process.c

unix linux 编程实践源代码

/* process.c
 * command processing layer
 * 
 * The process(char **arglist) function is called by the main loop
 * It sits in front of the execute() function.  This layer handles
 * two main classes of processing:
 * 	a) built-in functions (e.g. exit(), set, =, read, .. )
 * 	b) control structures (e.g. if, while, for)
 */

#include	<stdio.h>
#include	"smsh.h"

int is_control_command(char *);
int do_control_command(char **);
int ok_to_execute();

int process(char **args)
/*
 * purpose: process user command
 * returns: result of processing command
 * details: if a built-in then call appropriate function, if not execute()
 *  errors: arise from subroutines, handled there
 */
{
	int		rv = 0;

	if ( args[0] == NULL )
		rv = 0;
	else if ( is_control_command(args[0]) )
		rv = do_control_command(args);
	else if ( ok_to_execute() )
		rv = execute(args);
	return rv;
}