+# all of these support -c for stdout and -d for decompression,
+# mutt is commonly distributed with hooks for gz, bz2 and xz, at least
+# { foo => '' } means "--foo" is passed to the command-line,
+# otherwise { foo => '--bar' } passes "--bar"
+our %zsfx2cmd = (
+ gz => [ qw(GZIP pigz gzip), {
+ rsyncable => '', threads => '-p' } ],
+ bz2 => [ 'bzip2', {} ],
+ xz => [ 'xz', { threads => '-T' } ],
+ # XXX does anybody care for these? I prefer zstd on entire FSes,
+ # so it's probably not necessary on a per-file basis
+ # zst => [ 'zstd', { -default => [ qw(-q) ], # it's noisy by default
+ # rsyncable => '', threads => '-T' } ],
+ # zz => [ 'pigz', { -default => [ '--zlib' ],
+ # rsyncable => '', threads => '-p' }],
+ # lzo => [ 'lzop', {} ],
+ # lzma => [ 'lzma', {} ],
+);
+
+sub zsfx2cmd ($$$) {
+ my ($zsfx, $decompress, $lei) = @_;
+ my $x = $zsfx2cmd{$zsfx} // die "no support for suffix=.$zsfx";
+ my @info = @$x;
+ my $cmd_opt = pop @info;
+ my @cmd = (undef, $decompress ? qw(-dc) : qw(-c));
+ for my $exe (@info) {
+ # I think respecting client's ENV{GZIP} is OK, not sure
+ # about ENV overrides for other, less-common compressors
+ if ($exe eq uc($exe)) {
+ $exe = $lei->{env}->{$exe} or next;
+ }
+ $cmd[0] = which($exe) and last;
+ }
+ $cmd[0] // die join(' or ', @info)." missing for .$zsfx";
+ # push @cmd, @{$cmd_opt->{-default}} if $cmd_opt->{-default};
+ for my $bool (qw(rsyncable)) {
+ my $switch = $cmd_opt->{rsyncable} // next;
+ push @cmd, '--'.($switch || $bool);
+ }
+ for my $key (qw(threads)) { # support compression level?
+ my $switch = $cmd_opt->{$key} // next;
+ my $val = $lei->{opt}->{$key} // next;
+ push @cmd, $switch, $val;