diff --git a/.gitignore b/.gitignore
index 056aaef..357fc0b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,4 @@
 xzminidec
 buftest
 boottest
+bytetest
diff --git a/METADATA b/METADATA
index a2a2f4d..72800f8 100644
--- a/METADATA
+++ b/METADATA
@@ -3,13 +3,13 @@
 third_party {
   url {
     type: GIT
-    value: "https://git.tukaani.org/?p=xz-embedded.git"
+    value: "https://git.tukaani.org/xz-embedded.git"
   }
-  version: "79b68de5657beecfad575578a7181cf6fca869cb"
+  version: "3f438e15109229bb14ab45f285f4bff5412a9542"
   license_type: UNENCUMBERED
   last_upgrade_date {
-    year: 2017
-    month: 4
-    day: 7
+    year: 2021
+    month: 10
+    day: 11
   }
 }
diff --git a/README b/README
index 566d604..c8ca09c 100644
--- a/README
+++ b/README
@@ -84,6 +84,21 @@
     environment. Probably you should at least skim through it even if the
     default file works as is.
 
+Supporting concatenated .xz files
+
+    Regular .xz files can be concatenated as is and the xz command line
+    tool will decompress all streams from a concatenated file (a few
+    other popular formats and tools support this too). This kind of .xz
+    files aren't as uncommon as one might think because pxz, an early
+    threaded XZ compressor, created this kind of .xz files.
+
+    The xz_dec_run() function will stop after decompressing one stream.
+    This is good when XZ data is stored inside some other file format.
+    However, if one is decompressing regular standalone .xz files, one
+    will want to decompress all streams in the file. This is easy with
+    xz_dec_catrun(). To include support for xz_dec_catrun(), you need
+    to #define XZ_DEC_CONCATENATED in xz_config.h or in compiler flags.
+
 Integrity check support
 
     XZ Embedded always supports the integrity check types None and
diff --git a/linux/Documentation/xz.txt b/linux/Documentation/xz.txt
index 68329ac..1e1a915 100644
--- a/linux/Documentation/xz.txt
+++ b/linux/Documentation/xz.txt
@@ -13,13 +13,13 @@
     The XZ decompressor in Linux is called XZ Embedded. It supports
     the LZMA2 filter and optionally also BCJ filters. CRC32 is supported
     for integrity checking. The home page of XZ Embedded is at
-    <http://tukaani.org/xz/embedded.html>, where you can find the
+    <https://tukaani.org/xz/embedded.html>, where you can find the
     latest version and also information about using the code outside
     the Linux kernel.
 
     For userspace, XZ Utils provide a zlib-like compression library
     and a gzip-like command line tool. XZ Utils can be downloaded from
-    <http://tukaani.org/xz/>.
+    <https://tukaani.org/xz/>.
 
 XZ related components in the kernel
 
@@ -107,7 +107,7 @@
 Reporting bugs
 
     Before reporting a bug, please check that it's not fixed already
-    at upstream. See <http://tukaani.org/xz/embedded.html> to get the
+    at upstream. See <https://tukaani.org/xz/embedded.html> to get the
     latest code.
 
     Report bugs to <lasse.collin@tukaani.org> or visit #tukaani on
diff --git a/linux/include/linux/xz.h b/linux/include/linux/xz.h
index 0a4b38d..f3801eb 100644
--- a/linux/include/linux/xz.h
+++ b/linux/include/linux/xz.h
@@ -2,7 +2,7 @@
  * XZ decompressor
  *
  * Authors: Lasse Collin <lasse.collin@tukaani.org>
- *          Igor Pavlov <http://7-zip.org/>
+ *          Igor Pavlov <https://7-zip.org/>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
@@ -32,7 +32,7 @@
  * enum xz_mode - Operation mode
  *
  * @XZ_SINGLE:              Single-call mode. This uses less RAM than
- *                          than multi-call modes, because the LZMA2
+ *                          multi-call modes, because the LZMA2
  *                          dictionary doesn't need to be allocated as
  *                          part of the decoder state. All required data
  *                          structures are allocated at initialization,
@@ -198,7 +198,7 @@
 XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max);
 
 /**
- * xz_dec_run() - Run the XZ decoder
+ * xz_dec_run() - Run the XZ decoder for a single XZ stream
  * @s:          Decoder state allocated using xz_dec_init()
  * @b:          Input and output buffers
  *
@@ -214,10 +214,52 @@
  * cannot give the single-call decoder a too small buffer and then expect to
  * get that amount valid data from the beginning of the stream. You must use
  * the multi-call decoder if you don't want to uncompress the whole stream.
+ *
+ * Use xz_dec_run() when XZ data is stored inside some other file format.
+ * The decoding will stop after one XZ stream has been decompresed. To
+ * decompress regular .xz files which might have multiple concatenated
+ * streams, use xz_dec_catrun() instead.
  */
 XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b);
 
