utilities.c

/*
 * This file is governed by Licenses which are listed in
 * the LICENSE file, which shall be included in all copies
 * and redistributions of this project.
 */

#include "utilities.h"

/* check if a string is not zero and not empty */
extern int strnzero (const char *str) {
    if (str != NULL)
        return strncmp(str, "", 1) != 0;
    return 0;
}

/* The prompt function is based on ask_filename from:
 * $OpenBSD: ssh-keygen.c,v 1.290 2016/05/02 09:36:42 djm Exp $
 *
 * Original Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>,
 *                        Espoo, Finland  All rights reserved
 */

/* prompt for user input */
extern int prompt (const char *promptmsg, char *dest, size_t dest_len, const char *defaultval) {
    char buf[dest_len];
    
    /* if default value is given, copy that to dest already */
    if (strnzero(defaultval))
        snprintf(dest, dest_len, "%s", defaultval);

    /* display prompt */
    if (strnzero(dest))
	    printf("%s [%s]: ", promptmsg, dest);
    else
        printf("%s: ", promptmsg);
	fflush(stdout);
	
    /* get input from stdin */
    if (fgets(buf, sizeof buf, stdin) == NULL)
        return ERR_BAD_USER_INPUT;
    
    /* find newline and replace by \0 */
	buf[strcspn(buf, "\n")] = '\0';

    /* if the buffer now has nonzero length, copy that to dest */
	if (strnzero(buf)) strncpy(dest, buf, dest_len);

    return SUCCESS;
}


/* print contents of a string similar to hexdump */
extern void debugbuf (const char *name, const unsigned char *buf, size_t buf_len)
{
    printf("\n%8s   %s: %s", "address", "content of", name != NULL ? name : "UNKNOWN");
	for (size_t i = 0; i < buf_len; i++) {

		/* print empty line every 16 lines */
        if (i % 256 == 0) printf("\n");
        /* print address on newline */
        if (i % 16 == 0) printf("\n%08x  ", i);
        /* extra space every 8 bytes */
        if (i % 16 == 8) printf(" ");
        /* print contents in hex */
		printf(" %02x", buf[i]);
	}
    printf("\n\n");
}