Kernel: Make File::write() and File::read() return KResultOr<size_t>

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.

Kernel/Devices/BXVGADevice.h

@@ -47,8 +47,8 @@ private:
     virtual const char* class_name() const override { return "BXVGA"; }
     virtual bool can_read(const FileDescription&, size_t) const override { return true; }
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override { return -EINVAL; }
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override { return -EINVAL; }
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override { return -EINVAL; }
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override { return -EINVAL; }
     virtual bool read_blocks(unsigned, u16, u8*) override { return false; }
     virtual bool write_blocks(unsigned, u16, const u8*) override { return false; }
 

Kernel/Devices/DiskPartition.cpp

@@ -48,7 +48,7 @@ DiskPartition::~DiskPartition()
 {
 }
 
-ssize_t DiskPartition::read(FileDescription& fd, size_t offset, u8* outbuf, ssize_t len)
+KResultOr<size_t> DiskPartition::read(FileDescription& fd, size_t offset, u8* outbuf, size_t len)
 {
     unsigned adjust = m_block_offset * block_size();
 
@@ -70,7 +70,7 @@ bool DiskPartition::can_read(const FileDescription& fd, size_t offset) const
     return m_device->can_read(fd, offset + adjust);
 }
 
-ssize_t DiskPartition::write(FileDescription& fd, size_t offset, const u8* inbuf, ssize_t len)
+KResultOr<size_t> DiskPartition::write(FileDescription& fd, size_t offset, const u8* inbuf, size_t len)
 {
     unsigned adjust = m_block_offset * block_size();
 

Kernel/Devices/DiskPartition.h

@@ -40,9 +40,9 @@ public:
     virtual bool write_blocks(unsigned index, u16 count, const u8*) override;
 
     // ^BlockDevice
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
     virtual bool can_read(const FileDescription&, size_t) const override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_write(const FileDescription&, size_t) const override;
 
 private:

Kernel/Devices/FullDevice.cpp

@@ -46,18 +46,18 @@ bool FullDevice::can_read(const FileDescription&, size_t) const
     return true;
 }
 
-ssize_t FullDevice::read(FileDescription&, size_t, u8* buffer, ssize_t size)
+KResultOr<size_t> FullDevice::read(FileDescription&, size_t, u8* buffer, size_t size)
 {
-    ssize_t count = min(static_cast<ssize_t>(PAGE_SIZE), size);
-    memset(buffer, 0, (size_t)count);
+    ssize_t count = min(static_cast<size_t>(PAGE_SIZE), size);
+    memset(buffer, 0, count);
     return count;
 }
 
-ssize_t FullDevice::write(FileDescription&, size_t, const u8*, ssize_t size)
+KResultOr<size_t> FullDevice::write(FileDescription&, size_t, const u8*, size_t size)
 {
     if (size == 0)
         return 0;
-    return -ENOSPC;
+    return KResult(-ENOSPC);
 }
 
 }

Kernel/Devices/FullDevice.h

@@ -38,8 +38,8 @@ public:
 
 private:
     // ^CharacterDevice
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_read(const FileDescription&, size_t) const override;
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
     virtual const char* class_name() const override { return "FullDevice"; }

Kernel/Devices/KeyboardDevice.cpp

@@ -366,9 +366,9 @@ bool KeyboardDevice::can_read(const FileDescription&, size_t) const
     return !m_queue.is_empty();
 }
 
-ssize_t KeyboardDevice::read(FileDescription&, size_t, u8* buffer, ssize_t size)
+KResultOr<size_t> KeyboardDevice::read(FileDescription&, size_t, u8* buffer, size_t size)
 {
-    ssize_t nread = 0;
+    size_t nread = 0;
     while (nread < size) {
         if (m_queue.is_empty())
             break;
@@ -382,7 +382,7 @@ ssize_t KeyboardDevice::read(FileDescription&, size_t, u8* buffer, ssize_t size)
     return nread;
 }
 
-ssize_t KeyboardDevice::write(FileDescription&, size_t, const u8*, ssize_t)
+KResultOr<size_t> KeyboardDevice::write(FileDescription&, size_t, const u8*, size_t)
 {
     return 0;
 }

Kernel/Devices/KeyboardDevice.h

@@ -54,9 +54,9 @@ public:
     void set_maps(Keyboard::CharacterMapData character_map);
 