 /**
+ * xz_dec_catrun() - Run the XZ decoder with support for concatenated streams
+ * @s:          Decoder state allocated using xz_dec_init()
+ * @b:          Input and output buffers
+ * @finish:     This is an int instead of bool to avoid requiring stdbool.h.
+ *              As long as more input might be coming, finish must be false.
+ *              When the caller knows that it has provided all the input to
+ *              the decoder (some possibly still in b->in), it must set finish
+ *              to true. Only when finish is true can this function return
+ *              XZ_STREAM_END to indicate successful decompression of the
+ *              file. In single-call mode (XZ_SINGLE) finish is assumed to
+ *              always be true; the caller-provided value is ignored.
+ *
+ * This is like xz_dec_run() except that this makes it easy to decode .xz
+ * files with multiple streams (multiple .xz files concatenated as is).
+ * The rarely-used Stream Padding feature is supported too, that is, there
+ * can be null bytes after or between the streams. The number of null bytes
+ * must be a multiple of four.
+ *
+ * When finish is false and b->in_pos == b->in_size, it is possible that
+ * XZ_BUF_ERROR isn't returned even when no progress is possible (XZ_OK is
+ * returned instead). This shouldn't matter because in this situation a
+ * reasonable caller will attempt to provide more input or set finish to
+ * true for the next xz_dec_catrun() call anyway.
+ *
+ * For any struct xz_dec that has been initialized for multi-call mode:
+ * Once decoding has been started with xz_dec_run() or xz_dec_catrun(),
+ * the same function must be used until xz_dec_reset() or xz_dec_end().
+ * Switching between the two decoding functions without resetting results
+ * in undefined behavior.
+ *
+ * xz_dec_catrun() is only available if XZ_DEC_CONCATENATED was defined
+ * at compile time.
+ */
+XZ_EXTERN enum xz_ret xz_dec_catrun(struct xz_dec *s, struct xz_buf *b,
+				    int finish);
+
+/**
  * xz_dec_reset() - Reset an already allocated decoder state
  * @s:          Decoder state allocated using xz_dec_init()
  *
@@ -238,6 +280,112 @@
 XZ_EXTERN void xz_dec_end(struct xz_dec *s);
 
