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authorYann Collet <cyan@fb.com>2022-08-02 12:36:01 (GMT)
committerYann Collet <cyan@fb.com>2022-08-02 12:40:24 (GMT)
commit7d7cddfac1c438a4c781dbdc2ffeb248f668cd4c (patch)
tree1061baa3a184ba8002670bba5d09f9266aa71c0d /lib
parentefd123e1f150afe3c612ab392a28cb7475b0bd98 (diff)
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remove support of decompress_fast*() from decompress_generic()
since it's now supported by decompress_unsafe(). The goal is to improve maintenability of decompress_generic() by reducing its complexity.
Diffstat (limited to 'lib')
-rw-r--r--lib/lz4.c135
1 files changed, 43 insertions, 92 deletions
diff --git a/lib/lz4.c b/lib/lz4.c
index d041753..fe14609 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -1716,7 +1716,7 @@ int LZ4_saveDict (LZ4_stream_t* LZ4_dict, char* safeBuffer, int dictSize)
if (dictSize > 0) {
const BYTE* const previousDictEnd = dict->dictionary + dict->dictSize;
assert(dict->dictionary);
- LZ4_memmove(safeBuffer, previousDictEnd - dictSize, dictSize);
+ LZ4_memmove(safeBuffer, previousDictEnd - dictSize, (size_t)dictSize);
}
dict->dictionary = (const BYTE*)safeBuffer;
@@ -1731,7 +1731,6 @@ int LZ4_saveDict (LZ4_stream_t* LZ4_dict, char* safeBuffer, int dictSize)
* Decompression functions
********************************/
-typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
typedef enum { decode_full_block = 0, partial_decode = 1 } earlyEnd_directive;
#undef MIN
@@ -1870,7 +1869,7 @@ LZ4_decompress_unsafe_generic(
typedef enum { loop_error = -2, initial_error = -1, ok = 0 } variable_length_error;
LZ4_FORCE_INLINE unsigned
read_variable_length(const BYTE**ip, const BYTE* lencheck,
- int loop_check, int initial_check,
+ int initial_check,
variable_length_error* error)
{
U32 length = 0;
@@ -1883,7 +1882,7 @@ read_variable_length(const BYTE**ip, const BYTE* lencheck,
s = **ip;
(*ip)++;
length += s;
- if (loop_check && unlikely((*ip) >= lencheck)) { /* overflow detection */
+ if (unlikely((*ip) >= lencheck)) { /* overflow detection */
*error = loop_error;
return length;
}
@@ -1905,7 +1904,6 @@ LZ4_decompress_generic(
int srcSize,
int outputSize, /* If endOnInput==endOnInputSize, this value is `dstCapacity` */
- endCondition_directive endOnInput, /* endOnOutputSize, endOnInputSize */
earlyEnd_directive partialDecoding, /* full, partial */
dict_directive dict, /* noDict, withPrefix64k, usingExtDict */
const BYTE* const lowPrefix, /* always <= dst, == dst when no prefix */
@@ -1924,13 +1922,12 @@ LZ4_decompress_generic(
const BYTE* const dictEnd = (dictStart == NULL) ? NULL : dictStart + dictSize;
- const int safeDecode = (endOnInput==endOnInputSize);
- const int checkOffset = ((safeDecode) && (dictSize < (int)(64 KB)));
+ const int checkOffset = (dictSize < (int)(64 KB));
/* Set up the "end" pointers for the shortcut. */
- const BYTE* const shortiend = iend - (endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/;
- const BYTE* const shortoend = oend - (endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/;
+ const BYTE* const shortiend = iend - 14 /*maxLL*/ - 2 /*offset*/;
+ const BYTE* const shortoend = oend - 14 /*maxLL*/ - 18 /*maxML*/;
const BYTE* match;
size_t offset;
@@ -1942,13 +1939,12 @@ LZ4_decompress_generic(
