Some API cleanups

10 files changed, 282 insertions, 166 deletions

diff --git a/src/liblzma/api/lzma/base.h b/src/liblzma/api/lzma/base.h
index cb614176..e04e7504 100644
--- a/src/liblzma/api/lzma/base.h
+++ b/src/liblzma/api/lzma/base.h
@@ -34,82 +34,136 @@ typedef unsigned char lzma_bool;
 
 
 /**
+ * \brief       Type of reserved enumeration variable in structures
+ *
+ * To avoid breaking library ABI when new features are added, several
+ * structures contain extra variables that may be used in future. Since
+ * sizeof(enum) can be different than sizeof(int), and sizeof(enum) may
+ * even vary depending on the range of enumeration constants, we specify
+ * a separate type to be used for reserved enumeration variables. All
+ * enumeration constants in liblzma API will be non-negative and less
+ * than 128, which should guarantee that the ABI won't break even when
+ * new constants are added to existing enumerations.
+ */
+typedef enum {
+	LZMA_RESERVED_ENUM      = 0
+} lzma_reserved_enum;
+
+
+/**
  * \brief       Return values used by several functions in liblzma
  *
  * Check the descriptions of specific functions to find out which return
- * values they can return and the exact meanings of the values in every
- * situation. The descriptions given here are only suggestive.
+ * values they can return. With some functions the return values may have
+ * more specific meanings than described here; those differences are
+ * described per-function basis.
  */
 typedef enum {
-	LZMA_OK                 =  0,
+	LZMA_OK                 = 0,
 		/**<
 		 * \brief       Operation completed successfully
 		 */
 
-	LZMA_STREAM_END         =  1,
+	LZMA_STREAM_END         = 1,
 		/**<
 		 * \brief       End of stream was reached
 		 *
-		 * The application should pick the last remaining output
-		 * bytes from strm->next_out.
+		 * In encoder, LZMA_SYNC_FLUSH, LZMA_FULL_FLUSH, or
+		 * LZMA_FINISH was finished. In decoder, this indicates
+		 * that all the data was successfully decoded.
+		 *
+		 * In all cases, when LZMA_STREAM_END is returned, the last
+		 * output bytes should be picked from strm->next_out.
 		 */
 
-	LZMA_PROG_ERROR       = -2,
+	LZMA_NO_CHECK           = 2,
 		/**<
-		 * \brief       Programming error
+		 * \brief       Input stream has no integrity check
 		 *
-		 * This indicates that the arguments given to the function are
-		 * invalid or the internal state of the decoder is corrupt.
-		 *   - Function arguments are invalid or the structures
-		 *     pointed by the argument pointers are invalid
-		 *     e.g. if strm->next_out has been set to NULL and
-		 *     strm->avail_out > 0 when calling lzma_code().
-		 *   - lzma_* functions have been called in wrong order
-		 *     e.g. lzma_code() was called right after lzma_end().
-		 *   - If errors occur randomly, the reason might be flaky
-		 *     hardware.
+		 * This return value can be returned only if the
+		 * LZMA_TELL_NO_CHECK flag was used when initializing
+		 * the decoder. LZMA_NO_CHECK is just a warning, and
+		 * the decoding can be continued normally.
 		 *
-		 * If you think that your code is correct, this error code
-		 * can be a sign of a bug in liblzma. See the documentation
-		 * how to report bugs.
+		 * It is possible to call lzma_get_check() immediatelly after
+		 * lzma_code has returned LZMA_NO_CHECK. The result will
+		 * naturally be LZMA_CHECK_NONE, but the possibility to call
+		 * lzma_get_check() may be convenient in some applications.
 		 */
 
-	LZMA_DATA_ERROR         = -3,
+	LZMA_UNSUPPORTED_CHECK  = 3,
 		/**<
-		 * \brief       Data is corrupt
+		 * \brief       Cannot calculate the integrity check
+		 *
+		 * The usage of this return value is slightly different in
+		 * encoders and decoders.
 		 *
-		 * - Encoder: The input size doesn't match the uncompressed
-		 *   size given to lzma_*_encoder_init().
-		 * - Decoder: The input is corrupt. This includes corrupted
-		 *   header, corrupted compressed data, and unmatching
-		 *   integrity Check.
+		 * Encoders can return this value only from the initialization
+		 * function. If initialization fails with this value, the
+		 * encoding cannot be done, because there's no way to produce
+		 * output with the correct integrity check.
 		 *
-		 * \todo        What can be done if encoder returns this?
-		 *              Probably can continue by fixing the input
-		 *              amount, but make sure.
+		 * Decoders can return this value only from the lzma_code
+		 * function and only if the LZMA_TELL_UNSUPPORTED_CHECK flag
+		 * was used when initializing the decoder. The decoding can
+		 * still be continued normally even if the check type is
+		 * unsupported, but naturally the check will not be validated,
+		 * and possible errors may go undetected.
+		 *
+		 * With decoder, it is possible to call lzma_get_check()
+		 * immediatelly after lzma_code has returned
+		 * LZMA_UNSUPPORTED_CHECK. This way it is possible to find
+		 * out what the unsupported Check ID was.
 		 */
 