 /*
+ * Decompressor for MicroLZMA, an LZMA variant with a very minimal header.
+ * See xz_dec_microlzma_alloc() below for details.
+ *
+ * These functions aren't used or available in preboot code and thus aren't
+ * marked with XZ_EXTERN. This avoids warnings about static functions that
+ * are never defined.
+ */
+/**
+ * struct xz_dec_microlzma - Opaque type to hold the MicroLZMA decoder state
+ */
+struct xz_dec_microlzma;
+
+/**
+ * xz_dec_microlzma_alloc() - Allocate memory for the MicroLZMA decoder
+ * @mode        XZ_SINGLE or XZ_PREALLOC
+ * @dict_size   LZMA dictionary size. This must be at least 4 KiB and
+ *              at most 3 GiB.
+ *
+ * In contrast to xz_dec_init(), this function only allocates the memory
+ * and remembers the dictionary size. xz_dec_microlzma_reset() must be used
+ * before calling xz_dec_microlzma_run().
+ *
+ * The amount of allocated memory is a little less than 30 KiB with XZ_SINGLE.
+ * With XZ_PREALLOC also a dictionary buffer of dict_size bytes is allocated.
+ *
+ * On success, xz_dec_microlzma_alloc() returns a pointer to
+ * struct xz_dec_microlzma. If memory allocation fails or
+ * dict_size is invalid, NULL is returned.
+ *
+ * The compressed format supported by this decoder is a raw LZMA stream
+ * whose first byte (always 0x00) has been replaced with bitwise-negation
+ * of the LZMA properties (lc/lp/pb) byte. For example, if lc/lp/pb is
+ * 3/0/2, the first byte is 0xA2. This way the first byte can never be 0x00.
+ * Just like with LZMA2, lc + lp <= 4 must be true. The LZMA end-of-stream
+ * marker must not be used. The unused values are reserved for future use.
+ * This MicroLZMA header format was created for use in EROFS but may be used
+ * by others too.
+ */
+extern struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
+						       uint32_t dict_size);
+
+/**
+ * xz_dec_microlzma_reset() - Reset the MicroLZMA decoder state
+ * @s           Decoder state allocated using xz_dec_microlzma_alloc()
+ * @comp_size   Compressed size of the input stream
+ * @uncomp_size Uncompressed size of the input stream. A value smaller
+ *              than the real uncompressed size of the input stream can
+ *              be specified if uncomp_size_is_exact is set to false.
+ *              uncomp_size can never be set to a value larger than the
+ *              expected real uncompressed size because it would eventually
+ *              result in XZ_DATA_ERROR.
+ * @uncomp_size_is_exact  This is an int instead of bool to avoid
+ *              requiring stdbool.h. This should normally be set to true.
+ *              When this is set to false, error detection is weaker.
+ */
+extern void xz_dec_microlzma_reset(struct xz_dec_microlzma *s,
+				   uint32_t comp_size, uint32_t uncomp_size,
+				   int uncomp_size_is_exact);
+
+/**
+ * xz_dec_microlzma_run() - Run the MicroLZMA decoder
+ * @s           Decoder state initialized using xz_dec_microlzma_reset()
+ * @b:          Input and output buffers
+ *
+ * This works similarly to xz_dec_run() with a few important differences.
+ * Only the differences are documented here.
+ *
+ * The only possible return values are XZ_OK, XZ_STREAM_END, and
+ * XZ_DATA_ERROR. This function cannot return XZ_BUF_ERROR: if no progress
+ * is possible due to lack of input data or output space, this function will
+ * keep returning XZ_OK. Thus, the calling code must be written so that it
+ * will eventually provide input and output space matching (or exceeding)
+ * comp_size and uncomp_size arguments given to xz_dec_microlzma_reset().
+ * If the caller cannot do this (for example, if the input file is truncated
+ * or otherwise corrupt), the caller must detect this error by itself to
+ * avoid an infinite loop.
+ *
+ * If the compressed data seems to be corrupt, XZ_DATA_ERROR is returned.
+ * This can happen also when incorrect dictionary, uncompressed, or
+ * compressed sizes have been specified.
+ *
+ * With XZ_PREALLOC only: As an extra feature, b->out may be NULL to skip over
+ * uncompressed data. This way the caller doesn't need to provide a temporary
+ * output buffer for the bytes that will be ignored.
+ *
+ * With XZ_SINGLE only: In contrast to xz_dec_run(), the return value XZ_OK
+ * is also possible and thus XZ_SINGLE is actually a limited multi-call mode.
+ * After XZ_OK the bytes decoded so far may be read from the output buffer.
+ * It is possible to continue decoding but the variables b->out and b->out_pos
+ * MUST NOT be changed by the caller. Increasing the value of b->out_size is
+ * allowed to make more output space available; one doesn't need to provide
+ * space for the whole uncompressed data on the first call. The input buffer
+ * may be changed normally like with XZ_PREALLOC. This way input data can be
+ * provided from non-contiguous memory.
+ */
+extern enum xz_ret xz_dec_microlzma_run(struct xz_dec_microlzma *s,
+					struct xz_buf *b);
+
+/**
+ * xz_dec_microlzma_end() - Free the memory allocated for the decoder state
+ * @s:          Decoder state allocated using xz_dec_microlzma_alloc().
+ *              If s is NULL, this function does nothing.
+ */
+extern void xz_dec_microlzma_end(struct xz_dec_microlzma *s);
+
+/*
  * Standalone build (userspace build or in-kernel build for boot time use)
  * needs a CRC32 implementation. For normal in-kernel use, kernel's own
  * CRC32 module is used instead, and users of this module don't need to
diff --git a/linux/lib/decompress_unxz.c b/linux/lib/decompress_unxz.c
index 9f34eb5..7dfdde7 100644
--- a/linux/lib/decompress_unxz.c
+++ b/linux/lib/decompress_unxz.c
@@ -20,10 +20,10 @@
  *
  * The worst case for in-place decompression is that the beginning of
  * the file is compressed extremely well, and the rest of the file is
- * uncompressible. Thus, we must look for worst-case expansion when the
- * compressor is encoding uncompressible data.
+ * incompressible. Thus, we must look for worst-case expansion when the
+ * compressor is encoding incompressible data.
  *
- * The structure of the .xz file in case of a compresed kernel is as follows.
+ * The structure of the .xz file in case of a compressed kernel is as follows.
  * Sizes (as bytes) of the fields are in parenthesis.
  *
  *    Stream Header (12)
@@ -58,7 +58,7 @@
  * uncompressed size of the payload is in practice never less than the
  * payload size itself. The LZMA2 format would allow uncompressed size
  * to be less than the payload size, but no sane compressor creates such
- * files. LZMA2 supports storing uncompressible data in uncompressed form,
+ * files. LZMA2 supports storing incompressible data in uncompressed form,
  * so there's never a need to create payloads whose uncompressed size is
  * smaller than the compressed size.
  *
@@ -167,8 +167,8 @@
  * memeq and memzero are not used much and any remotely sane implementation
  * is fast enough. memcpy/memmove speed matters in multi-call mode, but
  * the kernel image is decompressed in single-call mode, in which only
- * memcpy speed can matter and only if there is a lot of uncompressible data
- * (LZMA2 stores uncompressible chunks in uncompressed form). Thus, the
+ * memmove speed can matter and only if there is a lot of incompressible data
+ * (LZMA2 stores incompressible chunks in uncompressed form). Thus, the
  * functions below should just be kept small; it's probably not worth
  * optimizing for speed.
  */
diff --git a/linux/lib/xz/Kconfig b/linux/lib/xz/Kconfig
index 08837db..3e58caf 100644
--- a/linux/lib/xz/Kconfig
+++ b/linux/lib/xz/Kconfig
@@ -38,6 +38,19 @@
 	default y if SPARC
 	select XZ_DEC_BCJ
 
