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Remove valgrind warnings from Item_str_concat

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This warning come from a copy() operation of type:
memcpy(ptr, ptr+A, B), which is safe but produces a warning
when run with valgrind.

To avoid the warning, I added copy_or_move() method which uses
memmove() instead of memcpy().

In 10.3 the change in item_strfunc::Item_func_concat() has to be mirroed
in Item_func_concat_oracle() to avoid future valgrind warnings.
This commit is contained in:
Michael Widenius 2018-09-20 06:13:43 +03:00
parent 29703e4f87
commit 6c97e85673
3 changed files with 23 additions and 3 deletions
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2
sql/item_strfunc.cc
View file

@ -603,7 +603,7 @@ String *Item_func_concat::val_str(String *str)
goto null;
if (res != str)
str->copy(res->ptr(), res->length(), res->charset());
str->copy_or_move(res->ptr(), res->length(), res->charset());
for (uint i= 1 ; i < arg_count ; i++)
{

23
sql/sql_string.cc
View file

@ -184,9 +184,9 @@ bool String::copy(const String &str)
bool String::copy(const char *str,size_t arg_length, CHARSET_INFO *cs)
{
DBUG_ASSERT(arg_length < UINT_MAX32);
if (alloc(arg_length))
return TRUE;
DBUG_ASSERT(arg_length < UINT_MAX32);
if (Ptr == str && arg_length == uint32(str_length))
{
/*
@ -203,6 +203,24 @@ bool String::copy(const char *str,size_t arg_length, CHARSET_INFO *cs)
return FALSE;
}
/*
Copy string, where strings may overlap.
Same as String::copy, but use memmove instead of memcpy to avoid warnings
from valgrind
*/
bool String::copy_or_move(const char *str,size_t arg_length, CHARSET_INFO *cs)
{
DBUG_ASSERT(arg_length < UINT_MAX32);
if (alloc(arg_length))
return TRUE;
if ((str_length=uint32(arg_length)))
memmove(Ptr,str,arg_length);
Ptr[arg_length]=0;
str_charset=cs;
return FALSE;
}
/*
Checks that the source string can be just copied to the destination string
@ -336,8 +354,9 @@ bool String::set_or_copy_aligned(const char *str,uint32 arg_length,
/* How many bytes are in incomplete character */
uint32 offset= (arg_length % cs->mbminlen);
if (!offset) /* All characters are complete, just copy */
if (!offset)
{
/* All characters are complete, just use given string */
set(str, arg_length, cs);
return FALSE;
}

1
sql/sql_string.h
View file

@ -429,6 +429,7 @@ public:
bool copy(); // Alloc string if not alloced
bool copy(const String &s); // Allocate new string
bool copy(const char *s,size_t arg_length, CHARSET_INFO *cs); // Allocate new string
bool copy_or_move(const char *s,size_t arg_length, CHARSET_INFO *cs);
static bool needs_conversion(uint32 arg_length,
CHARSET_INFO *cs_from, CHARSET_INFO *cs_to,
uint32 *offset);