-	LZMA_MEM_ERROR          = -4,
+	LZMA_GET_CHECK          = 4,
 		/**<
-		 * \brief       Cannot allocate memory
+		 * \brief       Integrity check type is now available
 		 *
-		 * Memory allocation failed.
+		 * This value can be returned only by the lzma_code() function
+		 * and only if the decoder was initialized with the
+		 * LZMA_TELL_ANY_CHECK flag. LZMA_GET_CHECK tells the
+		 * application that it may now call lzma_get_check() to find
+		 * out the Check ID. This can be used, for example, to
+		 * implement a decoder that accepts only files that have
+		 * strong enough integrity check.
 		 */
 
-	LZMA_BUF_ERROR          = -5,
+	LZMA_MEM_ERROR          = 5,
 		/**<
-		 * \brief       No progress is possible
+		 * \brief       Cannot allocate memory
+		 *
+		 * Memory allocation failed, or the size of the allocation
+		 * would be greater than SIZE_MAX.
 		 *
-		 * This may happen when avail_in or avail_out is zero.
+		 * Due to lazy coding, the coding cannot be continued even
+		 * if more memory were made available after LZMA_MEM_ERROR.
+		 */
+
+	LZMA_MEMLIMIT_ERROR     = 6,
+		/**
+		 * \brief       Memory usage limit was reached
+		 *
+		 * Decoder would need more memory than allowed by the
+		 * specified memory usage limit. To continue decoding,
+		 * the memory usage limit has to be increased. See functions
+		 * lzma_memlimit_get() and lzma_memlimit_set().
+		 */
+
+	LZMA_FORMAT_ERROR       = 7,
+		/**<
+		 * \brief       Unknown file format
 		 *
-		 * \note        This error is not fatal. Coding can continue
-		 *              normally once the reason for this error has
-		 *              been fixed.
+		 * The decoder did not recognize the input as supported file
+		 * format. This error can occur, for example, when trying to
+		 * decode LZMA_Alone format file with lzma_stream_decoder,
+		 * because lzma_stream_decoder accepts only the new .lzma
+		 * format.
 		 */
 
-	LZMA_HEADER_ERROR       = -6,
+	LZMA_HEADER_ERROR       = 8,
 		/**<
-		 * \brief       Invalid or unsupported header
+		 * \brief       Invalid or unsupported options
 		 *
 		 * Invalid or unsupported options, for example
 		 *  - unsupported filter(s) or filter options; or
@@ -119,33 +173,71 @@ typedef enum {
 		 * upgrading to a newer version of liblzma may help.
 		 */
 
-	LZMA_UNSUPPORTED_CHECK  = -7,
+	LZMA_DATA_ERROR         = 9,
 		/**<
-		 * \brief       Check type is unknown
+		 * \brief       Data is corrupt
+		 *
+		 * The usage of this return value is different in encoders
+		 * and decoders. In both encoder and decoder, the coding
+		 * cannot continue after this error.
+		 *
+		 * Encoders return this if size limits of the target file
+		 * format would be exceeded. These limits are huge, thus
+		 * getting this error from an encoder is mostly theoretical.
+		 * For example, the maximum compressed and uncompressed
+		 * size of a Stream created with lzma_stream_encoder is
+		 * 2^63 - 1 bytes (one byte less than 8 EiB).
 		 *
-		 * The type of Check is not supported, and thus the Check
-		 * cannot be calculated. In the encoder, this is an error.
-		 * In the decoder, this is only a warning and decoding can
-		 * still proceed normally (but the Check is ignored).
+		 * Decoders return this error if the input data is corrupt.
+		 * This can mean, for example, invalid CRC32 in headers
+		 * or invalid check of uncompressed data.
 		 */
 
