NAME¶

gd_include — add a format specification fragment to a dirfile

SYNOPSIS¶

#include <getdata.h>

DESCRIPTION¶

The gd_include() adds the format specification fragment given by the path include_file to the specified dirfile, possibly creating the fragment. This occurs as if, in the existing fragment indexed by parent_fragment, the following directive were present:

/INCLUDE <include_file>

(see dirfile-format(5)). If a parser callback function had been specified when the dirfile was opened using gd_cbopen(3), or added later with gd_parser_callback(3), this callback function will be called if a syntax error is encountered while parsing the included fragment. The flags argument should be a bitwise-or'd collection of the following flags, or zero if no flags are desired:

GD_BIG_ENDIAN

Specifies that raw data on disk is stored as big-endian data (most significant byte first). Specifying this flag along with the contradictory GD_LITTLE_ENDIAN will cause the library to assume that the endianness of the data is opposite to that of the native architecture.

This flag is ignored completely if an ENDIAN directive occurs in the fragment, unless GD_FORCE_ENDIAN is also specified.

GD_CREAT

An empty fragment will be created, if one does not already exist. The fragment will have mode S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH (0666), modified by the caller's umask value (see umask(2)).

GD_EXCL

Ensure that this call creates a new fragment: when specified along with GD_CREAT, the call will fail if the file specified by include_file already exists. Behaviour of this flag is undefined if GD_CREAT is not specified. This flag suffers from all the limitations of the O_EXCL flag as indicated in open(2).

GD_FORCE_ENCODING

Specifies that ENCODING directives (see dirfile-format(5)) found in the fragment should be ignored. The encoding scheme specified in flags will be used instead (see below).

GD_FORCE_ENDIAN

Specifies that ENDIAN directives (see dirfile-format(5)) found in the fragment should be ignored. When specified with one of GD_BIG_ENDIAN or GD_LITTLE_ENDIAN, the indicated endianness will be assumed. If this flag is specified with neither of those flags, the fragment will be assumed to have the endianness of the native architecture.

GD_IGNORE_DUPS

If the fragment specifies more than one field with the same name, or a field with the same name as an existing field, all but one of them will be ignored by the parser. Without this flag, parsing would fail with the GD_E_FORMAT error, possibly resulting in invocation of the registered callback function. Which of the duplicate fields is kept is not specified, nor whether an existing field takes precedence over a new one or not. As a result, this flag is typically only useful in the case where identical copies of a field specification line are present.

No indication is provided to indicate whether a duplicate field has been discarded. If finer grained control is required, the caller should handle GD_E_FORMAT_DUPLICATE suberrors itself with an appropriate callback function.

GD_IGNORE_REFS

If the dirfile currently has a reference field (either because one was specified explicitly, or else because the first RAW field was used), /REFERENCE directives in the included fragment will be ignored. Otherwise, a /REFERENCE directive in the included fragment will replace the current reference field in the dirfile.

GD_LITTLE_ENDIAN

Specifies that raw data on disk is stored as little-endian data (least significant byte first). Specifying this flag along with the contradictory GD_BIG_ENDIAN will cause the library to assume that the endianness of the data is opposite to that of the native architecture.

This flag is ignored completely if an ENDIAN directive occurs in the fragment, unless GD_FORCE_ENDIAN is also specified.

GD_PEDANTIC

Specifies that unrecognised lines found during the parsing of the fragment should always cause a fatal error. Without this flag, if a VERSION directive (see dirfile-format(5)) indicates that the fragment being opened conforms Standards Version newer than the version understood by the library, unrecognised lines will be silently ignored.

GD_TRUNC

If include_file already exists, it will be truncated before opening. If the file does not exist, this flag is ignored.

The flags argument may also be bitwise or'd with one of the following symbols indicating the default encoding scheme of the fragment. Like the endianness flags, the choice of encoding here is ignored if the encoding is specified in the fragment itself, unless GD_FORCE_ENCODED is also specified. If none of these symbols is present, GD_AUTO_ENCODED is assumed, unless the gd_include() call results in creation or truncation of the fragment. In that case, GD_UNENCODED is assumed. See dirfile-encoding(5) for details on dirfile encoding schemes.

GD_AUTO_ENCODED

Specifies that the encoding type is not known in advance, but should be detected by the GetData library. Detection is accomplished by searching for raw data files with extensions appropriate to the encoding scheme. This method will notably fail if the the library is called via putdata(3) to create a previously non-existent raw field unless a read is first successfully performed on the dirfile. Once the library has determined the encoding scheme for the first time, it remembers it for subsequent calls.

GD_BZIP2_ENDODED

Specifies that raw data files are compressed using the Burrows-Wheeler block sorting text compression algorithm and Huffman coding, as implemented in the bzip2 format.

GD_GZIP_ENDODED

Specifies that raw data files are compressed using Lempel-Ziv coding (LZ77) as implemented in the gzip format.

GD_LZMA_ENDODED

Specifies that raw data files are compressed using the Lempel-Ziv Markov Chain Algorithm (LZMA) as implemented in the xz container format.

GD_SLIM_ENCODED

Specifies that raw data files are compressed using the slimlib library.

GD_TEXT_ENCODED

Specifies that raw data files are encoded as text files containing one data sample per line.

GD_UNENCODED

Specifies that raw data files are not encoded, but written verbatim to disk.

RETURN VALUE¶

On success, gd_include() returns the format specification index of the newly added fragment. 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 supplied dirfile was opened in read-only mode.

GD_E_ALLOC

The library was unable to allocate memory.

GD_E_BAD_DIRFILE

The supplied dirfile was invalid.

GD_E_BAD_INDEX

The supplied parent fragment index was out of range.

GD_E_BAD_REFERENCE

The reference field specified by a /REFERENCE directive in the fragment (see dirfile-format(5)) was not found, or was not a RAW field.

GD_E_CALLBACK

The registered callback function returned an unrecognised response.

GD_E_FORMAT

A syntax error occurred in the fragment.

GD_E_INTERNAL_ERROR

An internal error occurred in the library while trying to perform the task. This indicates a bug in the library. Please report the incident to the maintainer.

GD_E_LINE_TOO_LONG

The parser encountered a line in the format specification longer than it was able to deal with. Lines are limited by the storage size of ssize_t. On 32-bit systems, this limits format specification lines to 2**31 characters. The limit is larger on 64-bit systems.

GD_E_OPEN_FRAGMENT

The fragment could not be opened or created.

GD_E_PROTECTED

The metadata of the parent fragment was protected from change.

GD_E_REFERENCE

The included fragment contained a /REFERENCE directive which referred to a non-existent field, or a field that was not of type RAW. In this case, the included fragment will still be added to the dirfile, but the /REFERENCE directive will be ignored. See also the BUGS section below.

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). When finished with it, the DIRFILE object may be de-allocated with a call to gd_close(3), even if the open failed.

BUGS¶

If this function fails with the error GD_E_REFERENCE, it typically results in no reference field being defined for the dirfile, even if the dirfile contains RAW fields. As a result, functions which rely on the reference field, such as gd_nframes(3), will operate incorrectly. Callers should explicitly set the reference field with gd_reference(3) in this case.

SEE ALSO¶

gd_open(3), gd_parser_callback(3), gd_reference(3), gd_uninclude(3), gd_error(3), gd_error_string(3), gd_fragmentname(3), gd_nfragments(3), dirfile(5), dirfile-encoding(5), dirfile-format(5)