[PHP-DEV] PHP 4.0 Bug #4351: Informix LVARCHAR fields returned from ifx_fetch_row() are too long From: alex.shepherd <email protected>
Date: 05/08/00

From: alex.shepherd <email protected>
Operating system: Debian Linux 2.2.14
PHP version: 4.0 Release Candidate 1
PHP Bug Type: Other
Bug description: Informix LVARCHAR fields returned from ifx_fetch_row() are too long

We are using PHP4RC1 with Informix 9.2 on Linux. I have just noticed something that was causing a problem when LVARCHAR fields are returned into a Row array.

The PHP string that a LVARCHAR field is returned into seems to have two extra NULLs on the end which was causing some other problems in our application. I have tried CHAR(255) and VERCHAR(255) which seem to work fine as the add_assoc_string() function uses strlen() to determine its length where as LVARCHAR uses add_assoc_stringl() which relies upon the passed length parameter.

To debug the problem I modified the following section of the code (lines 2116-2128 of ifx.ec) to cause a warning:

case SQLLVARCHAR:
             ifx_var_flag(&lvar_tmp,1);
      EXEC SQL GET DESCRIPTOR :descrpid VALUE :i :lvar_tmp = DATA;

        fieldleng=ifx_var_getlen(&lvar_tmp);

      if ((char_data = (char *)emalloc(fieldleng + 1)) == NULL) {
                   php_error(E_WARNING, "Out of memory");
            RETURN_FALSE;
                  }
//----Begin Debug Code Here---------
        php_error(E_WARNING,"ifx_fetch_row: SQLLVARCHAR ifx_var_getlen: %d strlen: %d", fieldleng, strlen( ifx_var_getdata(&lvar_tmp) ) ) ;
//----End Debug Code Here---------

      memcpy(char_data,ifx_var_getdata(&lvar_tmp),fieldleng);
        ifx_var_dealloc(&lvar_tmp);
      add_assoc_stringl(return_value, fieldname, char_data, fieldleng,0);
      break;

This causes the following line to be displayed in the browser:

Warning: ifx_fetch_row: SQLLVARCHAR ifx_var_getlen: 12 strlen: 10 in ifx_session.inc on line 110.

I had a look around in the ESQL/C manuals etc and they say the the call ifx_var_getlen() returns the size of a buffer needed to store the field data. My guess is that this includs a 16bit length word as well as the actual string and whould explain the two extra NULL chars.

To solve my imediate problem I have added 2 lines at line 2121 of ifx.ec:

        fieldleng=ifx_var_getlen(&lvar_tmp);

//----Begin Hack to Fix Problem---------
        if( fieldleng > 2 )
                fieldleng -= 2 ;
//----End Hack to Fix Problem---------

      if ((char_data = (char *)emalloc(fieldleng + 1)) == NULL) { 

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