Ubuntu Manpage: gd_match_entries — search the entry list of a Dirfile

Provided by: libgetdata-doc_0.11.0-4_all

NAME

       gd_match_entries — search the entry list of a Dirfile

SYNOPSIS

       #include <getdata.h>

       unsigned int gd_match_entries(DIRFILE *dirfile, const char *regex, int fragment, int type,
              unsigned int flags, const char ***entries);

DESCRIPTION

The gd_match_entries() function queries a dirfile(5) database specified by dirfile and all
the fields satisfying the provided criteria. If entries is not NULL, a list of matched
entries will be returned in *entries.

The match criteria are:

• If regex is non-NULL, it is a regular expression to match against the entry names.
Various regular expression grammars (or none) may be supported by the library. See
the REGULAR EXPRESSIONS section below for details.

• If the fragment argument is GD_ALL_FRAGMENTS, entries defined in all fragments are
matched. Otherwise only entries specified in the fragment indexed by fragment are
matched.

• The type argument should be one of the following symbols indicating an explicit
entry type to match:

GD_BIT_ENTRY, GD_CARRAY_ENTRY, GD_CONST_ENTRY, GD_DIVIDE_ENTRY,
GD_INDEX_ENTRY, GD_INDIR_ENTRY, GD_LINCOM_ENTRY, GD_LINTERP_ENTRY,
GD_MPLEX_ENTRY, GD_MULTIPLY_ENTRY, GD_PHASE_ENTRY, GD_POLYNOM_ENTRY,
GD_RAW_ENTRY, GD_RECIP_ENTRY, GD_SARRAY_ENTRY, GD_SBIT_ENTRY,
GD_SINDIR_ENTRY, GD_STRING_ENTRY, GD_WINDOW_ENTRY.

(GD_INDEX_ENTRY is a special field type for the implicit INDEX field) or else one
of the following special symbols:

GD_ALL_ENTRIES (=0)
Match entries of all types.

GD_ALIAS_ENTRIES
Match only aliases. This is the only way to match aliases which do not
point to valid field codes.

GD_SCALAR_ENTRIES
Match only scalar field types (CONST, CARRAY, SARRAY, STRING).

GD_VECTOR_ENTRIES
Match only numeric-valued vector field types (all field types except SINDIR
and the scalar field types listed above).

• The flags argument should be zero or more of the following flags, bitwise or'd
together:

GD_ENTRIES_HIDDEN
Match hidden entries (see gd_hidden(3)): normally hidden entries are
ignored;

GD_ENTRIES_NOALIAS
Don't match aliases: normally aliases are matched as if they had the entry
type of their target.

If regex is non-NULL, these flags may further be bitwise-or'd with the following
flags which affect the interpretation of the supplied regular expression:

GD_REGEX_PCRE, GD_REGEX_EXTENDED, GD_REGEX_ICASE, GD_REGEX_CASELESS,
GD_REGEX_JAVASCRIPT, GD_REGEX_UNICODE

See the REGULAR EXPRESSIONS section below for details. If regex is NULL, these
additional regular-expression-specific flags are ignored.

RETURN VALUE

       Upon successful completion, gd_match_entries() returns the number of entries  successfully
       matched. In this case, if entries is non-NULL, this function sets *entries to a pointer to
       a list of the matching entry names. This list is terminated by a NULL pointer. Memory  for
       the  list,  and  for  the strings it contains, is managed by GetData. None of the returned
       pointers should be free'd by the caller. The pointers returned are only valid  until  this
       function  is  called  again, and the associated memory will be deallocated when dirfile is
       closed (see gd_close(3)).

       If no entries match, but no error occurs, zero is returned. In this case,  if  entries  is
       non-NULL,  *entries  is still set to a non-NULL pointer, which points to a list containing
       only the terminating NULL.