+config XZ_DEC_MICROLZMA
+	bool "MicroLZMA decoder"
+	default n
+	help
+	  MicroLZMA is a header format variant where the first byte
+	  of a raw LZMA stream (without the end of stream marker) has
+	  been replaced with a bitwise-negation of the lc/lp/pb
+	  properties byte. MicroLZMA was created to be used in EROFS
+	  but can be used by other things too where wasting minimal
+	  amount of space for headers is important.
+
+	  Unless you know that you need this, say N.
+
 endif
 
 config XZ_DEC_BCJ
diff --git a/linux/lib/xz/xz_crc32.c b/linux/lib/xz/xz_crc32.c
index 34532d1..5627b00 100644
--- a/linux/lib/xz/xz_crc32.c
+++ b/linux/lib/xz/xz_crc32.c
@@ -2,7 +2,7 @@
  * CRC32 using the polynomial from IEEE-802.3
  *
  * Authors: Lasse Collin <lasse.collin@tukaani.org>
- *          Igor Pavlov <http://7-zip.org/>
+ *          Igor Pavlov <https://7-zip.org/>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
diff --git a/linux/lib/xz/xz_crc64.c b/linux/lib/xz/xz_crc64.c
index ca1caee..60c40f6 100644
--- a/linux/lib/xz/xz_crc64.c
+++ b/linux/lib/xz/xz_crc64.c
@@ -4,7 +4,7 @@
  * This file is similar to xz_crc32.c. See the comments there.
  *
  * Authors: Lasse Collin <lasse.collin@tukaani.org>
- *          Igor Pavlov <http://7-zip.org/>
+ *          Igor Pavlov <https://7-zip.org/>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
@@ -20,7 +20,11 @@
 
 XZ_EXTERN void xz_crc64_init(void)
 {
-	const uint64_t poly = 0xC96C5795D7870F42;
+	/*
+	 * The ULL suffix is needed for -std=gnu89 compatibility
+	 * on 32-bit platforms.
+	 */
+	const uint64_t poly = 0xC96C5795D7870F42ULL;
 
 	uint32_t i;
 	uint32_t j;
diff --git a/linux/lib/xz/xz_dec_bcj.c b/linux/lib/xz/xz_dec_bcj.c
index a768e6d..ef449e9 100644
--- a/linux/lib/xz/xz_dec_bcj.c
+++ b/linux/lib/xz/xz_dec_bcj.c
@@ -2,7 +2,7 @@
  * Branch/Call/Jump (BCJ) filter decoders
  *
  * Authors: Lasse Collin <lasse.collin@tukaani.org>
- *          Igor Pavlov <http://7-zip.org/>
+ *          Igor Pavlov <https://7-zip.org/>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
@@ -422,7 +422,7 @@
 
 	/*
 	 * Flush pending already filtered data to the output buffer. Return
-	 * immediatelly if we couldn't flush everything, or if the next
+	 * immediately if we couldn't flush everything, or if the next
 	 * filter in the chain had already returned XZ_STREAM_END.
 	 */
 	if (s->temp.filtered > 0) {
diff --git a/linux/lib/xz/xz_dec_lzma2.c b/linux/lib/xz/xz_dec_lzma2.c
index 08c3c80..c929f1c 100644
--- a/linux/lib/xz/xz_dec_lzma2.c
+++ b/linux/lib/xz/xz_dec_lzma2.c
@@ -2,7 +2,7 @@
  * LZMA2 decoder
  *
  * Authors: Lasse Collin <lasse.collin@tukaani.org>
- *          Igor Pavlov <http://7-zip.org/>
+ *          Igor Pavlov <https://7-zip.org/>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
@@ -147,8 +147,8 @@
 
 	/*
 	 * LZMA properties or related bit masks (number of literal
-	 * context bits, a mask dervied from the number of literal
-	 * position bits, and a mask dervied from the number
+	 * context bits, a mask derived from the number of literal
+	 * position bits, and a mask derived from the number
 	 * position bits)
 	 */
 	uint32_t lc;
@@ -248,6 +248,10 @@
 	 * before the first LZMA chunk.
 	 */
 	bool need_props;
+
+#ifdef XZ_DEC_MICROLZMA
+	bool pedantic_microlzma;
+#endif
 };
 
 struct xz_dec_lzma2 {
@@ -387,7 +391,14 @@
 
 		*left -= copy_size;
 
