Using usize limits 32-bit platforms to operate only on sizes of 4GiB
or less. While 32-bit platforms only have 4GiB of addressable memory,
not all operations require the data to be entirely in memory, so this
limitation can be lifted if we use u64 instead of usize.
This only fixes the core function, further commits fix the utilities
making use of this function.
If `conv=block,sync` command-line arguments are given and there is at
least one partial record read from the input (for example, if the
length of the input is not divisible by the value of the `ibs`
argument), then output an extra block of `cbs` spaces.
For example, no extra spaces are printed in this example because the
input is of length 10, a multiple of `ibs`:
$ printf "012\nabcde\n" \
> | dd ibs=5 cbs=5 conv=block,sync status=noxfer \
> && echo $
012 abcde$
2+0 records in
0+1 records out
But in this example, 5 extra spaces are printed because the length of
the input is not a multiple of `ibs`:
$ printf "012\nabcdefg\n" \
> | dd ibs=5 cbs=5 conv=block,sync status=noxfer \
> && echo $
012 abcde $
2+1 records in
0+1 records out
1 truncated record
The number of spaces printed is the size of the conversion block,
given by `cbs`.
This should correct the usage strings in both the `--help` and user documentation. Previously, sometimes the name of the utils did not show up correctly.
Create a new module `blocks.rs` to contain the block-related helper
functions. This commit only moves the location of the code and related
tests, it does not change the functionality of `dd`.
Collect structs, implementations, and functions that have to do with
reporting number of blocks read and written into their own new module,
`progress.rs`. This commit also adds docstrings for everything and
unit tests for the significant methods. This commit does not change
the behavior of `dd`, just the organization of the code to make it
more maintainable and testable.
Prevent `dd` from terminating with an error when given the
command-line argument `of=/dev/null`. This commit allows the call to
`File::set_len()` to result in an error without causing the process to
terminate prematurely.
