int gd_alter_spec(DIRFILE *dirfile, const char *line,
- int gd_malter_spec(DIRFILE *dirfile, const char *line, const char *parent, int recode);
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. In this case, the field's I/O pointer will be reset to the beginning-of-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 line 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 VALUEOn 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:
- The specified dirfile was opened read-only.
- The library was unable to allocate memory.
- The field specified in line was not found, or the parent field code was not found.
- The supplied dirfile was invalid.
- A syntax error was encountered in line.
- 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.
- 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.
- 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.
- 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.
- The encoding scheme of the indicated format specification fragment does not support translating the empty binary file associated with a modified RAW field.