small compress/uncompress modification after monty's review

mysql-test/r/func_compress.result

@@ -7,11 +7,6 @@ length(@test_compress_string)
 select uncompress(compress(@test_compress_string));
 uncompress(compress(@test_compress_string))
 string for test compress function aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 
-select uncompress(@test_compress_string);
-uncompress(@test_compress_string)
-NULL
-Warnings:
-Error	1254	Too big size of uncompressed data. The maximum size is 8192. (probably, length of uncompressed data was corrupted)
 select uncompressed_length(compress(@test_compress_string))=length(@test_compress_string);
 uncompressed_length(compress(@test_compress_string))=length(@test_compress_string)
 1
@@ -33,3 +28,15 @@ select concat('|',c,'|') from t1;
 concat('|',c,'|')
 |d|
 drop table t1;
+select compress("");
+compress("")
+
+select uncompress("");
+uncompress("")
+
+select uncompress(compress(""));
+uncompress(compress(""))
+
+select uncompressed_length("");
+uncompressed_length("")
+0

mysql-test/t/func_compress.test

@@ -7,7 +7,6 @@ select @test_compress_string:='string for test compress function aaaaaaaaaaaaaaa
 select length(@test_compress_string);
 
 select uncompress(compress(@test_compress_string));
-select uncompress(@test_compress_string);
 select uncompressed_length(compress(@test_compress_string))=length(@test_compress_string);
 select uncompressed_length(compress(@test_compress_string));
 select length(compress(@test_compress_string))<length(@test_compress_string);
@@ -17,4 +16,10 @@ insert into t1 (a,b,c) values (compress(@test_compress_string),compress(@test_co
 select uncompress(a) from t1;
 select uncompress(b) from t1;
 select concat('|',c,'|') from t1;
-drop table t1;
+drop table t1;
\ No newline at end of file
+
+select compress("");
+select uncompress("");
+select uncompress(compress(""));
+select uncompressed_length("");
+

sql/item_create.cc

@@ -646,7 +646,13 @@ Item *create_func_point(Item *a, Item *b)
   return new Item_func_point(a, b);
 }
 
-#ifdef HAVE_COMPRESS
+#if !defined(HAVE_COMPRESS)
+
+Item *create_func_compress           (Item*a __attribute__((unused))){return 0;}
+Item *create_func_uncompress         (Item*a __attribute__((unused))){return 0;}
+Item *create_func_uncompressed_length(Item*a __attribute__((unused))){return 0;}
+
+#else
 
 Item *create_func_compress(Item* a)
 {

sql/item_create.h

@@ -142,9 +142,7 @@ Item *create_func_numgeometries(Item *a);
 
 Item *create_func_point(Item *a, Item *b);
 
-#ifdef HAVE_COMPRESS
 Item *create_func_compress(Item *a);
 Item *create_func_uncompress(Item *a);
 Item *create_func_uncompressed_length(Item *a);
-#endif
 

sql/item_func.cc

@@ -993,7 +993,8 @@ longlong Item_func_uncompressed_length::val_int()
     return 0; /* purecov: inspected */
   }
   null_value=0;
-  return uint4korr(res->c_ptr());
+  if (res->is_empty()) return 0;
+  return uint4korr(res->c_ptr()) & 0x3FFFFFFF;
 }
 
 #endif /* HAVE_COMPRESS */

sql/item_strfunc.cc

@@ -2924,6 +2924,8 @@ String *Item_func_spatial_collection::val_str(String *str)
 String *Item_func_compress::val_str(String *str)
 {
   String *res= args[0]->val_str(str);
+  if (res->is_empty()) return res;
+
   int err= Z_OK;
   int code;
 
@@ -2939,14 +2941,13 @@ String *Item_func_compress::val_str(String *str)
    compress(compress(compress(...)))
    I.e. zlib give number 'at least'..
   */
-  uLongf new_size= (uLongf)((res->length()*120)/100)+12;
-
-  buffer.realloc((uint32)new_size+sizeof(int32)+sizeof(char));
+  ulong new_size= (ulong)((res->length()*120)/100)+12;
 