-	LZMA_FORMAT_ERROR        = -8,
+	LZMA_BUF_ERROR          = 10,
 		/**<
-		 * \brief       Unknown file format
+		 * \brief       No progress is possible
+		 *
+		 * This error code is returned when the coder cannot consume
+		 * any new input and produce any new output. The most common
+		 * reason for this error is that the input stream being
+		 * decoded is truncated or corrupt.
+		 *
+		 * This error is not fatal. Coding can be continued normally
+		 * by providing more input and/or more output space, if
+		 * possible.
+		 *
+		 * Typically the first call to lzma_code() that can do no
+		 * progress returns LZMA_OK instead of LZMA_BUF_ERROR. Only
+		 * the second consecutive call doing no progress will return
+		 * LZMA_BUF_ERROR. This is by design.
+		 *
+		 * With zlib, Z_BUF_ERROR may be returned even if the
+		 * application is doing nothing wrong. The above hack
+		 * guarantees that liblzma never returns LZMA_BUF_ERROR
+		 * to properly written applications unless the input file
+		 * is truncated or corrupt. This should simplify the
+		 * applications a little.
 		 */
 
-	LZMA_MEMLIMIT_ERROR     = -9,
-		/**
-		 * \brief       Memory usage limit was reached
+	LZMA_PROG_ERROR         = 11,
+		/**<
+		 * \brief       Programming error
 		 *
-		 * Decoder would need more memory than allowed by the
-		 * specified memory usage limit. To continue decoding,
-		 * the memory usage limit has to be increased. See functions
-		 * lzma_memlimit_get() and lzma_memlimit_set().
+		 * This indicates that the arguments given to the function are
+		 * invalid or the internal state of the decoder is corrupt.
+		 *   - Function arguments are invalid or the structures
+		 *     pointed by the argument pointers are invalid
+		 *     e.g. if strm->next_out has been set to NULL and
+		 *     strm->avail_out > 0 when calling lzma_code().
+		 *   - lzma_* functions have been called in wrong order
+		 *     e.g. lzma_code() was called right after lzma_end().
+		 *   - If errors occur randomly, the reason might be flaky
+		 *     hardware.
+		 *
+		 * If you think that your code is correct, this error code
+		 * can be a sign of a bug in liblzma. See the documentation
+		 * how to report bugs.
 		 */
-
-	LZMA_NO_CHECK = -10,
-	LZMA_SEE_CHECK = -11
 } lzma_ret;
 
 
@@ -176,17 +268,11 @@ typedef enum {
 		 * LZMA_STREAM_END. Then continue encoding normally.
 		 *
 		 * \note        Synchronous flushing is supported only by
-		 *              some filters. Some filters support it only
-		 *              partially.
-		 *
-		 * Decoder: Asks the decoder to decode only as much as is
-		 * needed to fill next_out. This decreases latency with some
-		 * filters, but is likely to decrease also throughput. It is
-		 * a good idea to use this flag only when it is likely that
-		 * you don't need more output soon.
+		 *              some filters. Using LZMA_SYNC_FLUSH with
+		 *              which such filters will make lzma_code()
+		 *              return LZMA_HEADER_ERROR.
 		 *
-		 * \note        With decoder, this is not comparable to
-		 *              zlib's Z_SYNC_FLUSH.
+		 * Decoders don't support LZMA_SYNC_FLUSH.
 		 */
 
 	LZMA_FULL_FLUSH = 2,
@@ -198,19 +284,25 @@ typedef enum {
 		 * it returns LZMA_STREAM_END. Then continue normally with
 		 * LZMA_RUN or finish the Stream with LZMA_FINISH.
 		 *
-		 * This action is supported only by Multi-Block Stream
-		 * encoder. If there is no unfinished Data Block, no empty
-		 * Data Block is created.
+		 * This action is supported only by Stream encoder and easy
+		 * encoder (which uses Stream encoder). If there is no
+		 * unfinished Block, no empty Block is created.
 		 */
 
 	LZMA_FINISH = 3
 		/**<
-		 * Finishes the encoding operation. All the input data must
+		 * Finishes the coding operation. All the input data must
 		 * have been given to the encoder (the last bytes can still
 		 * be pending in next_in). Call lzma_code() with LZMA_FINISH
-		 * until it returns LZMA_STREAM_END.
+		 * until it returns LZMA_STREAM_END. Once LZMA_FINISH has
+		 * been used, the amount of input must no longer be changed
+		 * by the application.
 		 *
-		 * This action is not supported by decoders.
+		 * When decoding, using LZMA_FINISH is optional unless the
+		 * LZMA_CONCATENATED flag was used when the decoder was
+		 * initialized. When LZMA_CONCATENATED was not used, the only
+		 * effect of LZMA_FINISH is that the amount of input must not
+		 * be changed just like in the encoder.
 		 */
 } lzma_action;
 
