polyglot_file_system.h

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/*
 * Copyright (c) 2024, 2026, Oracle and/or its affiliates.
 *
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 * as published by the Free Software Foundation.
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 *
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#ifndef ROUTER_SRC_JIT_EXECUTOR_INCLUDE_MYSQLROUTER_POLYGLOT_FILE_SYSTEM_H_
#define ROUTER_SRC_JIT_EXECUTOR_INCLUDE_MYSQLROUTER_POLYGLOT_FILE_SYSTEM_H_
 
#include <cstdint>
#include <memory>
#include <string>
 
#include "mysqlrouter/file_system_exceptions.h"
 
namespace shcore {
namespace polyglot {
 
class ISeekable_channel {
 public:
  virtual ~ISeekable_channel() = default;
  /**
   * Tells whether or not this channel is open.
   */
  virtual bool is_open() = 0;
 
  /**
   * Closes this channel.
   *
   * <p> After a channel is closed, any further attempt to invoke I/O
   * operations upon it will cause a ClosedChannelException to be thrown.
   *
   * <p> If this channel is already closed then invoking this method has no
   * effect.
   *
   * <p> This method may be invoked at any time.  If some other thread has
   * already invoked it, however, then another invocation will block until
   * the first invocation is complete, after which it will return without
   * effect. </p>
   *
   * @throws  IOException  If an I/O error occurs
   */
  virtual void close() = 0;
 
  /**
   * Reads a sequence of bytes from this channel into the given buffer.
   *
   * <p> Bytes are read starting at this channel's current position, and
   * then the position is updated with the number of bytes actually read.
   * Otherwise this method behaves exactly as specified in the
   * ReadableByteChannel interface.
   *
   * @throws  ClosedChannelException      {@inheritDoc}
   * @throws  AsynchronousCloseException  {@inheritDoc}
   * @throws  ClosedByInterruptException  {@inheritDoc}
   * @throws  NonReadableChannelException {@inheritDoc}
   */
  virtual int64_t read(void *buffer, size_t size) = 0;
 
  /**
   * Writes a sequence of bytes to this channel from the given buffer.
   *
   * <p> Bytes are written starting at this channel's current position, unless
   * the channel is connected to an entity such as a file that is opened with
   * the APPEND option, in which case the position is first advanced to the end.
   * The entity to which the channel is connected is grown, if necessary, to
   * accommodate the written bytes, and then the position is updated with the
   * number of bytes actually written. Otherwise this method behaves exactly as
   * specified by the WritableByteChannel interface.
   *
   * @throws  ClosedChannelException      {@inheritDoc}
   * @throws  AsynchronousCloseException  {@inheritDoc}
   * @throws  ClosedByInterruptException  {@inheritDoc}
   * @throws  NonWritableChannelException {@inheritDoc}
   */
  virtual int64_t write(const char *buffer, size_t size) = 0;
 
  /**
   * Returns this channel's position.
   *
   * @return  This channel's position,
   *          a non-negative integer counting the number of bytes
   *          from the beginning of the entity to the current position
   *
   * @throws  ClosedChannelException
   *          If this channel is closed
   * @throws  IOException
   *          If some other I/O error occurs
   */
  virtual int64_t position() = 0;
 
  /**
   * Sets this channel's position.
   *
   * <p> Setting the position to a value that is greater than the current size
   * is legal but does not change the size of the entity.  A later attempt to
   * read bytes at such a position will immediately return an end-of-file
   * indication.  A later attempt to write bytes at such a position will cause
   * the entity to grow to accommodate the new bytes; the values of any bytes
   * between the previous end-of-file and the newly-written bytes are
   * unspecified.
   *
   * <p> Setting the channel's position is not recommended when connected to
   * an entity, typically a file, that is opened with the APPEND option.
   * When opened for append, the position is first advanced to the end before
   * writing.
   *
   * @param  new_position
   *         The new position, a non-negative integer counting
   *         the number of bytes from the beginning of the entity
   *
   * @return  This channel
   *
   * @throws  ClosedChannelException
   *          If this channel is closed
   * @throws  IllegalArgumentException
   *          If the new position is negative
   * @throws  IOException
   *          If some other I/O error occurs
   */
  virtual ISeekable_channel &set_position(int64_t new_position) = 0;
 
  /**
   * Returns the current size of entity to which this channel is connected.
   *
   * @return  The current size, measured in bytes
   *
   * @throws  ClosedChannelException
   *          If this channel is closed
   * @throws  IOException
   *          If some other I/O error occurs
   */
  virtual int64_t size() = 0;
 
