file_io.h revision 292588
1/////////////////////////////////////////////////////////////////////////////// 2// 3/// \file file_io.h 4/// \brief I/O types and functions 5// 6// Author: Lasse Collin 7// 8// This file has been put into the public domain. 9// You can do whatever you want with this file. 10// 11/////////////////////////////////////////////////////////////////////////////// 12 13// Some systems have suboptimal BUFSIZ. Use a bit bigger value on them. 14// We also need that IO_BUFFER_SIZE is a multiple of 8 (sizeof(uint64_t)) 15#if BUFSIZ <= 1024 16# define IO_BUFFER_SIZE 8192 17#else 18# define IO_BUFFER_SIZE (BUFSIZ & ~7U) 19#endif 20 21 22/// is_sparse() accesses the buffer as uint64_t for maximum speed. 23/// Use an union to make sure that the buffer is properly aligned. 24typedef union { 25 uint8_t u8[IO_BUFFER_SIZE]; 26 uint32_t u32[IO_BUFFER_SIZE / sizeof(uint32_t)]; 27 uint64_t u64[IO_BUFFER_SIZE / sizeof(uint64_t)]; 28} io_buf; 29 30 31typedef struct { 32 /// Name of the source filename (as given on the command line) or 33 /// pointer to static "(stdin)" when reading from standard input. 34 const char *src_name; 35 36 /// Destination filename converted from src_name or pointer to static 37 /// "(stdout)" when writing to standard output. 38 char *dest_name; 39 40 /// File descriptor of the source file 41 int src_fd; 42 43 /// File descriptor of the target file 44 int dest_fd; 45 46 /// True once end of the source file has been detected. 47 bool src_eof; 48 49 /// If true, we look for long chunks of zeros and try to create 50 /// a sparse file. 51 bool dest_try_sparse; 52 53 /// This is used only if dest_try_sparse is true. This holds the 54 /// number of zero bytes we haven't written out, because we plan 55 /// to make that byte range a sparse chunk. 56 off_t dest_pending_sparse; 57 58 /// Stat of the source file. 59 struct stat src_st; 60 61 /// Stat of the destination file. 62 struct stat dest_st; 63 64} file_pair; 65 66 67/// \brief Initialize the I/O module 68extern void io_init(void); 69 70 71#ifndef TUKLIB_DOSLIKE 72/// \brief Write a byte to user_abort_pipe[1] 73/// 74/// This is called from a signal handler. 75extern void io_write_to_user_abort_pipe(void); 76#endif 77 78 79/// \brief Disable creation of sparse files when decompressing 80extern void io_no_sparse(void); 81 82 83/// \brief Open the source file 84extern file_pair *io_open_src(const char *src_name); 85 86 87/// \brief Open the destination file 88extern bool io_open_dest(file_pair *pair); 89 90 91/// \brief Closes the file descriptors and frees possible allocated memory 92/// 93/// The success argument determines if source or destination file gets 94/// unlinked: 95/// - false: The destination file is unlinked. 96/// - true: The source file is unlinked unless writing to stdout or --keep 97/// was used. 98extern void io_close(file_pair *pair, bool success); 99 100 101/// \brief Reads from the source file to a buffer 102/// 103/// \param pair File pair having the source file open for reading 104/// \param buf Destination buffer to hold the read data 105/// \param size Size of the buffer; assumed be smaller than SSIZE_MAX 106/// 107/// \return On success, number of bytes read is returned. On end of 108/// file zero is returned and pair->src_eof set to true. 109/// On error, SIZE_MAX is returned and error message printed. 110extern size_t io_read(file_pair *pair, io_buf *buf, size_t size); 111 112 113/// \brief Fix the position in src_fd 114/// 115/// This is used when --single-thream has been specified and decompression 116/// is successful. If the input file descriptor supports seeking, this 117/// function fixes the input position to point to the next byte after the 118/// decompressed stream. 119/// 120/// \param pair File pair having the source file open for reading 121/// \param rewind_size How many bytes of extra have been read i.e. 122/// how much to seek backwards. 123extern void io_fix_src_pos(file_pair *pair, size_t rewind_size); 124 125 126/// \brief Read from source file from given offset to a buffer 127/// 128/// This is remotely similar to standard pread(). This uses lseek() though, 129/// so the read offset is changed on each call. 130/// 131/// \param pair Seekable source file 132/// \param buf Destination buffer 133/// \param size Amount of data to read 134/// \param pos Offset relative to the beginning of the file, 135/// from which the data should be read. 136/// 137/// \return On success, false is returned. On error, error message 138/// is printed and true is returned. 139extern bool io_pread(file_pair *pair, io_buf *buf, size_t size, off_t pos); 140 141 142/// \brief Writes a buffer to the destination file 143/// 144/// \param pair File pair having the destination file open for writing 145/// \param buf Buffer containing the data to be written 146/// \param size Size of the buffer; assumed be smaller than SSIZE_MAX 147/// 148/// \return On success, zero is returned. On error, -1 is returned 149/// and error message printed. 150extern bool io_write(file_pair *pair, const io_buf *buf, size_t size); 151