worked on FAT stuff and tests

ext/sd/fat32/DirHelper.h

@@ -0,0 +1,130 @@
+#pragma once
+
+class DirHelper {
+
+	static constexpr const char* NAME = "FAT32_DirH";
+
+public:
+
+	enum class CreateType {
+		NONE,
+		DIR,
+		FILE
+	};
+
+	/**
+	 * get (or allocate, if needed) a new DirEntry with the given name absolute name
+	 * if the entry is allocated, it is UNTYPED
+	 * name: e.g. /path1/path2/path3 or /path1/path2/file.txt
+	 */
+	static DirHandle getOrCreate(FS& fs, ClusterNr dirStartCluster, const std::string& absName, CreateType ct) {
+
+		// determine the local name
+		Split s = split(absName);
+
+		{	// search for a matching existing entry
+			DirIterator di(fs, dirStartCluster);
+			while(true) {
+
+				DirHandle h = di.nextUsable();
+				if (!h.isValid()) {break;}
+
+				// found a matching entry
+				const std::string n = h.getName();
+				if (n == s.first) {
+
+					// are we done yet?
+					if (s.hasMore()) {
+						const ClusterNr subDirStartCluster = h.getFirstCluster();
+						return getOrCreate(fs, subDirStartCluster, s.next, ct);
+					} else {
+						return h;
+					}
+
+				}
+			}
+		}
+
+		// no matching entry found
+		if (ct == CreateType::NONE) {return DirHandle::invalid();}
+
+		{	// allocate a new DirEntry within the current directory
+
+			DirIterator di(fs, dirStartCluster);
+			DirHandle h = di.nextFree();
+			h.setName(s.first);
+			h.setSize(0);
+			h.setFirstCluster(0);
+
+			// if this is a sub-directory, allocate a new cluster for it
+			if (s.hasMore() || ct == CreateType::DIR) {
+
+				// allocate a cluster where the directory contents are to be stored
+				ClusterNr freeCluster = fs.allocFreeCluster(0);
+				h.setFirstCluster(freeCluster);
+				h.setDirectory();
+				fs.write(h);
+
+				// ensure the new cluster is initialized with all zeros (this is also equal to an immediate END_OF_DIRECTORY marker in the beginning
+				fs.zeroOutCluster(freeCluster);
+
+				DirIterator di2(fs, freeCluster);
+
+				// create the "." entry (pointer to current directory)
+				DirHandle h2 = di2.next();
+				h2.setDot(freeCluster);
+				fs.write(h2);
+
+				// create the ".." entry (pointer to parent directory)
+				DirHandle h3 = di2.next();
+				h3.setDotDot(dirStartCluster);
+				fs.write(h3);
+
+				// more path to process?
+				if (s.hasMore()) {
+					return getOrCreate(fs, freeCluster, s.next, ct);
+				} else {
+					return h;
+				}
+
+			} else {
+
+				fs.write(h);
+				return h;
+
+			}
+
+		}
+
+	}
+
+private:
+
+	struct Split {
+
+		std::string first;
+		std::string next;
+
+		Split(const std::string& first, const std::string& next) : first(first), next(next) {}
+
+		bool hasMore() const {return !next.empty();}
+
+	};
+
+	/** split "/path1/path2/path3/file.txt" into "path1" and "path2/path3/file.txt" */
+	static Split split(std::string absPath) {
+
+		if (absPath[0] == '/') {
+			absPath = absPath.substr(1);
+		}
+
+		std::size_t pos = absPath.find('/');
+		if (pos == std::string::npos) {
+			return Split(absPath, "");
+		} else {
+			return Split(absPath.substr(0, pos), absPath.substr(pos));
+		}
+
+	}
+
+};