file_io.h revision 207842
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/// \brief Disable creation of sparse files when decompressing 72extern void io_no_sparse(void); 73 74 75/// \brief Open the source file 76extern file_pair *io_open_src(const char *src_name); 77 78 79/// \brief Open the destination file 80extern bool io_open_dest(file_pair *pair); 81 82 83/// \brief Closes the file descriptors and frees possible allocated memory 84/// 85/// The success argument determines if source or destination file gets 86/// unlinked: 87/// - false: The destination file is unlinked. 88/// - true: The source file is unlinked unless writing to stdout or --keep 89/// was used. 90extern void io_close(file_pair *pair, bool success); 91 92 93/// \brief Reads from the source file to a buffer 94/// 95/// \param pair File pair having the source file open for reading 96/// \param buf Destination buffer to hold the read data 97/// \param size Size of the buffer; assumed be smaller than SSIZE_MAX 98/// 99/// \return On success, number of bytes read is returned. On end of 100/// file zero is returned and pair->src_eof set to true. 101/// On error, SIZE_MAX is returned and error message printed. 102extern size_t io_read(file_pair *pair, io_buf *buf, size_t size); 103 104 105/// \brief Read from source file from given offset to a buffer 106/// 107/// This is remotely similar to standard pread(). This uses lseek() though, 108/// so the read offset is changed on each call. 109/// 110/// \param pair Seekable source file 111/// \param buf Destination buffer 112/// \param size Amount of data to read 113/// \param pos Offset relative to the beginning of the file, 114/// from which the data should be read. 115/// 116/// \return On success, false is returned. On error, error message 117/// is printed and true is returned. 118extern bool io_pread(file_pair *pair, io_buf *buf, size_t size, off_t pos); 119 120 121/// \brief Writes a buffer to the destination file 122/// 123/// \param pair File pair having the destination file open for writing 124/// \param buf Buffer containing the data to be written 125/// \param size Size of the buffer; assumed be smaller than SSIZE_MAX 126/// 127/// \return On success, zero is returned. On error, -1 is returned 128/// and error message printed. 129extern bool io_write(file_pair *pair, const io_buf *buf, size_t size); 130