example_database_load.c

linux 下的源代码分析阅读器 red hat公司新版

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2004,2007 Oracle.  All rights reserved.
 */

#include "gettingstarted_common.h"

/* Forward declarations */
int usage(void);
int load_vendors_database(STOCK_DBS, char *);
size_t pack_string(char *, char *, size_t);
int load_inventory_database(STOCK_DBS, char *);

int
usage()
{
    fprintf(stderr, "example_database_load [-b <path to data files>]");
    fprintf(stderr, " [-h <database_home_directory>]\n");

    fprintf(stderr, "\tNote: Any path specified must end with your");
    fprintf(stderr, " system's path delimiter (/ or \\)\n");
    return (-1);
}

/*
 * Loads the contents of vendors.txt and inventory.txt into
 * Berkeley DB databases. Also causes the itemname secondary
 * database to be created and loaded.
 */
int
main(int argc, char *argv[])
{
    STOCK_DBS my_stock;
    int ch, ret;
    size_t size;
    char *basename, *inventory_file, *vendor_file;

    /* Initialize the STOCK_DBS struct */
    initialize_stockdbs(&my_stock);

   /* Initialize the base path. */
    basename = "./";

    /* Parse the command line arguments */
    while ((ch = getopt(argc, argv, "b:h:")) != EOF)
        switch (ch) {
        case 'h':
            if (optarg[strlen(optarg)-1] != '/' &&
                optarg[strlen(optarg)-1] != '\\')
                return (usage());
            my_stock.db_home_dir = optarg;
            break;
        case 'b':
            if (basename[strlen(basename)-1] != '/' &&
                basename[strlen(basename)-1] != '\\')
                return (usage());
            basename = optarg;
            break;
        case '?':
        default:
            return (usage());
        }

    /* Identify the files that will hold our databases */
    set_db_filenames(&my_stock);

    /* Find our input files */
    size = strlen(basename) + strlen(INVENTORY_FILE) + 1;
    inventory_file = malloc(size);
    snprintf(inventory_file, size, "%s%s", basename, INVENTORY_FILE);

    size = strlen(basename) + strlen(VENDORS_FILE) + 1;
    vendor_file = malloc(size);
    snprintf(vendor_file, size, "%s%s", basename, VENDORS_FILE);

    /* Open all databases */
    ret = databases_setup(&my_stock, "example_database_load", stderr);
    if (ret) {
        fprintf(stderr, "Error opening databases\n");
        databases_close(&my_stock);
        return (ret);
    }

    ret = load_vendors_database(my_stock, vendor_file);
    if (ret) {
        fprintf(stderr, "Error loading vendors database.\n");
        databases_close(&my_stock);
        return (ret);
    }
    ret = load_inventory_database(my_stock, inventory_file);
    if (ret) {
        fprintf(stderr, "Error loading inventory database.\n");
        databases_close(&my_stock);
        return (ret);
    }

    /* close our environment and databases */
    databases_close(&my_stock);

    printf("Done loading databases.\n");
    return (ret);
}

/*
 * Loads the contents of the vendors.txt file into
 * a database.
 */
int
load_vendors_database(STOCK_DBS my_stock, char *vendor_file)
{
    DBT key, data;
    char buf[MAXLINE];
    FILE *ifp;
    VENDOR my_vendor;

    /* Load the vendors database */
    ifp = fopen(vendor_file, "r");
    if (ifp == NULL) {
        fprintf(stderr, "Error opening file '%s'\n", vendor_file);
        return (-1);
    }

    while (fgets(buf, MAXLINE, ifp) != NULL) {
        /* zero out the structure */
        memset(&my_vendor, 0, sizeof(VENDOR));
        /* Zero out the DBTs */
        memset(&key, 0, sizeof(DBT));
        memset(&data, 0, sizeof(DBT));

        /*
         * Scan the line into the structure.
         * Convenient, but not particularly safe.
         * In a real program, there would be a lot more
         * defensive code here.
         */
        sscanf(buf,
          "%20[^#]#%20[^#]#%20[^#]#%3[^#]#%6[^#]#%13[^#]#%20[^#]#%20[^\n]",
          my_vendor.name, my_vendor.street,
          my_vendor.city, my_vendor.state,
          my_vendor.zipcode, my_vendor.phone_number,
          my_vendor.sales_rep, my_vendor.sales_rep_phone);