@@ -219,8 +311,10 @@ typedef enum {
  * \brief       Custom functions for memory handling
  *
  * A pointer to lzma_allocator may be passed via lzma_stream structure
- * to liblzma. The library will use these functions for memory handling
- * instead of the default malloc() and free().
+ * to liblzma, and some advanced function take pointer lzma_allocator as
+ * a separate function argument. The library will use the functions
+ * specified in lzma_allocator for memory handling instead of the default
+ * malloc() and free().
  *
  * liblzma doesn't make an internal copy of lzma_allocator. Thus, it is
  * OK to change these function pointers in the middle of the coding
@@ -255,6 +349,12 @@ typedef struct {
 	 * necessarily allocate the requested memory until it is actually
 	 * used. With small input files liblzma may actually need only a
 	 * fraction of the memory that it requested for allocation.
+	 *
+	 * \note        LZMA_MEM_ERROR is also used when the size of the
+	 *              allocation would be greater than SIZE_MAX. Thus,
+	 *              don't assume that the custom allocator must have
+	 *              returned NULL if some function from liblzma
+	 *              returns LZMA_MEM_ERROR.
 	 */
 	void *(*alloc)(void *opaque, size_t nmemb, size_t size);
 
@@ -266,9 +366,8 @@ typedef struct {
 	 * will use the standard free().
 	 *
 	 * \param       opaque  lzma_allocator.opaque (see below)
-	 * \param       ptr     Pointer returned by
-	 *                      lzma_allocator.alloc(), or when it
-	 *                      is set to NULL, a pointer returned
+	 * \param       ptr     Pointer returned by lzma_allocator.alloc(),
+	 *                      or when it is set to NULL, a pointer returned
 	 *                      by the standard malloc().
 	 */
 	void (*free)(void *opaque, void *ptr);
@@ -280,7 +379,7 @@ typedef struct {
 	 * and lzma_allocator.free(). This intended to ease implementing
 	 * custom memory allocation functions for use with liblzma.
 	 *
-	 * If you don't need this, you should set it to NULL.
+	 * If you don't need this, you should set this to NULL.
 	 */
 	void *opaque;
 
@@ -303,6 +402,13 @@ typedef struct lzma_internal_s lzma_internal;
  *   - defining custom memory hander functions; and
  *   - holding a pointer to coder-specific internal data structures.
  *
+ * When a new lzma_stream structure is allocated (either as automatic variable
+ * on stack or dynamically with malloc()), the new lzma_stream structure must
+ * be initialized to LZMA_STREAM_INIT.
+ *
+ * Before initializing a coder (for example, with lzma_stream_decoder()),
+ *
+ *
  * Before calling any of the lzma_*_init() functions the first time,
  * the application must reset lzma_stream to LZMA_STREAM_INIT. The
  * lzma_*_init() function will verify the options, allocate internal
@@ -341,7 +447,7 @@ typedef struct {
 	 */
 	lzma_allocator *allocator;
 
-	/** Internal state is not visible to outsiders. */
+	/** Internal state is not visible to applications. */
 	lzma_internal *internal;
 
 	/**
@@ -354,6 +460,8 @@ typedef struct {
 	void *reserved_ptr2;
 	uint64_t reserved_int1;
 	uint64_t reserved_int2;
+	lzma_reserved_enum reserved_enum1;
+	lzma_reserved_enum reserved_enum2;
 
 } lzma_stream;
 
@@ -367,51 +475,31 @@ typedef struct {
  *
  *     lzma_stream strm = LZMA_STREAM_INIT;
  *
- * If you need to initialize a dynamically allocatedlzma_stream, you can use
+ * If you need to initialize a dynamically allocated lzma_stream, you can use
  * memset(strm_pointer, 0, sizeof(lzma_stream)). Strictly speaking, this
  * violates the C standard since NULL may have different internal
  * representation than zero, but it should be portable enough in practice.
- * Anyway, for maximum portability, you could use this:
+ * Anyway, for maximum portability, you can use something like this:
  *
  *     lzma_stream tmp = LZMA_STREAM_INIT;
  *     *strm = tmp;
  */
 #define LZMA_STREAM_INIT \
-	{ NULL, 0, 0, NULL, 0, 0, NULL, NULL, NULL, NULL, 0, 0 }
+	{ NULL, 0, 0, NULL, 0, 0, NULL, NULL, NULL, NULL, 0, 0, 0, 0 }
 
