// SPDX-License-Identifier: 0BSD
///////////////////////////////////////////////////////////////////////////////
//
/// \file file_io.h
/// \brief I/O types and functions
//
// Author: Lasse Collin
//
///////////////////////////////////////////////////////////////////////////////
// Some systems have suboptimal BUFSIZ. Use a bit bigger value on them.
// We also need that IO_BUFFER_SIZE is a multiple of 8 (sizeof(uint64_t))
#if BUFSIZ <= 1024
# define IO_BUFFER_SIZE 8192
#else
# define IO_BUFFER_SIZE (BUFSIZ & ~7U)
#endif
#ifdef _MSC_VER
// The first one renames both "struct stat" -> "struct _stat64"
// and stat() -> _stat64(). The documentation mentions only
// "struct __stat64", not "struct _stat64", but the latter
// works too.
# define stat _stat64
# define fstat _fstat64
# define off_t __int64
#endif
/// is_sparse() accesses the buffer as uint64_t for maximum speed.
/// The u32 and u64 members must only be access through this union
/// to avoid strict aliasing violations. Taking a pointer of u8
/// should be fine as long as uint8_t maps to unsigned char which
/// can alias anything.
typedef union {
uint8_t u8[IO_BUFFER_SIZE];
uint32_t u32[IO_BUFFER_SIZE / sizeof(uint32_t)];
uint64_t u64[IO_BUFFER_SIZE / sizeof(uint64_t)];
} io_buf;
typedef struct {
/// Name of the source filename (as given on the command line) or
/// pointer to static "(stdin)" when reading from standard input.
const char *src_name;
/// Destination filename converted from src_name or pointer to static
/// "(stdout)" when writing to standard output.
char *dest_name;
/// File descriptor of the source file
int src_fd;
/// File descriptor of the target file
int dest_fd;
/// True once end of the source file has been detected.
bool src_eof;
/// For --flush-timeout: True if at least one byte has been read
/// since the previous flush or the start of the file.
bool src_has_seen_input;
/// For --flush-timeout: True when flushing is needed.
bool flush_needed;
/// If true, we look for long chunks of zeros and try to create
/// a sparse file.
bool dest_try_sparse;
/// This is used only if dest_try_sparse is true. This holds the
/// number of zero bytes we haven't written out, because we plan
/// to make that byte range a sparse chunk.
off_t dest_pending_sparse;
/// Stat of the source file.
struct stat src_st;
/// Stat of the destination file.
struct stat dest_st;
} file_pair;
/// \brief Initialize the I/O module
extern void io_init(void);
#ifndef TUKLIB_DOSLIKE
/// \brief Write a byte to user_abort_pipe[1]
///
/// This is called from a signal handler.
extern void io_write_to_user_abort_pipe(void);
#endif
/// \brief Disable creation of sparse files when decompressing
extern void io_no_sparse(void);
#ifdef ENABLE_SANDBOX
/// \brief main() calls this if conditions for sandboxing have been met.
extern void io_allow_sandbox(void);
#endif
/// \brief Open the source file
extern file_pair *io_open_src(const char *src_name);
/// \brief Open the destination file
extern bool io_open_dest(file_pair *pair);
/// \brief Closes the file descriptors and frees possible allocated memory
///
/// The success argument determines if source or destination file gets
/// unlinked:
/// - false: The destination file is unlinked.
/// - true: The source file is unlinked unless writing to stdout or --keep
/// was used.
extern void io_close(file_pair *pair, bool success);
/// \brief Reads from the source file to a buffer
///
/// \param pair File pair having the source file open for reading
/// \param buf Destination buffer to hold the read data
/// \param size Size of the buffer; must be at most IO_BUFFER_SIZE
///
/// \return On success, number of bytes read is returned. On end of
/// file zero is returned and pair->src_eof set to true.
/// On error, SIZE_MAX is returned and error message printed.
extern size_t io_read(file_pair *pair, io_buf *buf, size_t size);
/// \brief Fix the position in src_fd
///
/// This is used when --single-thream has been specified and decompression
/// is successful. If the input file descriptor supports seeking, this
/// function fixes the input position to point to the next byte after the
/// decompressed stream.
///
/// \param pair File pair having the source file open for reading
/// \param rewind_size How many bytes of extra have been read i.e.
/// how much to seek backwards.
extern void io_fix_src_pos(file_pair *pair, size_t rewind_size);
/// \brief Seek to the given absolute position in the source file
///
/// This calls lseek() and also clears pair->src_eof.
///
/// \param pair Seekable source file
/// \param pos Offset relative to the beginning of the file,
/// from which the data should be read.
///
/// \return On success, false is returned. On error, error message
/// is printed and true is returned.
extern bool io_seek_src(file_pair *pair, uint64_t pos);
/// \brief Read from source file from given offset to a buffer
///
/// This is remotely similar to standard pread(). This uses lseek() though,
/// so the read offset is changed on each call.
///
/// \param pair Seekable source file
/// \param buf Destination buffer
/// \param size Amount of data to read
/// \param pos Offset relative to the beginning of the file,
/// from which the data should be read.
///
/// \return On success, false is returned. On error, error message
/// is printed and true is returned.
extern bool io_pread(file_pair *pair, io_buf *buf, size_t size, uint64_t pos);
/// \brief Writes a buffer to the destination file
///
/// \param pair File pair having the destination file open for writing
/// \param buf Buffer containing the data to be written
/// \param size Size of the buffer; must be at most IO_BUFFER_SIZE
///
/// \return On success, zero is returned. On error, -1 is returned
/// and error message printed.
extern bool io_write(file_pair *pair, const io_buf *buf, size_t size);
