POSIX says
Copying shall begin at the point in the file indicated by the -c
number or -n number options.
The origin for counting shall be 1; that is, -c +1 represents the
first byte of the file, -c -1 the last.
The origin for counting shall be 1; that is, -n +1 represents the
first line of the file, -n -1 the last.
ls was using (old) UNIX spec (struct stat).st_[acm]time.
It now uses POSIX (struct stat).(struct timespec st_[acm]tim) which
gives time resolution in seconds and nanoseconds.
If two files have the same time in seconds, we extend the comparision to
nanoseconds.
Entities arrays in main() were arrays of pointer to entities and were
not compatible with entcmp().
They have been changed to being arrays of entities.
Thanks to Michael Forney <mforney@mforney.org> for having seen that.
Previously, entcmp was being passed struct entry **, when it expected
struct entry *.
Many autoconf-generated configure scripts use `ls -t` to determine whether or
not the system clock is behaving correctly. If they are sorted in the wrong
order, it produces an error.
checking whether build environment is sane... configure: error: newly created file is older than distributed files!
Check your system clock
After setting up qemu and testing od(1) in a Big Endian environment,
I found out that the conditional in the printing function was not
right.
Instead, it's supposed to be way simpler. While at it, we don't need
HOST_BIG_ENDIAN any more. Just set big_endian properly in main()
and be done with it.
The -e and -E flags allow the user to override the host endianness
and force od(1) to handle input according to a little (-e) or big (-E)
endian environment.
The previous handling was broken as bitshifts alone are already
endian-independent.
Looking at the old code, it became clear that the desired
functionality with the t-flag could not be added unless the
underlying data-structures were reworked.
Thus the only way to be successful was to rewrite the whole thing.
od(1) allows giving arbitrarily many type-specs per call, both via
-t x1o2... and -t x1 -t o2 and intermixed.
This fortunately is easy to parse.
Now, to be flexible, it should not only support types of integral
length. Erroring out like this is inacceptable:
$ echo -n "shrek"| od -t u3
od: invalid type string ‘u3’;
this system doesn't provide a 3-byte integral type
Thus, this new od(1) just collects the bytes until shortly before
printing, when the numbers are written into a long long with the
proper offset.
The bytes per line are just the lcm of all given type-lengths and >= 16.
They are equal to 16 for all types that are possible to print using
the old od(1)'s.
Endianness is of course also supported, needs some testing though,
especially on Big Endian systems.
The one specified by mdoc is hard to read for non-native
speakers from countries which read the date day-first (like
Germany, Greece, North-Korea, Swamp,...).
This is also consistent with how we generally specify dates
at suckless.org.
Rely on what the system provides. These are not standardized macros
but any relevant UNIX system will provide them.
We can revisit this in the future if something breaks.
The logic is simple, it's just a pain in the ass to fill the
data-structures.
Some lines had to be commented out, as glibc/musl apparently
have not fully implemented the mandatory variables for the
2013 corrigendum of POSIX 2008.
Also added a manpage and the necessary entries in README.
I also removed it from the TODO.
Yeah, if the skipping is longer than the file itself, we need
to take the skip value, not the address.
Also, only print the last newline when we've actually printed
at least 1 address.
If this flag is not given, od(1) automatically replaces duplicate
adjacent lines with an '*' for each reoccurence.
If this flag is set, thus, no such filtering occurs.
In this case this would mean having to somehow keep the last printed
line in some backbuffer, building the next line and then doing the
necessary comparisons. This basically means that we duplicate the
functionality provided with uniq(1).
So instead of
$ od -t a > dump
you'd rather do
$ od -t a | uniq -f 1 -c > dump
Skipping the first field is necessary, as the addresses obviously differ.
Now, I was thinking hard why this flag even exists. If POSIX mandated
to add the address before the asterisk, so we know the offset of duplicate
occurrences, this would make sense. However, this is not the case.
Using uniq(1) also gives nicer output:
~ $ echo "111111111111111111111111111111111111111111111111" | od -t a -v | uniq -f 1 -c
3 0000000 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 0000060 nl
1 0000061
in comparison to
$ echo "111111111111111111111111111111111111111111111111" | od -t a
0000000 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
*
0000060 nl
0000061
Before working on od(1), I didn't even know it would filter out
duplicate adjacent lines like that. This is also a matter of
predictability.
Concluding, the v-flag is implicitly set and users urged to just
use the existing tools provided by the system.
I don't think we would break scripts either. Firstly, it's rather
unlikely to have duplicate lines exactly matching the line-length of
od(1). Secondly, even if a script did that specifically, in the worst
case there would be a counting error or something.
Given od(1) is mostly used interactively, we can safely assume this
feature is for the benefit of the users.
Ditch this legacy POSIX crap!
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