        /* Now that we have our structure we can load it into the database. */

        /* Set up the database record's key */
        key.data = my_vendor.name;
        key.size = (u_int32_t)strlen(my_vendor.name) + 1;

        /* Set up the database record's data */
        data.data = &my_vendor;
        data.size = sizeof(VENDOR);

        /*
         * Note that given the way we built our struct, there's extra
         * bytes in it. Essentially we're using fixed-width fields with
         * the unused portion of some fields padded with zeros. This
         * is the easiest thing to do, but it does result in a bloated
         * database. Look at load_inventory_data() for an example of how
         * to avoid this.
         */

        /* Put the data into the database */
        my_stock.vendor_dbp->put(my_stock.vendor_dbp, 0, &key, &data, 0);
    } /* end vendors database while loop */

    fclose(ifp);
    return (0);
}

/*
 * Simple little convenience function that takes a buffer, a string,
 * and an offset and copies that string into the buffer at the
 * appropriate location. Used to ensure that all our strings
 * are contained in a single contiguous chunk of memory.
 */
size_t
pack_string(char *buffer, char *string, size_t start_pos)
{
    size_t string_size;

    string_size = strlen(string) + 1;
    memcpy(buffer+start_pos, string, string_size);

    return (start_pos + string_size);
}

/*
 * Loads the contents of the inventory.txt file into
 * a database. Note that because the itemname
 * secondary database is associated to the inventorydb
 * (see env_setup() in gettingstarted_common.c), the
 * itemname index is automatically created when this
 * database is loaded.
 */
int
load_inventory_database(STOCK_DBS my_stock, char *inventory_file)
{
    DBT key, data;
    char buf[MAXLINE];
    char databuf[MAXDATABUF];
    size_t bufLen, dataLen;
    FILE *ifp;

    /*
     * Rather than lining everything up nicely in a struct, we're being
     * deliberately a bit sloppy here. This function illustrates how to
     * store mixed data that might be obtained from various locations
     * in your application.
     */
    float price;
    int quantity;
    char category[MAXFIELD], name[MAXFIELD];
    char vendor[MAXFIELD], sku[MAXFIELD];

    /* Load the inventory database */
    ifp = fopen(inventory_file, "r");
    if (ifp == NULL) {
        fprintf(stderr, "Error opening file '%s'\n", inventory_file);
            return (-1);
    }

    while (fgets(buf, MAXLINE, ifp) != NULL) {
        /*
         * Scan the line into the appropriate buffers and variables.
         * Convenient, but not particularly safe. In a real
         * program, there would be a lot more defensive code here.
         */
        sscanf(buf,
          "%20[^#]#%20[^#]#%f#%i#%20[^#]#%20[^\n]",
          name, sku, &price, &quantity, category, vendor);

        /*
         * Now pack it into a single contiguous memory location for
         * storage.
         */
        memset(databuf, 0, MAXDATABUF);
        bufLen = 0;
        dataLen = 0;

        dataLen = sizeof(float);
        memcpy(databuf, &price, dataLen);
        bufLen += dataLen;

        dataLen = sizeof(int);
        memcpy(databuf + bufLen, &quantity, dataLen);
        bufLen += dataLen;

        bufLen = pack_string(databuf, name, bufLen);
        bufLen = pack_string(databuf, sku, bufLen);
        bufLen = pack_string(databuf, category, bufLen);
        bufLen = pack_string(databuf, vendor, bufLen);

        /* Zero out the DBTs */
        memset(&key, 0, sizeof(DBT));
        memset(&data, 0, sizeof(DBT));

        /* The key is the item's SKU */
        key.data = sku;
        key.size = (u_int32_t)strlen(sku) + 1;

        /* The data is the information that we packed into databuf. */
        data.data = databuf;
        data.size = (u_int32_t)bufLen;

        /* Put the data into the database */
        my_stock.vendor_dbp->put(my_stock.inventory_dbp, 0, &key, &data, 0);
    } /* end vendors database while loop */

    /* Cleanup */
    fclose(ifp);

    return (0);
}