NAME

       gd_alter_spec, gd_malter_spec — modify a field in a dirfile

SYNOPSIS

       #include <getdata.h>

       int gd_alter_spec(DIRFILE *dirfile, const char *line, int recode);

       int gd_malter_spec(DIRFILE *dirfile, const char *line, const char *parent, int recode);

DESCRIPTION

       The  gd_alter_spec() function modifies the field described by the field specification line in line to the
       dirfile specified by  dirfile.   The  gd_malter_spec()  function  behaves  similarly,  but  modifies  the
       metafield under the field indicated by the field code parent.  Field specification lines are described in
       detail in dirfile-format(5).

       The name of the field to be modified,  which  must  already  exist,  will  be  obtained  from  the  field
       specification  line.   When adding a metafield, line should only contain a field specification, and not a
       /META directive.

       If the modified field is of type RAW and the recode argument is non-zero, the binary file associated with
       the field will be converted for changes in data type and samples-per-frame.  If recode is zero, no binary
       file conversion will take place.

       If the modified field is of type LINTERP and the recode argument is non-zero, the look-up table file will
       be  moved if entry->table specifies a different path, overwriting an existing file with the new pathname,
       if present.  If the field specified by field_code is of type  other  than  RAW  or  LINTERP,  the  recode
       argument is ignored.

       Passing  these  functions  a directive line instead of a field specification line will result in a syntax
       error.  These functions never call the registered parser callback  function,  even  if  line  contains  a
       syntax error.

RETURN VALUE

       On  success, gd_alter_spec() and gd_malter_spec() return zero.   On error, -1 is returned and the dirfile
       error is set to a non-zero error value.  Possible error values are:

       GD_E_ACCMODE
               The specified dirfile was opened read-only.

       GD_E_ALLOC
               The library was unable to allocate memory.

       GD_E_BAD_CODE
               The field specified in line was not found, or the parent field code was not found.

       GD_E_BAD_DIRFILE
               The supplied dirfile was invalid.

       GD_E_FORMAT
               A syntax error was encountered in line.

       GD_E_LINE_TOO_LONG
               The supplied line was longer than the parser was able to deal with.  Lines  are  limited  by  the
               storage  size  of  ssize_t.   On  32-bit  systems, this limits line to 2**31 bytes.  The limit is
               larger on 64-bit systems.

       GD_E_PROTECTED
               The metadata of the fragment was protected from change.  Or, a request to  translate  the  binary
               file associated with a RAW field was attempted, but the data of the fragment was protected.

       GD_E_RAW_IO
               An  I/O error occurred while translating the binary file associated with a modified RAW field, or
               an I/O error occurred while attempting to rename a LINTERP table file.

       GD_E_UNKNOWN_ENCODING
               The encoding scheme of the indicated format specification fragment is not known to  the  library.
               As  a  result,  the library was unable to translate the binary file be associated with a modified
               RAW field.

       GD_E_UNSUPPORTED
               The encoding scheme of the indicated format specification fragment does not  support  translating
               the empty binary file associated with a modified RAW field.

       The dirfile error may be retrieved by calling gd_error(3).  A descriptive error string for the last error
       encountered can be obtained from a call to gd_error_string(3).

SEE ALSO

       gd_alter_bit(3),   gd_alter_const(3),   gd_alter_entry(3),    gd_alter_lincom(3),    gd_alter_linterp(3),
       gd_alter_multiply(3),  gd_alter_phase(3), gd_alter_raw(3), gd_alter_spec(3), gd_metaflush(3), gd_open(3),
       gd_error(3), gd_error_string(3), dirfile-format(5)