 
 /**
  * \brief       Encodes or decodes data
  *
  * Once the lzma_stream has been successfully initialized (e.g. with
- * lzma_stream_encoder_single()), the actual encoding or decoding is
- * done using this function.
+ * lzma_stream_encoder()), the actual encoding or decoding is done
+ * using this function. The application has to update strm->next_in,
+ * strm->avail_in, strm->next_out, and strm->avail_out to pass input
+ * to and get output from liblzma.
  *
- * \return      Some coders may have more exact meaning for different return
- *              values, which are mentioned separately in the description of
- *              the initialization functions. Here are the typical meanings:
- *              - LZMA_OK: So far all good.
- *              - LZMA_STREAM_END:
- *                  - Encoder: LZMA_SYNC_FLUSH, LZMA_FULL_FLUSH, or
- *                    LZMA_FINISH completed.
- *                  - Decoder: End of uncompressed data was reached.
- *              - LZMA_BUF_ERROR: Unable to progress. Provide more input or
- *                output space, and call this function again. This cannot
- *                occur if both avail_in and avail_out were non-zero (or
- *                there's a bug in liblzma).
- *              - LZMA_MEM_ERROR: Unable to allocate memory. Due to lazy
- *                programming, the coding cannot continue even if the
- *                application could free more memory. The next call must
- *                be lzma_end() or some initialization function.
- *              - LZMA_DATA_ERROR:
- *                  - Encoder: Filter(s) cannot process the given data.
- *                  - Decoder: Compressed data is corrupt.
- *              - LZMA_HEADER_ERROR: Unsupported options. Rebuilding liblzma
- *                with more features enabled or upgrading to a newer version
- *                may help, although usually this is a sign of invalid options
- *                (encoder) or corrupted input data (decoder).
- *              - LZMA_PROG_ERROR: Invalid arguments or the internal state
- *                of the coder is corrupt.
+ * See the description of the coder-specific initialization function to find
+ * out what `action' values are supported by the coder. See documentation of
+ * lzma_ret for the possible return values.
  */
 extern lzma_ret lzma_code(lzma_stream *strm, lzma_action action)
 		lzma_attr_warn_unused_result;
diff --git a/src/liblzma/api/lzma/check.h b/src/liblzma/api/lzma/check.h
index 18394a86..5cba362e 100644
--- a/src/liblzma/api/lzma/check.h
+++ b/src/liblzma/api/lzma/check.h
@@ -137,3 +137,13 @@ extern uint64_t lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
  * SHA256 functions are currently not exported to public API.
  * Contact the author if you think it should be.
  */
+
+
+/**
+ * \brief       Get the type of the integrity check
+ *
+ * This function can be called only immediatelly after lzma_code() has
+ * returned LZMA_NO_CHECK, LZMA_UNSUPPORTED_CHECK, or LZMA_GET_CHECK.
+ * Calling this function in any other situation has undefined behavior.
+ */
+extern lzma_check lzma_get_check(const lzma_stream *strm);
diff --git a/src/liblzma/api/lzma/container.h b/src/liblzma/api/lzma/container.h
index 27014856..2b719b04 100644
--- a/src/liblzma/api/lzma/container.h
+++ b/src/liblzma/api/lzma/container.h
@@ -94,7 +94,7 @@ typedef enum {
  *              On error (e.g. compression level is not supported),
  *              UINT32_MAX is returned.
  */
-extern uint32_t lzma_easy_memory_usage(lzma_easy_level level)
+extern uint64_t lzma_easy_memory_usage(lzma_easy_level level)
 		lzma_attr_pure;
 
 
@@ -177,10 +177,10 @@ extern lzma_ret lzma_alone_encoder(
 /**
  * This flag makes lzma_code() return LZMA_NO_CHECK if the input stream
  * being decoded has no integrity check. Note that when used with
- * lzma_auto_decoder(), all LZMA_Alone files will cause trigger LZMA_NO_CHECK
- * if LZMA_WARN_NO_CHECK is used.
+ * lzma_auto_decoder(), all LZMA_Alone files will trigger LZMA_NO_CHECK
+ * if LZMA_TELL_NO_CHECK is used.
  */
-#define LZMA_WARN_NO_CHECK              UINT32_C(0x01)
+#define LZMA_TELL_NO_CHECK              UINT32_C(0x01)
 
 
 /**
@@ -189,20 +189,30 @@ extern lzma_ret lzma_alone_encoder(
  * supported by this liblzma version or build. Such files can still be
  * decoded, but the integrity check cannot be verified.
  */
-#define LZMA_WARN_UNSUPPORTED_CHECK     UINT32_C(0x02)
+#define LZMA_TELL_UNSUPPORTED_CHECK     UINT32_C(0x02)
 
