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path: root/Kernel/Devices/ZeroDevice.h
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2021-12-28Kernel: Remove the kmalloc_eternal heap :^)Andreas Kling
This was a premature optimization from the early days of SerenityOS. The eternal heap was a simple bump pointer allocator over a static byte array. My original idea was to avoid heap fragmentation and improve data locality, but both ideas were rooted in cargo culting, not data. We would reserve 4 MiB at boot and only ended up using ~256 KiB, wasting the rest. This patch replaces all kmalloc_eternal() usage by regular kmalloc().
2021-11-08Kernel: Replace KResult and KResultOr<T> with Error and ErrorOr<T>Andreas Kling
We now use AK::Error and AK::ErrorOr<T> in both kernel and userspace! This was a slightly tedious refactoring that took a long time, so it's not unlikely that some bugs crept in. Nevertheless, it does pass basic functionality testing, and it's just real nice to finally see the same pattern in all contexts. :^)
2021-10-03Kernel: Use `operator ""sv` in all class_name() implementationsBrian Gianforcaro
Previously there was a mix of returning plain strings and returning explicit string views using `operator ""sv`. This change switches them all to standardized on `operator ""sv` as it avoids a call to strlen.
2021-09-17Kernel: Introduce the DeviceManagement singletonLiav A
This singleton simplifies many aspects that we struggled with before: 1. There's no need to make derived classes of Device expose the constructor as public anymore. The singleton is a friend of them, so he can call the constructor. This solves the issue with try_create_device helper neatly, hopefully for good. 2. Getting a reference of the NullDevice is now being done from this singleton, which means that NullDevice no longer needs to use its own singleton, and we can apply the try_create_device helper on it too :) 3. We can now defer registration completely after the Device constructor which means the Device constructor is merely assigning the major and minor numbers of the Device, and the try_create_device helper ensures it calls the after_inserting method immediately after construction. This creates a great opportunity to make registration more OOM-safe.
2021-09-11Kernel/Devices: Defer creation of SysFS component after the constructorLiav A
Instead of doing so in the constructor, let's do immediately after the constructor, so we can safely pass a reference of a Device, so the SysFSDeviceComponent constructor can use that object to identify whether it's a block device or a character device. This allows to us to not hold a device in SysFSDeviceComponent with a RefPtr. Also, we also call the before_removing method in both SlavePTY::unref and File::unref, so because Device has that method being overrided, it can ensure the device is removed always cleanly.
2021-09-08Kernel/Devices: Remove required_mode and device_name methodsLiav A
These methods are no longer needed because SystemServer is able to populate the DevFS on its own. Device absolute_path no longer assume a path to the /dev location, because it really should not assume any path to a Device node. Because StorageManagement still needs to know the storage name, we declare a virtual method only for StorageDevices to override, but this technique should really be removed later on.
2021-09-07Kernel: Rename FileDescription => OpenFileDescriptionAndreas Kling
Dr. POSIX really calls these "open file description", not just "file description", so let's call them exactly that. :^)
2021-07-11Kernel: Standardize the header include style to 'include <Kernel/...>'Brian Gianforcaro
This is the overwhelming standard in the project, but there were some cases in the kernel which were not following it, lets fix those cases!
2021-07-11Kernel: Make various T::class_name() and similar return StringViewAndreas Kling
Instead of returning char const*, we can also give you a StringView.
2021-06-19Kernel: Don't use naked new statements in init processLiav A
Instead, try to create the device objects in separate static methods, and if we fail for some odd reason to allocate memory for such devices, just panic with that reason.
2021-04-22Everything: Move to SPDX license identifiers in all files.Brian Gianforcaro
SPDX License Identifiers are a more compact / standardized way of representing file license information. See: https://spdx.dev/resources/use/#identifiers This was done with the `ambr` search and replace tool. ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
2021-03-17Kernel: Refactor storage stack with u64 as file operations offsetJean-Baptiste Boric
2021-01-22Kernel: Make device generate their own namesJean-Baptiste Boric
Besides removing the monolithic DevFSDeviceInode::determine_name() method, being able to determine a device's name inside the /dev hierarchy outside of DevFS has its uses.
2020-12-27Kernel: Add a method to determine the desired permissions of a DeviceLiav A
This method will be used later in DevFS, to set the appropriate permissions for each device node.
2020-09-13Kernel: Make copy_to/from_user safe and remove unnecessary checksTom
Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
2020-08-04Kernel: Make File::write() and File::read() return KResultOr<size_t>Andreas Kling
Instead of returning a ssize_t where negative values mean error, we now return KResultOr<size_t> and use the error state to report errors exclusively.
2020-04-10Kernel: Add explicit offset parameter to File::read etcConrad Pankoff
2020-02-16Kernel: Move all code into the Kernel namespaceAndreas Kling
2020-01-18Meta: Add license header to source filesAndreas Kling
As suggested by Joshua, this commit adds the 2-clause BSD license as a comment block to the top of every source file. For the first pass, I've just added myself for simplicity. I encourage everyone to add themselves as copyright holders of any file they've added or modified in some significant way. If I've added myself in error somewhere, feel free to replace it with the appropriate copyright holder instead. Going forward, all new source files should include a license header.
2019-11-04Kernel: Make File's can_read/can_write take a const FileDescription&Andreas Kling
Asking a File if we could possibly read or write it will never mutate the asking FileDescription&, so it should be const.
2019-07-03AK: Rename the common integer typedefs to make it obvious what they are.Andreas Kling
These types can be picked up by including <AK/Types.h>: * u8, u16, u32, u64 (unsigned) * i8, i16, i32, i64 (signed)
2019-06-07Kernel: Rename FileDescriptor to FileDescription.Andreas Kling
After reading a bunch of POSIX specs, I've learned that a file descriptor is the number that refers to a file description, not the description itself. So this patch renames FileDescriptor to FileDescription, and Process now has FileDescription* file_description(int fd).
2019-05-28Add clang-format fileRobin Burchell
Also run it across the whole tree to get everything using the One True Style. We don't yet run this in an automated fashion as it's a little slow, but there is a snippet to do so in makeall.sh.
2019-04-29Kernel: Have File virtuals take a FileDescriptor& rather than a Process&.Andreas Kling
This will allow us to implement different behaviors depending on the role of the descriptor a File is being accessed through.
2019-04-03Kernel: Move devices into Kernel/Devices/.Andreas Kling