table_data.c

开发snmp的开发包有两个开放的SNMP开发库

#include <net-snmp/net-snmp-config.h>

#if HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif

#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>

#include <net-snmp/agent/table.h>
#include <net-snmp/agent/table_data.h>
#include <net-snmp/agent/read_only.h>

/** @defgroup table_data table_data
 *  Helps you implement a table with datamatted storage.
 *  @ingroup table
 *
 *  This helper is obsolete.  If you are writing a new module, please
 *  consider using the table_tdata helper instead.
 *
 *  This helper helps you implement a table where all the indexes are
 *  expected to be stored within the agent itself and not in some
 *  external storage location.  It can be used to store a list of
 *  rows, where a row consists of the indexes to the table and a
 *  generic data pointer.  You can then implement a subhandler which
 *  is passed the exact row definition and data it must return data
 *  for or accept data for.  Complex GETNEXT handling is greatly
 *  simplified in this case.
 *
 *  @{
 */

/* ==================================
 *
 * Table Data API: Table maintenance
 *
 * ================================== */

/*
 * generates the index portion of an table oid from a varlist.
 */
void
netsnmp_table_data_generate_index_oid(netsnmp_table_row *row)
{
    build_oid(&row->index_oid, &row->index_oid_len, NULL, 0, row->indexes);
}

/** creates and returns a pointer to table data set */
netsnmp_table_data *
netsnmp_create_table_data(const char *name)
{
    netsnmp_table_data *table = SNMP_MALLOC_TYPEDEF(netsnmp_table_data);
    if (name && table)
        table->name = strdup(name);
    return table;
}

/** creates and returns a pointer to table data set */
netsnmp_table_row *
netsnmp_create_table_data_row(void)
{
    netsnmp_table_row *row = SNMP_MALLOC_TYPEDEF(netsnmp_table_row);
    return row;
}

/** clones a data row. DOES NOT CLONE THE CONTAINED DATA. */
netsnmp_table_row *
netsnmp_table_data_clone_row(netsnmp_table_row *row)
{
    netsnmp_table_row *newrow = NULL;
    if (!row)
        return NULL;

    memdup((u_char **) & newrow, (u_char *) row,
           sizeof(netsnmp_table_row));
    if (!newrow)
        return NULL;

    if (row->indexes) {
        newrow->indexes = snmp_clone_varbind(newrow->indexes);
        if (!newrow->indexes)
            return NULL;
    }

    if (row->index_oid) {
        memdup((u_char **) & newrow->index_oid,
               (u_char *) row->index_oid,
               row->index_oid_len * sizeof(oid));
        if (!newrow->index_oid)
            return NULL;
    }

    return newrow;
}

/** deletes a row's memory.
 *  returns the void data that it doesn't know how to delete. */
void           *
netsnmp_table_data_delete_row(netsnmp_table_row *row)
{
    void           *data;

    if (!row)
        return NULL;

    /*
     * free the memory we can 
     */
    if (row->indexes)
        snmp_free_varbind(row->indexes);
    SNMP_FREE(row->index_oid);
    data = row->data;
    free(row);

    /*
     * return the void * pointer 
     */
    return data;
}

/**
 * Adds a row of data to a given table (stored in proper lexographical order).
 *
 * returns SNMPERR_SUCCESS on successful addition.
 *      or SNMPERR_GENERR  on failure (E.G., indexes already existed)
 */
int
netsnmp_table_data_add_row(netsnmp_table_data *table,
                           netsnmp_table_row *row)
{
    int rc, dup = 0;
    netsnmp_table_row *nextrow = NULL, *prevrow;

    if (!row || !table)
        return SNMPERR_GENERR;

    if (row->indexes)
        netsnmp_table_data_generate_index_oid(row);

    /*
     * we don't store the index info as it
     * takes up memory. 
     */
    if (!table->store_indexes) {
        snmp_free_varbind(row->indexes);
        row->indexes = NULL;
    }

    if (!row->index_oid) {
        snmp_log(LOG_ERR,
                 "illegal data attempted to be added to table %s (no index)\n",
                 table->name);
        return SNMPERR_GENERR;
    }

    /*
     * check for simple append
     */
    if ((prevrow = table->last_row) != NULL) {
        rc = snmp_oid_compare(prevrow->index_oid, prevrow->index_oid_len,
                              row->index_oid, row->index_oid_len);
        if (0 == rc)
            dup = 1;
    }
    else
        rc = 1;
    
