diff options
Diffstat (limited to 'sql')
| -rw-r--r-- | sql/item_strfunc.cc | 45 | ||||
| -rw-r--r-- | sql/item_strfunc.h | 10 | ||||
| -rw-r--r-- | sql/sql_string.cc | 41 | ||||
| -rw-r--r-- | sql/sql_string.h | 10 |
4 files changed, 80 insertions, 26 deletions
diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc index fd5c47d25cb..204a2dfc663 100644 --- a/sql/item_strfunc.cc +++ b/sql/item_strfunc.cc @@ -39,6 +39,9 @@ C_MODE_START #include "../mysys/my_static.h" // For soundex_map C_MODE_END +/** + @todo Remove this. It is not safe to use a shared String object. + */ String my_empty_string("",default_charset_info); @@ -461,7 +464,7 @@ String *Item_func_des_encrypt::val_str(String *str) if ((null_value= args[0]->null_value)) return 0; // ENCRYPT(NULL) == NULL if ((res_length=res->length()) == 0) - return &my_empty_string; + return make_empty_result(); if (arg_count == 1) { @@ -652,7 +655,7 @@ String *Item_func_concat_ws::val_str(String *str) } if (i == arg_count) - return &my_empty_string; + return make_empty_result(); for (i++; i < arg_count ; i++) { @@ -803,7 +806,7 @@ String *Item_func_reverse::val_str(String *str) return 0; /* An empty string is a special case as the string pointer may be null */ if (!res->length()) - return &my_empty_string; + return make_empty_result(); if (tmp_value.alloced_length() < res->length() && tmp_value.realloc(res->length())) { @@ -1143,8 +1146,7 @@ String *Item_func_left::val_str(String *str) /* if "unsigned_flag" is set, we have a *huge* positive number. */ if ((length <= 0) && (!args[1]->unsigned_flag)) - return &my_empty_string; - + return make_empty_result(); if ((res->length() <= (ulonglong) length) || (res->length() <= (char_pos= res->charpos((int) length)))) return res; @@ -1187,7 +1189,7 @@ String *Item_func_right::val_str(String *str) /* if "unsigned_flag" is set, we have a *huge* positive number. */ if ((length <= 0) && (!args[1]->unsigned_flag)) - return &my_empty_string; /* purecov: inspected */ + return make_empty_result(); /* purecov: inspected */ if (res->length() <= (ulonglong) length) return res; /* purecov: inspected */ @@ -1226,7 +1228,7 @@ String *Item_func_substr::val_str(String *str) /* Negative or zero length, will return empty string. */ if ((arg_count == 3) && (length <= 0) && (length == 0 || !args[2]->unsigned_flag)) - return &my_empty_string; + return make_empty_result(); /* Assumes that the maximum length of a String is < INT_MAX32. */ /* Set here so that rest of code sees out-of-bound value as such. */ @@ -1237,12 +1239,12 @@ String *Item_func_substr::val_str(String *str) /* Assumes that the maximum length of a String is < INT_MAX32. */ if ((!args[1]->unsigned_flag && (start < INT_MIN32 || start > INT_MAX32)) || (args[1]->unsigned_flag && ((ulonglong) start > INT_MAX32))) - return &my_empty_string; + return make_empty_result(); start= ((start < 0) ? res->numchars() + start : start - 1); start= res->charpos((int) start); if ((start < 0) || ((uint) start + 1 > res->length())) - return &my_empty_string; + return make_empty_result(); length= res->charpos((int) length, (uint32) start); tmp_length= res->length() - start; @@ -1305,7 +1307,7 @@ String *Item_func_substr_index::val_str(String *str) null_value=0; uint delimiter_length= delimiter->length(); if (!res->length() || !delimiter_length || !count) - return &my_empty_string; // Wrong parameters + return make_empty_result(); // Wrong parameters res->set_charset(collation.collation); @@ -1654,7 +1656,7 @@ String *Item_func_password::val_str(String *str) if ((null_value=args[0]->null_value)) return 0; if (res->length() == 0) - return &my_empty_string; + return make_empty_result(); my_make_scrambled_password(tmp_value, res->ptr(), res->length()); str->set(tmp_value, SCRAMBLED_PASSWORD_CHAR_LENGTH, res->charset()); return str; @@ -1678,7 +1680,7 @@ String *Item_func_old_password::val_str(String *str) if ((null_value=args[0]->null_value)) return 0; if (res->length() == 0) - return &my_empty_string; + return make_empty_result(); my_make_scrambled_password_323(tmp_value, res->ptr(), res->length()); str->set(tmp_value, SCRAMBLED_PASSWORD_CHAR_LENGTH_323, res->charset()); return str; @@ -1706,8 +1708,7 @@ String *Item_func_encrypt::val_str(String *str) if ((null_value=args[0]->null_value)) return 0; if (res->length() == 0) - return &my_empty_string; - + return make_empty_result(); if (arg_count == 1) { // generate random salt time_t timestamp=current_thd->query_start(); @@ -1967,7 +1968,7 @@ String *Item_func_soundex::val_str(String *str) for ( ; ; ) /* Skip pre-space */ { if ((rc= cs->cset->mb_wc(cs, &wc, (uchar*) from, (uchar*) end)) <= 0) - return &my_empty_string; /* EOL or invalid byte sequence */ + return make_empty_result(); /* EOL or invalid byte sequence */ if (rc == 1 && cs->ctype) { @@ -1992,7 +1993,7 @@ String *Item_func_soundex::val_str(String *str) { /* Extra safety - should not really happen */ DBUG_ASSERT(false); - return &my_empty_string; + return make_empty_result(); } to+= rc; break; @@ -2289,7 +2290,7 @@ String *Item_func_make_set::val_str(String *str) else { if (tmp_str.copy(*res)) // Don't use 'str' - return &my_empty_string; + return make_empty_result(); result= &tmp_str; } } @@ -2299,11 +2300,11 @@ String *Item_func_make_set::val_str(String *str) { // Copy data to tmp_str if (tmp_str.alloc(result->length()+res->length()+1) || tmp_str.copy(*result)) - return &my_empty_string; + return make_empty_result(); result= &tmp_str; } if (tmp_str.append(STRING_WITH_LEN(","), &my_charset_bin) || tmp_str.append(*res)) - return &my_empty_string; + return make_empty_result(); } } } @@ -2442,7 +2443,7 @@ String *Item_func_repeat::val_str(String *str) null_value= 0; if (count <= 0 && (count == 0 || !args[1]->unsigned_flag)) - return &my_empty_string; + return make_empty_result(); /* Assumes that the maximum length of a String is < INT_MAX32. */ /* Bounds check on count: If this is triggered, we will error. */ @@ -2750,7 +2751,7 @@ String *Item_func_conv::val_str(String *str) ptr= longlong2str(dec, ans, to_base); if (str->copy(ans, (uint32) (ptr-ans), default_charset())) - return &my_empty_string; + return make_empty_result(); return str; } @@ -2917,7 +2918,7 @@ String *Item_func_hex::val_str(String *str) return 0; ptr= longlong2str(dec,ans,16); if (str->copy(ans,(uint32) (ptr-ans),default_charset())) - return &my_empty_string; // End of memory + return make_empty_result(); // End of memory return str; } diff --git a/sql/item_strfunc.h b/sql/item_strfunc.h index ab2bf006032..6645a4c637a 100644 --- a/sql/item_strfunc.h +++ b/sql/item_strfunc.h @@ -22,6 +22,16 @@ class Item_str_func :public Item_func { +protected: + /** + Sets the result value of the function an empty string, using the current + character set. No memory is allocated. + @retval A pointer to the str_value member. + */ + String *make_empty_result() { + str_value.set("", 0, collation.collation); + return &str_value; + } public: Item_str_func() :Item_func() { decimals=NOT_FIXED_DEC; } Item_str_func(Item *a) :Item_func(a) {decimals=NOT_FIXED_DEC; } diff --git a/sql/sql_string.cc b/sql/sql_string.cc index a41f4d52101..4f76943bde7 100644 --- a/sql/sql_string.cc +++ b/sql/sql_string.cc @@ -58,11 +58,33 @@ bool String::real_alloc(uint32 arg_length) } -/* -** Check that string is big enough. Set string[alloc_length] to 0 -** (for C functions) -*/ +/** + Allocates a new buffer on the heap for this String. + + - If the String's internal buffer is privately owned and heap allocated, + one of the following is performed. + + - If the requested length is greater than what fits in the buffer, a new + buffer is allocated, data moved and the old buffer freed. + + - If the requested length is less or equal to what fits in the buffer, a + null character is inserted at the appropriate position. + - If the String does not keep a private buffer on the heap, such a buffer + will be allocated and the string copied accoring to its length, as found + in String::length(). + + For C compatibility, the new string buffer is null terminated. + + @param alloc_length The requested string size in characters, excluding any + null terminator. + + @retval false Either the copy operation is complete or, if the size of the + new buffer is smaller than the currently allocated buffer (if one exists), + no allocation occured. + + @retval true An error occured when attempting to allocate memory. +*/ bool String::realloc(uint32 alloc_length) { uint32 len=ALIGN_SIZE(alloc_length+1); @@ -196,6 +218,17 @@ bool String::copy() return FALSE; } +/** + Copies the internal buffer from str. If this String has a private heap + allocated buffer where new data does not fit, a new buffer is allocated + before copying and the old buffer freed. Character set information is also + copied. + + @param str The string whose internal buffer is to be copied. + + @retval false Success. + @retval true Memory allocation failed. +*/ bool String::copy(const String &str) { if (alloc(str.str_length)) diff --git a/sql/sql_string.h b/sql/sql_string.h index b15179bcbe5..092e194646f 100644 --- a/sql/sql_string.h +++ b/sql/sql_string.h @@ -136,6 +136,16 @@ public: Alloced_length=0; str_charset=str.str_charset; } + + + /** + Points the internal buffer to the supplied one. The old buffer is freed. + @param str Pointer to the new buffer. + @param arg_length Length of the new buffer in characters, excluding any + null character. + @param cs Character set to use for interpreting string data. + @note The new buffer will not be null terminated. + */ inline void set(char *str,uint32 arg_length, CHARSET_INFO *cs) { free(); |