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Diffstat (limited to 'src/xz/file_io.h')
| -rw-r--r-- | src/xz/file_io.h | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/src/xz/file_io.h b/src/xz/file_io.h new file mode 100644 index 0000000..6992efa --- /dev/null +++ b/src/xz/file_io.h @@ -0,0 +1,179 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file file_io.h +/// \brief I/O types and functions +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +// 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 + + +/// 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); |