 
 /**
- * This flag makes lzma_code() return LZMA_READ_CHECK as soon as the type
- * of the integrity check is known. The type can then be read with
- * lzma_check_get().
+ * This flag makes lzma_code() return LZMA_GET_CHECK as soon as the type
+ * of the integrity check is known. The type can then be got with
+ * lzma_get_check().
  */
-#define LZMA_TELL_CHECK                 UINT32_C(0x04)
+#define LZMA_TELL_ANY_CHECK             UINT32_C(0x04)
 
 
 /**
- * This flag makes lzma_code() decode concatenated .lzma files.
- * FIXME Explain the changed API.
+ * This flag enables decoding of concatenated files with file formats that
+ * allow concatenating compressed files as is. From the formats currently
+ * supported by liblzma, only the new .lzma format allows concatenated files.
+ * Concatenated files are not allowed with the LZMA_Alone format.
+ *
+ * This flag also affects the usage of the `action' argument for lzma_code().
+ * When LZMA_CONCATENATED is used, lzma_code() won't return LZMA_STREAM_END
+ * unless LZMA_FINISH is used as `action'. Thus, the application has to set
+ * LZMA_FINISH in the same way as it does when encoding.
+ *
+ * If LZMA_CONCATENATED is not used, the decoders still accept LZMA_FINISH
+ * as `action' for lzma_code(), but the usage of LZMA_FINISH isn't required.
  */
 #define LZMA_CONCATENATED               UINT32_C(0x08)
 
@@ -210,11 +220,12 @@ extern lzma_ret lzma_alone_encoder(
 /**
  * \brief       Initializes decoder for .lzma Stream
  *
- * \param       strm        Pointer to propertily prepared lzma_stream
+ * \param       strm        Pointer to properly prepared lzma_stream
  * \param       memlimit    Rough memory usage limit as bytes
  *
  * \return      - LZMA_OK: Initialization was successful.
  *              - LZMA_MEM_ERROR: Cannot allocate memory.
+ *              - LZMA_HEADER_ERROR: Unsupported flags
  */
 extern lzma_ret lzma_stream_decoder(
 		lzma_stream *strm, uint64_t memlimit, uint32_t flags)
@@ -225,8 +236,8 @@ extern lzma_ret lzma_stream_decoder(
  * \brief       Decode .lzma Streams and LZMA_Alone files with autodetection
  *
  * Autodetects between the .lzma Stream and LZMA_Alone formats, and
- * calls lzma_stream_decoder_init() or lzma_alone_decoder_init() once
- * the type of the file has been detected.
+ * calls lzma_stream_decoder() or lzma_alone_decoder() once the type
+ * of the file has been detected.
  *
  * \param       strm        Pointer to propertily prepared lzma_stream
  * \param       memlimit    Rough memory usage limit as bytes
@@ -234,6 +245,7 @@ extern lzma_ret lzma_stream_decoder(
  *
  * \return      - LZMA_OK: Initialization was successful.
  *              - LZMA_MEM_ERROR: Cannot allocate memory.
+ *              - LZMA_HEADER_ERROR: Unsupported flags
  */
 extern lzma_ret lzma_auto_decoder(
 		lzma_stream *strm, uint64_t memlimit, uint32_t flags)
diff --git a/src/liblzma/common/auto_decoder.c b/src/liblzma/common/auto_decoder.c
index acfc3549..4272dadf 100644
--- a/src/liblzma/common/auto_decoder.c
+++ b/src/liblzma/common/auto_decoder.c
@@ -63,15 +63,15 @@ auto_decode(lzma_coder *coder, lzma_allocator *allocator,
 			return_if_error(lzma_alone_decoder_init(&coder->next,
 					allocator, coder->memlimit));
 
-			// If the application wants a warning about missing
+			// If the application wants to know about missing
 			// integrity check or about the check in general, we
 			// need to handle it here, because LZMA_Alone decoder
 			// doesn't accept any flags.
-			if (coder->flags & LZMA_WARN_NO_CHECK)
+			if (coder->flags & LZMA_TELL_NO_CHECK)
 				return LZMA_NO_CHECK;
 
-			if (coder->flags & LZMA_TELL_CHECK)
-				return LZMA_SEE_CHECK;
+			if (coder->flags & LZMA_TELL_ANY_CHECK)
+				return LZMA_GET_CHECK;
 		}
 
