The function basename from POSIX has a few unfortunate properties, it is
allowed to return a pointer to static memory. This is too unreliable,
therefore this trivial own implementation.
The previous output format had a %-20s conversion specifier. This
produced different output depending on the length of the pathname, which
was too difficult to normalize. By moving the directory name to the
end, it is no longer necessary to fill up any space, and the numbers are
always aligned properly.
As a result, 3 of the unit tests no longer need any special
postprocessing of their output.
The function name had been too ambiguous since it didn't mention the
particular directory that was initialized. Instead of that function,
Dir_InitCur is called directly from main_Init.
The pseudo CachedDir entry ".DOTLAST" is initialized at the very
beginning. The observable behavior is unchanged since this a
memory-only object with no connection to the file system.
The special path entry is called .DOTLAST, therefore the local variable
should have the same name.
A variable named 'base' must not point to the slash of a pathname. It
may only point to the character after the slash, everything else is
confusing, even if it's only for a brief moment.
Calling CachedDir_Assign requires that the variable be initialized. On
most systems, NULL is represented as all-zero bits already. This change
is only for the few other systems.
Add some comments explaining the implementation of Dir_AddDir since that
is tricky to read from the code alone.
Previously, the reference count for a newly created CacheDir had been
set to 1 in CacheNewDir. This was wrong because at that point, the
object had not been referenced by any nonlocal variable. The reference
count is no longer incremented at this point.
All callers of CacheNewDir either append the newly created CachedDir to
a SearchPath via Lst_Append and CachedDir_Ref, or they assign it to a
global variable via CachedDir_Assign.
Since the reference count is no longer wrongly incremented, it does not
need to be decremented more than necessary in Dir_End. To keep the code
simple and maintainable, all assignments to global variables are now
handled by CachedDir_Assign. Adding a CachedDir to a list is still done
manually via Lst_Append, and the corresponding code for decrementing is
in SearchPath_Clean and SearchPath_Free. These details may be cleaned
up in a follow-up commit.
As a result, when OpenDirs_Done is called in the unit tests, the list of
open directories is empty. It had been non-empty in a single unit test
before (dep-wildcards.mk), as a result of calling Dir_Expand.
The additional debug logging for the reference counting is not enabled
by default since it contains memory addresses, which makes the output
dependent on the memory allocator.
The function CachedDir_Destroy has been merged into CachedDir_Undef,
which had only been used in Dir_End before. The new name emphasizes
that it corresponds to CachedDir_Ref.
The memory management for dotLast is quite simple. It is initialized
exactly once main_Init > Init_Objdir > Dir_InitDir and freed exactly
once in main_CleanUp > Dir_End. Previously, dotLast was not freed at all.
The first call to CachedDir_Unref decremented the refCount to 0 but
didn't free anything. Next, CachedDir_Destroy was called, which
decremented the reference count to -1, therefore skipping the actual
freeing. This was probably an implementation mistake.
Since Dir_End is called at the very end of main_CleanUp, no code
accesses dotLast after it has been freed.
In a makefile with repeated ".CURDIR=." lines, Dir_AddDir is called with
a NULL path, once per line. Since the path is NULL, the search for
OpenDirs_Find is skipped and the directory is always read from disk.
The freshly read directory has a refCount of 1, and the refCount never
raises above 2.
In Dir_InitCur, the directory of the previous .CURDIR has a refCount of
2, which is decremented twice and then freed. After this, the new
directory is placed in the global 'cur', after incrementing its refCount
to 2.
It still seems wrong that the refCount of 'cur' is 2 instead of 1, but
it works well.
The function Dir_Destroy is an implementation detail of the cached
directories, and it should not be exported to the other modules. The
search paths, on the other hand, are the high-level API that may be used
by the other modules, as the concept of search paths is documented in
the manual page.
Instead of HashTable_CreateEntry and HashEntry_Set, several places just
need the HashEntry for storing a value in it. This makes the calling
code simpler to understand.
These parts of the code are already hard enough to understand since they
are about memory management and aliasing. Having a too detailed API for
the HashTable only distracts from these topics.
In the cache for stat(2) and lstat(2), only one of the two timestamps
was ever used. To prevent a result from stat(2) leaking into the cache
for lstat(2), there have been two completely separate caches all the
time. Using different fields in the struct was therefore unnecessary.
By removing the redundant field, the internal struct in the cache is the
same as the external struct. This makes one of them redundant, thus
struct make_stat has been renamed to cached_stat, which better describes
its purpose, and the internal struct cache_st has been removed.
Just as before, the cache prevents any direct access to its internal
data. When passing it to the caller, it is copied.
Just as before, the field names of struct cached_stat cannot correspond
to those from struct stat, since the latter are often defined as macros.
Therefore they are prefixed with cst instead of st.
The redundancy had been added on 2020-06-05.