  /**
   * Truncates the entity, to which this channel is connected, to the given
   * size.
   *
   * <p> If the given size is less than the current size then the entity is
   * truncated, discarding any bytes beyond the new end. If the given size is
   * greater than or equal to the current size then the entity is not modified.
   * In either case, if the current position is greater than the given size
   * then it is set to that size.
   *
   * <p> An implementation of this interface may prohibit truncation when
   * connected to an entity, typically a file, opened with the APPEND option.
   *
   * @param  size
   *         The new size, a non-negative byte count
   *
   * @return  This channel
   *
   * @throws  NonWritableChannelException
   *          If this channel was not opened for writing
   * @throws  ClosedChannelException
   *          If this channel is closed
   * @throws  IllegalArgumentException
   *          If the new size is negative
   * @throws  IOException
   *          If some other I/O error occurs
   */
  virtual ISeekable_channel &truncate(int64_t size) = 0;
};
 
class IDirectory_stream {};
 
class IFile_system {
 public:
  virtual ~IFile_system() = default;
 
  /**
   * Parses a path from an URI.
   *
   * @param uri the URI to be converted to Path
   * @return the Path representing given URI
   * @throws UnsupportedOperationException when URI scheme is not
   * supported
   * @throws IllegalArgumentException if preconditions on the {@code uri} do not
   * hold. The format of the URI is FileSystem specific.
   */
  virtual std::string parse_uri_path(const std::string &uri) = 0;
 
  /**
   * Parses a path from a String. This method is called only on the
   * FileSystem with {@code file} scheme.
   *
   * @param path the string path to be converted to Path
   * @return the Path
   * @throws UnsupportedOperationException when the FileSystem supports
   * only URI
   * @throws IllegalArgumentException if the {@code path} string cannot be
   * converted to a
   *             Path
   */
  virtual std::string parse_string_path(const std::string &path) = 0;
 
  /**
   * Checks existence and accessibility of a file.
   *
   * @param path the path to the file to check
   * @param flags the access modes to check, as a binary mask RWX
   * only.
   * @throws NoSuchFileException if the file denoted by the path does not exist
   * @throws IOException in case of IO error
   * @throws SecurityException if this FileSystem denied the operation
   */
  virtual void check_access(const std::string &path, int64_t flags) = 0;
 
  /**
   * Creates a directory.
   *
   * param dir the directory to create
   * param attrs the optional attributes to set atomically when creating the
   * directory
   * @throws FileAlreadyExistsException if a file on given path already exists
   * @throws IOException in case of IO error
   * @throws UnsupportedOperationException if the attributes contain an
   * attribute which cannot be set atomically
   * @throws SecurityException if this FileSystem denied the operation
   */
  virtual void create_directory(const std::string &path) = 0;
 
  /**
   * Deletes a file.
   *
   * @param path the path to the file to delete
   * @throws NoSuchFileException if a file on given path does not exist
   * @throws DirectoryNotEmptyException if the path denotes a non empty
   * directory
   * @throws IOException in case of IO error
   * @throws SecurityException if this FileSystem denied the operation
   */
  virtual void remove(const std::string &path) = 0;
 
  /**
   * Opens or creates a file returning a SeekableByteChannel to access
   * the file content.
   *
   * @param path the path to the file to open
   * @return the created SeekableByteChannel
   * @throws FileAlreadyExistsException if CREATE_NEW option is set and a file
   * already exists on given path
   * @throws IOException in case of IO error
   * @throws UnsupportedOperationException if the attributes contain an
   * attribute which cannot be set atomically
   * @throws IllegalArgumentException in case of invalid options combination
   * @throws SecurityException if this FileSystem denied the operation
   */
  virtual std::shared_ptr<ISeekable_channel> new_byte_channel(
      const std::string &path) = 0;
 
  /**
   * Returns directory entries.
   *
   * param dir the path to the directory to iterate entries for
   * param filter the filter
   * @return the new DirectoryStream
   * @throws NotDirectoryException when given path does not denote a directory
   * @throws IOException in case of IO error
   * @throws SecurityException if this FileSystem denied the operation
   */
  virtual std::shared_ptr<IDirectory_stream> new_directory_stream(
      const std::string &path) = 0;
 
  /**
   * Resolves given path to an absolute path.
   *
   * @param path the path to resolve, may be a non normalized path
   * @return an absolute Path
   * @throws SecurityException if this FileSystem denied the operation
   */
  virtual std::string to_absolute_path(const std::string &path) = 0;
 
  /**
   * Returns the real (canonical) path of an existing file.
   *
   * @param path the path to resolve, may be a non normalized path
   * param linkOptions options determining how the symbolic links should be
   * handled
   * @return an absolute canonical path
   * @throws IOException in case of IO error
   * @throws SecurityException if this FileSystem denied the operation
   */
  virtual std::string to_real_path(const std::string &path) = 0;
};
 
}  // namespace polyglot
}  // namespace shcore
 
#endif  // ROUTER_SRC_JIT_EXECUTOR_INCLUDE_MYSQLROUTER_POLYGLOT_FILE_SYSTEM_H_