WIP on cache tools

persistent-data/file_utils.cc

@@ -0,0 +1,57 @@
+#include "persistent-data/math_utils.h"
+#include "persistent-data/file_utils.h"
+
+#include <linux/fs.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+using namespace base;
+
+//----------------------------------------------------------------
+
+persistent_data::block_address
+persistent_data::get_nr_blocks(string const &path)
+{
+	using namespace persistent_data;
+
+	struct stat info;
+	block_address nr_blocks;
+
+	int r = ::stat(path.c_str(), &info);
+	if (r)
+		throw runtime_error("Couldn't stat dev path");
+
+	if (S_ISREG(info.st_mode) && info.st_size)
+		nr_blocks = div_up<block_address>(info.st_size, MD_BLOCK_SIZE);
+
+	else if (S_ISBLK(info.st_mode)) {
+		// To get the size of a block device we need to
+		// open it, and then make an ioctl call.
+		int fd = ::open(path.c_str(), O_RDONLY);
+		if (fd < 0)
+			throw runtime_error("couldn't open block device to ascertain size");
+
+		r = ::ioctl(fd, BLKGETSIZE64, &nr_blocks);
+		if (r) {
+			::close(fd);
+			throw runtime_error("ioctl BLKGETSIZE64 failed");
+		}
+		::close(fd);
+		nr_blocks = div_down<block_address>(nr_blocks, MD_BLOCK_SIZE);
+	} else
+		// FIXME: needs a better message
+		throw runtime_error("bad path");
+
+	return nr_blocks;
+}
+
+persistent_data::block_manager<>::ptr
+persistent_data::open_bm(std::string const &dev_path, block_io<>::mode m)
+{
+	block_address nr_blocks = get_nr_blocks(dev_path);
+	return block_manager<>::ptr(new block_manager<>(dev_path, nr_blocks, 1, m));
+}
+
+//----------------------------------------------------------------