In the description of 3111908b03, it says
that the functions must be able to handle st being NULL, but recurse
always passes a valid pointer. The only function that was ever passed
NULL was rm(), but this was changed to go through recurse in
2f4ab52739, so now the checks are
pointless.
recurse() is getting smarter every day. I expect it to pass the Turing
test in a few months.
Along the way, it was reported that "rm -f" on nonexistant files reports
their missing as an internal recurse()-error.
So recurse() knows when to shut up, I added the SILENT flag to fix all
these things.
The restructuring of recurse() in the last few weeks actually broke
the recursion-flags in different tools.
As a long-term goal, the recursor should have a field "maxdepth"
which should be "1" for the non-Rflag-case. "0" stands for unlimited.
Okay, why yet another recurse()-refactor?
The last one added the recursor-struct, which simplified things
on the user-end, but there was still one thing that bugged me a lot:
Previously, all fn()'s were forced to (l)stat the paths themselves.
This does not work well when you try to keep up with H-, L- and P-
flags at the same time, as each utility-function would have to set
the right function-pointer for (l)stat every single time.
This is not desirable. Furthermore, recurse should be easy to use
and not involve trouble finding the right (l)stat-function to do it
right.
So, what we needed was a stat-argument for each fn(), so it is
directly accessible. This was impossible to do though when the
fn()'s are still directly called by the programs to "start" the
recurse.
Thus, the fundamental change is to make recurse() the function to
go, while designing the fn()'s in a way they can "live" with st
being NULL (we don't want a null-pointer-deref).
What you can see in this commit is the result of this work. Why
all this trouble instead of using nftw?
The special thing about recurse() is that you tell the function
when to recurse() in your fn(). You don't need special flags to
tell nftw() to skip the subtree, just to give an example.
The only single downside to this is that now, you are not allowed
to unconditionally call recurse() from your fn(). It has to be
a directory.
However, that is a cost I think is easily weighed up by the
advantages.
Another thing is the history: I added a procedure at the end of
the outmost recurse to free the history. This way we don't leak
memory.
A simple optimization on the side:
- if (h->dev == st.st_dev && h->ino == st.st_ino)
+ if (h->ino == st.st_ino && h->dev == st.st_dev)
First compare the likely difference in inode-numbers instead of
checking the unlikely condition that the device-numbers are
different.
For loop detection, a history is mandatory. In the process of also
adding a flexible struct to recurse, the recurse-definition was moved
to fs.h.
The motivation behind the struct is to allow easy extensions to the
recurse-function without having to change the prototypes of all
functions in the process.
Adding flags is really simple as well now.
Using the recursor-struct, it's also easier to see which defaults
apply to a program (for instance, which type of follow, ...).
Another change was to add proper stat-lstat-usage in recurse. It
was wrong before.
While auditing du(1) I realized that there's no way the over 100 lines
of procedures in du() would pass the audit.
Instead, I decided to rewrite this section using recurse() from libutil.
However, the issue was that you'd need some kind of payload to count
the number of bytes in the subdirectories and use them in the higher
hierarchies.
The solution is to add a "void *data" data pointer to each recurse-
function-prototype, which we might also be able to use in other
recurse-applications.
recurse() itself had to be augmented with a recurse_samedev-flag, which
basically prevents recurse from leaving the current device.
Now, let's take a closer look at the audit:
1) Removing the now unnecessary util-functions push, pop, xrealpath,
rename print() to printpath(), localize some global variables.
2) Only pass the block count to nblks instead of the entire stat-
pointer.
3) Fix estrtonum to use the minimum of LLONG_MAX and SIZE_MAX.
4) Use idiomatic argv+argc-loop
5) Report proper exit-status.
The HLP-changes to sbase have been a great addition of functionality,
but they kind of "polluted" the enmasse() and recurse() prototypes.
As this will come in handy in the future, knowing at which "depth"
you are inside a recursing function is an important functionality.
Instead of having a special HLP-flag passed to enmasse, each sub-
function needs to provide it on its own and can calculate results
based on the current depth (for instance, 'H' implies 'P' at
depth > 0).
A special case is recurse(), because it actually depends on the
follow-type. A new flag "recurse_follow" brings consistency into
what used to be spread across different naming conventions (fflag,
HLP_flag, ...).
This also fixes numerous bugs with the behaviour of HLP in the
tools using it.
Michael Forney
FRIGN
sin
Tai Chi Minh Ralph Eastwood