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-rw-r--r--src/lib/util/ioprocs.h138
1 files changed, 138 insertions, 0 deletions
diff --git a/src/lib/util/ioprocs.h b/src/lib/util/ioprocs.h
index 78c06e71318..0a4e5c384f0 100644
--- a/src/lib/util/ioprocs.h
+++ b/src/lib/util/ioprocs.h
@@ -27,6 +27,14 @@ class osd_file;
namespace util {
+/// \defgroup ioprocs Generic I/O interfaces
+/// \{
+
+/// \brief Interface to an input stream
+///
+/// Represents a stream producing a sequence of bytes with no further
+/// structure.
+/// \sa write_stream read_write_stream random_read
class read_stream
{
public:
@@ -34,10 +42,29 @@ public:
virtual ~read_stream() = default;
+ /// \brief Read from the current position in the stream
+ ///
+ /// Reads up to the specified number of bytes from the stream into
+ /// the supplied buffer. May read less than the requested number of
+ /// bytes if the end of the stream is reached or an error occurs.
+ /// If the stream supports seeking, reading starts at the current
+ /// position in the stream, and the current position is incremented
+ /// by the number of bytes read.
+ /// \param [out] buffer Destination buffer. Must be large enough to
+ /// hold the requested number of bytes.
+ /// \param [in] length Maximum number of bytes to read.
+ /// \param [out] actual Number of bytes actually read. Will always
+ /// be less than or equal to the requested length.
+ /// \return An error condition if reading stopped due to an error.
virtual std::error_condition read(void *buffer, std::size_t length, std::size_t &actual) noexcept = 0;
};
+/// \brief Interface to an output stream
+///
+/// Represents a stream that accepts a sequence of bytes with no further
+/// structure.
+/// \sa read_stream read_write_stream random_write
class write_stream
{
public:
@@ -45,12 +72,43 @@ public:
virtual ~write_stream() = default;
+ /// \brief Finish writing data
+ ///
+ /// Performs any tasks necessary to finish writing data to the
+ /// stream and guarantee that the written data can be read in its
+ /// entirety. Further writes may not be possible.
+ /// \return An error condition if the operation fails.
virtual std::error_condition finalize() noexcept = 0;
+
+ /// \brief Flush application-side caches
+ ///
+ /// Flushes any caches to the underlying stream. Success does not
+ /// guarantee that data has reached persistent storage.
+ /// \return An error condition if flushing caches fails.
virtual std::error_condition flush() noexcept = 0;
+
+ /// \brief Write at the current position in the stream
+ ///
+ /// Writes up to the specified number of bytes from the supplied
+ /// buffer to the stream. May write less than the requested number
+ /// of bytes if an error occurs. If the stream supports seeking,
+ /// writing starts at the current position in the stream, and the
+ /// current position is incremented by the number of bytes written.
+ /// \param [in] buffer Buffer containing the data to write. Must
+ /// contain at least the specified number of bytes.
+ /// \param [in] length Number of bytes to write.
+ /// \param [out] actual Number of bytes actually written. Will
+ /// always be less than or equal to the requested length.
+ /// \return An error condition if writing stopped due to an error.
virtual std::error_condition write(void const *buffer, std::size_t length, std::size_t &actual) noexcept = 0;
};
+/// \brief Interface to an I/O stream
+///
+/// Represents an object that acts as both a source of and sink for byte
+/// sequences.
+/// \sa read_stream write_stream random_read_write
class read_write_stream : public virtual read_stream, public virtual write_stream
{
public:
@@ -58,41 +116,121 @@ public:
};
+/// \brief Interface to a byte sequence that supports seeking
+///
+/// Provides an interface for controlling the position within a byte
+/// sequence that supports seeking.
+/// \sa random_read random_write random_read_write
class random_access
{
public:
virtual ~random_access() = default;
+ /// \brief Set the position in the stream
+ ///
+ /// Sets the position for the next read or write operation. It may
+ /// be possible to set the position beyond the end of the stream.
+ /// \param [in] offset The offset in bytes, relative to the position
+ /// specified by the whence parameter.
