dict_union.c

[詳解]

/*++
/* NAME
/*  dict_union 3
/* SUMMARY
/*  dictionary manager interface for union of tables
/* SYNOPSIS
/*  #include <dict_union.h>
/*
/*  DICT    *dict_union_open(name, open_flags, dict_flags)
/*  const char *name;
/*  int open_flags;
/*  int dict_flags;
/* DESCRIPTION
/*  dict_union_open() opens a sequence of one or more tables.
/*  Example: "\fBunionmap:{\fItype_1:name_1, ..., type_n:name_n\fR}".
/*
/*  Each "unionmap:" query is given to each table in the specified
/*  order. All found results are concatenated, separated by
/*  comma.  The unionmap table produces no result when all
/*  lookup tables return no result.
/*
/*  The first and last characters of a "unionmap:" table name
/*  must be '{' and '}'. Within these, individual maps are
/*  separated with comma or whitespace.
/*
/*  The open_flags and dict_flags arguments are passed on to
/*  the underlying dictionaries.
/* SEE ALSO
/*  dict(3) generic dictionary manager
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*
/*  Wietse Venema
/*  Google, Inc.
/*  111 8th Avenue
/*  New York, NY 10011, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <string.h>

/* Utility library. */

#include <msg.h>
#include <mymalloc.h>
#include <htable.h>
#include <dict.h>
#include <dict_union.h>
#include <stringops.h>
#include <vstring.h>

/* Application-specific. */

typedef struct {
    DICT    dict;           /* generic members */
    ARGV   *map_union;          /* pipelined tables */
    VSTRING *re_buf;            /* reply buffer */
} DICT_UNION;

#define STR(x) vstring_str(x)

/* dict_union_lookup - search a bunch of tables and combine the results */

static const char *dict_union_lookup(DICT *dict, const char *query)
{
    static const char myname[] = "dict_union_lookup";
    DICT_UNION *dict_union = (DICT_UNION *) dict;
    DICT   *map;
    char  **cpp;
    char   *dict_type_name;
    const char *result = 0;

    /*
     * After Roel van Meer, postfix-users mailing list, Sept 2014.
     */
    VSTRING_RESET(dict_union->re_buf);
    for (cpp = dict_union->map_union->argv; (dict_type_name = *cpp) != 0; cpp++) {
    if ((map = dict_handle(dict_type_name)) == 0)
        msg_panic("%s: dictionary \"%s\" not found", myname, dict_type_name);
    if ((result = dict_get(map, query)) != 0) {
        if (VSTRING_LEN(dict_union->re_buf) > 0)
        VSTRING_ADDCH(dict_union->re_buf, ',');
        vstring_strcat(dict_union->re_buf, result);
    } else if (map->error != 0) {
        DICT_ERR_VAL_RETURN(dict, map->error, 0);
    }
    }
    DICT_ERR_VAL_RETURN(dict, DICT_ERR_NONE,
            VSTRING_LEN(dict_union->re_buf) > 0 ?
            STR(dict_union->re_buf) : 0);
}

/* dict_union_close - disassociate from a bunch of tables */

static void dict_union_close(DICT *dict)
{
    DICT_UNION *dict_union = (DICT_UNION *) dict;
    char  **cpp;
    char   *dict_type_name;

    for (cpp = dict_union->map_union->argv; (dict_type_name = *cpp) != 0; cpp++)
    dict_unregister(dict_type_name);
    argv_free(dict_union->map_union);
    vstring_free(dict_union->re_buf);
    dict_free(dict);
}

/* dict_union_open - open a bunch of tables */

DICT   *dict_union_open(const char *name, int open_flags, int dict_flags)
{
    static const char myname[] = "dict_union_open";
    DICT_UNION *dict_union;
    char   *saved_name = 0;
    char   *dict_type_name;
    ARGV   *argv = 0;
    char  **cpp;
    DICT   *dict;
    int     match_flags = 0;
    struct DICT_OWNER aggr_owner;
    size_t  len;

    /*
     * Clarity first. Let the optimizer worry about redundant code.
     */
#define DICT_UNION_RETURN(x) do { \
          if (saved_name != 0) \
              myfree(saved_name); \
          if (argv != 0) \
              argv_free(argv); \
          return (x); \
      } while (0)

    /*
     * Sanity checks.
     */
    if (open_flags != O_RDONLY)
    DICT_UNION_RETURN(dict_surrogate(DICT_TYPE_UNION, name,
                     open_flags, dict_flags,
                  "%s:%s map requires O_RDONLY access mode",
                     DICT_TYPE_UNION, name));

    /*
     * Split the table name into its constituent parts.
     */
    if ((len = balpar(name, CHARS_BRACE)) == 0 || name[len] != 0
    || *(saved_name = mystrndup(name + 1, len - 2)) == 0
    || ((argv = argv_splitq(saved_name, CHARS_COMMA_SP, CHARS_BRACE)),
        (argv->argc == 0)))
    DICT_UNION_RETURN(dict_surrogate(DICT_TYPE_UNION, name,
                     open_flags, dict_flags,
                     "bad syntax: \"%s:%s\"; "
                     "need \"%s:{type:name...}\"",
                     DICT_TYPE_UNION, name,
                     DICT_TYPE_UNION));

    /*
     * The least-trusted table in the set determines the over-all trust
     * level. The first table determines the pattern-matching flags.
     */
    DICT_OWNER_AGGREGATE_INIT(aggr_owner);
    for (cpp = argv->argv; (dict_type_name = *cpp) != 0; cpp++) {
    if (msg_verbose)
        msg_info("%s: %s", myname, dict_type_name);
    if (strchr(dict_type_name, ':') == 0)
        DICT_UNION_RETURN(dict_surrogate(DICT_TYPE_UNION, name,
                         open_flags, dict_flags,
                         "bad syntax: \"%s:%s\"; "
                         "need \"%s:{type:name...}\"",
                         DICT_TYPE_UNION, name,
                         DICT_TYPE_UNION));
    if ((dict = dict_handle(dict_type_name)) == 0)
        dict = dict_open(dict_type_name, open_flags, dict_flags);
    dict_register(dict_type_name, dict);
    DICT_OWNER_AGGREGATE_UPDATE(aggr_owner, dict->owner);
    if (cpp == argv->argv)
        match_flags = dict->flags & (DICT_FLAG_FIXED | DICT_FLAG_PATTERN);
    }

    /*
     * Bundle up the result.
     */
    dict_union =
    (DICT_UNION *) dict_alloc(DICT_TYPE_UNION, name, sizeof(*dict_union));
    dict_union->dict.lookup = dict_union_lookup;
    dict_union->dict.close = dict_union_close;
    dict_union->dict.flags = dict_flags | match_flags;
    dict_union->dict.owner = aggr_owner;
    dict_union->re_buf = vstring_alloc(100);
    dict_union->map_union = argv;
    argv = 0;
    DICT_UNION_RETURN(DICT_DEBUG (&dict_union->dict));
}