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Kernel: Implement basic support for sys$mmap() with MAP_PRIVATE

Browse source 
You can now mmap a file as private and writable, and the changes you
make will only be visible to you.

This works because internally a MAP_PRIVATE region is backed by a
unique PrivateInodeVMObject instead of using the globally shared
SharedInodeVMObject like we always did before. :^)

Fixes #1045.
This commit is contained in:
Andreas Kling 2020-02-28 20:47:27 +01:00
parent aa1e209845
commit 8fbdda5a2d
11 changed files with 45 additions and 31 deletions
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12
Kernel/FileSystem/InodeFile.cpp
View file

@ -29,6 +29,7 @@
#include <Kernel/FileSystem/InodeFile.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
#include <Kernel/Process.h>
#include <Kernel/VM/PrivateInodeVMObject.h>
#include <Kernel/VM/SharedInodeVMObject.h>
namespace Kernel {
@ -60,11 +61,18 @@ ssize_t InodeFile::write(FileDescription& description, const u8* data, ssize_t c
return nwritten;
}
KResultOr<Region*> InodeFile::mmap(Process& process, FileDescription& description, VirtualAddress preferred_vaddr, size_t offset, size_t size, int prot)
KResultOr<Region*> InodeFile::mmap(Process& process, FileDescription& description, VirtualAddress preferred_vaddr, size_t offset, size_t size, int prot, bool shared)
{
ASSERT(offset == 0);
// FIXME: If PROT_EXEC, check that the underlying file system isn't mounted noexec.
auto* region = process.allocate_region_with_vmobject(preferred_vaddr, size, SharedInodeVMObject::create_with_inode(inode()), offset, description.absolute_path(), prot);
RefPtr<InodeVMObject> vmobject;
if (shared)
vmobject = SharedInodeVMObject::create_with_inode(inode());
else
vmobject = PrivateInodeVMObject::create_with_inode(inode());
if (!vmobject)
return KResult(-ENOMEM);
auto* region = process.allocate_region_with_vmobject(preferred_vaddr, size, *vmobject, offset, description.absolute_path(), prot);
if (!region)
return KResult(-ENOMEM);
return region;