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-rw-r--r--perl-install/resize_fat/io.pm74
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;
+}