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Kernel: Let the user read/write more than one page from/to dev files

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Previously reads and writes to /dev/zero, /dev/full, /dev/null and
/dev/random were limited to 4096 bytes.

This removes that restriction so that users can enjoy more zero bytes
in their buffers.
This commit is contained in:
Gunnar Beutner 2021-05-27 09:13:49 +02:00 • committed by Andreas Kling
parent a272c04c8a
commit 1ce32ef675
4 changed files with 7 additions and 9 deletions
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5
Kernel/Devices/FullDevice.cpp
View file

@ -28,10 +28,9 @@ bool FullDevice::can_read(const FileDescription&, size_t) const
KResultOr<size_t> FullDevice::read(FileDescription&, u64, UserOrKernelBuffer& buffer, size_t size) KResultOr<size_t> FullDevice::read(FileDescription&, u64, UserOrKernelBuffer& buffer, size_t size)
{ {
ssize_t count = min(static_cast<size_t>(PAGE_SIZE), size); if (!buffer.memset(0, size))
if (!buffer.memset(0, count))
return EFAULT; return EFAULT;
return count; return size;
} }
KResultOr<size_t> FullDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t size) KResultOr<size_t> FullDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t size)

2
Kernel/Devices/NullDevice.cpp
View file

@ -43,7 +43,7 @@ KResultOr<size_t> NullDevice::read(FileDescription&, u64, UserOrKernelBuffer&, s
KResultOr<size_t> NullDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t buffer_size) KResultOr<size_t> NullDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t buffer_size)
{ {
return min(static_cast<size_t>(PAGE_SIZE), buffer_size); return buffer_size;
} }
} }

2
Kernel/Devices/RandomDevice.cpp
View file

@ -34,7 +34,7 @@ KResultOr<size_t> RandomDevice::read(FileDescription&, u64, UserOrKernelBuffer&
KResultOr<size_t> RandomDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t size) KResultOr<size_t> RandomDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t size)
{ {
// FIXME: Use input for entropy? I guess that could be a neat feature? // FIXME: Use input for entropy? I guess that could be a neat feature?
return min(static_cast<size_t>(PAGE_SIZE), size); return size;
} }
} }

7
Kernel/Devices/ZeroDevice.cpp
View file

@ -26,15 +26,14 @@ bool ZeroDevice::can_read(const FileDescription&, size_t) const
KResultOr<size_t> ZeroDevice::read(FileDescription&, u64, UserOrKernelBuffer& buffer, size_t size) KResultOr<size_t> ZeroDevice::read(FileDescription&, u64, UserOrKernelBuffer& buffer, size_t size)
{ {
ssize_t count = min(static_cast<size_t>(PAGE_SIZE), size); if (!buffer.memset(0, size))
if (!buffer.memset(0, count))
return EFAULT; return EFAULT;
return count; return size;
} }
KResultOr<size_t> ZeroDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t size) KResultOr<size_t> ZeroDevice::write(FileDescription&, u64, const UserOrKernelBuffer&, size_t size)
{ {
return min(static_cast<size_t>(PAGE_SIZE), size); return size;
} }
} }