/* Special cases */
assert(lowPrefix <= op);
- if ((endOnInput) && (unlikely(outputSize==0))) {
+ if (unlikely(outputSize==0)) {
/* Empty output buffer */
if (partialDecoding) return 0;
return ((srcSize==1) && (*ip==0)) ? 0 : -1;
}
- if ((!endOnInput) && (unlikely(outputSize==0))) { return (*ip==0 ? 1 : -1); }
- if ((endOnInput) && unlikely(srcSize==0)) { return -1; }
+ if (unlikely(srcSize==0)) { return -1; }
/* Currently the fast loop shows a regression on qualcomm arm chips. */
#if LZ4_FAST_DEC_LOOP
@@ -1961,46 +1957,31 @@ LZ4_decompress_generic(
while (1) {
/* Main fastloop assertion: We can always wildcopy FASTLOOP_SAFE_DISTANCE */
assert(oend - op >= FASTLOOP_SAFE_DISTANCE);
- if (endOnInput) { assert(ip < iend); }
+ assert(ip < iend);
token = *ip++;
length = token >> ML_BITS; /* literal length */
- assert(!endOnInput || ip <= iend); /* ip < iend before the increment */
-
/* decode literal length */
if (length == RUN_MASK) {
variable_length_error error = ok;
- length += read_variable_length(&ip, iend-RUN_MASK, (int)endOnInput, (int)endOnInput, &error);
+ length += read_variable_length(&ip, iend-RUN_MASK, 1, &error);
if (error == initial_error) { goto _output_error; }
- if ((safeDecode) && unlikely((uptrval)(op)+length<(uptrval)(op))) { goto _output_error; } /* overflow detection */
- if ((safeDecode) && unlikely((uptrval)(ip)+length<(uptrval)(ip))) { goto _output_error; } /* overflow detection */
+ if (unlikely((uptrval)(op)+length<(uptrval)(op))) { goto _output_error; } /* overflow detection */
+ if (unlikely((uptrval)(ip)+length<(uptrval)(ip))) { goto _output_error; } /* overflow detection */
/* copy literals */
cpy = op+length;
LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH);
- if (endOnInput) { /* LZ4_decompress_safe() */
- if ((cpy>oend-32) || (ip+length>iend-32)) { goto safe_literal_copy; }
- LZ4_wildCopy32(op, ip, cpy);
- } else { /* LZ4_decompress_fast() */
- if (cpy>oend-8) { goto safe_literal_copy; }
- LZ4_wildCopy8(op, ip, cpy); /* LZ4_decompress_fast() cannot copy more than 8 bytes at a time :
- * it doesn't know input length, and only relies on end-of-block properties */
- }
+ if ((cpy>oend-32) || (ip+length>iend-32)) { goto safe_literal_copy; }
+ LZ4_wildCopy32(op, ip, cpy);
ip += length; op = cpy;
} else {
cpy = op+length;
- if (endOnInput) { /* LZ4_decompress_safe() */
- DEBUGLOG(7, "copy %u bytes in a 16-bytes stripe", (unsigned)length);
- /* We don't need to check oend, since we check it once for each loop below */
- if (ip > iend-(16 + 1/*max lit + offset + nextToken*/)) { goto safe_literal_copy; }
- /* Literals can only be 14, but hope compilers optimize if we copy by a register size */
- LZ4_memcpy(op, ip, 16);
- } else { /* LZ4_decompress_fast() */
- /* LZ4_decompress_fast() cannot copy more than 8 bytes at a time :
- * it doesn't know input length, and relies on end-of-block properties */
- LZ4_memcpy(op, ip, 8);
- if (length > 8) { LZ4_memcpy(op+8, ip+8, 8); }
- }
+ DEBUGLOG(7, "copy %u bytes in a 16-bytes stripe", (unsigned)length);
+ /* We don't need to check oend, since we check it once for each loop below */
+ if (ip > iend-(16 + 1/*max lit + offset + nextToken*/)) { goto safe_literal_copy; }
+ /* Literals can only be 14, but hope compilers optimize if we copy by a register size */
