All versions of SSL are considered deprecated now, so let's ask OpenSSl
to only use TLSv1. We still ask it to load those ciphers for
compatibility with servers which want to use an older hello but will use
TLS for encryption.
For good measure we also disable compression, which can be exploitable,
if the OpenSSL version supports it.
The OpenSSL library-loading functions do not expect to be called
multiple times. Add a flag in the non-threaded libgit2 init so we only
call once.
This fixes#2446.
Bring together all of the OpenSSL initialization to
git_threads_init() so it's together and doesn't need locks.
Moving it here also gives us libssh2 thread safety (when built against
openssl).
The OpenSSL init functions are not reentrant, which means that running
multiple fetches in parallel can cause us to crash.
Use a mutex to init OpenSSL, and since we're adding this extra checks,
init it only once.
1) Call to git_shutdown results in setting git__n_shutdown_callbacks
to -1. Next call to git__on_shutdown results in ABW (Array Bound Write)
for array git__shutdown_callbacks. In the current Implementation,
git_atomic_dec is called git__n_shutdown_callbacks + 1 times. I have
modified it to a for loop so that it is more readable. It would not
set git__n_shutdown_callbacks to a negative number and reset the
elements of git__shutdown_callbacks to NULL.
2) In function git_sysdir_get, shutdown function is registered only if
git_sysdir__dirs_shutdown_set is set to 0. However, after this variable
is set to 1, it is never reset to 0. If git_sysdir_global_init is
called again from synchronized_threads_init it does not register
shutdown function for this subsystem.
Increasingly there are a number of components that want to do some
cleanup at global shutdown time (at least if there are not going
to be memory leaks). This creates a very simple system of shutdown
hooks that will be invoked by git_threads_shutdown. Right now, the
maximum number of hooks is hardcoded, but since adding a hook is
not a public API, it should be fine and I thought it was better to
start off with really simple code.
This loads SRWLock APIs at runtime and in their absence (i.e. on
Windows before Vista) falls back on a regular CRITICAL_SECTION
that will not permit concurrent readers.
It is obviously quite a serious problem if this happens, but mutex
initialization can fail and we should detect it. It's a bit like
a memory allocation failure, in that you're probably pretty screwed
if this occurs, but at least we'll catch it.
This builds on the earlier thread safety work to make it so that
setting the odb, index, refdb, or config for a repository is done
in a threadsafe manner with minimized locking time. This is done
by adding a lock to the repository object and using it to guard
the assignment of the above listed pointers. The lock is only
held to assign the pointer value.
This also contains some minor fixes to the other work with pack
files to reduce the time that locks are being held to and fix an
apparently memory leak.
This switches the APIs for setting and getting the global/system
search paths from using git_strarray to using a simple string with
GIT_PATH_LIST_SEPARATOR delimited paths, just as the environment
PATH variable would contain. This makes it simpler to get and set
the value.
I also added code to expand "$PATH" when setting a new value to
embed the old value of the path. This means that I no longer
require separate actions to PREPEND to the value.
This could also use PTHREAD_MUTEX_INITIALIZER, but a dynamic initializer seems like a more portable concept, and we won't need another #define on top of git_mutex_init()
Up to now, the idea was that the user would do all the operations for
one repository in the same thread. Thus we could have the
memory-mapped window information thread-local and avoid any locking.
This is not practical in a few environments, such as Apple's GCD which
allocates threads arbitrarily or the .NET CLR, where the OS-level
thread can change at any moment.
Make the control structure global and protect it with a mutex so we
don't depend on the thread currently executing the code.
This adds a `git_pool` object that can do simple paged memory
allocation with free for the entire pool at once. Using this,
you can replace many small allocations with large blocks that
can then cheaply be doled out in small pieces. This is best
used when you plan to free the small blocks all at once - for
example, if they represent the parsed state from a file or data
stream that are either all kept or all discarded.
There are two real patterns of usage for `git_pools`: either
for "string" allocation, where the item size is a single byte
and you end up just packing the allocations in together, or for
"fixed size" allocation where you are allocating a large object
(e.g. a `git_oid`) and you generally just allocation single
objects that can be tightly packed. Of course, you can use it
for other things, but those two cases are the easiest.
See `global.c` for a description of what we're doing.
When libgit2 is built with GIT_THREADS support, the threading system
must be explicitly initialized with `git_threads_init()`.
