/* argv.c
 *
 * Neal Nelson 2009.10.16
 *
 * Construct a NULL terminated argv array of strings from an input line.
 * BUGS: The mkargv mallocs but does not free, so the main loop is
 *       leaking memory on every call to mkargv. It now seems to me better
 *       to just hard-allocate fixed space in the main shell loop for
 *       the argv string array.
 */

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

#define MAXLINE 81
#define MAXARGV 5

/* Prototypes */
char **mkargv(char *buf);

main()
{ char buf[MAXLINE];
  char **argv;
  int i;

  printf("mkArgv: enter words on a line, ^d to quit\n>");
  while (fgets(buf, MAXLINE, stdin) != NULL )
  { argv = mkargv(buf);
    for (i=0; argv[i] != (char *)NULL; i++) printf("  %s\n",argv[i]);
    printf(">");
  }
  printf("\n");
}

char **mkargv(char *buf)
{ char *p;                                /* p points to progress in buf */
  char **argv;
  int len, argc;
  char ws[] = " \n\t\r\f\v";

  argv = (char **)calloc(MAXARGV+1, sizeof(char *));
  p = buf + strspn(buf,ws);               /* skip leading whitespace */
  for (argc = 0; *p != '\0' && argc < MAXARGV; argc++) 
  { len = strcspn(p,ws);                  /* get next word */
    argv[argc] = (char *)calloc(len+1,sizeof(char));
    strncpy(argv[argc],p,len);
    *(argv[argc] + len) = '\0';           /* string terminator */
    p = p+len;                            /* point past this word */
    p = p + strspn(p,ws);                 /* skip trailing whitespace */
  }

  argv[argc] = (char *)NULL;              /* end of string array */
  return argv;
}