crypt_log_usage.c

// SPDX-License-Identifier: LGPL-2.1-or-later
/*
 * libcryptsetup API log example
 *
 * Copyright (C) 2011-2025 Red Hat, Inc. All rights reserved.
 */
 
#include <stdio.h>
#include <sys/types.h>
#include <syslog.h>
#include <unistd.h>
#include <libcryptsetup.h>
 
/*
 * This is an example of crypt_set_log_callback API callback.
 *
 */
static void simple_syslog_wrapper(int level, const char *msg, void *usrptr)
{
        const char *prefix = (const char *)usrptr;
        int priority;
 
        switch(level) {
                case CRYPT_LOG_NORMAL:  priority = LOG_NOTICE; break;
                case CRYPT_LOG_ERROR:   priority = LOG_ERR;    break;
                case CRYPT_LOG_VERBOSE: priority = LOG_INFO;   break;
                case CRYPT_LOG_DEBUG:   priority = LOG_DEBUG;  break;
                default:
                        fprintf(stderr, "Unsupported log level requested!\n");
                        return;
        }
 
        if (prefix)
                syslog(priority, "%s:%s", prefix, msg);
        else
                syslog(priority, "%s", msg);
}
 
int main(void)
{
        struct crypt_device *cd;
        char usrprefix[] = "cslog_example";
        int r;
 
        if (geteuid()) {
                printf("Using of libcryptsetup requires super user privileges.\n");
                return 1;
        }
 
        openlog("cryptsetup", LOG_CONS | LOG_PID, LOG_USER);
 
        /* Initialize empty crypt device context */
        r = crypt_init(&cd, NULL);
        if (r < 0) {
                printf("crypt_init() failed.\n");
                return 2;
        }
 
        /* crypt_set_log_callback() - register a log callback for crypt context */
        crypt_set_log_callback(cd, &simple_syslog_wrapper, (void *)usrprefix);
 
        /* send messages ithrough the crypt_log() interface */
        crypt_log(cd, CRYPT_LOG_NORMAL, "This is normal log message");
        crypt_log(cd, CRYPT_LOG_ERROR, "This is error log message");
        crypt_log(cd, CRYPT_LOG_VERBOSE, "This is verbose log message");
        crypt_log(cd, CRYPT_LOG_DEBUG, "This is debug message");
 
        /* release crypt context */
        crypt_free(cd);
 
        /* Initialize default (global) log callback */
        crypt_set_log_callback(NULL, &simple_syslog_wrapper, NULL);
 
        crypt_log(NULL, CRYPT_LOG_NORMAL, "This is normal log message");
        crypt_log(NULL, CRYPT_LOG_ERROR, "This is error log message");
        crypt_log(NULL, CRYPT_LOG_VERBOSE, "This is verbose log message");
        crypt_log(NULL, CRYPT_LOG_DEBUG, "This is debug message");
 
        closelog();
        return 0;
}