(child_open_for_compress, flush_write, flush_read): Use it to write
buffers.
(open_archive): Report error if fstat of archive fails.
Improve efficiency of check for /dev/null.
Also, fix some corner cases with remote archives and /dev/null checking.
(close_archive): Test for input fifo only if not remote.
Truncate output archive only if it's not remote.
Output a trailing NUL unless the value won't fit without it;
this is backward compatible with Unix tar (and with GNU Emacs).
(finish_header): No need to append NUL to chksum, now that
to_oct is doing it.
(intconv): Remove; use xstrto* fns instead.
("xstrtol.h"): Include.
(check_decimal): Remove.
(long_options, usage, OPTION_STRING, decode_options):
Remove -y, --bzip2, --unbzip2.
(decode_options): Use xget_version instead of get_version.
Check for overflow with -b and -L and RECORD_SIZE_OPTION.
Replace invocations of check_decimal with xstrtoumax.
(from_oct): Add forward decl.
(read_header): Return HEADER_FAILURE if we can't parse the checksum.
(from_oct): Report an error only if TYPE is nonzero.
Quote any funny characters in bad header.
when the original value is out of range. Do not append a space to the
output; modern tars don't. When a value is out of range, specify the
maximum value, not the number of bits.
(GID_NOBODY, UID_NOBODY): New macros.
(gid_to_oct, uid_to_oct): Use them as substitutes.
(finish_header): Do not assume that UINTMAX_TO_OCT appends a space.
(dump_file): Check whether the file changed as we read it.
size_from_oct, time_from_oct, uid_from_oct, uintmax_from_oct):
Use TYPE_MAXIMUM instead of macros like OFF_MAX, which are not reliable
(e.g. OFF_MAX in AIX 4.2 is incorrect).