-		memcpy(dict->buf + dict->pos, b->in + b->in_pos, copy_size);
+		/*
+		 * If doing in-place decompression in single-call mode and the
+		 * uncompressed size of the file is larger than the caller
+		 * thought (i.e. it is invalid input!), the buffers below may
+		 * overlap and cause undefined behavior with memcpy().
+		 * With valid inputs memcpy() would be fine here.
+		 */
+		memmove(dict->buf + dict->pos, b->in + b->in_pos, copy_size);
 		dict->pos += copy_size;
 
 		if (dict->full < dict->pos)
@@ -397,7 +408,11 @@
 			if (dict->pos == dict->end)
 				dict->pos = 0;
 
-			memcpy(b->out + b->out_pos, b->in + b->in_pos,
+			/*
+			 * Like above but for multi-call mode: use memmove()
+			 * to avoid undefined behavior with invalid input.
+			 */
+			memmove(b->out + b->out_pos, b->in + b->in_pos,
 					copy_size);
 		}
 
@@ -408,6 +423,12 @@
 	}
 }
 
+#ifdef XZ_DEC_MICROLZMA
+#	define DICT_FLUSH_SUPPORTS_SKIPPING true
+#else
+#	define DICT_FLUSH_SUPPORTS_SKIPPING false
+#endif
+
 /*
  * Flush pending data from dictionary to b->out. It is assumed that there is
  * enough space in b->out. This is guaranteed because caller uses dict_limit()
@@ -421,8 +442,19 @@
 		if (dict->pos == dict->end)
 			dict->pos = 0;
 
-		memcpy(b->out + b->out_pos, dict->buf + dict->start,
-				copy_size);
+		/*
+		 * These buffers cannot overlap even if doing in-place
+		 * decompression because in multi-call mode dict->buf
+		 * has been allocated by us in this file; it's not
+		 * provided by the caller like in single-call mode.
+		 *
+		 * With MicroLZMA, b->out can be NULL to skip bytes that
+		 * the caller doesn't need. This cannot be done with XZ
+		 * because it would break BCJ filters.
+		 */
+		if (!DICT_FLUSH_SUPPORTS_SKIPPING || b->out != NULL)
+			memcpy(b->out + b->out_pos, dict->buf + dict->start,
+					copy_size);
 	}
 
 	dict->start = dict->pos;
@@ -484,11 +516,11 @@
 }
 
 /*
- * Decode one bit. In some versions, this function has been splitted in three
+ * Decode one bit. In some versions, this function has been split in three
  * functions so that the compiler is supposed to be able to more easily avoid
  * an extra branch. In this particular version of the LZMA decoder, this
  * doesn't seem to be a good idea (tested with GCC 3.3.6, 3.4.6, and 4.3.3
- * on x86). Using a non-splitted version results in nicer looking code too.
+ * on x86). Using a non-split version results in nicer looking code too.
  *
  * NOTE: This must return an int. Do not make it return a bool or the speed
  * of the code generated by GCC 3.x decreases 10-15 %. (GCC 4.3 doesn't care,
@@ -761,7 +793,7 @@
 }
 
 /*
- * Reset the LZMA decoder and range decoder state. Dictionary is nore reset
+ * Reset the LZMA decoder and range decoder state. Dictionary is not reset
  * here, because LZMA state may be reset without resetting the dictionary.
  */
 static void lzma_reset(struct xz_dec_lzma2 *s)
@@ -774,6 +806,7 @@
 	s->lzma.rep1 = 0;
 	s->lzma.rep2 = 0;
 	s->lzma.rep3 = 0;
+	s->lzma.len = 0;
 
 	/*
 	 * All probabilities are initialized to the same value. This hack
@@ -1146,6 +1179,7 @@
 
 		if (DEC_IS_DYNALLOC(s->dict.mode)) {
 			if (s->dict.allocated < s->dict.size) {
+				s->dict.allocated = s->dict.size;
 				vfree(s->dict.buf);
 				s->dict.buf = vmalloc(s->dict.size);
 				if (s->dict.buf == NULL) {
@@ -1156,8 +1190,6 @@
 		}
 	}
 
-	s->lzma.len = 0;
-
 	s->lzma2.sequence = SEQ_CONTROL;
 	s->lzma2.need_dict_reset = true;
 