+ /// \param [in] whence One of SEEK_SET, SEEK_CUR or SEEK_END, to
+ /// interpret the offset parameter relative to the beginning of
+ /// the stream, the current position in the stream, or the end of
+ /// the stream, respectively.
+ /// \return An error condition of the operation failed.
virtual std::error_condition seek(std::int64_t offset, int whence) noexcept = 0;
+
+ /// \brief Get the current position in the stream
+ ///
+ /// Gets the position in the stream for the next read or write
+ /// operation. The position may be beyond the end of the stream.
+ /// \param [out] result The position in bytes relative to the
+ /// beginning of the stream. Not valid if the operation fails.
+ /// \return An error condition if the operation failed.
virtual std::error_condition tell(std::uint64_t &result) noexcept = 0;
+
+ /// \brief Get the length of the stream
+ ///
+ /// Gets the current length of the stream.
+ /// \param [out] result The lenght of the stream in bytes. Not
+ /// valid if the operation fails.
+ /// \return An error condtion if the operation failed.
virtual std::error_condition length(std::uint64_t &result) noexcept = 0;
};
+/// \brief Interface to a random-access byte input sequence
+///
+/// Provides an interface for reading from aritrary positions within a
+/// byte sequence. No further structure is provided.
+/// \sa read_stream random_write random_read_write
class random_read : public virtual read_stream, public virtual random_access
{
public:
using ptr = std::unique_ptr<random_read>;
+ /// \brief Read from specified position
+ ///
+ /// Reads up to the specified number of bytes into the supplied
+ /// buffer. If seeking is supported, reading starts at the
+ /// specified position and the current position is unaffected. May
+ /// read less than the requested number of bytes if the end of the
+ /// stream is encountered or an error occurs.
+ /// \param [in] offset The position to start reading from, specified
+ /// as a number of bytes from the beginning of the stream.
+ /// \param [out] buffer Destination buffer. Must be large enough to
+ /// hold the requested number of bytes.
+ /// \param [in] length Maximum number of bytes to read.
+ /// \param [out] actual Number of bytes actually read. Will always
+ /// be less than or equal to the requested length.
+ /// \return An error condition if seeking failed or reading stopped
+ /// due to an error.
virtual std::error_condition read_at(std::uint64_t offset, void *buffer, std::size_t length, std::size_t &actual) noexcept = 0;
};
+/// \brief Interface to a random-access byte output sequence
+///
+/// Provides an interface for writing to arbitrary positions within a
+/// byte sequence. No further structure is provided.
+/// \sa write_stream random_read random_read_write
class random_write : public virtual write_stream, public virtual random_access
{
public:
using ptr = std::unique_ptr<random_write>;
+ /// \brief Write at specified position
+ ///
+ /// Writes up to the specified number of bytes from the supplied
+ /// buffer. If seeking is supported, writing starts at the
+ /// specified position and the current position is unaffected. May
+ /// write less than the requested number of bytes if an error
+ /// occurs.
+ /// \param [in] offset The position to start writing at, specified
+ /// as a number of bytes from the beginning of the stream.
+ /// \param [in] buffer Buffer containing the data to write. Must
+ /// contain at least the specified number of bytes.
+ /// \param [in] length Number of bytes to write.
+ /// \param [out] actual Number of bytes actually written. Will
+ /// always be less than or equal to the requested length.
+ /// \return An error condition if seeking failed or writing stopped
+ /// due to an error.
virtual std::error_condition write_at(std::uint64_t offset, void const *buffer, std::size_t length, std::size_t &actual) noexcept = 0;
};
+/// \brief Interface to a random-access read/write byte sequence
+///
+/// Provides an interface for reading from and writing to arbitrary
+/// positions within a byte sequence. No further structure is provided.
+/// \sa random_read random_write read_write_stream
class random_read_write : public read_write_stream, public virtual random_read, public virtual random_write
{
public:
using ptr = std::unique_ptr<random_read_write>;
};
+/// \}
+
random_read::ptr ram_read(void const *data, std::size_t size) noexcept;
random_read::ptr ram_read(void const *data, std::size_t size, std::uint8_t filler) noexcept;