Add doxygen annotations to all public headers

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 228 insertions, 0 deletions

diff --git a/include/sqfs/dir.h b/include/sqfs/dir.h
index 6bcb278..19c1289 100644
--- a/include/sqfs/dir.h
+++ b/include/sqfs/dir.h
@@ -22,26 +22,150 @@
 
 #include "sqfs/predef.h"
 
+/**
+ * @file dir.h
+ *
+ * @brief Contains on-disk data structures for the directory table and
+ *        declarations for the @ref sqfs_dir_writer_t.
+ */
+
+/**
+ * @struct sqfs_dir_writer_t
+ *
+ * @brief Abstracts generating of directory entries
+ *
+ * SquashFS stores directory entries and inodes seperated from each other. The
+ * inodes are stored in a series of meta data blocks before another series of
+ * meta data blocks that contain the directory entries. Directory inodes point
+ * to meta data block (and offset) where its contents are listed and the
+ * entries in turn point back to the inodes that represent them.
+ *
+ * There are some rules to this. Directory entries have to be written in
+ * ASCIIbetical ordering. Up to 256 entries are preceeded by a header. The
+ * entries use delta encoding for inode numbers and block locations relative to
+ * the header, so every time the inodes cross a meta data block boundary, if
+ * the difference in inode number gets too large, or if the entry count would
+ * exceed 256, a new header has to be emitted. Even if the inode pointed to is
+ * an extended type, the entry in the header still has to indicate the base
+ * type.
+ *
+ * In addtion to that, extended directory inodes can contain an index for
+ * faster lookup. The index points to each header and requires a new header to
+ * be emitted if the entries cross a block boundary.
+ *
+ * The dir writer takes care of all of this and provides a simple interface for
+ * adding entries. Internally it fills data into a meta data writer and
+ * generates an index that it can, on request, write to another meta data
+ * writer used for inodes.
+ */
+
 #define SQFS_MAX_DIR_ENT 256
 
+/**
+ * @struct sqfs_dir_header_t
+ *
+ * @brief On-disk data structure of a directory header
+ *
+ * See @ref sqfs_dir_writer_t for an overview on how SquashFS stores
+ * directories on disk.
+ */
 struct sqfs_dir_header_t {
+	/**
+	 * @brief The number of @ref sqfs_dir_entry_t entries that are
+	 *        following.
+	 *
+	 * This value is stored off by one and the total count must not
+	 * exceed 256.
+	 */
 	uint32_t count;
+
+	/**
+	 * @brief The location of the meta data block containing the inodes for
+	 *        the entries that follow, relative to the start of the inode
+	 *        table.
+	 */
 	uint32_t start_block;
+
+	/**
+	 * @brief The inode number of the first entry.
+	 */
 	uint32_t inode_number;
 };
 
+/**
+ * @struct sqfs_dir_entry_t
+ *
+ * @brief On-disk data structure of a directory entry. Many of these
+ *        follow a single @ref sqfs_dir_header_t.
+ *
+ * See @ref sqfs_dir_writer_t for an overview on how SquashFS stores
+ * directories on disk.
+ */
 struct sqfs_dir_entry_t {
+	/**
+	 * @brief An offset into the uncompressed meta data block containing
+	 *        the coresponding inode.
+	 */
 	uint16_t offset;
+
+	/**
+	 * @brief Signed difference of the inode number from the one
+	 *        in the @ref sqfs_dir_header_t.
+	 */
 	int16_t inode_diff;
+
+	/**
+	 * @brief The @ref E_SQFS_INODE_TYPE value for the inode that this
+	 *        entry represents.
+	 */
 	uint16_t type;
+
+	/**
+	 * @brief The size of the entry name
+	 *
+	 * This value is stored off-by-one.
+	 */
 	uint16_t size;
+
+	/**
+	 * @brief The name of the directory entry (no trailing null-byte).
+	 */
 	uint8_t name[];
 };
 
+/**
+ * @struct sqfs_dir_index_t
+ *
+ * @brief On-disk data structure of a directory index. A series of those
+ *        can follow an @ref sqfs_inode_dir_ext_t.
+ *
+ * See @ref sqfs_dir_writer_t for an overview on how SquashFS stores
+ * directories on disk.
+ */
 struct sqfs_dir_index_t {
+	/**
+	 * @brief Linear byte offset into the decompressed directory listing.
+	 */
 	uint32_t index;
+
+	/**
+	 * @brief Location of the meta data block, relative to the directory
+	 *        table start.
+	 */
 	uint32_t start_block;
+
+	/**
+	 * @brief Size of the name of the first entry after the header.
+	 *
+	 * This value is stored off-by-one.
+	 */
 	uint32_t size;
+
+	/**
+	 * @brief Name of the name of the first entry after the header.
+	 *
+	 * No trailing null-byte.
+	 */
 	uint8_t name[];
 };
 
