package resize_fat::io; # $Id: io.pm 208669 2004-08-12 04:20:25Z prigaux $ use diagnostics; use strict; use resize_fat::fat; use c; 1; sub read($$$) { my ($fs, $pos, $size) = @_; my $buf = "\0" x $size; sysseek $fs->{fd}, $pos, 0 or die "seeking to byte #$pos failed on device $fs->{fs_name}"; sysread $fs->{fd}, $buf, $size or die "reading at byte #$pos failed on device $fs->{fs_name}"; $buf; } sub write($$$$) { my ($fs, $pos, $_size, $buf) = @_; sysseek $fs->{fd}, $pos, 0 or die "seeking to byte #$pos failed on device $fs->{fs_name}"; syswrite $fs->{fd}, $buf or die "writing at byte #$pos failed on device $fs->{fs_name}"; } sub read_cluster($$) { my ($fs, $cluster) = @_; my $buf; my $pos = $fs->{cluster_offset} / 512 + $cluster * ($fs->{cluster_size} / 512); c::lseek_sector(fileno $fs->{fd}, $pos, 0) or die "seeking to sector #$pos failed on device $fs->{fs_name}"; sysread $fs->{fd}, $buf, $fs->{cluster_size} or die "reading at sector #$pos failed on device $fs->{fs_name}"; $buf; } sub write_cluster($$$) { my ($fs, $cluster, $buf) = @_; my $pos = $fs->{cluster_offset} / 512 + $cluster * ($fs->{cluster_size} / 512); c::lseek_sector(fileno $fs->{fd}, $pos, 0) or die "seeking to sector #$pos failed on device $fs->{fs_name}"; syswrite $fs->{fd}, $buf or die "writing at sector #$pos failed on device $fs->{fs_name}"; } sub read_file($$) { my ($fs, $cluster) = @_; my $buf = ''; for (; !resize_fat::fat::is_eof($cluster); $cluster = resize_fat::fat::next($fs, $cluster)) { $cluster == 0 and die "Bad FAT: unterminated chain\n"; $buf .= read_cluster($fs, $cluster); } $buf; } sub open { my ($fs) = @_; sysopen $fs->{fd}, $fs->{fs_name}, 2 or sysopen $fs->{fd}, $fs->{fs_name}, 0 or die "error opening device $fs->{fs_name} for writing\n"; }