    /*
     * if no last row, or newrow < last row, search the table and
     * insert it into the table in the proper oid-lexographical order 
     */
    if (rc > 0) {
        for (nextrow = table->first_row, prevrow = NULL;
             nextrow != NULL; prevrow = nextrow, nextrow = nextrow->next) {
            if (NULL == nextrow->index_oid) {
                DEBUGMSGT(("table_data_add_data", "row doesn't have index!\n"));
                /** xxx-rks: remove invalid row? */
                continue;
            }
            rc = snmp_oid_compare(nextrow->index_oid, nextrow->index_oid_len,
                                  row->index_oid, row->index_oid_len);
            if(rc > 0)
                break;
            if (0 == rc) {
                dup = 1;
                break;
            }
        }
    }

    if (dup) {
        /*
         * exact match.  Duplicate entries illegal 
         */
        snmp_log(LOG_WARNING,
                 "duplicate table data attempted to be entered. row exists\n");
        return SNMPERR_GENERR;
    }

    /*
     * ok, we have the location of where it should go 
     */
    /*
     * (after prevrow, and before nextrow) 
     */
    row->next = nextrow;
    row->prev = prevrow;

    if (row->next)
        row->next->prev = row;

    if (row->prev)
        row->prev->next = row;

    if (NULL == row->prev)      /* it's the (new) first row */
        table->first_row = row;
    if (NULL == row->next)      /* it's the last row */
        table->last_row = row;

    DEBUGMSGTL(("table_data_add_data", "added something...\n"));

    return SNMPERR_SUCCESS;
}

/** swaps out origrow with newrow.  This does *not* delete/free anything! */
NETSNMP_INLINE void
netsnmp_table_data_replace_row(netsnmp_table_data *table,
                               netsnmp_table_row *origrow,
                               netsnmp_table_row *newrow)
{
    netsnmp_table_data_remove_row(table, origrow);
    netsnmp_table_data_add_row(table, newrow);
}

/**
 * removes a row of data to a given table and returns it (no free's called)
 *
 * returns the row pointer itself on successful removing.
 *      or NULL on failure (bad arguments)
 */
netsnmp_table_row *
netsnmp_table_data_remove_row(netsnmp_table_data *table,
                              netsnmp_table_row *row)
{
    if (!row || !table)
        return NULL;

    if (row->prev)
        row->prev->next = row->next;
    else
        table->first_row = row->next;

    if (row->next)
        row->next->prev = row->prev;
    else
        table->last_row = row->prev;

    return row;
}

/**
 * removes and frees a row of data to a given table and returns the void *
 *
 * returns the void * data on successful deletion.
 *      or NULL on failure (bad arguments)
 */
void           *
netsnmp_table_data_remove_and_delete_row(netsnmp_table_data *table,
                                         netsnmp_table_row *row)
{
    if (!row || !table)
        return NULL;

    /*
     * remove it from the list 
     */
    netsnmp_table_data_remove_row(table, row);
    return netsnmp_table_data_delete_row(row);
}

    /* =====================================
     * Generic API - mostly renamed wrappers
     * ===================================== */

netsnmp_table_data *
netsnmp_table_data_create_table(const char *name, long flags)
{
    return netsnmp_create_table_data( name );
}

void
netsnmp_table_data_delete_table( netsnmp_table_data *table )
{
    netsnmp_table_row *row, *nextrow;

    if (!table)
        return;

    for (row = table->first_row; row; row=nextrow) {
        nextrow   = row->next;
        row->next = NULL;
        netsnmp_table_data_delete_row(row);
        /* Can't delete table-specific entry memory */
    }
    table->first_row = NULL;

    if (table->name) {
        SNMP_FREE(table->name);
        table->name = NULL;
    }
    SNMP_FREE(table);
    return;
}

netsnmp_table_row *
netsnmp_table_data_create_row( void* entry )
{
    netsnmp_table_row *row = SNMP_MALLOC_TYPEDEF(netsnmp_table_row);
    if (row)
        row->data = entry;
    return row;
}

    /* netsnmp_table_data_clone_row() defined above */

int
netsnmp_table_data_copy_row( netsnmp_table_row  *old_row,
                             netsnmp_table_row  *new_row )
{
    if (!old_row || !new_row)
        return -1;

    memcpy(new_row, old_row, sizeof(netsnmp_table_row));