4mARCHIVE_WRITE_OPEN24m(3) Library Functions Manual 4mARCHIVE_WRITE_OPEN24m(3) 1mNAME0m archive_write_open, archive_write_open2, archive_write_open_fd, archive_write_open_FILE, archive_write_open_filename, archive_write_open_memory — functions for creating archives 1mLIBRARY0m Streaming Archive Library (libarchive, -larchive) 1mSYNOPSIS0m 1m#include 0m 4mint0m 1marchive_write_open22m(4mstruct24m 4marchive24m 4m*24m, 4mvoid24m 4m*client_data24m, 4marchive_open_callback24m 4m*24m, 4marchive_write_callback24m 4m*24m, 4marchive_close_callback24m 4m*24m); 4mint0m 1marchive_write_open222m(4mstruct24m 4marchive24m 4m*24m, 4mvoid24m 4m*client_data24m, 4marchive_open_callback24m 4m*24m, 4marchive_write_callback24m 4m*24m, 4marchive_close_callback24m 4m*24m, 4marchive_free_callback24m 4m*24m); 4mint0m 1marchive_write_open_fd22m(4mstruct24m 4marchive24m 4m*24m, 4mint24m 4mfd24m); 4mint0m 1marchive_write_open_FILE22m(4mstruct24m 4marchive24m 4m*24m, 4mFILE24m 4m*file24m); 4mint0m 1marchive_write_open_filename22m(4mstruct24m 4marchive24m 4m*24m, 4mconst24m 4mchar24m 4m*filename24m); 4mint0m 1marchive_write_open_memory22m(4mstruct24m 4marchive24m 4m*24m, 4mvoid24m 4m*buffer24m, 4msize_t24m 4mbufferSize24m, 4msize_t24m 4m*outUsed24m); 1mDESCRIPTION0m 1marchive_write_open22m() Freeze the settings, open the archive, and prepare for writing entries. This is the most generic form of this function, which accepts pointers to three callback functions which will be in‐ voked by the compression layer to write the constructed archive. This does not alter the default archive padding. 1marchive_write_open222m() Same as 1marchive_write_open22m() with an additional fourth free callback. This function should be preferred to 1marchive_write_open22m(). 1marchive_write_open_fd22m() A convenience form of 1marchive_write_open22m() that accepts a file descriptor. The 1marchive_write_open_fd22m() function is safe for use with tape drives or other block-oriented devices. 1marchive_write_open_FILE22m() A convenience form of 1marchive_write_open22m() that accepts a 4mFILE0m 4m*24m pointer. Note that 1marchive_write_open_FILE22m() is not safe for writing to tape drives or other devices that require correct blocking. 1marchive_write_open_file22m() A deprecated synonym for 1marchive_write_open_filename22m(). 1marchive_write_open_filename22m() A convenience form of 1marchive_write_open22m() that accepts a file‐ name. A NULL argument indicates that the output should be written to standard output; an argument of “-” will open a file with that name. If you have not invoked 1marchive_write_set_bytes_in_last_block22m(), then 1marchive_write_open_filename22m() will adjust the last-block padding depending on the file: it will enable padding when writing to standard output or to a character or block device node, it will disable padding otherwise. You can override this by manually invoking 1marchive_write_set_bytes_in_last_block22m() before calling 1marchive_write_open222m(). The 1marchive_write_open_filename22m() function is safe for use with tape drives or other block-oriented devices. 1marchive_write_open_memory22m() A convenience form of 1marchive_write_open222m() that accepts a pointer to a block of memory that will receive the archive. The final 4msize_t24m 4m*24m argument points to a variable that will be updated after each write to reflect how much of the buffer is currently in use. You should be careful to ensure that this variable remains allocated until after the archive is closed. This function will disable padding unless you have specifically set the block size. More information about the 4mstruct24m 4marchive24m object and the overall design of the library can be found in the 4mlibarchive24m(3) overview. Note that the convenience forms above vary in how they block the out‐ put. See 4marchive_write_blocksize24m(3) if you need to control the block size used for writes or the end-of-file padding behavior. 1mCLIENT CALLBACKS0m To use this library, you will need to define and register callback functions that will be invoked to write data to the resulting archive. These functions are registered by calling 1marchive_write_open222m(): 4mtypedef24m 4mint24m 1marchive_open_callback22m(4mstruct24m 4marchive24m 4m*24m, 4mvoid0m 4m*client_data24m) The open callback is invoked by 1marchive_write_open22m(). It should return 1mARCHIVE_OK 22mif the underlying file or data source is successfully opened. If the open fails, it should call 1marchive_set_error22m() to reg‐ ister an error code and message and return 1mARCHIVE_FATAL22m. Please note that if open fails, close is not called and resources must be freed in‐ side the open callback or with the free callback. 4mtypedef24m 4mla_ssize_t24m 1marchive_write_callback22m(4mstruct24m 4marchive24m 4m*24m, 4mvoid24m 4m*client_data24m, 4mconst24m 4mvoid24m 4m*buffer24m, 4msize_t24m 4mlength24m) The write callback is invoked whenever the library needs to write raw bytes to the archive. For correct blocking, each call to the write callback function should translate into a single 4mwrite24m(2) system call. This is especially critical when writing archives to tape drives. On success, the write callback should return the number of bytes actually written. On error, the callback should invoke 1marchive_set_error22m() to register an error code and message and return -1. 4mtypedef24m 4mint24m 1marchive_close_callback22m(4mstruct24m 4marchive24m 4m*24m, 4mvoid0m 4m*client_data24m) The close callback is invoked by archive_close when the archive pro‐ cessing is complete. If the open callback fails, the close callback is not invoked. The callback should return 1mARCHIVE_OK 22mon success. On failure, the callback should invoke 1marchive_set_error22m() to register an error code and message and return 1mARCHIVE_FATAL22m. 4mtypedef24m 4mint24m 1marchive_free_callback22m(4mstruct24m 4marchive24m 4m*24m, 4mvoid0m 4m*client_data24m) The free callback is always invoked on archive_free. The return code of this callback is not processed. Note that if the client-provided write callback function returns a non- zero value, that error will be propagated back to the caller through whatever API function resulted in that call, which may include 1marchive_write_header22m(), 1marchive_write_data22m(), 1marchive_write_close22m(), 1marchive_write_finish22m(), or 1marchive_write_free22m(). The client callback can call 1marchive_set_error22m() to provide values that can then be re‐ trieved by 1marchive_errno22m() and 1marchive_error_string22m(). 1mRETURN VALUES0m These functions return 1mARCHIVE_OK 22mon success, or 1mARCHIVE_FATAL22m. 1mERRORS0m Detailed error codes and textual descriptions are available from the 1marchive_errno22m() and 1marchive_error_string22m() functions. 1mSEE ALSO0m 4mtar24m(1), 4marchive_write24m(3), 4marchive_write_blocksize24m(3), 4marchive_write_filter24m(3), 4marchive_write_format24m(3), 4marchive_write_new24m(3), 4marchive_write_set_options24m(3), 4mlibarchive24m(3), 4mcpio24m(5), 4mmtree24m(5), 4mtar24m(5) Debian November 12, 2020 4mARCHIVE_WRITE_OPEN24m(3)