When a configuration file is locked, any updates made to it will be done
to the in-memory copy of the file. This allows for multiple updates to
happen while we hold the lock, preventing races during complex
config-file manipulation.
Instead of writing into the filebuf directly, make the functions to
write the modified config file write into a buffer which can then be
dumped into the lockfile for committing.
This allows us to re-use the same code for modifying a locked
configuration, as we can simply skip the last step of dumping the data
to disk.
Some brain damaged tolower() implementations appear to want to
take the locale into account, and this may require taking some
insanely aggressive lock on the locale and slowing down what should
be the most trivial of trivial calls for people who just want to
downcase ASCII.
When writing a configuration file, we want to take a lock on the
new file (eg, `config.lock`) before opening the configuration file
(`config`) for reading so that we can prevent somebody from changing
the contents underneath us.
When updating a configuration file, we want to copy the old data
from the file to preserve comments and funny whitespace, instead
of writing it in some "canonical" format. Thus, we keep a
pointer to the start of the line and the line length to preserve
these things we don't care to rewrite.
Previously we would try to be clever when writing the configuration
file and try to stop parsing (and simply copy the rest of the old
file) when we either found the value we were trying to write,
or when we left the section that value was in, the assumption being
that there was no more work to do.
Regrettably, you can have another section with the same name later
in the file, and we must cope with that gracefully, thus we read the
whole file in order to write a new file.
Now, writing a file looks even more than reading. Pull the config
parsing out into its own function that can be used by both reading
and writing the configuration.
If git_config_delete is to work properly in the presence of duplicate section
headers, it cannot stop searching at the end of the first matching section, as
there may be another matching section later.
When config_write is used for deletion (value = NULL), it may only terminate
when the desired key is found or there are no sections left to parse.
The regcomp function returns a non-zero value if compilation of
a regular expression fails. In most places we only check for
negative values, but positive values indicate an error, as well.
Fix this tree-wide, fixing a segmentation fault when calling
git_config_iterator_glob_new with an invalid regexp.
This changes the get_entry() method to return a refcounted version of
the config entry, which you have to free when you're done.
This allows us to avoid freeing the memory in which the entry is stored
on a refresh, which may happen at any time for a live config.
For this reason, get_string() has been forbidden on live configs and a
new function get_string_buf() has been added, which stores the string in
a git_buf which the user then owns.
The functions which parse the string value takea advantage of the
borrowing to parse safely and then release the entry.
Make our overflow checking look more like gcc and clang's, so that
we can substitute it out with the compiler instrinsics on platforms
that support it. This means dropping the ability to pass `NULL` as
an out parameter.
As a result, the macros also get updated to reflect this as well.
Fixes#2869. If included file includes more files, it may reallocate
cfg_file->readers, hence invalidate not only `r` pointer, but `result`
pointer as well.
* Error-handling is cleaned up to only let a file-not-found error
through, not other sorts of errors. And when a file-not-found
error happens, we clean up the error.
* Test now checks that file-not-found introduces no error. And
other minor cleanups.
For example, if you have
[include]
path = foo
and foo didn't exist, git_config_open_ondisk() would just give up
on the rest of the file. Now it ignores the unresolved include
without error and continues reading the rest of the file.
In the check for multiline, we traverse the backslashes from the end
backwards and int the end assert that we haven't gone past the beginning
of the line. We make sure of this in the loop condition, but we also
check in the return value.
However, for certain configurations, a line in a multiline variable
might be empty to aid formatting. In that case, 'end' == 'start', since
we ended up looking at the first char which made it a multiline.
There is no need for the (end > start) check in the return, since the
loop guarantees we won't go further back than the first char in the
line, and we do accept the first char to be the final backslash.
This fixes#2483.
Now that our strmap is no longer modified but replaced, we can use the
same strmap for the snapshot's values and it will be freed when we don't
need it anymore.
When we delete an entry, we also want to refresh the configuration to
catch any changes that happened externally.
This allows us to simplify the logic, as we no longer need to delete
these variables internally. The whole state will be refreshed and the
deleted entries won't be there.
With the isolation of complex reads, we can now try to refresh the
on-disk file before reading a value from it.
This changes the semantics a bit, as before we could be sure that a
string we got from the configuration was valid until we wrote or
refreshed. This is no longer the case, as a read can also invalidate the
pointer.
Current code sets the active map to a new one and builds it whilst it's
active. This is a race condition with someone else trying to access the
same config.
Instead, let's build up our new map and swap the active and new one.
In order to have consistent views of the config files for remotes,
submodules et al. and a configuration that represents what is currently
stored on-disk, we need a way to provide a view of the configuration
that does not change.
The goal here is to provide the snapshotting part by creating a
read-only copy of the state of the configuration at a particular point
in time, which does not change when a repository's main config changes.
This adds a basic test of doing simultaneous diffs on multiple
threads and adds basic locking for the attr file cache because
that was the immediate problem that arose from these tests.
This adds `git_config__lookup_entry` which will look up a key in
a config and return either the entry or NULL if the key was not
present. Optionally, it can either suppress all errors or can
return them (although not finding the key is not an error for this
function). Unlike other accessors, this does not normalize the
config key string, so it must only be used when the key is known
to be in normalized form (i.e. all lower-case before the first dot
and after the last dot, with no invalid characters).
This also adds three high-level helper functions to look up config
values with no errors and a fallback value. The three functions
are for string, bool, and int values, and will resort to the
fallback value for any error that arises. They are:
* `git_config__get_string_force`
* `git_config__get_bool_force`
* `git_config__get_int_force`
None of them normalize the config `key` either, so they can only
be used for internal cases where the key is known to be in normal
format.
