George Bișoc
abe89d7cde
This fixes an issue where ReactOS would assert on QuotaUsage == 0 as the process was still taking up quotas during a quota block de-reference with root cause of ThisBufferLength member field being 0 which made process quota charging/returning flow unbalanced. In addition to that, on FsRtlCancelNotify routine API all we must ensure that if PsChargePoolQuota or ExAllocatePoolWithTag function fails we have to handle the raised exceptions accordingly and return the charged quota back (if we actually charged quotas that is). With said, wrap that part of code with SEH. === DOCUMENTATION REMARKS === The cause of the assert is due to the fact ThisBufferLength was being handled wrongly ever since, until this commit. When FsRtl of the Executive has to filter reported changes (with logic algorithm implemented in FsRtlNotifyFilterReportChange function), the said function will charge the quota of a given process with an amount that is represented as the buffer length whose size is expressed in bytes. This length buffer is preserved in a local variable called NumberOfBytes, which is initialized from BufferLength member field of notification structure or from the length from stack parameters pointed from an IRP. As it currently stands, the code is implemented in such a way that FsRtlNotifyFilterReportChange will charge quotas to a process but it doesn't assign the buffer length to ThisBufferLength. On the first glimpse ThisBufferLength and BufferLength are very similar members that serve exact same purpose but in reality there's a subtle distinction between the two. BufferLength is a member whose length size is given by FSDs (filesystem drivers) during a notification dispatching. Whenever FsRtl receives the notification structure packed with data from the filesystem, the length pointed by BufferLength gets passed to ThisBufferLength and from now on the kernel has to use this member for the whole time of its task to accomplish whatever request it's been given by the filesystem. In other words, BufferLength is strictly used only to pass length size data to the kernel by initializing ThisBufferLength based on that length and unequivocally the kernel uses this member field. What we're doing is that ThisBufferLength never receives the length from BufferLength therefore whenever FsRtl component has to return quotas back it'll return an amount of 0 (which means no amount to return) and that's a bug in the kernel.
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What is ReactOS?
ReactOS™ is an Open Source effort to develop a quality operating system that is compatible with applications and drivers written for the Microsoft® Windows™ NT family of operating systems (NT4, 2000, XP, 2003, Vista, 7).
The ReactOS project, although currently focused on Windows Server 2003 compatibility, is always keeping an eye toward compatibility with Windows Vista and future Windows NT releases.
The code of ReactOS is licensed under GNU GPL 2.0.
Product quality warning
ReactOS is currently an Alpha quality operating system. This means that ReactOS is under heavy development and you have to be ready to encounter some problems. Different things may not work well and it can corrupt the data present on your hard disk. It is HIGHLY recommended to test ReactOS on a virtual machine or on a computer with no sensitive or critical data!
Building
To build the system it is strongly advised to use the ReactOS Build Environment (RosBE). Up-to-date versions for Windows and for Unix/GNU-Linux are available from our download page at: "Build Environment".
Alternatively one can use Microsoft Visual C++ (MSVC) version 2015+. Building with MSVC is covered here: "Visual Studio or Microsoft Visual C++".
See "Building ReactOS" article for more details.
Binaries
To build ReactOS you must run the configure script in the directory you want to have your build files. Choose configure.cmd or configure.sh depending on your system. Then run ninja <modulename> to build a module you want or just ninja to build all modules.
Bootable images
To build a bootable CD image run ninja bootcd from the build directory. This will create a CD image with a filename bootcd.iso.
You can always download fresh binary builds of bootable images from the "Daily builds" page.
Installing
By default, ReactOS currently can only be installed on a machine that has a FAT16 or FAT32 partition as the active (bootable) partition. The partition on which ReactOS is to be installed (which may or may not be the bootable partition) must also be formatted as FAT16 or FAT32. ReactOS Setup can format the partitions if needed.
Starting with 0.4.10, ReactOS can be installed using the BtrFS file system. But consider this as an experimental feature and thus regressions not triggered on FAT setup may be observed.
To install ReactOS from the bootable CD distribution, extract the archive contents. Then burn the CD image, boot from it, and follow the instructions.
See "Installing ReactOS" Wiki page or INSTALL for more details.
Testing
If you discover a bug in ReactOS search on JIRA first - it might be reported already. If not report the bug providing logs and as much information as possible.
See "File Bugs" for a guide.
NOTE: The bug tracker is not for discussions. Please use our official chat or our forum.
Contributing 
We are always looking for developers! Check how to contribute if you are willing to participate.
Legal notice: If you have seen proprietary Microsoft Windows source code (including but not limited to the leaked Windows NT 3.5, NT 4, 2000 source code and the Windows Research Kernel), your contribution won't be accepted because of potential copyright violation.
Try out cloud-based ReactOS development using Gitpod and Docker:
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More information
ReactOS is a Free and Open Source operating system based on the Windows architecture, providing support for existing applications and drivers, and an alternative to the current dominant consumer operating system.
It is not another wrapper built on Linux, like WINE. It does not attempt or plan to compete with WINE; in fact, the user-mode part of ReactOS is almost entirely WINE-based and our two teams have cooperated closely in the past.
ReactOS is also not "yet another OS". It does not attempt to be a third player like any other alternative OS out there. People are not meant to uninstall Linux and use ReactOS instead; ReactOS is a replacement for Windows users who want a Windows replacement that behaves just like Windows.
More information is available at: reactos.org.
Also see the media/doc subdirectory for some sparse notes.
Who is responsible
Active devs are listed as members of GitHub organization. See also the CREDITS file for others.
Code mirrors
The main development is done on GitHub. We have an alternative mirror in case GitHub is down.
There is also an obsolete SVN archive repository that is kept for historical purposes.