Description:
The function mysql_fetch_fields() returns an array of MYSQL_FIELD objects. The definition of the MYSQL_FIELD typedef changed recently (I am not sure which version) from a 40 byte struct to an 80 byte struct in the header mysql.h.
When using the mysql_fetch_fields() function provided with the Windows Essentials (x86) version of the library libmysql.lib, it returns MYSQL_FIELD objects with the old format typedef instead of the new one.
This causes code recompiled with the 4.1.12a includes & library to break.
How to repeat:
Compile the following code with 4.1.12a where 'result' is already obtained from a query. Note that the query must return more than 1 field to see the problem.
unsigned int num_fields;
unsigned int i;
MYSQL_FIELD *fields;
num_fields = mysql_num_fields(result);
fields = mysql_fetch_fields(result);
for(i = 0; i < num_fields; i++)
{
printf("Field %u is %s\n", i, fields[i].name); // NOTE A
}
NOTE A
=====
Crashed here when i > num_fields/2.
Suggested fix:
Changing MYSQL_FIELD struct in the header mysql.h
from:
typedef struct st_mysql_field {
char *name; /* Name of column */
char *org_name; /* Original column name, if an alias */
char *table; /* Table of column if column was a field */
char *org_table; /* Org table name, if table was an alias */
char *db; /* Database for table */
char *catalog; /* Catalog for table */
char *def; /* Default value (set by mysql_list_fields) */
unsigned long length; /* Width of column (create length) */
unsigned long max_length; /* Max width for selected set */
unsigned int name_length;
unsigned int org_name_length;
unsigned int table_length;
unsigned int org_table_length;
unsigned int db_length;
unsigned int catalog_length;
unsigned int def_length;
unsigned int flags; /* Div flags */
unsigned int decimals; /* Number of decimals in field */
unsigned int charsetnr; /* Character set */
enum enum_field_types type; /* Type of field. See mysql_com.h for types */
} MYSQL_FIELD;
to:
typedef struct st_mysql_field {
char *name; /* Name of column */
char *table; /* Table of column if column was a field */
char *org_table; /* Org table name if table was an alias */
char *db; /* Database for table */
char *def; /* Default value (set by mysql_list_fields) */
unsigned long length; /* Width of column */
unsigned long max_length; /* Max width of selected set */
unsigned int flags; /* Div flags */
unsigned int decimals; /* Number of decimals in field */
enum enum_field_types type; /* Type of field. Se mysql_com.h for types */
} MYSQL_FIELD;
will temporarily fix the problem.
Description: The function mysql_fetch_fields() returns an array of MYSQL_FIELD objects. The definition of the MYSQL_FIELD typedef changed recently (I am not sure which version) from a 40 byte struct to an 80 byte struct in the header mysql.h. When using the mysql_fetch_fields() function provided with the Windows Essentials (x86) version of the library libmysql.lib, it returns MYSQL_FIELD objects with the old format typedef instead of the new one. This causes code recompiled with the 4.1.12a includes & library to break. How to repeat: Compile the following code with 4.1.12a where 'result' is already obtained from a query. Note that the query must return more than 1 field to see the problem. unsigned int num_fields; unsigned int i; MYSQL_FIELD *fields; num_fields = mysql_num_fields(result); fields = mysql_fetch_fields(result); for(i = 0; i < num_fields; i++) { printf("Field %u is %s\n", i, fields[i].name); // NOTE A } NOTE A ===== Crashed here when i > num_fields/2. Suggested fix: Changing MYSQL_FIELD struct in the header mysql.h from: typedef struct st_mysql_field { char *name; /* Name of column */ char *org_name; /* Original column name, if an alias */ char *table; /* Table of column if column was a field */ char *org_table; /* Org table name, if table was an alias */ char *db; /* Database for table */ char *catalog; /* Catalog for table */ char *def; /* Default value (set by mysql_list_fields) */ unsigned long length; /* Width of column (create length) */ unsigned long max_length; /* Max width for selected set */ unsigned int name_length; unsigned int org_name_length; unsigned int table_length; unsigned int org_table_length; unsigned int db_length; unsigned int catalog_length; unsigned int def_length; unsigned int flags; /* Div flags */ unsigned int decimals; /* Number of decimals in field */ unsigned int charsetnr; /* Character set */ enum enum_field_types type; /* Type of field. See mysql_com.h for types */ } MYSQL_FIELD; to: typedef struct st_mysql_field { char *name; /* Name of column */ char *table; /* Table of column if column was a field */ char *org_table; /* Org table name if table was an alias */ char *db; /* Database for table */ char *def; /* Default value (set by mysql_list_fields) */ unsigned long length; /* Width of column */ unsigned long max_length; /* Max width of selected set */ unsigned int flags; /* Div flags */ unsigned int decimals; /* Number of decimals in field */ enum enum_field_types type; /* Type of field. Se mysql_com.h for types */ } MYSQL_FIELD; will temporarily fix the problem.