 	// Fall through
@@ -116,11 +116,11 @@ auto_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
 
 
 static lzma_check
-auto_decoder_see_check(const lzma_coder *coder)
+auto_decoder_get_check(const lzma_coder *coder)
 {
-	// It is LZMA_Alone if see_check is NULL.
-	return coder->next.see_check == NULL ? LZMA_CHECK_NONE
-			: coder->next.see_check(coder->next.coder);
+	// It is LZMA_Alone if get_check is NULL.
+	return coder->next.get_check == NULL ? LZMA_CHECK_NONE
+			: coder->next.get_check(coder->next.coder);
 }
 
 
@@ -140,7 +140,7 @@ auto_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 
 		next->code = &auto_decode;
 		next->end = &auto_decoder_end;
-		next->see_check = &auto_decoder_see_check;
+		next->get_check = &auto_decoder_get_check;
 		next->coder->next = LZMA_NEXT_CODER_INIT;
 	}
 
diff --git a/src/liblzma/common/common.c b/src/liblzma/common/common.c
index feac9cbf..c5f5039d 100644
--- a/src/liblzma/common/common.c
+++ b/src/liblzma/common/common.c
@@ -296,3 +296,10 @@ lzma_end(lzma_stream *strm)
 
 	return;
 }
+
+
+extern LZMA_API lzma_check
+lzma_get_check(const lzma_stream *strm)
+{
+	return strm->internal->next.get_check(strm->internal->next.coder);
+}
diff --git a/src/liblzma/common/common.h b/src/liblzma/common/common.h
index 81f2a9a4..bb999842 100644
--- a/src/liblzma/common/common.h
+++ b/src/liblzma/common/common.h
@@ -60,10 +60,10 @@
 /// Supported flags that can be passed to lzma_stream_decoder()
 /// or lzma_auto_decoder().
 #define LZMA_SUPPORTED_FLAGS \
-	(LZMA_WARN_NO_CHECK \
-	| LZMA_WARN_UNSUPPORTED_CHECK \
-	| LZMA_TELL_CHECK \
-	| LZMA_CONCATENATED)
+	( LZMA_TELL_NO_CHECK \
+	| LZMA_TELL_UNSUPPORTED_CHECK \
+	| LZMA_TELL_ANY_CHECK \
+	| LZMA_CONCATENATED )
 
 
 ///////////
@@ -134,10 +134,11 @@ struct lzma_next_coder_s {
 
 	/// Pointer to function to return the type of the integrity check.
 	/// Most coders won't support this.
-	lzma_check (*see_check)(const lzma_coder *coder);
+	lzma_check (*get_check)(const lzma_coder *coder);
 
-// 	uint64_t (*memconfig)(
-// 			lzma_coder *coder, uint64_t memlimit, bool change);
+	/// Pointer to function to get and/or change the memory usage limit.
+	/// If memlimit == 0, the limit is not changed.
+	uint64_t (*memconfig)(lzma_coder *coder, uint64_t memlimit);
 };
 
 
@@ -148,7 +149,8 @@ struct lzma_next_coder_s {
 		.init = (uintptr_t)(NULL), \
 		.code = NULL, \
 		.end = NULL, \
-		.see_check = NULL, \
+		.get_check = NULL, \
+		.memconfig = NULL, \
 	}
 
 
diff --git a/src/liblzma/common/easy.c b/src/liblzma/common/easy.c
index ae0e4f74..6f6dc0fa 100644
--- a/src/liblzma/common/easy.c
+++ b/src/liblzma/common/easy.c
@@ -113,7 +113,7 @@ lzma_easy_encoder(lzma_stream *strm, lzma_easy_level level)
 }
 
 
-extern LZMA_API uint32_t
+extern LZMA_API uint64_t
 lzma_easy_memory_usage(lzma_easy_level level)
 {
 	lzma_filter filters[5];
diff --git a/src/liblzma/common/stream_decoder.c b/src/liblzma/common/stream_decoder.c
index cf7af7ac..7d1df9cc 100644
--- a/src/liblzma/common/stream_decoder.c
+++ b/src/liblzma/common/stream_decoder.c
@@ -55,14 +55,14 @@ struct lzma_coder_s {
 
 	/// If true, LZMA_NO_CHECK is returned if the Stream has
 	/// no integrity check.
-	bool warn_no_check;
+	bool tell_no_check;
 
 	/// If true, LZMA_UNSUPPORTED_CHECK is returned if the Stream has
 	/// an integrity check that isn't supported by this liblzma build.
-	bool warn_unsupported_check;
+	bool tell_unsupported_check;
 
