linux-5.10/lib/decompress_unzstd.c

1 // SPDX-License-Identifier: GPL-2.0
4  * Important notes about in-place decompression
14  * The worst case for in-place decompression is that the beginning of
16  * uncompressible. Thus, we must look for worst-case expansion when the
22  *    Frame Header: (18)
26  * The frame header and checksum overhead is at most 22 bytes.
43  *   - 22 bytes for the .zst file format headers;
44  *   - 3 bytes per every 128 KiB of uncompressed size (one block header per
46  *   - 128 KiB (biggest possible zstd block size) to make sure that the
59  * zstd's only source dependeny is xxhash, which has no source
85  * Size of the input and output buffers in multi-call mode.
109 		error("ZSTD-compressed data is corrupt");  in handle_zstd_error()
112 		error("ZSTD-compressed data is probably corrupt");  in handle_zstd_error()
115 	return -1;  in handle_zstd_error()
120  * We can allocate less memory (no circular buffer for the sliding window),
135 		err = -1;  in decompress_single()
139 	 * Find out how large the frame actually is, there may be junk at  in decompress_single()
140 	 * the end of the frame that ZSTD_decompressDCtx() can't handle.  in decompress_single()
182 	 * ZSTD decompression code won't be happy if the buffer size is so big  in __unzstd()
184 	 * it as big as possible without having the end address overflow.  in __unzstd()
187 		out_len = UINTPTR_MAX - (uintptr_t)out_buf;  in __unzstd()
206 			err = -1;  in __unzstd()
212 	/* Read the first chunk, since we need to decode the frame header. */  in __unzstd()
216 		error("ZSTD-compressed data is truncated");  in __unzstd()
217 		err = -1;  in __unzstd()
220 	/* Set the first non-empty input buffer. */  in __unzstd()
229 			err = -1;  in __unzstd()
252 		error("ZSTD-compressed data has an incomplete frame header");  in __unzstd()
253 		err = -1;  in __unzstd()
257 		error("ZSTD-compressed data has too large a window size");  in __unzstd()
258 		err = -1;  in __unzstd()
271 		err = -1;  in __unzstd()
277 	 * Read more data if necessary (error if no more data can be read).  in __unzstd()
291 			in_len = fill ? fill(in_buf, ZSTD_IOBUF_SIZE) : -1;  in __unzstd()
293 				error("ZSTD-compressed data is truncated");  in __unzstd()
294 				err = -1;  in __unzstd()
300 		/* Returns zero when the frame is complete. */  in __unzstd()
309 				err = -1;  in __unzstd()