+ LZ4_memcpy(op, ip, 16);
ip += length; op = cpy;
}
@@ -2015,9 +1996,9 @@ LZ4_decompress_generic(
if (length == ML_MASK) {
variable_length_error error = ok;
if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) { goto _output_error; } /* Error : offset outside buffers */
- length += read_variable_length(&ip, iend - LASTLITERALS + 1, (int)endOnInput, 0, &error);
+ length += read_variable_length(&ip, iend - LASTLITERALS + 1, 0, &error);
if (error != ok) { goto _output_error; }
- if ((safeDecode) && unlikely((uptrval)(op)+length<(uptrval)op)) { goto _output_error; } /* overflow detection */
+ if (unlikely((uptrval)(op)+length<(uptrval)op)) { goto _output_error; } /* overflow detection */
length += MINMATCH;
if (op + length >= oend - FASTLOOP_SAFE_DISTANCE) {
goto safe_match_copy;
@@ -2091,11 +2072,10 @@ LZ4_decompress_generic(
/* Main Loop : decode remaining sequences where output < FASTLOOP_SAFE_DISTANCE */
while (1) {
+ assert(ip < iend);
token = *ip++;
length = token >> ML_BITS; /* literal length */
- assert(!endOnInput || ip <= iend); /* ip < iend before the increment */
-
/* A two-stage shortcut for the most common case:
* 1) If the literal length is 0..14, and there is enough space,
* enter the shortcut and copy 16 bytes on behalf of the literals
@@ -2105,11 +2085,11 @@ LZ4_decompress_generic(
* those 18 bytes earlier, upon entering the shortcut (in other words,
* there is a combined check for both stages).
*/
- if ( (endOnInput ? length != RUN_MASK : length <= 8)
+ if ( (length != RUN_MASK)
/* strictly "less than" on input, to re-enter the loop with at least one byte */
- && likely((endOnInput ? ip < shortiend : 1) & (op <= shortoend)) ) {
+ && likely((ip < shortiend) & (op <= shortoend)) ) {
/* Copy the literals */
- LZ4_memcpy(op, ip, endOnInput ? 16 : 8);
+ LZ4_memcpy(op, ip, 16);
op += length; ip += length;
/* The second stage: prepare for match copying, decode full info.
@@ -2140,10 +2120,10 @@ LZ4_decompress_generic(
/* decode literal length */
if (length == RUN_MASK) {
variable_length_error error = ok;
- length += read_variable_length(&ip, iend-RUN_MASK, (int)endOnInput, (int)endOnInput, &error);
+ length += read_variable_length(&ip, iend-RUN_MASK, 1, &error);
if (error == initial_error) { goto _output_error; }
- if ((safeDecode) && unlikely((uptrval)(op)+length<(uptrval)(op))) { goto _output_error; } /* overflow detection */
- if ((safeDecode) && unlikely((uptrval)(ip)+length<(uptrval)(ip))) { goto _output_error; } /* overflow detection */
+ if (unlikely((uptrval)(op)+length<(uptrval)(op))) { goto _output_error; } /* overflow detection */
+ if (unlikely((uptrval)(ip)+length<(uptrval)(ip))) { goto _output_error; } /* overflow detection */
}
/* copy literals */
@@ -2152,9 +2132,7 @@ LZ4_decompress_generic(
safe_literal_copy:
#endif
LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH);
- if ( ((endOnInput) && ((cpy>oend-MFLIMIT) || (ip+length>iend-(2+1+LASTLITERALS))) )
- || ((!endOnInput) && (cpy>oend-WILDCOPYLENGTH)) )
- {
+ if ((cpy>oend-MFLIMIT) || (ip+length>iend-(2+1+LASTLITERALS))) {
/* We've either hit the input parsing restriction or the output parsing restriction.
* In the normal scenario, decoding a full block, it must be the last sequence,
* otherwise it's an error (invalid input or dimensions).