@@ -1173,3 +1205,140 @@
 
 	kfree(s);
 }
+
+#ifdef XZ_DEC_MICROLZMA
+/* This is a wrapper struct to have a nice struct name in the public API. */
+struct xz_dec_microlzma {
+	struct xz_dec_lzma2 s;
+};
+
+enum xz_ret xz_dec_microlzma_run(struct xz_dec_microlzma *s_ptr,
+				 struct xz_buf *b)
+{
+	struct xz_dec_lzma2 *s = &s_ptr->s;
+
+	/*
+	 * sequence is SEQ_PROPERTIES before the first input byte,
+	 * SEQ_LZMA_PREPARE until a total of five bytes have been read,
+	 * and SEQ_LZMA_RUN for the rest of the input stream.
+	 */
+	if (s->lzma2.sequence != SEQ_LZMA_RUN) {
+		if (s->lzma2.sequence == SEQ_PROPERTIES) {
+			/* One byte is needed for the props. */
+			if (b->in_pos >= b->in_size)
+				return XZ_OK;
+
+			/*
+			 * Don't increment b->in_pos here. The same byte is
+			 * also passed to rc_read_init() which will ignore it.
+			 */
+			if (!lzma_props(s, ~b->in[b->in_pos]))
+				return XZ_DATA_ERROR;
+
+			s->lzma2.sequence = SEQ_LZMA_PREPARE;
+		}
+
+		/*
+		 * xz_dec_microlzma_reset() doesn't validate the compressed
+		 * size so we do it here. We have to limit the maximum size
+		 * to avoid integer overflows in lzma2_lzma(). 3 GiB is a nice
+		 * round number and much more than users of this code should
+		 * ever need.
+		 */
+		if (s->lzma2.compressed < RC_INIT_BYTES
+				|| s->lzma2.compressed > (3U << 30))
+			return XZ_DATA_ERROR;
+
+		if (!rc_read_init(&s->rc, b))
+			return XZ_OK;
+
+		s->lzma2.compressed -= RC_INIT_BYTES;
+		s->lzma2.sequence = SEQ_LZMA_RUN;
+
+		dict_reset(&s->dict, b);
+	}
+
+	/* This is to allow increasing b->out_size between calls. */
+	if (DEC_IS_SINGLE(s->dict.mode))
+		s->dict.end = b->out_size - b->out_pos;
+
+	while (true) {
+		dict_limit(&s->dict, min_t(size_t, b->out_size - b->out_pos,
+					   s->lzma2.uncompressed));
+
+		if (!lzma2_lzma(s, b))
+			return XZ_DATA_ERROR;
+
+		s->lzma2.uncompressed -= dict_flush(&s->dict, b);
+
+		if (s->lzma2.uncompressed == 0) {
+			if (s->lzma2.pedantic_microlzma) {
+				if (s->lzma2.compressed > 0 || s->lzma.len > 0
+						|| !rc_is_finished(&s->rc))
+					return XZ_DATA_ERROR;
+			}
+
+			return XZ_STREAM_END;
+		}
+
+		if (b->out_pos == b->out_size)
+			return XZ_OK;
+
+		if (b->in_pos == b->in_size
+				&& s->temp.size < s->lzma2.compressed)
+			return XZ_OK;
+	}
+}
+
+struct xz_dec_microlzma *xz_dec_microlzma_alloc(enum xz_mode mode,
+						uint32_t dict_size)
+{
+	struct xz_dec_microlzma *s;
+
+	/* Restrict dict_size to the same range as in the LZMA2 code. */
+	if (dict_size < 4096 || dict_size > (3U << 30))
+		return NULL;
+
+	s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (s == NULL)
+		return NULL;
+
+	s->s.dict.mode = mode;
+	s->s.dict.size = dict_size;
+
+	if (DEC_IS_MULTI(mode)) {
+		s->s.dict.end = dict_size;
+
+		s->s.dict.buf = vmalloc(dict_size);
+		if (s->s.dict.buf == NULL) {
+			kfree(s);
+			return NULL;
+		}
+	}
+
+	return s;
+}
+
+void xz_dec_microlzma_reset(struct xz_dec_microlzma *s, uint32_t comp_size,
+			    uint32_t uncomp_size, int uncomp_size_is_exact)
+{
+	/*
+	 * comp_size is validated in xz_dec_microlzma_run().
+	 * uncomp_size can safely be anything.
+	 */
+	s->s.lzma2.compressed = comp_size;
+	s->s.lzma2.uncompressed = uncomp_size;
+	s->s.lzma2.pedantic_microlzma = uncomp_size_is_exact;
+
+	s->s.lzma2.sequence = SEQ_PROPERTIES;
+	s->s.temp.size = 0;
+}
+
+void xz_dec_microlzma_end(struct xz_dec_microlzma *s)
+{
+	if (DEC_IS_MULTI(s->s.dict.mode))
+		vfree(s->s.dict.buf);
+
+	kfree(s);
+}
+#endif
diff --git a/linux/lib/xz/xz_dec_stream.c b/linux/lib/xz/xz_dec_stream.c
index f69581b..2c41f5f 100644
--- a/linux/lib/xz/xz_dec_stream.c
+++ b/linux/lib/xz/xz_dec_stream.c
@@ -35,7 +35,8 @@
 		SEQ_INDEX,
 		SEQ_INDEX_PADDING,
 		SEQ_INDEX_CRC32,
-		SEQ_STREAM_FOOTER
+		SEQ_STREAM_FOOTER,
+		SEQ_STREAM_PADDING
 	} sequence;
 