     // ^CharacterDevice
-    virtual ssize_t read(FileDescription&, size_t, u8* buffer, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
     virtual bool can_read(const FileDescription&, size_t) const override;
-    virtual ssize_t write(FileDescription&, size_t, const u8* buffer, ssize_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
 
     virtual const char* purpose() const override { return class_name(); }

Kernel/Devices/MBVGADevice.h

@@ -47,8 +47,8 @@ private:
     virtual const char* class_name() const override { return "MBVGA"; }
     virtual bool can_read(const FileDescription&, size_t) const override { return true; }
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override { return -EINVAL; }
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override { return -EINVAL; }
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override { return -EINVAL; }
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override { return -EINVAL; }
     virtual bool read_blocks(unsigned, u16, u8*) override { return false; }
     virtual bool write_blocks(unsigned, u16, const u8*) override { return false; }
 

Kernel/Devices/NullDevice.cpp

@@ -52,14 +52,14 @@ bool NullDevice::can_read(const FileDescription&, size_t) const
     return true;
 }
 
-ssize_t NullDevice::read(FileDescription&, size_t, u8*, ssize_t)
+KResultOr<size_t> NullDevice::read(FileDescription&, size_t, u8*, size_t)
 {
     return 0;
 }
 
-ssize_t NullDevice::write(FileDescription&, size_t, const u8*, ssize_t buffer_size)
+KResultOr<size_t> NullDevice::write(FileDescription&, size_t, const u8*, size_t buffer_size)
 {
-    return min(static_cast<ssize_t>(PAGE_SIZE), buffer_size);
+    return min(static_cast<size_t>(PAGE_SIZE), buffer_size);
 }
 
 }

Kernel/Devices/NullDevice.h

@@ -40,8 +40,8 @@ public:
 
 private:
     // ^CharacterDevice
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
     virtual bool can_read(const FileDescription&, size_t) const override;
     virtual const char* class_name() const override { return "NullDevice"; }

Kernel/Devices/PATADiskDevice.cpp

@@ -80,7 +80,7 @@ void PATADiskDevice::set_drive_geometry(u16 cyls, u16 heads, u16 spt)
     m_sectors_per_track = spt;
 }
 
-ssize_t PATADiskDevice::read(FileDescription&, size_t offset, u8* outbuf, ssize_t len)
+KResultOr<size_t> PATADiskDevice::read(FileDescription&, size_t offset, u8* outbuf, size_t len)
 {
     unsigned index = offset / block_size();
     u16 whole_blocks = len / block_size();
@@ -121,7 +121,7 @@ bool PATADiskDevice::can_read(const FileDescription&, size_t offset) const
     return offset < (m_cylinders * m_heads * m_sectors_per_track * block_size());
 }
 
-ssize_t PATADiskDevice::write(FileDescription&, size_t offset, const u8* inbuf, ssize_t len)
+KResultOr<size_t> PATADiskDevice::write(FileDescription&, size_t offset, const u8* inbuf, size_t len)
 {
     unsigned index = offset / block_size();
     u16 whole_blocks = len / block_size();

Kernel/Devices/PATADiskDevice.h

@@ -61,9 +61,9 @@ public:
     void set_drive_geometry(u16, u16, u16);
 
     // ^BlockDevice
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
     virtual bool can_read(const FileDescription&, size_t) const override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_write(const FileDescription&, size_t) const override;
 
 protected:

Kernel/Devices/PS2MouseDevice.cpp

@@ -324,7 +324,7 @@ bool PS2MouseDevice::can_read(const FileDescription&, size_t) const
     return !m_queue.is_empty();
 }
 
-ssize_t PS2MouseDevice::read(FileDescription&, size_t, u8* buffer, ssize_t size)
+KResultOr<size_t> PS2MouseDevice::read(FileDescription&, size_t, u8* buffer, size_t size)
 {
     ASSERT(size > 0);
     size_t nread = 0;
@@ -344,7 +344,7 @@ ssize_t PS2MouseDevice::read(FileDescription&, size_t, u8* buffer, ssize_t size)
     return nread;
 }
 
-ssize_t PS2MouseDevice::write(FileDescription&, size_t, const u8*, ssize_t)
+KResultOr<size_t> PS2MouseDevice::write(FileDescription&, size_t, const u8*, size_t)
 {
     return 0;
 }

Kernel/Devices/PS2MouseDevice.h

@@ -44,8 +44,8 @@ public:
 
     // ^CharacterDevice
     virtual bool can_read(const FileDescription&, size_t) const override;
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
 
     virtual const char* purpose() const override { return class_name(); }

Kernel/Devices/RandomDevice.cpp

@@ -43,16 +43,16 @@ bool RandomDevice::can_read(const FileDescription&, size_t) const
     return true;
 }
 
-ssize_t RandomDevice::read(FileDescription&, size_t, u8* buffer, ssize_t size)
+KResultOr<size_t> RandomDevice::read(FileDescription&, size_t, u8* buffer, size_t size)
 {
     get_good_random_bytes(buffer, size);
     return size;
 }
 
