/*
   * Operating System Interface
   *
   * This provides access to useful OS routines for the sandbox architecture.
   * They are kept in a separate file so we can include system headers.
   *
   * Copyright (c) 2011 The Chromium OS Authors.
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  #ifndef __OS_H__
  #define __OS_H__
  
  #include <linux/types.h>
  
  struct sandbox_state;
  
  /**
   * Access to the OS read() system call
   *
   * \param fd	File descriptor as returned by os_open()
   * \param buf	Buffer to place data
   * \param count	Number of bytes to read
   * \return number of bytes read, or -1 on error
   */
  ssize_t os_read(int fd, void *buf, size_t count);
  
  /**
   * Access to the OS read() system call with non-blocking access
   *
   * \param fd	File descriptor as returned by os_open()
   * \param buf	Buffer to place data
   * \param count	Number of bytes to read
   * \return number of bytes read, or -1 on error
   */
  ssize_t os_read_no_block(int fd, void *buf, size_t count);
  
  /**
   * Access to the OS write() system call
   *
   * \param fd	File descriptor as returned by os_open()
   * \param buf	Buffer containing data to write
   * \param count	Number of bytes to write
   * \return number of bytes written, or -1 on error
   */
  ssize_t os_write(int fd, const void *buf, size_t count);
  
  /**
   * Access to the OS lseek() system call
   *
   * \param fd	File descriptor as returned by os_open()
   * \param offset	File offset (based on whence)
   * \param whence	Position offset is relative to (see below)
   * \return new file offset
   */
  off_t os_lseek(int fd, off_t offset, int whence);
  
  /* Defines for "whence" in os_lseek() */
  #define OS_SEEK_SET	0
  #define OS_SEEK_CUR	1
  #define OS_SEEK_END	2
  
  /**
   * Access to the OS open() system call
   *
   * \param pathname	Pathname of file to open
   * \param flags		Flags, like O_RDONLY, O_RDWR
   * \return file descriptor, or -1 on error
   */
  int os_open(const char *pathname, int flags);
  
  #define OS_O_RDONLY	0
  #define OS_O_WRONLY	1
  #define OS_O_RDWR	2
  #define OS_O_MASK	3	/* Mask for read/write flags */
  #define OS_O_CREAT	0100
  
  /**
   * Access to the OS close() system call
   *
   * \param fd	File descriptor to close
   * \return 0 on success, -1 on error
   */
  int os_close(int fd);
  
  /**
   * Access to the OS unlink() system call
   *
   * \param pathname Path of file to delete
   * \return 0 for success, other for error
   */
  int os_unlink(const char *pathname);
  
  /**
   * Access to the OS exit() system call
   *
   * This exits with the supplied return code, which should be 0 to indicate
   * success.
   *
   * @param exit_code	exit code for U-Boot
   */
  void os_exit(int exit_code) __attribute__((noreturn));
  
  /**
   * Put tty into raw mode to mimic serial console better
   *
   * @param fd		File descriptor of stdin (normally 0)
   * @param allow_sigs	Allow Ctrl-C, Ctrl-Z to generate signals rather than
   *			be handled by U-Boot
   */
  void os_tty_raw(int fd, bool allow_sigs);
  
  /**
   * Acquires some memory from the underlying os.
   *
   * \param length	Number of bytes to be allocated
   * \return Pointer to length bytes or NULL on error
   */
  void *os_malloc(size_t length);
  
  /**
   * Free memory previous allocated with os_malloc()/os_realloc()
   *
   * This returns the memory to the OS.
   *
   * \param ptr		Pointer to memory block to free
   */
  void os_free(void *ptr);
  
  /**
   * Reallocate previously-allocated memory to increase/decrease space
   *
   * This works in a similar way to the C library realloc() function. If
   * length is 0, then ptr is freed. Otherwise the space used by ptr is
   * expanded or reduced depending on whether length is larger or smaller
   * than before.
   *
   * If ptr is NULL, then this is similar to calling os_malloc().
   *
   * This function may need to move the memory block to make room for any
   * extra space, in which case the new pointer is returned.
   *
   * \param ptr		Pointer to memory block to reallocate
   * \param length	New length for memory block
   * \return pointer to new memory block, or NULL on failure or if length
   *	is 0.
   */
  void *os_realloc(void *ptr, size_t length);
  
