Merge pull request #936 from lz4/alignTest

More alignment tests

5 files changed, 77 insertions, 108 deletions

diff --git a/lib/README.md b/lib/README.md
index 3653c81..ee5d3ba 100644
--- a/lib/README.md
+++ b/lib/README.md
@@ -77,6 +77,10 @@ The following build macro can be selected to adjust source code behavior at comp
   In most cases, it's not expected to be necessary,
   but it can be legitimately considered for less common platforms.
 
+- `LZ4_ALIGN_TEST` : alignment test ensures that the memory area
+  passed as argument to become a compression state is suitable aligned.
+  This test can be disabled, if it proves flaky, by setting this value to 0.
+
 
 #### Amalgamation
 
diff --git a/lib/lz4.c b/lib/lz4.c
index 6adfafd..9d547e5 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -178,6 +178,12 @@
 #define unlikely(expr)   expect((expr) != 0, 0)
 #endif
 
+/* Should the alignment test prove unreliable, for some reason,
+ * it can be disabled by setting LZ4_ALIGN_TEST to 0 */
+#ifndef LZ4_ALIGN_TEST  /* can be externally provided */
+# define LZ4_ALIGN_TEST 1
+#endif
+
 
 /*-************************************
 *  Memory routines
@@ -243,6 +249,11 @@ static const int LZ4_minLength = (MFLIMIT+1);
 #  define DEBUGLOG(l, ...) {}    /* disabled */
 #endif
 
+static int LZ4_isAligned(const void* ptr, size_t alignment)
+{
+    return ((size_t)ptr & (alignment -1)) == 0;
+}
+
 
 /*-************************************
 *  Types
@@ -457,7 +468,7 @@ LZ4_memcpy_using_offset(BYTE* dstPtr, const BYTE* srcPtr, BYTE* dstEnd, const si
 
     switch(offset) {
     case 1:
-        memset(v, *srcPtr, 8);
+        MEM_INIT(v, *srcPtr, 8);
         break;
     case 2:
         LZ4_memcpy(v, srcPtr, 2);
@@ -1406,27 +1417,23 @@ LZ4_stream_t* LZ4_createStream(void)
     return lz4s;
 }
 
-#ifndef _MSC_VER  /* for some reason, Visual fails the aligment test on 32-bit x86 :
-                     it reports an aligment of 8-bytes,
-                     while actually aligning LZ4_stream_t on 4 bytes. */
 static size_t LZ4_stream_t_alignment(void)
 {
+#if LZ4_ALIGN_TEST
     typedef struct { char c; LZ4_stream_t t; } t_a;
     return sizeof(t_a) - sizeof(LZ4_stream_t);
-}
+#else
+    return 1;  /* effectively disabled */
 #endif
+}
 
 LZ4_stream_t* LZ4_initStream (void* buffer, size_t size)
 {
     DEBUGLOG(5, "LZ4_initStream");
     if (buffer == NULL) { return NULL; }
     if (size < sizeof(LZ4_stream_t)) { return NULL; }
-#ifndef _MSC_VER  /* for some reason, Visual fails the aligment test on 32-bit x86 :
-                     it reports an aligment of 8-bytes,
-                     while actually aligning LZ4_stream_t on 4 bytes. */
-    if (((size_t)buffer) & (LZ4_stream_t_alignment() - 1)) { return NULL; } /* alignment check */
-#endif
-    MEM_INIT(buffer, 0, sizeof(LZ4_stream_t));
+    if (!LZ4_isAligned(buffer, LZ4_stream_t_alignment())) return NULL;
+    MEM_INIT(buffer, 0, sizeof(LZ4_stream_t_internal));
     return (LZ4_stream_t*)buffer;
 }
 
@@ -1435,7 +1442,7 @@ LZ4_stream_t* LZ4_initStream (void* buffer, size_t size)
 void LZ4_resetStream (LZ4_stream_t* LZ4_stream)
 {
     DEBUGLOG(5, "LZ4_resetStream (ctx:%p)", LZ4_stream);
-    MEM_INIT(LZ4_stream, 0, sizeof(LZ4_stream_t));
+    MEM_INIT(LZ4_stream, 0, sizeof(LZ4_stream_t_internal));
 }
 
 void LZ4_resetStream_fast(LZ4_stream_t* ctx) {
diff --git a/lib/lz4.h b/lib/lz4.h
index b11275e..c4324af 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -573,68 +573,60 @@ LZ4LIB_STATIC_API void LZ4_attach_dictionary(LZ4_stream_t* workingStream, const
  **************************************************************
  * Do not use these definitions directly.
  * They are only exposed to allow static allocation of `LZ4_stream_t` and `LZ4_streamDecode_t`.
- * Accessing members will expose code to API and/or ABI break in future versions of the library.
+ * Accessing members will expose user code to API and/or ABI break in future versions of the library.
  **************************************************************/
 #define LZ4_HASHLOG   (LZ4_MEMORY_USAGE-2)
 #define LZ4_HASHTABLESIZE (1 << LZ4_MEMORY_USAGE)
 #define LZ4_HASH_SIZE_U32 (1 << LZ4_HASHLOG)       /* required as macro for static allocation */
 