 	/* Position in variable-length integers and Check fields */
@@ -423,12 +424,12 @@
 	 * check types too, but then the check won't be verified and
 	 * a warning (XZ_UNSUPPORTED_CHECK) will be given.
 	 */
+	if (s->temp.buf[HEADER_MAGIC_SIZE + 1] > XZ_CHECK_MAX)
+		return XZ_OPTIONS_ERROR;
+
 	s->check_type = s->temp.buf[HEADER_MAGIC_SIZE + 1];
 
 #ifdef XZ_DEC_ANY_CHECK
-	if (s->check_type > XZ_CHECK_MAX)
-		return XZ_OPTIONS_ERROR;
-
 	if (s->check_type > XZ_CHECK_CRC32 && !IS_CRC64(s->check_type))
 		return XZ_UNSUPPORTED_CHECK;
 #else
@@ -742,6 +743,10 @@
 				return XZ_OK;
 
 			return dec_stream_footer(s);
+
+		case SEQ_STREAM_PADDING:
+			/* Never reached, only silencing a warning */
+			break;
 		}
 	}
 
@@ -809,6 +814,79 @@
 	return ret;
 }
 
+#ifdef XZ_DEC_CONCATENATED
+XZ_EXTERN enum xz_ret xz_dec_catrun(struct xz_dec *s, struct xz_buf *b,
+				    int finish)
+{
+	enum xz_ret ret;
+
+	if (DEC_IS_SINGLE(s->mode)) {
+		xz_dec_reset(s);
+		finish = true;
+	}
+
+	while (true) {
+		if (s->sequence == SEQ_STREAM_PADDING) {
+			/*
+			 * Skip Stream Padding. Its size must be a multiple
+			 * of four bytes which is tracked with s->pos.
+			 */
+			while (true) {
+				if (b->in_pos == b->in_size) {
+					/*
+					 * Note that if we are repeatedly
+					 * given no input and finish is false,
+					 * we will keep returning XZ_OK even
+					 * though no progress is being made.
+					 * The lack of XZ_BUF_ERROR support
+					 * isn't a problem here because a
+					 * reasonable caller will eventually
+					 * provide more input or set finish
+					 * to true.
+					 */
+					if (!finish)
+						return XZ_OK;
+
+					if (s->pos != 0)
+						return XZ_DATA_ERROR;
+
+					return XZ_STREAM_END;
+				}
+
+				if (b->in[b->in_pos] != 0x00) {
+					if (s->pos != 0)
+						return XZ_DATA_ERROR;
+
+					break;
+				}
+
+				++b->in_pos;
+				s->pos = (s->pos + 1) & 3;
+			}
+
+			/*
+			 * More input remains. It should be a new Stream.
+			 *
+			 * In single-call mode xz_dec_run() will always call
+			 * xz_dec_reset(). Thus, we need to do it here only
+			 * in multi-call mode.
+			 */
+			if (DEC_IS_MULTI(s->mode))
+				xz_dec_reset(s);
+		}
+
+		ret = xz_dec_run(s, b);
+
+		if (ret != XZ_STREAM_END)
+			break;
+
+		s->sequence = SEQ_STREAM_PADDING;
+	}
+
+	return ret;
+}
+#endif
+
 XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max)
 {
 	struct xz_dec *s = kmalloc(sizeof(*s), GFP_KERNEL);
diff --git a/linux/lib/xz/xz_dec_syms.c b/linux/lib/xz/xz_dec_syms.c
index 32eb3c0..61098c6 100644
--- a/linux/lib/xz/xz_dec_syms.c
+++ b/linux/lib/xz/xz_dec_syms.c
@@ -15,8 +15,15 @@
 EXPORT_SYMBOL(xz_dec_run);
 EXPORT_SYMBOL(xz_dec_end);
 
+#ifdef CONFIG_XZ_DEC_MICROLZMA
+EXPORT_SYMBOL(xz_dec_microlzma_alloc);
+EXPORT_SYMBOL(xz_dec_microlzma_reset);
+EXPORT_SYMBOL(xz_dec_microlzma_run);
+EXPORT_SYMBOL(xz_dec_microlzma_end);
+#endif
+
 MODULE_DESCRIPTION("XZ decompressor");
-MODULE_VERSION("1.0");
+MODULE_VERSION("1.1");
 MODULE_AUTHOR("Lasse Collin <lasse.collin@tukaani.org> and Igor Pavlov");
 
