1 files changed, 74 insertions, 0 deletions
diff --git a/perl-install/resize_fat/io.pm b/perl-install/resize_fat/io.pm
new file mode 100644
index 000000000..48309db91
--- /dev/null
+++ b/perl-install/resize_fat/io.pm
@@ -0,0 +1,74 @@
+package resize_fat::io;
+
+use diagnostics;
+use strict;
+
+use resize_fat::fat;
+
+1;
+
+
+sub read($$$) {
+    my ($fs, $pos, $size) = @_;
+    my $buf;
+    sysseek $fs->{fd}, $pos, 0 or die "seeking to byte #$pos failed on device $fs->{fs_name}";
+    sysread $fs->{fd}, $buf, $size or die "reading at byte #$pos failed on device $fs->{fs_name}";
+    $buf;
+}
+sub write($$$$) {
+    my ($fs, $pos, $size, $buf) = @_;
+    sysseek $fs->{fd}, $pos, 0 or die "seeking to byte #$pos failed on device $fs->{fs_name}";
+    syswrite $fs->{fd}, $buf or die "writing at byte #$pos failed on device $fs->{fs_name}";
+}
+
+sub read_cluster($$) {
+    my ($fs, $cluster) = @_;
+    my $buf;
+
+    eval {
+	$buf = &read($fs,
+		     $fs->{cluster_offset} + $cluster * $fs->{cluster_size},
+		     $fs->{cluster_size});
+    }; @$ and die "reading cluster #$cluster failed on device $fs->{fs_name}";
+    $buf;
+}
+sub write_cluster($$$) {
+    my ($fs, $cluster, $buf) = @_;
+
+    eval {
+    &write($fs,
+	   $fs->{cluster_offset} + $cluster * $fs->{cluster_size},
+	   $fs->{cluster_size},
+	   $buf);
+    }; @$ and die "writing cluster #$cluster failed on device $fs->{fs_name}";
+}
+
+sub read_file($$) {
+    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);
+    }
+    $buf;
+}
+
+sub check_mounted($) {
+    my ($f) = @_;
+
+    local *F;
+    open F, "/proc/mounts" or die "error opening /proc/mounts\n";
+    foreach (<F>) {
+	/^$f\s/ and die "device is mounted";
+    }
+}
+
+sub open($) {
+    my ($fs) = @_;
+
+    check_mounted($fs->{device});
+
+    sysopen F, $fs->{fs_name}, 2 or sysopen F, $fs->{fs_name}, 0 or die "error opening device $fs->{fs_name} for writing\n";
+    $fs->{fd} = \*F;
+}