[NOMERGE] [WIP] [RFC PATCH 2/2] staging: erofs: use the new LZ4_decompress_safe_partial

[Gao Xiang]

Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
 drivers/staging/erofs/unzip_lz4.c | 189 +-------------------------------------
 1 file changed, 2 insertions(+), 187 deletions(-)

diff --git a/drivers/staging/erofs/unzip_lz4.c b/drivers/staging/erofs/unzip_lz4.c
index b1ea23f..32e8ab7 100644
--- a/drivers/staging/erofs/unzip_lz4.c
+++ b/drivers/staging/erofs/unzip_lz4.c
@@ -41,196 +41,11 @@
  *	Sven Schmidt <4sschmid at informatik.uni-hamburg.de>
  */
 #include "internal.h"
-#include <asm/unaligned.h>
-#include "lz4defs.h"
-
-/*
- * no public solution to solve our requirement yet.
- * see: <required buffer size for LZ4_decompress_safe_partial>
- *      https://groups.google.com/forum/#!topic/lz4c/_3kkz5N6n00
- */
-static FORCE_INLINE int customized_lz4_decompress_safe_partial(
-	const void * const source,
-	void * const dest,
-	int inputSize,
-	int outputSize)
-{
-	/* Local Variables */
-	const BYTE *ip = (const BYTE *) source;
-	const BYTE * const iend = ip + inputSize;
-
-	BYTE *op = (BYTE *) dest;
-	BYTE * const oend = op + outputSize;
-	BYTE *cpy;
-
-	static const unsigned int dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };
-	static const int dec64table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };
-
-	/* Empty output buffer */
-	if (unlikely(outputSize == 0))
-		return ((inputSize == 1) && (*ip == 0)) ? 0 : -1;
-
-	/* Main Loop : decode sequences */
-	while (1) {
-		size_t length;
-		const BYTE *match;
-		size_t offset;
-
-		/* get literal length */
-		unsigned int const token = *ip++;
-
-		length = token>>ML_BITS;
-
-		if (length == RUN_MASK) {
-			unsigned int s;
-
-			do {
-				s = *ip++;
-				length += s;
-			} while ((ip < iend - RUN_MASK) & (s == 255));
-
-			if (unlikely((size_t)(op + length) < (size_t)(op))) {
-				/* overflow detection */
-				goto _output_error;
-			}
-			if (unlikely((size_t)(ip + length) < (size_t)(ip))) {
-				/* overflow detection */
-				goto _output_error;
-			}
-		}
-
-		/* copy literals */
-		cpy = op + length;
-		if ((cpy > oend - WILDCOPYLENGTH) ||
-			(ip + length > iend - (2 + 1 + LASTLITERALS))) {
-			if (cpy > oend) {
-				memcpy(op, ip, length = oend - op);
-				op += length;
-				break;
-			}
-
-			if (unlikely(ip + length > iend)) {
-				/*
-				 * Error :
-				 * read attempt beyond
-				 * end of input buffer
-				 */
-				goto _output_error;
-			}
-
-			memcpy(op, ip, length);
-			ip += length;
-			op += length;
-
-			if (ip > iend - 2)
-				break;
-			/* Necessarily EOF, due to parsing restrictions */
-			/* break; */
-		} else {
-			LZ4_wildCopy(op, ip, cpy);
-			ip += length;
-			op = cpy;
-		}
-
-		/* get offset */
-		offset = LZ4_readLE16(ip);
-		ip += 2;
-		match = op - offset;
-
-		if (unlikely(match < (const BYTE *)dest)) {
-			/* Error : offset outside buffers */
-			goto _output_error;
-		}
-
-		/* get matchlength */
-		length = token & ML_MASK;
-		if (length == ML_MASK) {
-			unsigned int s;
-
-			do {
-				s = *ip++;
-
-				if (ip > iend - LASTLITERALS)
-					goto _output_error;
-
-				length += s;
-			} while (s == 255);
-
-			if (unlikely((size_t)(op + length) < (size_t)op)) {
-				/* overflow detection */
-				goto _output_error;
-			}
-		}
-
-		length += MINMATCH;
-
-		/* copy match within block */
-		cpy = op + length;
-
-		if (unlikely(cpy >= oend - WILDCOPYLENGTH)) {
-			if (cpy >= oend) {
-				while (op < oend)
-					*op++ = *match++;
-				break;
-			}
-			goto __match;
-		}
-
-		/* costs ~1%; silence an msan warning when offset == 0 */
-		LZ4_write32(op, (U32)offset);
-
-		if (unlikely(offset < 8)) {
-			const int dec64 = dec64table[offset];
-
-			op[0] = match[0];
-			op[1] = match[1];
-			op[2] = match[2];
-			op[3] = match[3];
-			match += dec32table[offset];
-			memcpy(op + 4, match, 4);
-			match -= dec64;
-		} else {
-			LZ4_copy8(op, match);
-			match += 8;
-		}
-
-		op += 8;
-
-		if (unlikely(cpy > oend - 12)) {
-			BYTE * const oCopyLimit = oend - (WILDCOPYLENGTH - 1);
-
-			if (op < oCopyLimit) {
-				LZ4_wildCopy(op, match, oCopyLimit);
-				match += oCopyLimit - op;
-				op = oCopyLimit;
-			}
-__match:
-			while (op < cpy)
-				*op++ = *match++;
-		} else {
-			LZ4_copy8(op, match);
-
-			if (length > 16)
-				LZ4_wildCopy(op + 8, match + 8, cpy);
-		}
-
-		op = cpy; /* correction */
-	}
-	DBG_BUGON((void *)ip - source > inputSize);
-	DBG_BUGON((void *)op - dest > outputSize);
-
-	/* Nb of output bytes decoded */
-	return (int) ((void *)op - dest);
-
-	/* Overflow error detected */
-_output_error:
-	return -ERANGE;
-}
+#include <linux/lz4.h>
 
 int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen)
 {
-	int ret = customized_lz4_decompress_safe_partial(in,
-		out, inlen, outlen);
+	int ret = LZ4_decompress_safe_partial(in, out, inlen, outlen, outlen);
 
 	if (ret >= 0)
 		return ret;
-- 
1.9.1