-ssize_t RandomDevice::write(FileDescription&, size_t, const u8*, ssize_t size)
+KResultOr<size_t> RandomDevice::write(FileDescription&, size_t, const u8*, size_t size)
 {
     // FIXME: Use input for entropy? I guess that could be a neat feature?
-    return min(static_cast<ssize_t>(PAGE_SIZE), size);
+    return min(static_cast<size_t>(PAGE_SIZE), size);
 }
 
 }

Kernel/Devices/RandomDevice.h

@@ -38,8 +38,8 @@ public:
 
 private:
     // ^CharacterDevice
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_read(const FileDescription&, size_t) const override;
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
     virtual const char* class_name() const override { return "RandomDevice"; }

Kernel/Devices/SB16.cpp

@@ -172,7 +172,7 @@ bool SB16::can_read(const FileDescription&, size_t) const
     return false;
 }
 
-ssize_t SB16::read(FileDescription&, size_t, u8*, ssize_t)
+KResultOr<size_t> SB16::read(FileDescription&, size_t, u8*, size_t)
 {
     return 0;
 }
@@ -226,7 +226,7 @@ void SB16::wait_for_irq()
     disable_irq();
 }
 
-ssize_t SB16::write(FileDescription&, size_t, const u8* data, ssize_t length)
+KResultOr<size_t> SB16::write(FileDescription&, size_t, const u8* data, size_t length)
 {
     if (!m_dma_region) {
         auto page = MM.allocate_supervisor_physical_page();

Kernel/Devices/SB16.h

@@ -46,8 +46,8 @@ public:
 
     // ^CharacterDevice
     virtual bool can_read(const FileDescription&, size_t) const override;
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
 
     virtual const char* purpose() const override { return class_name(); }

Kernel/Devices/SerialDevice.cpp

@@ -45,7 +45,7 @@ bool SerialDevice::can_read(const FileDescription&, size_t) const
     return (get_line_status() & DataReady) != 0;
 }
 
-ssize_t SerialDevice::read(FileDescription&, size_t, u8* buffer, ssize_t size)
+KResultOr<size_t> SerialDevice::read(FileDescription&, size_t, u8* buffer, size_t size)
 {
     if (!size)
         return 0;
@@ -63,7 +63,7 @@ bool SerialDevice::can_write(const FileDescription&, size_t) const
     return (get_line_status() & EmptyTransmitterHoldingRegister) != 0;
 }
 
-ssize_t SerialDevice::write(FileDescription&, size_t, const u8* buffer, ssize_t size)
+KResultOr<size_t> SerialDevice::write(FileDescription&, size_t, const u8* buffer, size_t size)
 {
     if (!size)
         return 0;

Kernel/Devices/SerialDevice.h

@@ -43,9 +43,9 @@ public:
 
     // ^CharacterDevice
     virtual bool can_read(const FileDescription&, size_t) const override;
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
     virtual bool can_write(const FileDescription&, size_t) const override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
 
     enum InterruptEnable {
         LowPowerMode = 0x01 << 5,

Kernel/Devices/ZeroDevice.cpp

@@ -44,16 +44,16 @@ bool ZeroDevice::can_read(const FileDescription&, size_t) const
     return true;
 }
 
-ssize_t ZeroDevice::read(FileDescription&, size_t, u8* buffer, ssize_t size)
+KResultOr<size_t> ZeroDevice::read(FileDescription&, size_t, u8* buffer, size_t size)
 {
-    ssize_t count = min(static_cast<ssize_t>(PAGE_SIZE), size);
-    memset(buffer, 0, (size_t)count);
+    ssize_t count = min(static_cast<size_t>(PAGE_SIZE), size);
+    memset(buffer, 0, count);
     return count;
 }
 
-ssize_t ZeroDevice::write(FileDescription&, size_t, const u8*, ssize_t size)
+KResultOr<size_t> ZeroDevice::write(FileDescription&, size_t, const u8*, size_t size)
 {
-    return min(static_cast<ssize_t>(PAGE_SIZE), size);
+    return min(static_cast<size_t>(PAGE_SIZE), size);
 }
 
 }

Kernel/Devices/ZeroDevice.h

@@ -38,8 +38,8 @@ public:
 
 private:
     // ^CharacterDevice
-    virtual ssize_t read(FileDescription&, size_t, u8*, ssize_t) override;
-    virtual ssize_t write(FileDescription&, size_t, const u8*, ssize_t) override;
+    virtual KResultOr<size_t> read(FileDescription&, size_t, u8*, size_t) override;
+    virtual KResultOr<size_t> write(FileDescription&, size_t, const u8*, size_t) override;
     virtual bool can_read(const FileDescription&, size_t) const override;
     virtual bool can_write(const FileDescription&, size_t) const override { return true; }
     virtual const char* class_name() const override { return "ZeroDevice"; }