-  Byte *body= ((Byte*)buffer.c_ptr())+sizeof(int32);
-  err= compress(body, &new_size,(const Bytef*)res->c_ptr(), res->length());
+  buffer.realloc((uint32)new_size + 4);
+  Byte *body= ((Byte*)buffer.c_ptr()) + 4;
   
-  if (err != Z_OK)
+  if ((err= compress(body, &new_size,
+		     (const Bytef*)res->c_ptr(), res->length())) != Z_OK)
   {
     code= err==Z_MEM_ERROR ? ER_ZLIB_Z_MEM_ERROR : ER_ZLIB_Z_BUF_ERROR;
     push_warning(current_thd,MYSQL_ERROR::WARN_LEVEL_ERROR,code,ER(code));
@@ -2954,18 +2955,8 @@ String *Item_func_compress::val_str(String *str)
     return 0;
   }
   
-  int4store(buffer.c_ptr(),res->length());
-  buffer.length((uint32)new_size+sizeof(int32));
-  
-  /* This is for the stupid char fields which trimm ' ': */
-  char *last_char= ((char*)body)+new_size-1;
-  if (*last_char == ' ')
-  {
-    *++last_char= '.';
-    new_size++;
-  }
-  
-  buffer.length((uint32)new_size+sizeof(int32));
+  int4store(buffer.c_ptr(),res->length() & 0x3FFFFFFF);
+  buffer.length((uint32)new_size + 4);
   
   return &buffer;
 }
@@ -2973,7 +2964,9 @@ String *Item_func_compress::val_str(String *str)
 String *Item_func_uncompress::val_str(String *str)
 {
   String *res= args[0]->val_str(str);
-  uLongf new_size= uint4korr(res->c_ptr());
+  if (res->is_empty()) return res;
+
+  ulong new_size= uint4korr(res->c_ptr()) & 0x3FFFFFFF;
   int err= Z_OK;
   uint code;
   
@@ -2982,16 +2975,14 @@ String *Item_func_uncompress::val_str(String *str)
     push_warning_printf(current_thd,MYSQL_ERROR::WARN_LEVEL_ERROR,
 			ER_TOO_BIG_FOR_UNCOMPRESS,
 			ER(ER_TOO_BIG_FOR_UNCOMPRESS),MAX_BLOB_WIDTH);
-    null_value= 1;
+    null_value= 0;
     return 0;
   }
   
   buffer.realloc((uint32)new_size);
   
-  err= uncompress((Byte*)buffer.c_ptr(), &new_size, 
-		  ((const Bytef*)res->c_ptr())+sizeof(int32),res->length());
-  
-  if (err == Z_OK)
+  if ((err= uncompress((Byte*)buffer.c_ptr(), &new_size, 
+		       ((const Bytef*)res->c_ptr())+4,res->length())) == Z_OK)
   {
     buffer.length((uint32)new_size);
     return &buffer;

sql/lex.h

@@ -448,9 +448,7 @@ static SYMBOL sql_functions[] = {
   { "CHARACTER_LENGTH", SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_char_length)},
   { "COALESCE",		SYM(COALESCE),0,0},
   { "COERCIBILITY",	SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_coercibility)},
-#ifdef HAVE_COMPRESS
   { "COMPRESS",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_compress)},
-#endif
   { "CONCAT",		SYM(CONCAT),0,0},
   { "CONCAT_WS",	SYM(CONCAT_WS),0,0},
   { "CONNECTION_ID",	SYM(FUNC_ARG0),0,CREATE_FUNC(create_func_connection_id)},
@@ -627,10 +625,8 @@ static SYMBOL sql_functions[] = {
   { "TOUCHES",		SYM(FUNC_ARG2),0,CREATE_FUNC(create_func_touches)},
   { "TRIM",		SYM(TRIM),0,0},
   { "UCASE",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_ucase)},
-#ifdef HAVE_COMPRESS
   { "UNCOMPRESS",	SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_uncompress)},
   { "UNCOMPRESSED_LENGTH", SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_uncompressed_length)},
-#endif
   { "UNIQUE_USERS",	SYM(UNIQUE_USERS),0,0},
   { "UNIX_TIMESTAMP",	SYM(UNIX_TIMESTAMP),0,0},
   { "UPPER",		SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_ucase)},