#include <stdio.h>
#include <libmawk.h>

/*
	Purpose: manipulate or deny opening specific files and commands
	Run: ./app -f test.awk
*/

/* called any time the script wants to open a new file or command
   (print redirection or getline);
   return:
    - orig_name of OK as is
    - buff after filling in a new file name or command there
    - another string const (won't be freed)
    - NULL to deny opening the file/running the command */

const char *fn_rewrite(const char *orig_name, char *buff, int buff_size, int type)
{
	switch (type) {
		case F_IN:
			/* wants to read - allow any read-only op */
			return orig_name;

		case F_TRUNC:
		case F_APPEND:
			/* wants to write a file - redirect to out.txt */
			return "out.txt";

		case PIPE_OUT:
		case PIPE_IN:
			{
				static const char *wrapper = "echo '%s'"; /* unsafe: %s may contain '. */

				/* run command - rewrite to use echo instead */
				if (sizeof(orig_name) > buff_size - strlen(wrapper) - 2)
					return NULL; /* too long, we can't easily wrap, deny */

				sprintf(buff, wrapper, orig_name);
				return buff;
			}
		default:
			/* ...if the API changes in the future: deny! */
			return NULL;
	}
}

int main(int argc, char **argv)
{
	mawk_state_t *m;

	/* init a context in stages */
	m = libmawk_initialize_stage1();              /* alloc context */
	libmawk_initialize_stdio(m, 1, 1, 1);
	m->file_name_rewrite = fn_rewrite;            /* hook file name for rewriting */
	m = libmawk_initialize_stage2(m, argc, argv); /* set up with no arguments */
	m = libmawk_initialize_stage3(m);             /* execute BEGIN */


	if (m == NULL) {
		fprintf(stderr, "libmawk_initialize failed, exiting\n");
		return 1;
	}

	/* run END and free the context */
	libmawk_uninitialize(m);

	return 0;
}