1ARCHIVE_READ_OPEN(3) BSD Library Functions Manual ARCHIVE_READ_OPEN(3) 2 3NAME 4 archive_read_open, archive_read_open2, archive_read_open_fd, 5 archive_read_open_FILE, archive_read_open_filename, 6 archive_read_open_memory — functions for reading streaming archives 7 8LIBRARY 9 Streaming Archive Library (libarchive, -larchive) 10 11SYNOPSIS 12 #include <archive.h> 13 14 int 15 archive_read_open(struct archive *, void *client_data, 16 archive_open_callback *, archive_read_callback *, 17 archive_close_callback *); 18 19 int 20 archive_read_open2(struct archive *, void *client_data, 21 archive_open_callback *, archive_read_callback *, 22 archive_skip_callback *, archive_close_callback *); 23 24 int 25 archive_read_open_FILE(struct archive *, FILE *file); 26 27 int 28 archive_read_open_fd(struct archive *, int fd, size_t block_size); 29 30 int 31 archive_read_open_filename(struct archive *, const char *filename, 32 size_t block_size); 33 34 int 35 archive_read_open_memory(struct archive *, const void *buff, 36 size_t size); 37 38DESCRIPTION 39 archive_read_open() 40 The same as archive_read_open2(), except that the skip callback 41 is assumed to be NULL. 42 archive_read_open2() 43 Freeze the settings, open the archive, and prepare for reading 44 entries. This is the most generic version of this call, which 45 accepts four callback functions. Most clients will want to use 46 archive_read_open_filename(), archive_read_open_FILE(), 47 archive_read_open_fd(), or archive_read_open_memory() instead. 48 The library invokes the client-provided functions to obtain raw 49 bytes from the archive. 50 archive_read_open_FILE() 51 Like archive_read_open(), except that it accepts a FILE * 52 pointer. This function should not be used with tape drives or 53 other devices that require strict I/O blocking. 54 archive_read_open_fd() 55 Like archive_read_open(), except that it accepts a file descrip‐ 56 tor and block size rather than a set of function pointers. Note 57 that the file descriptor will not be automatically closed at end- 58 of-archive. This function is safe for use with tape drives or 59 other blocked devices. 60 archive_read_open_file() 61 This is a deprecated synonym for archive_read_open_filename(). 62 archive_read_open_filename() 63 Like archive_read_open(), except that it accepts a simple file‐ 64 name and a block size. A NULL filename represents standard in‐ 65 put. This function is safe for use with tape drives or other 66 blocked devices. 67 archive_read_open_memory() 68 Like archive_read_open(), except that it accepts a pointer and 69 size of a block of memory containing the archive data. 70 71 A complete description of the struct archive and struct archive_entry ob‐ 72 jects can be found in the overview manual page for libarchive(3). 73 74CLIENT CALLBACKS 75 The callback functions must match the following prototypes: 76 77 typedef la_ssize_t archive_read_callback(struct archive *, 78 void *client_data, const void **buffer) 79 80 typedef la_int64_t archive_skip_callback(struct archive *, 81 void *client_data, off_t request) 82 83 typedef int archive_open_callback(struct archive *, void 84 *client_data) 85 86 typedef int archive_close_callback(struct archive *, void 87 *client_data) 88 89 The open callback is invoked by archive_open(). It should return 90 ARCHIVE_OK if the underlying file or data source is successfully opened. 91 If the open fails, it should call archive_set_error() to register an er‐ 92 ror code and message and return ARCHIVE_FATAL. 93 94 The read callback is invoked whenever the library requires raw bytes from 95 the archive. The read callback should read data into a buffer, set the 96 const void **buffer argument to point to the available data, and return a 97 count of the number of bytes available. The library will invoke the read 98 callback again only after it has consumed this data. The library imposes 99 no constraints on the size of the data blocks returned. On end-of-file, 100 the read callback should return zero. On error, the read callback should 101 invoke archive_set_error() to register an error code and message and re‐ 102 turn -1. 103 104 The skip callback is invoked when the library wants to ignore a block of 105 data. The return value is the number of bytes actually skipped, which 106 may differ from the request. If the callback cannot skip data, it should 107 return zero. If the skip callback is not provided (the function pointer 108 is NULL ), the library will invoke the read function instead and simply 109 discard the result. A skip callback can provide significant performance 110 gains when reading uncompressed archives from slow disk drives or other 111 media that can skip quickly. 112 113 The close callback is invoked by archive_close when the archive process‐ 114 ing is complete. The callback should return ARCHIVE_OK on success. On 115 failure, the callback should invoke archive_set_error() to register an 116 error code and message and return ARCHIVE_FATAL. 117 118RETURN VALUES 119 These functions return ARCHIVE_OK on success, or ARCHIVE_FATAL. 120 121ERRORS 122 Detailed error codes and textual descriptions are available from the 123 archive_errno() and archive_error_string() functions. 124 125SEE ALSO 126 tar(1), archive_read(3), archive_read_data(3), archive_read_filter(3), 127 archive_read_format(3), archive_read_set_options(3), archive_util(3), 128 libarchive(3), tar(5) 129 130BSD February 2, 2012 BSD 131