Otherwise, we run into problems in a typical autoconf-based build
system:
- config.status is created at some point between two seconds.
- config.status is run, generating Makefile by first writing to a file
in /tmp, and then mv-ing it to Makefile.
- If this mv happens before the beginning of the next second, Makefile
will be created with the same tv_sec as config.status, but with
tv_nsec = 0.
- When make runs, it sees that Makefile is older than config.status,
and re-runs config.status to generate Makefile.
In general, POSIX does not define /dev/std{in, out, err} because it
does not want to depend on the dev-filesystem.
For utilities, it thus introduced the '-'-keyword to denote standard
input (and output in some cases) and the programs have to deal with
it accordingly.
Sadly, the design of many tools doesn't allow strict shell-redirections
and many scripts don't even use this feature when possible.
Thus, we made the decision to implement it consistently across all
tools where it makes sense (namely those which read files).
Along the way, I spotted some behavioural bugs in libutil/crypt.c and
others where it was forgotten to fshut the files after use.
This allows for creating dangling symlinks with force applied:
# Before:
$ ln -sf non-existant target
ln: stat non-existent: No such file or directory
$ ls -l target
ls: lstat target: No such file or directory
# After:
$ ln -sf non-existant target
$ ls -l target
lrwxrwxrwx 1 eu users 12 May 08 07:50 target -> non-existent
This also allows creating relative non-dangling symlinks with force applied:
touch existant; mkdir dir
# Before
$ ln -sf ../existant dir
ln: stat ../existant: No such file or directory
$ ls -l dir
# After
$ ln -sf ../existant dir
$ ls -l dir
lrwxrwxrwx 1 eu users 11 May 08 07:53 existant -> ../existant
The check for whether each src and to pairs are on the same device with the
same inode are only needed for hardlinks so that a forcefull link does
not remove the underlying file:
touch f; mkdir dir
# Before:
$ ln -f f f dir
ln: f and f are the same file
$ ls -i f dir/f
3670611 dir/f
3670611 f
# After:
$ ln -f f f dir
ln: f and f are the same file
$ ls -i f dir/f
4332236 dir/f
4332236 f
Use the *at functions instead of building paths manually. We do
still have path-building in recurse() and other areas, but the
long-term goal is to rid most interfaces of that for practical
and security reasons.
In this case, it's more or less trivial.
Also, refactor the manpage to be more consistent with the others.
BUGFIX: Return exit status 3 on error.
General convention is to use size_t to store sizes of all kinds.
Internally, the function uses double anyway, but at least this
doesn't clobber up the API any more and there's a chance in the
future to make this function a bit cleaner and not use this dirty
static buffer hack any more.
We've already seen the issue with echo(1): Before we changed it to
ignore "--", the command
$ echo --
did not work as expected. Given POSIX mandated this and makes most
sense, in the interest of consistency the other tools need to be
streamlined for that as well.
Looking at yes(1) for instance, there's no reason to skip "--" in
the argument list.
We do not have long options like GNU does and there's no reason to
tinker with that here.
The majority of tools changed are ones taking lists of arguments
or only a single one. There's no reason why dirname should "fail"
on "--". In the end, this is a valid name.
The practice of hand-holding the user was established with the GNU
coreutils. "--help" and "--version" long-options are a disgrace to
what could've been done properly with manpages.
