QDBM Library for Mongoose OS https://mongoose-os.com/

This library provides support for the embedded database QDBM for use on the esp8266 and esp32 platforms with some limitations.

Language support

Only the 'C' files are compiled at this time.

File System limitations

The library depends on the lstat, ftruncate, and fsync functions, which are not implemented on Mongoose OS. There is no support in the virtual file system for symbolic links or truncating files, therefore the following behavior is implemented:

• lstat invokes the stat function.
• ftruncate only truncates the file to 0 bytes. Any other length is not supported. All QDBM functions pass 0, so this should work.
• fsync always returns 0.

These functions are implemented under the support folder.

Additionally, locking a file is not supported, so ensure DP_ONOLCK mode is set when opening a database.

Example

#include "mgos.h"
#include <depot.h>
#include <stdlib.h>
#include <stdio.h>

#define NAME     "mikio"
#define NUMBER   "000-1234-5678"
#define DBNAME   "book"

enum mgos_app_init_result mgos_app_init(void) {
    DEPOT *depot;
    char *val;

    /* open the database */
    if(!(depot = dpopen(DBNAME, DP_OWRITER | DP_OCREAT | DP_ONOLCK, -1))){
        fprintf(stderr, "dpopen: %s\n", dperrmsg(dpecode));
        return;
    }

    /* store the record */
    if(!dpput(depot, NAME, -1, NUMBER, -1, DP_DOVER)){
        fprintf(stderr, "dpput: %s\n", dperrmsg(dpecode));
    }

    /* retrieve the record */
    if(!(val = dpget(depot, NAME, -1, 0, -1, NULL))){
        fprintf(stderr, "dpget: %s\n", dperrmsg(dpecode));
    } else {
        printf("Name: %s\n", NAME);
        printf("Number: %s\n", val);
        free(val);
    }

    /* close the database */
    if(!dpclose(depot)){
        fprintf(stderr, "dpclose: %s\n", dperrmsg(dpecode));
        return;
    }

    return MGOS_APP_INIT_SUCCESS;
}