indeterminate = 0;
uintmax_t n = indeterminate;
char *suffix;
strtol_error e = xstrtoumax (str, &suffix, 10, &n, "bcEGkKMPTwYZ0");
static char const suffixes[] = "bcEGkKMPTwYZ0";
strtol_error e = xstrtoumax (str, &suffix, 10, &n, suffixes);
intmax_t result;
if ((e & ~LONGINT_OVERFLOW) == LONGINT_INVALID_SUFFIX_CHAR
&& *suffix == 'x')
&& suffix[-1] != 'B' && *suffix == 'B')
{
strtol_error invalid2 = LONGINT_OK;
intmax_t result = parse_integer (suffix + 1, &invalid2);
if ((invalid2 & ~LONGINT_OVERFLOW) != LONGINT_OK)
{
*invalid = invalid2;
return result;
suffix++;
if (!*suffix)
e &= ~LONGINT_INVALID_SUFFIX_CHAR;
}
if (INT_MULTIPLY_WRAPV (n, result, &result))
if ((e & ~LONGINT_OVERFLOW) == LONGINT_INVALID_SUFFIX_CHAR
&& *suffix == 'x' && ! (suffix[-1] == 'B' && strchr (suffix + 1, 'B')))
{
*invalid = LONGINT_OVERFLOW;
return INTMAX_MAX;
uintmax_t o;
strtol_error f = xstrtoumax (suffix + 1, &suffix, 10, &o, suffixes);
if ((f & ~LONGINT_OVERFLOW) != LONGINT_OK)
{
e = f;
result = indeterminate;
}
if (result == 0)
else if (INT_MULTIPLY_WRAPV (n, o, &result)
|| (result != 0 && ((e | f) & LONGINT_OVERFLOW)))
{
if (STRPREFIX (str, "0x"))
e = LONGINT_OVERFLOW;
result = INTMAX_MAX;
}
else
{
if (result == 0 && STRPREFIX (str, "0x"))
error (0, 0,
_("warning: %s is a zero multiplier; "
"use %s if that is intended"),
quote_n (0, "0x"), quote_n (1, "00x"));
e = LONGINT_OK;
}
else if ((e | invalid2) & LONGINT_OVERFLOW)
}
else if (n <= INTMAX_MAX)
result = n;
else
{
*invalid = LONGINT_OVERFLOW;
return INTMAX_MAX;
e = LONGINT_OVERFLOW;
result = INTMAX_MAX;
}
return result;
}
if (INTMAX_MAX < n)
{
*invalid = e | LONGINT_OVERFLOW;
return INTMAX_MAX;
}
if (e != LONGINT_OK)
*invalid = e;
return n;
return result;
}
/* OPERAND is of the form "X=...". Return true if X is NAME. */
@@ -1495,6 +1490,7 @@ scanargs (int argc, char *const *argv)
intmax_t count = INTMAX_MAX;
intmax_t skip = 0;
intmax_t seek = 0;
bool count_B = false, skip_B = false, seek_B = false;
for (int i = optind; i < argc; i++)
{
@@ -1529,6 +1525,7 @@ scanargs (int argc, char *const *argv)
{
strtol_error invalid = LONGINT_OK;
intmax_t n = parse_integer (val, &invalid);
bool has_B = !!strchr (val, 'B');
intmax_t n_min = 0;
intmax_t n_max = INTMAX_MAX;
idx_t *converted_idx = NULL;
@@ -1565,11 +1562,20 @@ scanargs (int argc, char *const *argv)
converted_idx = &conversion_blocksize;
}
else if (operand_is (name, "skip") || operand_is (name, "iseek"))
{
skip = n;
skip_B = has_B;
}
else if (operand_is (name + (*name == 'o'), "seek"))
{
seek = n;
seek_B = has_B;
}
else if (operand_is (name, "count"))
{
count = n;
count_B = has_B;
}
else
{
error (0, 0, _("unrecognized operand %s"),
@@ -1615,20 +1621,8 @@ scanargs (int argc, char *const *argv)
usage (EXIT_FAILURE);
}
if (input_flags & O_SEEK_BYTES)
{
error (0, 0, "%s: %s", _("invalid input flag"), quote ("seek_bytes"));
usage (EXIT_FAILURE);
}
if (output_flags & (O_COUNT_BYTES | O_SKIP_BYTES))
{
error (0, 0, "%s: %s", _("invalid output flag"),
quote (output_flags & O_COUNT_BYTES
? "count_bytes" : "skip_bytes"));
usage (EXIT_FAILURE);
}
if (skip_B)
input_flags |= O_SKIP_BYTES;
if (input_flags & O_SKIP_BYTES && skip != 0)
{
skip_records = skip / input_blocksize;
@@ -1637,6 +1631,8 @@ scanargs (int argc, char *const *argv)
else if (skip != 0)
skip_records = skip;
if (count_B)
input_flags |= O_COUNT_BYTES;
if (input_flags & O_COUNT_BYTES && count != INTMAX_MAX)
{
max_records = count / input_blocksize;
@@ -1645,6 +1641,8 @@ scanargs (int argc, char *const *argv)
else if (count != INTMAX_MAX)
max_records = count;
if (seek_B)
output_flags |= O_SEEK_BYTES;
if (output_flags & O_SEEK_BYTES && seek != 0)
{
seek_records = seek / output_blocksize;

