xsh_cat.c

Go to the documentation of this file.

/* xsh_cat.c - xsh_cat */

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

/*------------------------------------------------------------------------
 * xsh_cat - shell command to cat one or more files
 *------------------------------------------------------------------------
 */
shellcmd xsh_cat(int nargs, char *args[])
{
    int32   i;          /* index into proctabl      */
    int32   nextch;         /* character read from file */
    did32   descr;          /* descriptor for a file    */
    char    *argptr;        /* pointer to next arg string   */


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

    if (nargs == 2 && strncmp(args[1], "--help", 7) == 0) {
        printf("Use: %s [file...]\n\n", args[0]);
        printf("Description:\n");
        printf("\twrites contents of files or stdin to stdout\n");
        printf("Options:\n");
        printf("\tfile...\tzero or more file names\n");
        printf("\t--help\t display this help and exit\n");
        return 0;
    }

    if (nargs == 1) {
        nextch = getc(stdin);
        while (nextch != EOF) {
            putc(stdout, nextch);
            nextch = getc(stdin);
        }
        return 0;
    }
    for (i = 1; i < nargs; i++) {
        argptr = args[i];
        if ( (argptr[0] == '-') && (argptr[1] == NULLCH) ) {
            descr = stdin;
        } else {
            descr = open(NAMESPACE, argptr, "ro");
            if (descr == (did32)SYSERR) {
                fprintf(stderr, "%s: cannot open file %s\n",
                    args[0], argptr);
                return 1;
            }
        }
        nextch = getc(descr);
        while (nextch != EOF) {
            putc(stdout, nextch);
            nextch = getc(descr);
        }
        close(descr);
    }
    return 0;
}