/*
 * GETINTDRIVER -- program to call an integer reading function
 *
 * Compiling: put the getint function in getint.c, then say:
 * 	gcc -ansi -pedantic -Wall -o getint getintdriver.c getint.c
 *
 * Usage: getint
 *
 * Inputs (from standard input)
 *      -- a line of text
 *      -- EOF to exit
 *      -- special handling of 2246, 2247, 2248, 2249
 * Outputs (to standard output)
 * 	-- a prompt when it expects input
 *	-- outputs indicating the success or failure of the getint call
 *	-- if input is integer 2246, also indicate whether getint() handles
 *		a NULL first argument correctly
 *	-- if input is integer 2247, also indicate whether getint() handles
 *		a NULL second argument correctly
 *	-- if input is integer 2248, also indicate whether getint() handles
 *		a NULL third argument correctly
 *	-- if input is integer 2249, also indicate whether getint() handles
 *		a NULL dereferencing of the third argument correctly
 * Errors (to standard error)
 * 	-- nothing printed
 *
 * Exit Code: 0
 *
 * written for ECS 030, Fall 2015
 * 
 * Matt Bishop, Oct. 28, 2015
 *      original program written
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * macros
 *
 * how to test for bogus arguments
 */
#define	BADARG1	2246		/* if read, test handling of NULL first arg */
#define	BADARG2	2247		/* if read, test handling of NULL second arg */
#define	BADARG3	2248		/* if read, test handling of NULL third arg */
#define	BADARG4	2249		/* if read, test handling of NULL dereference for third arg */

/*
 *  prototypes
 */
int getint(char *, int *, char **);	/* function to read an integer */

/*
 * this function calls getint with various illegal parameters
 *
 * Parameter:	int	number to trigger test (or not)
 * 			numbers that do not trigger tests are ignored
 * 			BADARG1		test NULL argument 1
 * 			BADARG2		test NULL argument 2
 * 			BADARG3		test NULL argument 3
 * 			BADARG4		test argument 3 pointing to NULL
 * Returns:	nothing
 * Exceptions:	none
 * Side Effects:	prints a 1-line message identifying the test run and
 * 			giving the success or failure of the test
 */
void checkargs(int testno)
{
	char line[10];		/* array used for input line */
	int inpnum = 0;		/* space for the read number */
	char *nextch = line;	/* where the getint function leaves off */
	int rv;			/* return value from getint() */

	/*
	 * just copy some characters into line
	 */
	(void) strcpy(line, "987654321");

	/*
	 * process any magic numbers (see above)
	 */
	switch(testno){
	case BADARG1:		/* NULL first argument */
		if ((rv = getint(NULL, &inpnum, &nextch)) == -1)
			printf("Passed NULL first argument test\n");
		else
			printf("Failed NULL first argument test; returned %d\n", rv);
		break;
	case BADARG2:		/* NULL second argument */
		if ((rv = getint(line, NULL, &nextch)) == -1)
			printf("Passed NULL second argument test\n");
		else
			printf("Failed NULL second argument test; returned %d\n", rv);
		break;
	case BADARG3:		/* NULL third argument */
		if ((rv = getint(line, &inpnum, NULL)) == -1)
			printf("Passed NULL third argument test\n");
		else
			printf("Failed NULL third argument test; returned %d\n", rv);
		break;
	case BADARG4:		/* NULL dereference of third  argument */
		nextch = NULL;
		if ((rv = getint(line, &inpnum, &nextch)) == -1)
			printf("Passed NULL third argument dereference test\n");
		else
			printf("Failed NULL third argument dereference test; returned %d\n", rv);
		break;
	default:		/* ignore any other number */
		break;
	}
}

/*
 * it all starts at the main routine
 */
int main(void)
{
	char buf[1024];			/* input buffer */
	int numread;			/* number read from input */
	char *nextch = buf;		/* where we left off */
	int rv;				/* return value of getint() */

	/*
	 * loop until end of file
	 * prompting the user for an input line
	 */
	while(printf("> "), fgets(buf, 1024, stdin) != NULL){
		/* clobber any trailing newline */
		if (buf[strlen(buf) - 1] == '\n')
			buf[strlen(buf) - 1] = '\0';
		/*
		 * now process the line -- read the leading integer
		 * and report if it is not an integer or if
		 * it is too big or too small to represent
		 */
		switch(rv = getint(buf, &numread, &nextch)){
		case -1:		/* illegal parameter */
			printf("Illegal call -- internal inconsistency\n");
			break;
		case 0:			/* no leading integer */
			printf("No number -- string is \"%s\"\n", nextch);
			if (buf != nextch)
				printf("Note -- third arguent should point to first, but it doesn't\n");
			break;
		case 1:			/* read number, all's well */
			printf("Read integer %d; rest of string is \"%s\"\n", numread, nextch);
			break;
		case 2:			/* read number but it's too big */
			printf("Integer overflow (+ve) -- string is \"%s\"\n", nextch);
			break;
		case 3:			/* read number but it's too negative */
			printf("Integer underflow (-ve) -- string is \"%s\"\n", nextch);
			break;
		default:		/* huh? should never happen */
			printf("Unknown return value %d\n", rv);
			break;
		}
		/*
		 * now check for illegal arguments
		 */
		if (rv == 1)
			checkargs(numread);
	}

	/*
	 * sweet dreams ...
	 */
	return(0);
}