       On error, this function also returns zero.  If entries is non-NULL,  *entries  is  set  to
       NULL  in  this case (which can be used to distinguish this case from the zero-match case).
       This function furthermore stores a negative-valued error code in the DIRFILE object  which
       may be retrieved by a subsequent call to gd_error(3).  Possible error codes are:

       GD_E_ARGUMENT
               There  was an error in the supplied regular expression. See the REGULAR EXPRESSION
               section below for details.

       GD_E_BAD_CODE
               The supplied parent field code was not found, or referred to a metafield itself.

       GD_E_BAD_DIRFILE
               The supplied dirfile was invalid.

       GD_E_BAD_ENTRY
               The type parameter supplied was not one of the symbols listed above.

       GD_E_UNSUPPORTED
               The regex parameter was non-NULL, but the library lacked support for the specified
               regular expression grammar. See the REGULAR EXPRESSION section below for details.

       A descriptive error string for the error may be obtained by calling gd_error_string(3).

REGULAR EXPRESSIONS

Regular expression support in GetData is provided by external libraries and is optional.
Whether a particular regular expression library is supported by GetData is determined when
the library is built. Preprocessor symbols are present in getdata.h to provide compile-
time support to programs building against GetData indicating what support the GetData
library was built with.

GetData supports the following regular expression libraries:

• The POSIX.2 regular expression library, which provides support for both basic and
extended POSIX regular expressions. See regex(7) for details. The POSIX regular
expression library is derived from Henry Spencer's original regex package found in
BSD. If GetData lacks support for POSIX regular expressions, the symbol GD_NO_REGEX
will be defined in getdata.h.

• Perl-compatible Regular Expressions (PCRE), which provides a modern, full-featured
regular expression grammar. See pcre(3) for details. If GetData lacks support for
PCREs, the symbol GD_NO_PCRE will be defined in getdata.h.

Support for one, both, or neither library may be enabled in the GetData library when it is
built.

When calling gd_match_entries(), the choice of regular expression grammar to use is
controlled by bitwise-or'ing flags with zero or more of the following symbols:

GD_REGEX_PCRE
Use the Perl-compatible Regular Expression (PCRE) library for regular expression
matching. Without this flag, the POSIX regex library is used.

GD_REGEX_CASELESS
GD_REGEX_ICASE
Perform case-insensitive matching. These two symbols are synonyms. This is
equivalent to the REG_ICASE flag in regex(3) and the PCRE_CASELESS flag in
pcreapi(3).

The following flags are only supported when using the PCRE library (i.e., when
GD_REGEX_PCRE is also specified):

GD_REGEX_JAVASCRIPT
Enable Javascript compatibility mode in the PCRE library. This results in a
regular expression grammar that mimics more closely Javascript's regular
expressions than Perl's. See the PCRE_JAVASCRIPT_COMPAT flag in pcreapi(3) for
details.

GD_REGEX_UNICODE
Interpret the supplied regex, as well as the Dirfile's entry names, as UTF-8
sequences. Without this flag, they are all assumed to be ASCII sequences. When
this flag is specified, the flags PCRE_UTF8 and BPCRE_BSR_UNICODE are passed to
the PCRE library. Without it, the flags PCRE_BSR_ANYCRLF is used instead. See
pcreapi(3) for details.

In addition to the above, the flags PCRE_DOLLAR_ENDONLY and PCRE_DOTALL are always passed
to the PCRE library. Note, however, that the PCRE grammar also permits overriding most of
these flags by specifying different options in the regex pattern itself.

GetData does not return captured substrings to the caller, nor does it support PCRE
callouts.

If the caller attempts to use a regular expression library for which support has not been
built into GetData, GD_E_UNSUPPORTED will be returned. It is always possible for the
caller avoid this error at runtime by checking for GD_NO_REGEX or GD_NO_PCRE at compile
time.

Errors returned by the regular expression compiler itself will be reported to the caller
with GD_E_ARGUMENT.

HISTORY