xsh_sleep.c

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/* xsh_sleep.c - xsh_sleep */

#include <xinu.h>
#include <stdio.h>
#include <string.h>

/*------------------------------------------------------------------------
 * xsh_sleep  -  Shell command to delay for a specified number of seconds
 *------------------------------------------------------------------------
 */
shellcmd xsh_sleep(int nargs, char *args[])
{
    int32   delay;          /* Delay in seconds     */
    char    *chptr;         /* Walks through argument   */
    char    ch;         /* Next character of argument   */

    /* For argument '--help', emit help about the 'sleep' command   */

    if (nargs == 2 && strncmp(args[1], "--help", 7) == 0) {
        printf("Use: %s\n\n", args[0]);
        printf("Description:\n");
        printf("\tDelay for a specified number of seconds\n");
        printf("Options:\n");
        printf("\t--help\t display this help and exit\n");
        return 0;
    }

    /* Check for valid number of arguments */

    if (nargs > 2) {
        fprintf(stderr, "%s: too many arguments\n", args[0]);
        fprintf(stderr, "Try '%s --help' for more information\n",
                args[0]);
        return 1;
    }

    if (nargs != 2) {
        fprintf(stderr, "%s: argument in error\n", args[0]);
        fprintf(stderr, "Try '%s --help' for more information\n",
                args[0]);
        return 1;
    }

    chptr = args[1];
    ch = *chptr++;
    delay = 0;
    while (ch != NULLCH) {
        if ( (ch < '0') || (ch > '9') ) {
            fprintf(stderr, "%s: nondigit in argument\n",
                args[0]);
            return 1;
        }
        delay = 10*delay + (ch - '0');
        ch = *chptr++;
    }
    sleep(delay);
    return 0;
}