 #if defined(__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
-#include <stdint.h>
-
-typedef struct LZ4_stream_t_internal LZ4_stream_t_internal;
-struct LZ4_stream_t_internal {
-    uint32_t hashTable[LZ4_HASH_SIZE_U32];
-    uint32_t currentOffset;
-    uint32_t tableType;
-    const uint8_t* dictionary;
-    const LZ4_stream_t_internal* dictCtx;
-    uint32_t dictSize;
-};
-
-typedef struct {
-    const uint8_t* externalDict;
-    size_t extDictSize;
-    const uint8_t* prefixEnd;
-    size_t prefixSize;
-} LZ4_streamDecode_t_internal;
-
+# include <stdint.h>
+  typedef  int8_t  LZ4_i8;
+  typedef uint8_t  LZ4_byte;
+  typedef uint16_t LZ4_u16;
+  typedef uint32_t LZ4_u32;
 #else
+  typedef   signed char  LZ4_i8;
+  typedef unsigned char  LZ4_byte;
+  typedef unsigned short LZ4_u16;
+  typedef unsigned int   LZ4_u32;
+#endif
 
 typedef struct LZ4_stream_t_internal LZ4_stream_t_internal;
 struct LZ4_stream_t_internal {
-    unsigned int hashTable[LZ4_HASH_SIZE_U32];
-    unsigned int currentOffset;
-    unsigned int tableType;
-    const unsigned char* dictionary;
+    LZ4_u32 hashTable[LZ4_HASH_SIZE_U32];
+    LZ4_u32 currentOffset;
+    LZ4_u32 tableType;
+    const LZ4_byte* dictionary;
     const LZ4_stream_t_internal* dictCtx;
-    unsigned int dictSize;
+    LZ4_u32 dictSize;
 };
 
 typedef struct {
-    const unsigned char* externalDict;
-    const unsigned char* prefixEnd;
+    const LZ4_byte* externalDict;
     size_t extDictSize;
+    const LZ4_byte* prefixEnd;
     size_t prefixSize;
 } LZ4_streamDecode_t_internal;
 
-#endif
 
 /*! LZ4_stream_t :
- *  information structure to track an LZ4 stream.
+ *  Do not use below internal definitions directly !
+ *  Declare or allocate an LZ4_stream_t instead.
  *  LZ4_stream_t can also be created using LZ4_createStream(), which is recommended.
  *  The structure definition can be convenient for static allocation
  *  (on stack, or as part of larger structure).
  *  Init this structure with LZ4_initStream() before first use.
  *  note : only use this definition in association with static linking !
- *    this definition is not API/ABI safe, and may change in a future version.
+ *  this definition is not API/ABI safe, and may change in future versions.
  */
-#define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE-3)) + 4 + ((sizeof(void*)==16) ? 4 : 0) /*AS-400*/ )
-#define LZ4_STREAMSIZE     (LZ4_STREAMSIZE_U64 * sizeof(unsigned long long))
+#define LZ4_STREAMSIZE       16416  /* static size, for inter-version compatibility */
+#define LZ4_STREAMSIZE_VOIDP (LZ4_STREAMSIZE / sizeof(void*))
 union LZ4_stream_u {
-    unsigned long long table[LZ4_STREAMSIZE_U64];
+    void* table[LZ4_STREAMSIZE_VOIDP];
     LZ4_stream_t_internal internal_donotuse;
-} ;  /* previously typedef'd to LZ4_stream_t */
+}; /* previously typedef'd to LZ4_stream_t */
+
 
 /*! LZ4_initStream() : v1.9.0+
  *  An LZ4_stream_t structure must be initialized at least once.
diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index a126c83..15bedec 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -53,7 +53,7 @@
 #include "lz4hc.h"
 
