linux-master/lib/decompress_unxz.c

11  * Important notes about in-place decompression
13  * At least on x86, the kernel is decompressed in place: the compressed data
21  * The worst case for in-place decompression is that the beginning of
26  * The structure of the .xz file in case of a compressed kernel is as follows.
27  * Sizes (as bytes) of the fields are in parenthesis.
39  * 2-4 Blocks just in case. Because Stream Header and also Block Header
50  * LZMA2 stores the data in chunks. Each chunk has a header whose size is
53  * may be up to 64 KiB of actual payload in the chunk. Often the payload is
58  * uncompressed size of the payload is in practice never less than the
61  * files. LZMA2 supports storing incompressible data in uncompressed form,
91  * Thus, when updating Deflate-only in-place kernel decompressor to
119  * is not available in early phase of booting.
162  * FIXME: Not all basic memory functions are provided in architecture-specific
167  * is fast enough. memcpy/memmove speed matters in multi-call mode, but
168  * the kernel image is decompressed in single-call mode, in which only
170  * (LZMA2 stores incompressible chunks in uncompressed form). Thus, the
202 /* Not static to avoid a conflict with the prototype in the Linux headers. */
239 /* Size of the input and output buffers in multi-call mode */
243  * This function implements the API defined in <linux/decompress/generic.h>.
250 STATIC int INIT unxz(unsigned char *in, long in_size,
286 	if (in == NULL) {
288 		in = malloc(XZ_IOBUF_SIZE);
289 		if (in == NULL)
293 	b.in = in;
308 				in_size = fill(in, XZ_IOBUF_SIZE);
339 			free(in);
355 		/* This can occur only in multi-call mode. */
360 		error("Input is not in the XZ format (wrong magic bytes)");
374 		error("Bug in the XZ decompressor");