Improve future compatibility for the 64-bit I/O channel functions

Provide a C language wrapper function for io_channel_read_blk64() and
io_channel_write_blk64() instead of using a C preprocessor macro, with
an fallback to the old 32-bit functions if an application-provided I/O
channel manager doesn't supply 64-bit method functions and the block
numbers can fit in 32-bit integer.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 32 insertions, 0 deletions

diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
index e50d7e41..8d732530 100644
--- a/lib/ext2fs/io_manager.c
+++ b/lib/ext2fs/io_manager.c
@@ -67,3 +67,35 @@ errcode_t io_channel_write_byte(io_channel channel, unsigned long offset,
 
 	return EXT2_ET_UNIMPLEMENTED;
 }
+
+errcode_t io_channel_read_blk64(io_channel channel, unsigned long long block,
+				 int count, void *data)
+{
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+
+	if (channel->manager->read_blk64)
+		return (channel->manager->read_blk64)(channel, block,
+						      count, data);
+
+	if ((block >> 32) != 0)
+		return EXT2_ET_IO_CHANNEL_NO_SUPPORT_64;
+
+	return (channel->manager->read_blk)(channel, (unsigned long) block,
+					     count, data);
+}
+
+errcode_t io_channel_write_blk64(io_channel channel, unsigned long long block,
+				 int count, const void *data)
+{
+	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+
+	if (channel->manager->write_blk64)
+		return (channel->manager->write_blk64)(channel, block,
+						       count, data);
+
+	if ((block >> 32) != 0)
+		return EXT2_ET_IO_CHANNEL_NO_SUPPORT_64;
+
+	return (channel->manager->write_blk)(channel, (unsigned long) block,
+					     count, data);
+}