 
-/*===   Common LZ4 definitions   ===*/
+/*===   Common definitions   ===*/
 #if defined(__GNUC__)
 #  pragma GCC diagnostic ignored "-Wunused-function"
 #endif
@@ -61,15 +61,16 @@
 #  pragma clang diagnostic ignored "-Wunused-function"
 #endif
 
-/*===   Enums   ===*/
-typedef enum { noDictCtx, usingDictCtxHc } dictCtx_directive;
-
-
 #define LZ4_COMMONDEFS_ONLY
 #ifndef LZ4_SRC_INCLUDED
 #include "lz4.c"   /* LZ4_count, constants, mem */
 #endif
 
+
+/*===   Enums   ===*/
+typedef enum { noDictCtx, usingDictCtxHc } dictCtx_directive;
+
+
 /*===   Constants   ===*/
 #define OPTIMAL_ML (int)((ML_MASK-1)+MINMATCH)
 #define LZ4_OPT_NUM   (1<<12)
@@ -161,8 +162,7 @@ int LZ4HC_countBack(const BYTE* const ip, const BYTE* const match,
 LZ4_FORCE_INLINE U32 LZ4HC_rotatePattern(size_t const rotate, U32 const pattern)
 {
     size_t const bitsToRotate = (rotate & (sizeof(pattern) - 1)) << 3;
-    if (bitsToRotate == 0)
-        return pattern;
+    if (bitsToRotate == 0) return pattern;
     return LZ4HC_rotl32(pattern, (int)bitsToRotate);
 }
 
@@ -919,27 +919,22 @@ LZ4HC_compress_generic (
 
 int LZ4_sizeofStateHC(void) { return (int)sizeof(LZ4_streamHC_t); }
 
-#ifndef _MSC_VER  /* for some reason, Visual fails the aligment test on 32-bit x86 :
-                   * it reports an aligment of 8-bytes,
-                   * while actually aligning LZ4_streamHC_t on 4 bytes. */
 static size_t LZ4_streamHC_t_alignment(void)
 {
+#if LZ4_ALIGN_TEST
     typedef struct { char c; LZ4_streamHC_t t; } t_a;
     return sizeof(t_a) - sizeof(LZ4_streamHC_t);
-}
+#else
+    return 1;  /* effectively disabled */
 #endif
+}
 
 /* state is presumed correctly initialized,
  * in which case its size and alignment have already been validate */
 int LZ4_compress_HC_extStateHC_fastReset (void* state, const char* src, char* dst, int srcSize, int dstCapacity, int compressionLevel)
 {
     LZ4HC_CCtx_internal* const ctx = &((LZ4_streamHC_t*)state)->internal_donotuse;
-#ifndef _MSC_VER  /* for some reason, Visual fails the aligment test on 32-bit x86 :
-                   * it reports an aligment of 8-bytes,
-                   * while actually aligning LZ4_streamHC_t on 4 bytes. */
-    assert(((size_t)state & (LZ4_streamHC_t_alignment() - 1)) == 0);  /* check alignment */
-#endif
-    if (((size_t)(state)&(sizeof(void*)-1)) != 0) return 0;   /* Error : state is not aligned for pointers (32 or 64 bits) */
+    if (!LZ4_isAligned(state, LZ4_streamHC_t_alignment())) return 0;
     LZ4_resetStreamHC_fast((LZ4_streamHC_t*)state, compressionLevel);
     LZ4HC_init_internal (ctx, (const BYTE*)src);
     if (dstCapacity < LZ4_compressBound(srcSize))
@@ -1010,11 +1005,7 @@ LZ4_streamHC_t* LZ4_initStreamHC (void* buffer, size_t size)
     LZ4_streamHC_t* const LZ4_streamHCPtr = (LZ4_streamHC_t*)buffer;
     if (buffer == NULL) return NULL;
     if (size < sizeof(LZ4_streamHC_t)) return NULL;
-#ifndef _MSC_VER  /* for some reason, Visual fails the aligment test on 32-bit x86 :
-                   * it reports an aligment of 8-bytes,
-                   * while actually aligning LZ4_streamHC_t on 4 bytes. */
-    if (((size_t)buffer) & (LZ4_streamHC_t_alignment() - 1)) return NULL;  /* alignment check */
-#endif
+    if (!LZ4_isAligned(buffer, LZ4_streamHC_t_alignment())) return NULL;
     /* if compilation fails here, LZ4_STREAMHCSIZE must be increased */
     LZ4_STATIC_ASSERT(sizeof(LZ4HC_CCtx_internal) <= LZ4_STREAMHCSIZE);
     DEBUGLOG(4, "LZ4_initStreamHC(%p, %u)", LZ4_streamHCPtr, (unsigned)size);
diff --git a/lib/lz4hc.h b/lib/lz4hc.h
index 44e35bb..3d441fb 100644
--- a/lib/lz4hc.h
+++ b/lib/lz4hc.h
@@ -198,57 +198,32 @@ LZ4LIB_API int LZ4_saveDictHC (LZ4_streamHC_t* streamHCPtr, char* safeBuffer, in
 #define LZ4HC_HASH_MASK (LZ4HC_HASHTABLESIZE - 1)
 