@@ -2164,7 +2142,6 @@ LZ4_decompress_generic(
/* Since we are partial decoding we may be in this block because of the output parsing
* restriction, which is not valid since the output buffer is allowed to be undersized.
*/
- assert(endOnInput);
DEBUGLOG(7, "partialDecoding: copying literals, close to input or output end")
DEBUGLOG(7, "partialDecoding: literal length = %u", (unsigned)length);
DEBUGLOG(7, "partialDecoding: remaining space in dstBuffer : %i", (int)(oend - op));
@@ -2185,14 +2162,10 @@ LZ4_decompress_generic(
length = (size_t)(oend-op);
}
} else {
- /* We must be on the last sequence because of the parsing limitations so check
- * that we exactly regenerate the original size (must be exact when !endOnInput).
- */
- if ((!endOnInput) && (cpy != oend)) { goto _output_error; }
/* We must be on the last sequence (or invalid) because of the parsing limitations
* so check that we exactly consume the input and don't overrun the output buffer.
*/
- if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) {
+ if ((ip+length != iend) || (cpy > oend)) {
DEBUGLOG(6, "should have been last run of literals")
DEBUGLOG(6, "ip(%p) + length(%i) = %p != iend (%p)", ip, (int)length, ip+length, iend);
DEBUGLOG(6, "or cpy(%p) > oend(%p)", cpy, oend);
@@ -2225,9 +2198,9 @@ LZ4_decompress_generic(
_copy_match:
if (length == ML_MASK) {
variable_length_error error = ok;
- length += read_variable_length(&ip, iend - LASTLITERALS + 1, (int)endOnInput, 0, &error);
+ length += read_variable_length(&ip, iend - LASTLITERALS + 1, 0, &error);
if (error != ok) goto _output_error;
- if ((safeDecode) && unlikely((uptrval)(op)+length<(uptrval)op)) goto _output_error; /* overflow detection */
+ if (unlikely((uptrval)(op)+length<(uptrval)op)) goto _output_error; /* overflow detection */
}
length += MINMATCH;
@@ -2315,12 +2288,8 @@ LZ4_decompress_generic(
}
/* end of decoding */
- if (endOnInput) {
- DEBUGLOG(5, "decoded %i bytes", (int) (((char*)op)-dst));
- return (int) (((char*)op)-dst); /* Nb of output bytes decoded */
- } else {
- return (int) (((const char*)ip)-src); /* Nb of input bytes read */
- }
+ DEBUGLOG(5, "decoded %i bytes", (int) (((char*)op)-dst));
+ return (int) (((char*)op)-dst); /* Nb of output bytes decoded */
/* Overflow error detected */
_output_error:
@@ -2335,7 +2304,7 @@ LZ4_FORCE_O2
int LZ4_decompress_safe(const char* source, char* dest, int compressedSize, int maxDecompressedSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxDecompressedSize,
- endOnInputSize, decode_full_block, noDict,
+ decode_full_block, noDict,
(BYTE*)dest, NULL, 0);
}
@@ -2344,7 +2313,7 @@ int LZ4_decompress_safe_partial(const char* src, char* dst, int compressedSize,
{
dstCapacity = MIN(targetOutputSize, dstCapacity);
return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity,
- endOnInputSize, partial_decode,
+ partial_decode,
noDict, (BYTE*)dst, NULL, 0);
}
@@ -2352,15 +2321,9 @@ LZ4_FORCE_O2
int LZ4_decompress_fast(const char* source, char* dest, int originalSize)
{
DEBUGLOG(5, "LZ4_decompress_fast");
-#if 0
- return LZ4_decompress_generic(source, dest, 0, originalSize,
- endOnOutputSize, decode_full_block, withPrefix64k,
- (BYTE*)dest - 64 KB, NULL, 0);
-#else
return LZ4_decompress_unsafe_generic(
(const BYTE*)source, (BYTE*)dest, originalSize,
0, NULL, 0);
-#endif
}
/*===== Instantiate a few more decoding cases, used more than once. =====*/