 /*
diff --git a/linux/lib/xz/xz_lzma2.h b/linux/lib/xz/xz_lzma2.h
index 071d67b..92d852d 100644
--- a/linux/lib/xz/xz_lzma2.h
+++ b/linux/lib/xz/xz_lzma2.h
@@ -2,7 +2,7 @@
  * LZMA2 definitions
  *
  * Authors: Lasse Collin <lasse.collin@tukaani.org>
- *          Igor Pavlov <http://7-zip.org/>
+ *          Igor Pavlov <https://7-zip.org/>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
diff --git a/linux/lib/xz/xz_private.h b/linux/lib/xz/xz_private.h
index 482b90f..d9fd49b 100644
--- a/linux/lib/xz/xz_private.h
+++ b/linux/lib/xz/xz_private.h
@@ -37,6 +37,9 @@
 #		ifdef CONFIG_XZ_DEC_SPARC
 #			define XZ_DEC_SPARC
 #		endif
+#		ifdef CONFIG_XZ_DEC_MICROLZMA
+#			define XZ_DEC_MICROLZMA
+#		endif
 #		define memeq(a, b, size) (memcmp(a, b, size) == 0)
 #		define memzero(buf, size) memset(buf, 0, size)
 #	endif
diff --git a/linux/lib/xz/xz_stream.h b/linux/lib/xz/xz_stream.h
index 66cb5a7..430bb3a 100644
--- a/linux/lib/xz/xz_stream.h
+++ b/linux/lib/xz/xz_stream.h
@@ -19,7 +19,7 @@
 
 /*
  * See the .xz file format specification at
- * http://tukaani.org/xz/xz-file-format.txt
+ * https://tukaani.org/xz/xz-file-format.txt
  * to understand the container format.
  */
 
diff --git a/userspace/Makefile b/userspace/Makefile
index 5bd6b28..1acacf0 100644
--- a/userspace/Makefile
+++ b/userspace/Makefile
@@ -7,11 +7,14 @@
 # You can do whatever you want with this file.
 #
 
+# gcc -std=gnu89 is used because Linux uses it. It is fine to omit it as
+# the code is also C99/C11 compatible. With clang you may wish to omit
+# either -std=gnu89 or -pedantic as having both gives quite a few warnings.
 CC = gcc -std=gnu89
 BCJ_CPPFLAGS = -DXZ_DEC_X86 -DXZ_DEC_POWERPC -DXZ_DEC_IA64 \
 		-DXZ_DEC_ARM -DXZ_DEC_ARMTHUMB -DXZ_DEC_SPARC
-CPPFLAGS = -DXZ_USE_CRC64 -DXZ_DEC_ANY_CHECK
-CFLAGS = -ggdb3 -O2 -pedantic -Wall -Wextra
+CPPFLAGS = -DXZ_USE_CRC64 -DXZ_DEC_ANY_CHECK -DXZ_DEC_CONCATENATED
+CFLAGS = -ggdb3 -O2 -pedantic -Wall -Wextra -Wno-long-long
 RM = rm -f
 VPATH = ../linux/include/linux ../linux/lib/xz
 COMMON_SRCS = xz_crc32.c xz_crc64.c xz_dec_stream.c xz_dec_lzma2.c xz_dec_bcj.c
@@ -44,5 +47,5 @@
 
 .PHONY: clean
 clean:
-	-$(RM) $(COMMON_OBJS) $(XZMINIDEC_OBJS) $(BUFTEST_OBJS) \
-		$(BOOTTEST_OBJS) $(PROGRAMS)
+	-$(RM) $(COMMON_OBJS) $(XZMINIDEC_OBJS) $(BYTETEST_OBJS) \
+		$(BUFTEST_OBJS) $(BOOTTEST_OBJS) $(PROGRAMS)
diff --git a/userspace/xz_config.h b/userspace/xz_config.h
index eb9dac1..ee590d7 100644
--- a/userspace/xz_config.h
+++ b/userspace/xz_config.h
@@ -10,6 +10,9 @@
 #ifndef XZ_CONFIG_H
 #define XZ_CONFIG_H
 
+/* Uncomment to enable building of xz_dec_catrun(). */
+/* #define XZ_DEC_CONCATENATED */
+
 /* Uncomment to enable CRC64 support. */
 /* #define XZ_USE_CRC64 */
 
diff --git a/userspace/xzminidec.c b/userspace/xzminidec.c
index ba07413..b542109 100644
--- a/userspace/xzminidec.c
+++ b/userspace/xzminidec.c
@@ -61,10 +61,22 @@
 	while (true) {
 		if (b.in_pos == b.in_size) {
 			b.in_size = fread(in, 1, sizeof(in), stdin);
+
+			if (ferror(stdin)) {
+				msg = "Read error\n";
+				goto error;
+			}
+
 			b.in_pos = 0;
 		}
 
-		ret = xz_dec_run(s, &b);
+		/*
+		 * There are a few ways to set the "finish" (the third)
+		 * argument. We could use feof(stdin) but testing in_size
+		 * is fine too and may also work in applications that don't
+		 * use FILEs.
+		 */
+		ret = xz_dec_catrun(s, &b, b.in_size == 0);
 
 		if (b.out_pos == sizeof(out)) {
 			if (fwrite(out, 1, b.out_pos, stdout) != b.out_pos) {