  /**
   * Access to the usleep function of the os
   *
   * \param usec Time to sleep in micro seconds
   */
  void os_usleep(unsigned long usec);
  
  /**
   * Gets a monotonic increasing number of nano seconds from the OS
   *
   * \return A monotonic increasing time scaled in nano seconds
   */
  uint64_t os_get_nsec(void);
  
  /**
   * Parse arguments and update sandbox state.
   *
   * @param state		Sandbox state to update
   * @param argc		Argument count
   * @param argv		Argument vector
   * @return 0 if ok, and program should continue;
   *	1 if ok, but program should stop;
   *	-1 on error: program should terminate.
   */
  int os_parse_args(struct sandbox_state *state, int argc, char *argv[]);
  
  /*
   * Types of directory entry that we support. See also os_dirent_typename in
   * the C file.
   */
  enum os_dirent_t {
  	OS_FILET_REG,		/* Regular file */
  	OS_FILET_LNK,		/* Symbolic link */
  	OS_FILET_DIR,		/* Directory */
  	OS_FILET_UNKNOWN,	/* Something else */
  
  	OS_FILET_COUNT,
  };
  
  /** A directory entry node, containing information about a single dirent */
  struct os_dirent_node {
  	struct os_dirent_node *next;	/* Pointer to next node, or NULL */
  	ulong size;			/* Size of file in bytes */
  	enum os_dirent_t type;		/* Type of entry */
  	char name[0];			/* Name of entry */
  };
  
  /**
   * Get a directionry listing
   *
   * This allocates and returns a linked list containing the directory listing.
   *
   * @param dirname	Directory to examine
   * @param headp		Returns pointer to head of linked list, or NULL if none
   * @return 0 if ok, -ve on error
   */
  int os_dirent_ls(const char *dirname, struct os_dirent_node **headp);
  
  /**
   * Get the name of a directory entry type
   *
   * @param type		Type to cehck
   * @return string containing the name of that type, or "???" if none/invalid
   */
  const char *os_dirent_get_typename(enum os_dirent_t type);
  
  /**
   * Get the size of a file
   *
   * @param fname		Filename to check
   * @param size		size of file is returned if no error
   * @return 0 on success or -1 if an error ocurred
   */
  int os_get_filesize(const char *fname, loff_t *size);
  
  /**
   * Write a character to the controlling OS terminal
   *
   * This bypasses the U-Boot console support and writes directly to the OS
   * stdout file descriptor.
   *
   * @param ch	Character to write
   */
  void os_putc(int ch);
  
  /**
   * Write a string to the controlling OS terminal
   *
   * This bypasses the U-Boot console support and writes directly to the OS
   * stdout file descriptor.
   *
   * @param str	String to write (note that 
   is not appended)
   */
  void os_puts(const char *str);
  
  /**
   * Write the sandbox RAM buffer to a existing file
   *
   * @param fname		Filename to write memory to (simple binary format)
   * @return 0 if OK, -ve on error
   */
  int os_write_ram_buf(const char *fname);
  
  /**
   * Read the sandbox RAM buffer from an existing file
   *
   * @param fname		Filename containing memory (simple binary format)
   * @return 0 if OK, -ve on error
   */
  int os_read_ram_buf(const char *fname);
  
  /**
   * Jump to a new executable image
   *
   * This uses exec() to run a new executable image, after putting it in a
   * temporary file. The same arguments and environment are passed to this
   * new image, with the addition of:
   *
   *	-j <filename>	Specifies the filename the image was written to. The
   *			calling image may want to delete this at some point.
   *	-m <filename>	Specifies the file containing the sandbox memory
   *			(ram_buf) from this image, so that the new image can
   *			have access to this. It also means that the original
   *			memory filename passed to U-Boot will be left intact.
   *
   * @param dest		Buffer containing executable image
   * @param size		Size of buffer
   */
  int os_jump_to_image(const void *dest, int size);
  
  #endif