53
tests/dd/bytes.sh
View File

@@ -18,39 +18,46 @@
. "${srcdir=.}/tests/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
# count bytes
for operands in "count=14B" "count=14 iflag=count_bytes"; do
dd $operands conv=swab < in > out 2> /dev/null || fail=1
case $(cat out) in
1032547698badc) ;;
*) fail=1 ;;
esac
esac
done
# skip_bytes
echo 0123456789abcdefghijklm > in || framework_failure_
dd skip=10 iflag=skip_bytes < in > out 2> /dev/null || fail=1
case $(cat out) in
for operands in "iseek=10B" "skip=10 iflag=skip_bytes"; do
# skip bytes
dd $operands < in > out 2> /dev/null || fail=1
case $(cat out) in
abcdefghijklm) ;;
*) fail=1 ;;
esac
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
# skip records and bytes from pipe
echo 0123456789abcdefghijklm |
dd $operands bs=2 > out 2> /dev/null || fail=1
case $(cat out) in
abcdefghijklm) ;;
*) fail=1 ;;
esac
esac
done
# seek bytes
echo abcdefghijklm |
dd bs=5 seek=8 oflag=seek_bytes > out 2> /dev/null || fail=1
printf '\0\0\0\0\0\0\0\0abcdefghijklm\n' > expected
compare expected out || fail=1
# Just truncation, no I/O
dd bs=5 seek=8 oflag=seek_bytes of=out2 count=0 2> /dev/null || fail=1
truncate -s8 expected2
compare expected2 out2 || fail=1
printf '\0\0\0\0\0\0\0\0abcdefghijklm\n' > expected
for operands in "oseek=8B" "seek=8 oflag=seek_bytes"; do
# seek bytes
echo abcdefghijklm |
dd $operands bs=5 > out 2> /dev/null || fail=1
compare expected out || fail=1
# Just truncation, no I/O
dd $operands bs=5 of=out2 count=0 2> /dev/null || fail=1
compare expected2 out2 || fail=1
done
Exit $fail

2
tests/dd/nocache_eof.sh
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@@ -78,7 +78,7 @@ advised_to_eof || fail=1
# Ensure sub page size offsets are handled.
# I.e., only page aligned offsets are sent to fadvise.
if ! strace -o dd.strace -e fadvise64,fadvise64_64 dd status=none \
if=in.f of=out.f bs=1M oflag=direct seek=512 oflag=seek_bytes; then
if=in.f of=out.f bs=1M oflag=direct oseek=512B; then
warn_ '512 byte aligned O_DIRECT is not supported on this (file) system'
# The current file system may not support O_DIRECT,
# or older XFS had a page size alignment requirement