Config parsing (4/4): Proposed starting interface

Russ Allbery rra at
Thu May 10 16:46:21 UTC 2001

(Note that this doesn't yet deal with writing configuration files, only
reading them.  Writing hasn't been forgotten, though.)

/*  $Id$
**  Configuration file parsing interface.


#include <inn/defines.h>

/* Avoid including <inn/vector.h> unless the client needs it. */
struct vector;

/* The opaque data type representing a configuration tree. */
struct config_group_s;
typedef struct config_group_s *config_group;


/* Parse the given file and build a configuration tree.  This does purely
   syntactic parsing; no semantic checking is done.  After the file name, a
   NULL-terminated list of const char * pointers should be given, naming the
   top-level group types that the caller is interested in.  If none are given
   (if the second argument is NULL), the entire file is parsed.  (This is
   purely for efficiency reasons; if one doesn't care about speed, everything
   will work the same if no types are given.)

   Returns a config_group for the top-level group representing the entire
   file.  Generally one never wants to query parameters in this group;
   instead, the client should then call config_find_group for the group type
   of interest.  Returns NULL on failure to read the file or on a parse
   failure; errors are reported via warn. */
config_group config_parse_file(const char *file, /* types */ ...);

/* config_find_group returns the first group of the given type found in the
   tree rooted at its argument.  config_next_group returns the next group in
   the tree of the same type as the given group (or NULL if none is found).
   This can be used to do such things as enumerate all "peer" groups in a
   configuration file. */
config_group config_find_group(config_group, const char *type);
config_group config_next_group(config_group);

/* Accessor functions for group information. */
const char *config_group_type(config_group);
const char *config_group_tag(config_group);

/* Look up a parameter in a given config tree.  The second argument is the
   name of the parameter, and the result will be stored in the third argument
   if the function returns true.  If it returns false, the third argument is
   unchanged and that parameter wasn't set (or was set to an invalid value for
   the expected type). */
bool config_param_boolean(config_group, const char *, bool *);
bool config_param_integer(config_group, const char *, long *);
bool config_param_real(config_group, const char *, double *);
bool config_param_string(config_group, const char *, const char **);
bool config_param_list(config_group, const char *, struct vector *);

/* Free all space allocated by the tree rooted at config_group.  One normally
   never wants to do this.  WARNING: This includes the storage allocated for
   all strings returned by config_param_string and config_param_list for any
   configuration groups in this tree. */
void config_free(config_group);


#endif /* INN_CONFPARSE_H */

Russ Allbery (rra at             <>

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