-	/// If true, LZMA_SEE_CHECK is returned after decoding Stream Header.
-	bool tell_check;
+	/// If true, LZMA_GET_CHECK is returned after decoding Stream Header.
+	bool tell_any_check;
 
 	/// If true, we will decode concatenated Streams that possibly have
 	/// Stream Padding between or after them. LZMA_STREAM_END is returned
@@ -141,17 +141,17 @@ stream_decode(lzma_coder *coder, lzma_allocator *allocator,
 
 		// Detect if there's no integrity check or if it is
 		// unsupported if those were requested by the application.
-		if (coder->warn_no_check && coder->stream_flags.check
+		if (coder->tell_no_check && coder->stream_flags.check
 				== LZMA_CHECK_NONE)
 			return LZMA_NO_CHECK;
 
-		if (coder->warn_unsupported_check
+		if (coder->tell_unsupported_check
 				&& !lzma_check_is_supported(
 					coder->stream_flags.check))
 			return LZMA_UNSUPPORTED_CHECK;
 
-		if (coder->tell_check)
-			return LZMA_SEE_CHECK;
+		if (coder->tell_any_check)
+			return LZMA_GET_CHECK;
 	}
 
 	// Fall through
@@ -366,7 +366,7 @@ stream_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
 
 
 static lzma_check
-stream_decoder_see_check(const lzma_coder *coder)
+stream_decoder_get_check(const lzma_coder *coder)
 {
 	return coder->stream_flags.check;
 }
@@ -388,19 +388,18 @@ lzma_stream_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 
 		next->code = &stream_decode;
 		next->end = &stream_decoder_end;
-		next->see_check = &stream_decoder_see_check;
+		next->get_check = &stream_decoder_get_check;
 
 		next->coder->block_decoder = LZMA_NEXT_CODER_INIT;
 		next->coder->index_hash = NULL;
 	}
 
 	next->coder->memlimit = memlimit;
-	next->coder->warn_no_check = (flags & LZMA_WARN_NO_CHECK) != 0;
-	next->coder->warn_unsupported_check
-			= (flags & LZMA_WARN_UNSUPPORTED_CHECK) != 0;
-	next->coder->tell_check = (flags & LZMA_TELL_CHECK) != 0;
-	next->coder->concatenated
-			= (flags & LZMA_CONCATENATED) != 0;
+	next->coder->tell_no_check = (flags & LZMA_TELL_NO_CHECK) != 0;
+	next->coder->tell_unsupported_check
+			= (flags & LZMA_TELL_UNSUPPORTED_CHECK) != 0;
+	next->coder->tell_any_check = (flags & LZMA_TELL_ANY_CHECK) != 0;
+	next->coder->concatenated = (flags & LZMA_CONCATENATED) != 0;
 
 	return stream_decoder_reset(next->coder, allocator);
 }
diff --git a/src/lzma/process.c b/src/lzma/process.c
index 084b2c57..b24de698 100644
--- a/src/lzma/process.c
+++ b/src/lzma/process.c
@@ -172,7 +172,7 @@ single_init(thread_data *t)
 			break;
 		}
 	} else {
-		const uint32_t flags = LZMA_WARN_UNSUPPORTED_CHECK
+		const uint32_t flags = LZMA_TELL_UNSUPPORTED_CHECK
 				| LZMA_CONCATENATED;
 
 		switch (opt_header) {
diff --git a/src/lzmadec/lzmadec.c b/src/lzmadec/lzmadec.c
index ed5947ad..b69723b4 100644
--- a/src/lzmadec/lzmadec.c
+++ b/src/lzmadec/lzmadec.c
@@ -97,9 +97,7 @@ help(void)
 "  -M, --memory=NUM   use NUM bytes of memory at maximum; the suffixes\n"
 "                     k, M, G, Ki, Mi, and Gi are supported.\n"
 "      --format=FMT   accept only files in the given file format;\n"
-"                     possible FMTs are `auto', `native', `single',\n"
-"                     `multi', and `alone', of which `single' and `multi'\n"
-"                     are aliases for `native'\n"
+"                     possible FMTs are `auto', `native', and alone',\n"
 "  -h, --help         display this help and exit\n"
 "  -V, --version      display version and license information and exit\n"
 "\n"
@@ -302,7 +300,7 @@ parse_options(int argc, char **argv)
 static void
 init(void)
 {
-	const uint32_t flags = LZMA_WARN_UNSUPPORTED_CHECK | LZMA_CONCATENATED;
+	const uint32_t flags = LZMA_TELL_UNSUPPORTED_CHECK | LZMA_CONCATENATED;
 	lzma_ret ret;
 
 	switch (format_type) {