Add a bounded read option for the file system

2017-04-13 20:16:42 -05:00
parent 9183815634
commit bf110e5341
3 changed files with 85 additions and 20 deletions
@@ -103,7 +103,7 @@ class FileStore {

 		struct StatInfo {
 			InodeId_t inodeId;
-			typename Header::FsSize_t  size;
+			typename Header::FsSize_t size;
 			uint8_t fileType;
 		};

@@ -143,7 +143,7 @@ class FileStore {
 				typename Header::FsSize_t getRight();

 				void setData(void *data, typename Header::FsSize_t size);
-				void *getData();
+				uint8_t *getData();
 		};

 		Header m_header;
@@ -186,6 +186,20 @@ class FileStore {
 		 */
 		int read(InodeId_t id, void *data, typename Header::FsSize_t *size);

+		/**
+		 * Reads the "file" at the given id. You are responsible for freeing
+		 * the data when done with it.
+		 * @param id id of the "file"
+		 * @param readStart where in the data to start reading
+		 * @param readSize how much data to read
+		 * @param data pointer to the pointer where the data is stored
+		 * @param size pointer to a value that will be assigned the size of data
+		 * @return 0 if read is a success
+		 */
+		int read(InodeId_t id, typename Header::FsSize_t readStart,
+			      typename Header::FsSize_t readSize, void *data,
+					typename Header::FsSize_t *size);
+
 		/**
 		 * Reads the stat information of the inode of the given inode id.
 		 * If the returned inode id is 0, then the requested inode was not found.
@@ -240,6 +254,20 @@ class FileStore {
 		 */
 		Inode *getInodeParent(Inode *root, InodeId_t id, typename Header::FsSize_t targetAddr);

+		/**
+		 * Reads the "file" at the given id. You are responsible for freeing
+		 * the data when done with it.
+		 * @param inode inode of the "file"
+		 * @param readStart where in the data to start reading
+		 * @param readSize how much data to read
+		 * @param data pointer to the pointer where the data is stored
+		 * @param size pointer to a value that will be assigned the size of data
+		 * @return 0 if read is a success
+		 */
+		int read(Inode *inode, typename Header::FsSize_t readStart,
+			      typename Header::FsSize_t readSize, void *data,
+					typename Header::FsSize_t *size);
+
 		/**
 		 * Removes the inode of the given ID.
 		 * @param id the id of the file
@@ -391,8 +419,8 @@ void FileStore<Header>::Inode::setData(void *data, typename Header::FsSize_t siz


 template<typename Header>
-void *FileStore<Header>::Inode::getData() {
-	return this + 1;
+uint8_t *FileStore<Header>::Inode::getData() {
+	return (uint8_t*) (this + 1);
 }


@@ -538,14 +566,29 @@ void FileStore<Header>::updateInodeAddress(InodeId_t id, typename Header::FsSize
 template<typename Header>
 int FileStore<Header>::read(InodeId_t id, void *data, typename Header::FsSize_t *size) {
 	auto inode = getInode(ptr<Inode*>(m_header.getRootInode()), id);
+	return inode ? read(inode, 0, inode->getDataLen(), data, size) : 1;
+}
+
+template<typename Header>
+int FileStore<Header>::read(InodeId_t id, typename Header::FsSize_t readStart,
+		typename Header::FsSize_t readSize, void *data, typename Header::FsSize_t *size) {
+	auto inode = getInode(ptr<Inode*>(m_header.getRootInode()), id);
+	return inode ? read(inode, readStart, readSize, data, size) : 1;
+}
+
+template<typename Header>
+int FileStore<Header>::read(Inode *inode, typename Header::FsSize_t readStart,
+		typename Header::FsSize_t readSize, void *data, typename Header::FsSize_t *size) {
 	int retval = 1;
-	if (inode) {
-		if (size) {
-			*size = inode->getDataLen();
-		}
-		ox_memcpy(data, inode->getData(), inode->getDataLen());
-		retval = 0;
+	// be sure read size is not greater than what is available to read
+	if (inode->getDataLen() + readStart < readSize) {
+		readSize = inode->getDataLen();
 	}
+	if (size) {
+		*size = readSize;
+	}
+	ox_memcpy(data, inode->getData() + readStart, inode->getDataLen());
+	retval = 0;
 	return retval;
 }

@@ -34,7 +34,9 @@ class FileSystem {
 	public:
 		virtual ~FileSystem() {};

-		virtual int read(uint64_t inode, void *buffer, size_t size) = 0;
+		virtual int read(uint64_t inode, void *buffer, size_t *size) = 0;
+
+		virtual int read(uint64_t inode, size_t readStart, size_t readSize, void *buffer, size_t *size) = 0;

 		virtual uint8_t *read(uint64_t inode, size_t *size) = 0;

@@ -110,9 +112,11 @@ class FileSystemTemplate: public FileSystem {

 		int read(const char *path, void *buffer);

-		uint8_t *read(uint64_t inode, size_t *size) override;
+		int read(uint64_t inode, void *buffer, size_t *size) override;

-		int read(uint64_t inode, void *buffer, size_t size) override;
+		int read(uint64_t inode, size_t readStart, size_t readSize, void *buffer, size_t *size);
+
+		uint8_t *read(uint64_t inode, size_t *size) override;

 		void resize(uint64_t size = 0) override;

@@ -174,18 +178,35 @@ FileStat FileSystemTemplate<FileStore, FS_TYPE>::stat(uint64_t inode) {
 #pragma warning(disable:4244)
 #endif
 template<typename FileStore, FsType FS_TYPE>
-int FileSystemTemplate<FileStore, FS_TYPE>::read(uint64_t inode, void *buffer, size_t size) {
-	auto err = 1;
-	auto s = store->stat(inode);
-	if (size == s.size) {
-		err = store->read(inode, buffer, nullptr);
+int FileSystemTemplate<FileStore, FS_TYPE>::read(uint64_t inode, void *buffer, size_t *size) {
+	if (size) {
+		auto stat = store->stat(inode);
+		*size = stat.size;
 	}
-	return err;
+	return store->read(inode, buffer, nullptr);
+;
 }
 #ifdef _MSC_VER
 #pragma warning(default:4244)
 #endif

+#ifdef _MSC_VER
+#pragma warning(disable:4244)
+#endif
+template<typename FileStore, FsType FS_TYPE>
+int FileSystemTemplate<FileStore, FS_TYPE>::read(uint64_t inode, size_t readStart,
+                                                 size_t readSize, void *buffer,
+                                                 size_t *size) {
+	if (size) {
+		auto stat = store->stat(inode);
+		*size = stat.size;
+	}
+	return store->read(inode, readStart, readSize, buffer, nullptr);
+}
+#ifdef _MSC_VER
+#pragma warning(disable:4244)
+#endif
+
 #ifdef _MSC_VER
 #pragma warning(disable:4244)
 #endif
@@ -201,6 +201,7 @@ int write(int argc, char **args, bool expand) {
 							auto needed = fs->size() + fs->spaceNeeded(srcSize);
 							fsSize = needed;
 							fs = expandCopyCleanup(fs, needed);
+							fsBuff = fs->buff();
 						}
 						err |= fs->write(inode, srcBuff, srcSize);

@@ -231,7 +232,7 @@ int write(int argc, char **args, bool expand) {
 							err = 1;
 						}
 					}
-					delete []fsBuff;
+					delete []srcBuff;
 				} else {
 					err = 1;
 					fprintf(stderr, "Could not load source file: %s.\n", srcPath);