1ARCHIVE_WRITE_OPEN(3) BSD Library Functions Manual ARCHIVE_WRITE_OPEN(3) 2 3NAME 4 archive_write_open, archive_write_open2, archive_write_open_fd, 5 archive_write_open_FILE, archive_write_open_filename, 6 archive_write_open_memory — functions for creating archives 7 8LIBRARY 9 Streaming Archive Library (libarchive, -larchive) 10 11SYNOPSIS 12 #include <archive.h> 13 14 int 15 archive_write_open(struct archive *, void *client_data, 16 archive_open_callback *, archive_write_callback *, 17 archive_close_callback *); 18 19 int 20 archive_write_open2(struct archive *, void *client_data, 21 archive_open_callback *, archive_write_callback *, 22 archive_close_callback *, archive_free_callback *); 23 24 int 25 archive_write_open_fd(struct archive *, int fd); 26 27 int 28 archive_write_open_FILE(struct archive *, FILE *file); 29 30 int 31 archive_write_open_filename(struct archive *, const char *filename); 32 33 int 34 archive_write_open_memory(struct archive *, void *buffer, 35 size_t bufferSize, size_t *outUsed); 36 37DESCRIPTION 38 archive_write_open() 39 Freeze the settings, open the archive, and prepare for writing 40 entries. This is the most generic form of this function, which 41 accepts pointers to three callback functions which will be in‐ 42 voked by the compression layer to write the constructed archive. 43 This does not alter the default archive padding. 44 45 archive_write_open2() 46 Same as archive_write_open() with an additional fourth free call‐ 47 back. This function should be preferred to archive_write_open(). 48 49 archive_write_open_fd() 50 A convenience form of archive_write_open() that accepts a file 51 descriptor. The archive_write_open_fd() function is safe for use 52 with tape drives or other block-oriented devices. 53 54 archive_write_open_FILE() 55 A convenience form of archive_write_open() that accepts a FILE * 56 pointer. Note that archive_write_open_FILE() is not safe for 57 writing to tape drives or other devices that require correct 58 blocking. 59 60 archive_write_open_file() 61 A deprecated synonym for archive_write_open_filename(). 62 63 archive_write_open_filename() 64 A convenience form of archive_write_open() that accepts a file‐ 65 name. A NULL argument indicates that the output should be writ‐ 66 ten to standard output; an argument of “-” will open a file with 67 that name. If you have not invoked 68 archive_write_set_bytes_in_last_block(), then 69 archive_write_open_filename() will adjust the last-block padding 70 depending on the file: it will enable padding when writing to 71 standard output or to a character or block device node, it will 72 disable padding otherwise. You can override this by manually in‐ 73 voking archive_write_set_bytes_in_last_block() before calling 74 archive_write_open2(). The archive_write_open_filename() func‐ 75 tion is safe for use with tape drives or other block-oriented de‐ 76 vices. 77 78 archive_write_open_memory() 79 A convenience form of archive_write_open2() that accepts a 80 pointer to a block of memory that will receive the archive. The 81 final size_t * argument points to a variable that will be updated 82 after each write to reflect how much of the buffer is currently 83 in use. You should be careful to ensure that this variable re‐ 84 mains allocated until after the archive is closed. This function 85 will disable padding unless you have specifically set the block 86 size. 87 More information about the struct archive object and the overall design 88 of the library can be found in the libarchive(3) overview. 89 90 Note that the convenience forms above vary in how they block the output. 91 See archive_write_blocksize(3) if you need to control the block size used 92 for writes or the end-of-file padding behavior. 93 94CLIENT CALLBACKS 95 To use this library, you will need to define and register callback func‐ 96 tions that will be invoked to write data to the resulting archive. These 97 functions are registered by calling archive_write_open2(): 98 99 typedef int archive_open_callback(struct archive *, void 100 *client_data) 101 102 The open callback is invoked by archive_write_open(). It should return 103 ARCHIVE_OK if the underlying file or data source is successfully opened. 104 If the open fails, it should call archive_set_error() to register an er‐ 105 ror code and message and return ARCHIVE_FATAL. Please note that if open 106 fails, close is not called and resources must be freed inside the open 107 callback or with the free callback. 108 109 typedef la_ssize_t archive_write_callback(struct archive *, 110 void *client_data, const void *buffer, size_t length) 111 112 The write callback is invoked whenever the library needs to write raw 113 bytes to the archive. For correct blocking, each call to the write call‐ 114 back function should translate into a single write(2) system call. This 115 is especially critical when writing archives to tape drives. On success, 116 the write callback should return the number of bytes actually written. 117 On error, the callback should invoke archive_set_error() to register an 118 error code and message and return -1. 119 120 typedef int archive_close_callback(struct archive *, void 121 *client_data) 122 123 The close callback is invoked by archive_close when the archive process‐ 124 ing is complete. If the open callback fails, the close callback is not 125 invoked. The callback should return ARCHIVE_OK on success. On failure, 126 the callback should invoke archive_set_error() to register an error code 127 and message and return 128 129 typedef int archive_free_callback(struct archive *, void 130 *client_data) 131 132 The free callback is always invoked on archive_free. The return code of 133 this callback is not processed. 134 135 Note that if the client-provided write callback function returns a non- 136 zero value, that error will be propagated back to the caller through 137 whatever API function resulted in that call, which may include 138 archive_write_header(), archive_write_data(), archive_write_close(), 139 archive_write_finish(), or archive_write_free(). The client callback can 140 call archive_set_error() to provide values that can then be retrieved by 141 archive_errno() and archive_error_string(). 142 143RETURN VALUES 144 These functions return ARCHIVE_OK on success, or ARCHIVE_FATAL. 145 146ERRORS 147 Detailed error codes and textual descriptions are available from the 148 archive_errno() and archive_error_string() functions. 149 150SEE ALSO 151 tar(1), archive_write(3), archive_write_blocksize(3), 152 archive_write_filter(3), archive_write_format(3), archive_write_new(3), 153 archive_write_set_options(3), libarchive(3), cpio(5), mtree(5), tar(5) 154 155BSD November 12, 2020 BSD 156