API: add `LZ4_decompress_safe_partial_usingDict` API

feature request: #1051

Signed-off-by: Qi Wang <wangqi@linux.alibaba.com>

2 files changed, 49 insertions, 1 deletions

diff --git a/lib/lz4.c b/lib/lz4.c
index a2272cf..7f4f175 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -700,7 +700,9 @@ int LZ4_compress_forceExtDict (LZ4_stream_t* LZ4_dict, const char* source, char*
 int LZ4_decompress_safe_forceExtDict(const char* source, char* dest,
                                      int compressedSize, int maxOutputSize,
                                      const void* dictStart, size_t dictSize);
-
+int LZ4_decompress_safe_partial_forceExtDict(const char* source, char* dest,
+                                     int compressedSize, int targetOutputSize, int dstCapacity,
+                                     const void* dictStart, size_t dictSize);
 #if defined (__cplusplus)
 }
 #endif
@@ -2228,6 +2230,15 @@ int LZ4_decompress_safe_withPrefix64k(const char* source, char* dest, int compre
                                   (BYTE*)dest - 64 KB, NULL, 0);
 }
 
+LZ4_FORCE_O2
+static int LZ4_decompress_safe_partial_withPrefix64k(const char* source, char* dest, int compressedSize, int targetOutputSize, int dstCapacity)
+{
+    dstCapacity = MIN(targetOutputSize, dstCapacity);
+    return LZ4_decompress_generic(source, dest, compressedSize, dstCapacity,
+                                  endOnInputSize, 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)
 {
@@ -2246,6 +2257,16 @@ static int LZ4_decompress_safe_withSmallPrefix(const char* source, char* dest, i
 }
 
 LZ4_FORCE_O2
+static int LZ4_decompress_safe_partial_withSmallPrefix(const char* source, char* dest, int compressedSize, int targetOutputSize, int dstCapacity,
+                                               size_t prefixSize)
+{
+    dstCapacity = MIN(targetOutputSize, dstCapacity);
+    return LZ4_decompress_generic(source, dest, compressedSize, dstCapacity,
+                                  endOnInputSize, partial_decode, noDict,
+                                  (BYTE*)dest-prefixSize, NULL, 0);
+}
+
+LZ4_FORCE_O2
 int LZ4_decompress_safe_forceExtDict(const char* source, char* dest,
                                      int compressedSize, int maxOutputSize,
                                      const void* dictStart, size_t dictSize)
@@ -2256,6 +2277,17 @@ int LZ4_decompress_safe_forceExtDict(const char* source, char* dest,
 }
 
 LZ4_FORCE_O2
+int LZ4_decompress_safe_partial_forceExtDict(const char* source, char* dest,
+                                     int compressedSize, int targetOutputSize, int dstCapacity,
+                                     const void* dictStart, size_t dictSize)
+{
+    dstCapacity = MIN(targetOutputSize, dstCapacity);
+    return LZ4_decompress_generic(source, dest, compressedSize, dstCapacity,
+                                  endOnInputSize, partial_decode, usingExtDict,
+                                  (BYTE*)dest, (const BYTE*)dictStart, dictSize);
+}
+
+LZ4_FORCE_O2
 static int LZ4_decompress_fast_extDict(const char* source, char* dest, int originalSize,
                                        const void* dictStart, size_t dictSize)
 {
@@ -2447,6 +2479,21 @@ int LZ4_decompress_safe_usingDict(const char* source, char* dest, int compressed
     return LZ4_decompress_safe_forceExtDict(source, dest, compressedSize, maxOutputSize, dictStart, (size_t)dictSize);
 }
 
+int LZ4_decompress_safe_partial_usingDict(const char* source, char* dest, int compressedSize, int targetOutputSize, int dstCapacity, const char* dictStart, int dictSize)
+{
+    if (dictSize==0)
+        return LZ4_decompress_safe_partial(source, dest, compressedSize, targetOutputSize, dstCapacity);
+    if (dictStart+dictSize == dest) {
+        if (dictSize >= 64 KB - 1) {
+            return LZ4_decompress_safe_partial_withPrefix64k(source, dest, compressedSize, targetOutputSize, dstCapacity);
+        }
+        assert(dictSize >= 0);
+        return LZ4_decompress_safe_partial_withSmallPrefix(source, dest, compressedSize, targetOutputSize, dstCapacity, (size_t)dictSize);
+    }
+    assert(dictSize >= 0);
+    return LZ4_decompress_safe_partial_forceExtDict(source, dest, compressedSize, targetOutputSize, dstCapacity, dictStart, (size_t)dictSize);
+}
+
 int LZ4_decompress_fast_usingDict(const char* source, char* dest, int originalSize, const char* dictStart, int dictSize)
 {
     if (dictSize==0 || dictStart+dictSize == dest)
diff --git a/lib/lz4.h b/lib/lz4.h
index 6c068c6..07cc18e 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -430,6 +430,7 @@ LZ4LIB_API int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecod
  */
 LZ4LIB_API int LZ4_decompress_safe_usingDict (const char* src, char* dst, int srcSize, int dstCapcity, const char* dictStart, int dictSize);
 
+LZ4LIB_API int LZ4_decompress_safe_partial_usingDict(const char* source, char* dest, int compressedSize, int targetOutputSize, int maxOutputSize, const char* dictStart, int dictSize);
 #endif /* LZ4_H_2983827168210 */