@@ -2369,7 +2332,7 @@ LZ4_FORCE_O2 /* Exported, an obsolete API function. */
int LZ4_decompress_safe_withPrefix64k(const char* source, char* dest, int compressedSize, int maxOutputSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
- endOnInputSize, decode_full_block, withPrefix64k,
+ decode_full_block, withPrefix64k,
(BYTE*)dest - 64 KB, NULL, 0);
}
@@ -2378,22 +2341,16 @@ static int LZ4_decompress_safe_partial_withPrefix64k(const char* source, char* d
{
dstCapacity = MIN(targetOutputSize, dstCapacity);
return LZ4_decompress_generic(source, dest, compressedSize, dstCapacity,
- endOnInputSize, partial_decode, withPrefix64k,
+ partial_decode, withPrefix64k,
(BYTE*)dest - 64 KB, NULL, 0);
}
/* Another obsolete API function, paired with the previous one. */
int LZ4_decompress_fast_withPrefix64k(const char* source, char* dest, int originalSize)
{
-#if 0
- /* LZ4_decompress_fast doesn't validate match offsets,
- * and thus serves well with any prefixed dictionary. */
- return LZ4_decompress_fast(source, dest, originalSize);
-#else
return LZ4_decompress_unsafe_generic(
(const BYTE*)source, (BYTE*)dest, originalSize,
64 KB, NULL, 0);
-#endif
}
LZ4_FORCE_O2
@@ -2401,7 +2358,7 @@ static int LZ4_decompress_safe_withSmallPrefix(const char* source, char* dest, i
size_t prefixSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
- endOnInputSize, decode_full_block, noDict,
+ decode_full_block, noDict,
(BYTE*)dest-prefixSize, NULL, 0);
}
@@ -2411,7 +2368,7 @@ static int LZ4_decompress_safe_partial_withSmallPrefix(const char* source, char*
{
dstCapacity = MIN(targetOutputSize, dstCapacity);
return LZ4_decompress_generic(source, dest, compressedSize, dstCapacity,
- endOnInputSize, partial_decode, noDict,
+ partial_decode, noDict,
(BYTE*)dest-prefixSize, NULL, 0);
}
@@ -2421,7 +2378,7 @@ int LZ4_decompress_safe_forceExtDict(const char* source, char* dest,
const void* dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
- endOnInputSize, decode_full_block, usingExtDict,
+ decode_full_block, usingExtDict,
(BYTE*)dest, (const BYTE*)dictStart, dictSize);
}
@@ -2432,7 +2389,7 @@ int LZ4_decompress_safe_partial_forceExtDict(const char* source, char* dest,
{
dstCapacity = MIN(targetOutputSize, dstCapacity);
return LZ4_decompress_generic(source, dest, compressedSize, dstCapacity,
- endOnInputSize, partial_decode, usingExtDict,
+ partial_decode, usingExtDict,
(BYTE*)dest, (const BYTE*)dictStart, dictSize);
}
@@ -2440,15 +2397,9 @@ LZ4_FORCE_O2
static int LZ4_decompress_fast_extDict(const char* source, char* dest, int originalSize,
const void* dictStart, size_t dictSize)
{
-#if 0
- return LZ4_decompress_generic(source, dest, 0, originalSize,
- endOnOutputSize, decode_full_block, usingExtDict,
- (BYTE*)dest, (const BYTE*)dictStart, dictSize);
-#else
return LZ4_decompress_unsafe_generic(
(const BYTE*)source, (BYTE*)dest, originalSize,
0, (const BYTE*)dictStart, dictSize);
-#endif
}
/* The "double dictionary" mode, for use with e.g. ring buffers: the first part
@@ -2460,7 +2411,7 @@ int LZ4_decompress_safe_doubleDict(const char* source, char* dest, int compresse
size_t prefixSize, const void* dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
- endOnInputSize, decode_full_block, usingExtDict,
+ decode_full_block, usingExtDict,
(BYTE*)dest-prefixSize, (const BYTE*)dictStart, dictSize);
}