---
name: "gd_alter_encoding"
section: "3"
platform: "linux"
package: "libgetdata-doc"
version: "0.11.0-15"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/gd_alter_encoding"
---

# gd\_alter\_encoding(3)

modify the binary encoding of data in a Dirfile

## NAME

gd\_alter\_encoding — modify the binary encoding of data in a Dirfile

## SYNOPSIS

**#include \<getdata.h\>**

**int gd\_alter\_encoding(DIRFILE \****dirfile***, unsigned int** *encoding***,** **int** *fragment\_index***, int** *recode***);**

## DESCRIPTION

The **gd\_alter\_encoding**() function sets the binary encoding of the format specification fragment given by *fragment\_index* to the encoding specified by *encoding* in the [dirfile(5)](/dirfile/5.md) database specified by *dirfile*. The binary encoding of a fragment indicate the encoding of data stored in binary files associated with **RAW** fields defined in the specified fragment.  The binary encoding of a fragment containing no **RAW** fields is ignored.

The *encoding* argument should be one of the following symbols:

-

  **GD\_UNENCODED**, **GD\_BZIP2\_ENCODED**, **GD\_FLAC\_ENCODED**, **GD\_GZIP\_ENCODED**, **GD\_LZMA\_ENCODED**, **GD\_SLIM\_ENCODED**, **GD\_SIE\_ENCODED**, **GD\_TEXT\_ENCODED**.

See [**gd\_open**(3)](/gd_open/3.md) and [dirfile-encoding(5)](/dirfile-encoding/5.md) for the meanings of these symbols and details on the supported encoding schemes.

In addition to being simply a valid fragment index, *fragment\_index* may also be the special value **GD\_ALL\_FRAGMENTS**, which indicates that the encoding of all fragments in the database should be changed.

If the *recode* argument is non-zero, this call will recode the binary data of affected **RAW** fields to account for the change in binary encoding.  If the encoding of the fragment is encoding insensitive, or if the data type is only one byte in size, no change is made.  The I/O pointer of all affected **RAW** fields is reset to the beginning-of-frame.

If *recode* is zero, affected binary files are left untouched.

## RETURN VALUE

Upon successful completion, **gd\_alter\_encoding**() returns zero.  On error, it returns a negative-valued error code.  Possible error codes are:\
  .TP 8 **GD\_E\_ACCMODE** The specified dirfile was opened read-only.\
  .TP 8 **GD\_E\_ALLOC** The library was unable to allocate memory.\
  .TP 8 **GD\_E\_BAD\_DIRFILE** The supplied dirfile was invalid.\
  .TP 8 **GD\_E\_BAD\_INDEX** The supplied index was out of range.\
  .TP 8 **GD\_E\_IO** An I/O error occurred while attempting to recode a binary file.\
  .TP 8 **GD\_E\_PROTECTED** The metadata of the given format specification fragment was protected from change, or the binary data of the fragment was protected from change and binary file recoding was requested.\
  .TP 8 **GD\_E\_UNCLEAN\_DB** An error occurred while moving the recoded file into place.  As a result, the database may be in an unclean state.  See the **NOTES** section below for recovery instructions.  In this case, the dirfile will be flagged as invalid, to prevent further database corruption.  It should be immediately closed.\
  .TP 8 **GD\_E\_UNKNOWN\_ENCODING** The encoding scheme of the fragment is unknown.\
  .TP 8 **GD\_E\_UNSUPPORTED** The encoding scheme of the fragment does not support binary file recoding.

The error code is also stored in the **DIRFILE** object and may be retrieved after this function returns by calling [**gd\_error**(3)](/gd_error/3.md). A descriptive error string for the error may be obtained by calling [**gd\_error\_string**(3)](/gd_error_string/3.md).

## NOTES

A binary file recoding occurs out-of-place.  As a result, sufficient space must be present on the filesystem for the binary files of all **RAW** fields in the fragment both before and after translation.  If all fragments are updated by specifying **GD\_ALL\_FRAGMENTS**, the recoding occurs one fragment at a time.

An error code of **GD\_E\_UNCLEAN\_DB** indicates a system error occurred while moving the re-encoded binary data into place or when deleting the old data.  If this happens, the database may be left in an unclean state.  The caller should check the filesystem directly to ascertain the state of the dirfile data before continuing.  For recovery instructions, see the file /usr/share/doc/getdata/unclean\_database\_recovery.txt.

## HISTORY

The function **dirfile\_alter\_encoding**() appeared in GetData-0.5.0.

In GetData-0.7.0, this function was renamed to **gd\_alter\_encoding**().

in GetData-0.10.0, the error return from this function changed from -1 to a negative-valued error code.

## SEE ALSO

[**gd\_error**(3)](/gd_error/3.md), [**gd\_error\_string**(3)](/gd_error_string/3.md), [**gd\_encoding**(3)](/gd_encoding/3.md), [**gd\_open**(3)](/gd_open/3.md), [dirfile(5)](/dirfile/5.md), [dirfile-format(5)](/dirfile-format/5.md)