@@ -49,25 +173,129 @@ struct sqfs_dir_index_t {
 extern "C" {
 #endif
 
+/**
+ * @brief Create a directory writer.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * @param dm A pointer to a meta data writer that the generated directory
+ *           entries should be written to.
+ *
+ * @return A pointer to a directory writer on success, NULL on
+ *         allocation failure.
+ */
 SQFS_API sqfs_dir_writer_t *sqfs_dir_writer_create(sqfs_meta_writer_t *dm);
 
+/**
+ * @brief Destroy a directory writer and free all its memory.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * @param writer A pointer to a directory writer object.
+ */
 SQFS_API void sqfs_dir_writer_destroy(sqfs_dir_writer_t *writer);
 
+/**
+ * @brief Begin writing a directory, i.e. reset and initialize all internal
+ *        state neccessary.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * @param writer A pointer to a directory writer object.
+ *
+ * @return Zero on success, a @ref E_SQFS_ERROR value on failure.
+ */
 SQFS_API int sqfs_dir_writer_begin(sqfs_dir_writer_t *writer);
 
+/**
+ * @brief Add add a directory entry.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * @param writer A pointer to a directory writer object.
+ * @param name The name of the directory entry.
+ * @param inode_num The inode number of the entry.
+ * @param inode_ref A reference to the inode, i.e. the meta data block offset
+ *                  is stored in bits 16 to 48 and the lower 16 bit hold an
+ *                  offset into the block.
+ * @param mode A file mode, i.e. type and permission bits from which the entry
+ *             type is derived internally.
+ *
+ * @return Zero on success, a @ref E_SQFS_ERROR value on failure.
+ */
 SQFS_API int sqfs_dir_writer_add_entry(sqfs_dir_writer_t *writer,
 				       const char *name,
 				       uint32_t inode_num, uint64_t inode_ref,
 				       mode_t mode);
 
+/**
+ * @brief Finish writing a directory listing and write everything out to the
+ *        meta data writer.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * @param writer A pointer to a directory writer object.
+ *
+ * @return Zero on success, a @ref E_SQFS_ERROR value on failure.
+ */
 SQFS_API int sqfs_dir_writer_end(sqfs_dir_writer_t *writer);
 
+/**
+ * @brief Get the total, uncompressed size of the last written
+ *        directory in bytes.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * Call this function after @ref sqfs_dir_writer_end to get the uncompressed
+ * size of the directory listing that is required for the directory inodes.
+ * And also to determine which kind of directory inode to create.
+ *
+ * @param writer A pointer to a directory writer object.
+ *
+ * @return The size of the entire, uncompressed listing in bytes.
+ */
 SQFS_API size_t sqfs_dir_writer_get_size(sqfs_dir_writer_t *writer);
 
+/**
+ * @brief Get the location of the last written directory.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * Call this function after @ref sqfs_dir_writer_end to get the location of
+ * the directory listing that is required for the directory inodes.
+ *
+ * @param writer A pointer to a directory writer object.
+ *
+ * @return A meta data reference, i.e. bits 16 to 48 contain the block start
+ *         and the lower 16 bit an offset into the uncompressed block.
+ */
 SQFS_API uint64_t sqfs_dir_writer_get_dir_reference(sqfs_dir_writer_t *writer);
 
+/**
+ * @brief Get the size of the index of the last written directory.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * Call this function after @ref sqfs_dir_writer_end to get the size of
+ * the directory index that is required for extended directory inodes.
+ *
+ * @param writer A pointer to a directory writer object.
+ *
+ * @return The number of index entries.
+ */
 SQFS_API size_t sqfs_dir_writer_get_index_size(sqfs_dir_writer_t *writer);
 
+/**
+ * @brief Write the index of the index of the last written directory to
+ *        a meta data writer after the extended directory inode.
+ *
+ * @memberof sqfs_dir_writer_create
+ *
+ * @param writer A pointer to a directory writer object.
+ * @param im A pointer to a meta data writer to write the index to.
+ *
+ * @return Zero on success, a @ref E_SQFS_ERROR value on failure.
+ */
 SQFS_API int sqfs_dir_writer_write_index(sqfs_dir_writer_t *writer,
 					 sqfs_meta_writer_t *im);