kmx git

Commit	Date	Message
5c6180b5	2019-11-29T11:06:11	global: convert to fiber-local storage to fix exit races On Windows platforms, we automatically clean up the thread-local storage upon detaching a thread via `DllMain()`. The thing is that this happens for every thread of applications that link against the libgit2 DLL, even those that don't have anything to do with libgit2 itself. As a result, we cannot assume that these unsuspecting threads make use of our `git_libgit2_init()` and `git_libgit2_shutdow()` reference counting, which may lead to racy situations: Thread 1 Thread 2 git_libgit2_shutdown() DllMain(DETACH_THREAD) git__free_tls_data() git_atomic_dec() == 0 git__free_tls_data() TlsFree(_tls_index) TlsGetValue(_tls_index) Due to the second thread never having executed `git_libgit2_init()`, the first thread will clean up TLS data and as a result also free the `_tls_index` variable. When detaching the second thread, we unconditionally access the now-free'd `_tls_index` variable, which is obviously not going to work out well. Fix the issue by converting the code to use fiber-local storage instead of thread-local storage. While FLS will behave the exact same as TLS if no fibers are in use, it does allow us to specify a destructor similar to the one that is accepted by pthread_key_create(3P). Like this, we do not have to manually free indices anymore, but will let the FLS handle calling the destructor. This allows us to get rid of `DllMain()` completely, as we only used it to keep track of when threads were exiting and results in an overall simplification of TLS cleanup.
759ec7d4	2019-06-15T22:01:00	win32: cast GetProcAddress to void * before casting GetProcAddress is prototyped to return a `FARPROC`, which is meant to be a generic function pointer. It's literally `int (FAR WINAPI * FARPROC)()` which gcc complains if you attempt to cast to a `void ()(GIT_SRWLOCK )`. Cast to a `void *` before casting to avoid warnings about the arguments.
0c7f49dd	2017-06-30T13:39:01	Make sure to always include "common.h" first Next to including several files, our "common.h" header also declares various macros which are then used throughout the project. As such, we have to make sure to always include this file first in all implementation files. Otherwise, we might encounter problems or even silent behavioural differences due to macros or defines not being defined as they should be. So in fact, our header and implementation files should make sure to always include "common.h" first. This commit does so by establishing a common include pattern. Header files inside of "src" will now always include "common.h" as its first other file, separated by a newline from all the other includes to make it stand out as special. There are two cases for the implementation files. If they do have a matching header file, they will always include this one first, leading to "common.h" being transitively included as first file. If they do not have a matching header file, they instead include "common.h" as first file themselves. This fixes the outlined problems and will become our standard practice for header and source files inside of the "src/" from now on.
82f15896	2016-11-18T07:19:22	threads: introduce `git_thread_exit` Introduce `git_thread_exit`, which will allow threads to terminate at an arbitrary time, returning a `void `. On Windows, this means that we need to store the current `git_thread` in TLS, so that we can set its `return` value when terminating. We cannot simply use `ExitThread`, since Win32 returns `DWORD`s from threads; we return `void `.
aab266c9	2016-06-20T20:07:33	threads: add platform-independent thread initialization function
8aaa9fb6	2016-06-20T18:21:42	win32: rename pthread.{c,h} to thread.{c,h} The old pthread-file did re-implement the pthreads API with exact symbol matching. As the thread-abstraction has now been split up between Unix- and Windows-specific files within the `git_` namespace to avoid symbol-clashes between libgit2 and pthreads, the rewritten wrappers have nothing to do with pthreads anymore. Rename the Windows-specific pthread-files to honor this change.

5c6180b5

2019-11-29T11:06:11

global: convert to fiber-local storage to fix exit races On Windows platforms, we automatically clean up the thread-local storage upon detaching a thread via `DllMain()`. The thing is that this happens for every thread of applications that link against the libgit2 DLL, even those that don't have anything to do with libgit2 itself. As a result, we cannot assume that these unsuspecting threads make use of our `git_libgit2_init()` and `git_libgit2_shutdow()` reference counting, which may lead to racy situations: Thread 1 Thread 2 git_libgit2_shutdown() DllMain(DETACH_THREAD) git__free_tls_data() git_atomic_dec() == 0 git__free_tls_data() TlsFree(_tls_index) TlsGetValue(_tls_index) Due to the second thread never having executed `git_libgit2_init()`, the first thread will clean up TLS data and as a result also free the `_tls_index` variable. When detaching the second thread, we unconditionally access the now-free'd `_tls_index` variable, which is obviously not going to work out well. Fix the issue by converting the code to use fiber-local storage instead of thread-local storage. While FLS will behave the exact same as TLS if no fibers are in use, it does allow us to specify a destructor similar to the one that is accepted by pthread_key_create(3P). Like this, we do not have to manually free indices anymore, but will let the FLS handle calling the destructor. This allows us to get rid of `DllMain()` completely, as we only used it to keep track of when threads were exiting and results in an overall simplification of TLS cleanup.

759ec7d4

2019-06-15T22:01:00

win32: cast GetProcAddress to void * before casting GetProcAddress is prototyped to return a `FARPROC`, which is meant to be a generic function pointer. It's literally `int (FAR WINAPI * FARPROC)()` which gcc complains if you attempt to cast to a `void (*)(GIT_SRWLOCK *)`. Cast to a `void *` before casting to avoid warnings about the arguments.

0c7f49dd

2017-06-30T13:39:01

Make sure to always include "common.h" first Next to including several files, our "common.h" header also declares various macros which are then used throughout the project. As such, we have to make sure to always include this file first in all implementation files. Otherwise, we might encounter problems or even silent behavioural differences due to macros or defines not being defined as they should be. So in fact, our header and implementation files should make sure to always include "common.h" first. This commit does so by establishing a common include pattern. Header files inside of "src" will now always include "common.h" as its first other file, separated by a newline from all the other includes to make it stand out as special. There are two cases for the implementation files. If they do have a matching header file, they will always include this one first, leading to "common.h" being transitively included as first file. If they do not have a matching header file, they instead include "common.h" as first file themselves. This fixes the outlined problems and will become our standard practice for header and source files inside of the "src/" from now on.

82f15896

2016-11-18T07:19:22

threads: introduce `git_thread_exit` Introduce `git_thread_exit`, which will allow threads to terminate at an arbitrary time, returning a `void *`. On Windows, this means that we need to store the current `git_thread` in TLS, so that we can set its `return` value when terminating. We cannot simply use `ExitThread`, since Win32 returns `DWORD`s from threads; we return `void *`.

aab266c9

2016-06-20T20:07:33

threads: add platform-independent thread initialization function

8aaa9fb6

2016-06-20T18:21:42

win32: rename pthread.{c,h} to thread.{c,h} The old pthread-file did re-implement the pthreads API with exact symbol matching. As the thread-abstraction has now been split up between Unix- and Windows-specific files within the `git_` namespace to avoid symbol-clashes between libgit2 and pthreads, the rewritten wrappers have nothing to do with pthreads anymore. Rename the Windows-specific pthread-files to honor this change.

thodg/libgit2/src/win32/thread.c

src/win32/thread.c

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