Add LZMA_DEFAULT_MAGIC support
--- busybox-1.17.1/include/unarchive.h
+++ busybox-1.17.1/include/unarchive.h
@@ -9,6 +9,8 @@
 	COMPRESS_MAGIC = 0x1f9d,
 	GZIP_MAGIC  = 0x1f8b,
 	BZIP2_MAGIC = 'B' * 256 + 'Z',
+	/* lzma default options: lc=3 lp=0 pb=2, historic % 256 == 0 */
+	LZMA_DEFAULT_MAGIC = 0x5d00,
 	/* .xz signature: 0xfd, '7', 'z', 'X', 'Z', 0x00 */
 	/* More info at: http://tukaani.org/xz/xz-file-format.txt */
 	XZ_MAGIC1   = 0xfd * 256 + '7',
@@ -20,6 +22,8 @@
 	COMPRESS_MAGIC = 0x9d1f,
 	GZIP_MAGIC  = 0x8b1f,
 	BZIP2_MAGIC = 'Z' * 256 + 'B',
+	/* lzma default options: lc=3 lp=0 pb=2, historic % 256 == 0 */
+	LZMA_DEFAULT_MAGIC = 0x5d,
 	XZ_MAGIC1   = '7' * 256 + 0xfd,
 	XZ_MAGIC2   = ((0 * 256 + 'Z') * 256 + 'X') * 256 + 'z',
 	XZ_MAGIC1a  = (('X' * 256 + 'z') * 256 + '7') * 256 + 0xfd,

--- busybox-1.17.1/libbb/read_printf.c
+++ busybox-1.17.1/libbb/read_printf.c
@@ -286,6 +286,17 @@
 # endif
 		goto found_magic;
 	}
+	if (ENABLE_FEATURE_SEAMLESS_LZMA
+	 && magic.b16[0] == LZMA_DEFAULT_MAGIC
+	) {
+# if BB_MMU
+		xformer = unpack_lzma_stream;
+		xlseek(fd, offset, SEEK_CUR);
+# else
+		xformer_prog = "unlzma";
+# endif
+		goto found_magic;
+	}
 	if (ENABLE_FEATURE_SEAMLESS_XZ
 	 && magic.b16[0] == XZ_MAGIC1
 	) {
@@ -342,7 +353,8 @@
 			/* .lzma has no header/signature, just trust it */
 			open_transformer(fd, unpack_lzma_stream, "unlzma");
 		else
-		if ((ENABLE_FEATURE_SEAMLESS_GZ && strcmp(sfx, "gz") == 0)
+		if (((ENABLE_FEATURE_SEAMLESS_GZ|ENABLE_FEATURE_SEAMLESS_LZMA)
+		  && strcmp(sfx, "gz") == 0)
 		 || (ENABLE_FEATURE_SEAMLESS_BZ2 && strcmp(sfx, "bz2") == 0)
 		 || (ENABLE_FEATURE_SEAMLESS_XZ && strcmp(sfx, "xz") == 0)
 		) {