 
-#if defined(__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
-#include <stdint.h>
-
-typedef struct LZ4HC_CCtx_internal LZ4HC_CCtx_internal;
-struct LZ4HC_CCtx_internal
-{
-    uint32_t   hashTable[LZ4HC_HASHTABLESIZE];
-    uint16_t   chainTable[LZ4HC_MAXD];
-    const uint8_t* end;         /* next block here to continue on current prefix */
-    const uint8_t* base;        /* All index relative to this position */
-    const uint8_t* dictBase;    /* alternate base for extDict */
-    uint32_t   dictLimit;       /* below that point, need extDict */
-    uint32_t   lowLimit;        /* below that point, no more dict */
-    uint32_t   nextToUpdate;    /* index from which to continue dictionary update */
-    short      compressionLevel;
-    int8_t     favorDecSpeed;   /* favor decompression speed if this flag set,
-                                   otherwise, favor compression ratio */
-    int8_t     dirty;           /* stream has to be fully reset if this flag is set */
-    const LZ4HC_CCtx_internal* dictCtx;
-};
-
-#else
-
 typedef struct LZ4HC_CCtx_internal LZ4HC_CCtx_internal;
 struct LZ4HC_CCtx_internal
 {
-    unsigned int   hashTable[LZ4HC_HASHTABLESIZE];
-    unsigned short chainTable[LZ4HC_MAXD];
-    const unsigned char* end;        /* next block here to continue on current prefix */
-    const unsigned char* base;       /* All index relative to this position */
-    const unsigned char* dictBase;   /* alternate base for extDict */
-    unsigned int   dictLimit;        /* below that point, need extDict */
-    unsigned int   lowLimit;         /* below that point, no more dict */
-    unsigned int   nextToUpdate;     /* index from which to continue dictionary update */
-    short          compressionLevel;
-    char           favorDecSpeed;    /* favor decompression speed if this flag set,
-                                        otherwise, favor compression ratio */
-    char           dirty;            /* stream has to be fully reset if this flag is set */
+    LZ4_u32   hashTable[LZ4HC_HASHTABLESIZE];
+    LZ4_u16   chainTable[LZ4HC_MAXD];
+    const LZ4_byte* end;       /* next block here to continue on current prefix */
+    const LZ4_byte* base;      /* All index relative to this position */
+    const LZ4_byte* dictBase;  /* alternate base for extDict */
+    LZ4_u32   dictLimit;       /* below that point, need extDict */
+    LZ4_u32   lowLimit;        /* below that point, no more dict */
+    LZ4_u32   nextToUpdate;    /* index from which to continue dictionary update */
+    short     compressionLevel;
+    LZ4_i8    favorDecSpeed;   /* favor decompression speed if this flag set,
+                                  otherwise, favor compression ratio */
+    LZ4_i8    dirty;           /* stream has to be fully reset if this flag is set */
     const LZ4HC_CCtx_internal* dictCtx;
 };
 
-#endif
-
 
 /* Do not use these definitions directly !
  * Declare or allocate an LZ4_streamHC_t instead.
  */
-#define LZ4_STREAMHCSIZE       (4*LZ4HC_HASHTABLESIZE + 2*LZ4HC_MAXD + 56 + ((sizeof(void*)==16) ? 56 : 0) /* AS400*/ ) /* 262200 or 262256*/
-#define LZ4_STREAMHCSIZE_SIZET (LZ4_STREAMHCSIZE / sizeof(size_t))
+#define LZ4_STREAMHCSIZE       262200  /* static size, for inter-version compatibility */
+#define LZ4_STREAMHCSIZE_VOIDP (LZ4_STREAMHCSIZE / sizeof(void*))
 union LZ4_streamHC_u {
-    size_t table[LZ4_STREAMHCSIZE_SIZET];
+    void* table[LZ4_STREAMHCSIZE_VOIDP];
     LZ4HC_CCtx_internal internal_donotuse;
 }; /* previously typedef'd to LZ4_streamHC_t */