mirror of
https://github.com/SerenityOS/serenity
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77 lines
2.7 KiB
C++
77 lines
2.7 KiB
C++
#pragma once
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#include <AK/AKString.h>
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#include <AK/RefCounted.h>
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#include <AK/NonnullRefPtr.h>
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#include <AK/Types.h>
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#include <Kernel/KResult.h>
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#include <Kernel/UnixTypes.h>
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#include <Kernel/VirtualAddress.h>
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class FileDescription;
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class Process;
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class Region;
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// File is the base class for anything that can be referenced by a FileDescription.
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//
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// The most important functions in File are:
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//
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// read() and write()
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// - Implement reading and writing.
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// - Return the number of bytes read/written, OR a negative error code.
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//
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// can_read() and can_write()
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//
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// - Used to implement blocking I/O, and the select() and poll() syscalls.
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// - Return true if read() or write() would succeed, respectively.
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// - Note that can_read() should return true in EOF conditions,
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// and a subsequent call to read() should return 0.
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//
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// ioctl()
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//
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// - Optional. If unimplemented, ioctl() on this File will fail with -ENOTTY.
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// - Can be overridden in subclasses to implement arbitrary functionality.
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// - Subclasses should take care to validate incoming addresses before dereferencing.
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//
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// mmap()
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//
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// - Optional. If unimplemented, mmap() on this File will fail with -ENODEV.
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// - Called by mmap() when userspace wants to memory-map this File somewhere.
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// - Should create a Region in the Process and return it if successful.
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class File : public RefCounted<File> {
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public:
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virtual ~File();
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virtual KResultOr<NonnullRefPtr<FileDescription>> open(int options);
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virtual void close();
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virtual bool can_read(FileDescription&) const = 0;
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virtual bool can_write(FileDescription&) const = 0;
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virtual ssize_t read(FileDescription&, byte*, ssize_t) = 0;
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virtual ssize_t write(FileDescription&, const byte*, ssize_t) = 0;
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virtual int ioctl(FileDescription&, unsigned request, unsigned arg);
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virtual KResultOr<Region*> mmap(Process&, FileDescription&, VirtualAddress preferred_vaddr, size_t offset, size_t size, int prot);
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virtual String absolute_path(const FileDescription&) const = 0;
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virtual KResult truncate(off_t) { return KResult(-EINVAL); }
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virtual const char* class_name() const = 0;
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virtual bool is_seekable() const { return false; }
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virtual bool is_inode() const { return false; }
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virtual bool is_shared_memory() const { return false; }
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virtual bool is_fifo() const { return false; }
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virtual bool is_device() const { return false; }
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virtual bool is_tty() const { return false; }
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virtual bool is_master_pty() const { return false; }
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virtual bool is_block_device() const { return false; }
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virtual bool is_character_device() const { return false; }
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virtual bool is_socket() const { return false; }
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protected:
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File();
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};
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