archive_read_data_block(3) functions for reading streaming archives

Other Alias

archive_read_data, archive_read_data_skip, archive_read_data_into_fd


Streaming Archive Library (libarchive, -larchive)


In archive.h Ft la_ssize_t Fn archive_read_data struct archive * void *buff size_t len Ft int Fo archive_read_data_block Fa struct archive * Fa const void **buff Fa size_t *len Fa off_t *offset Fc Ft int Fn archive_read_data_skip struct archive * Ft int Fn archive_read_data_into_fd struct archive * int fd


Fn archive_read_data
Read data associated with the header just read. Internally, this is a convenience function that calls Fn archive_read_data_block and fills any gaps with nulls so that callers see a single continuous stream of data.
Fn archive_read_data_block
Return the next available block of data for this entry. Unlike Fn archive_read_data , the Fn archive_read_data_block function avoids copying data and allows you to correctly handle sparse files, as supported by some archive formats. The library guarantees that offsets will increase and that blocks will not overlap. Note that the blocks returned from this function can be much larger than the block size read from disk, due to compression and internal buffer optimizations.
Fn archive_read_data_skip
A convenience function that repeatedly calls Fn archive_read_data_block to skip all of the data for this archive entry. Note that this function is invoked automatically by Fn archive_read_next_header2 if the previous entry was not completely consumed.
Fn archive_read_data_into_fd
A convenience function that repeatedly calls Fn archive_read_data_block to copy the entire entry to the provided file descriptor.


Most functions return zero on success, non-zero on error. The possible return codes include: ARCHIVE_OK (the operation succeeded), ARCHIVE_WARN (the operation succeeded but a non-critical error was encountered), ARCHIVE_EOF (end-of-archive was encountered), ARCHIVE_RETRY (the operation failed but can be retried), and ARCHIVE_FATAL (there was a fatal error; the archive should be closed immediately).

Fn archive_read_data returns a count of bytes actually read or zero at the end of the entry. On error, a value of ARCHIVE_FATAL ARCHIVE_WARN or ARCHIVE_RETRY is returned.


Detailed error codes and textual descriptions are available from the Fn archive_errno and Fn archive_error_string functions.