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

#if !defined EX_USAGE || !defined EX_SOFTWARE
#	include <sysexits.h>
#endif

/* Done while looking at plan9ports' src/cmd/p.c.
 * Taken from plan9 are the interface (minus p(1)'s shell escaping and the
 * ability to page multiple files) and the practice of reading /dev/tty to get
 * keyboard input without going through stdin. Also, a newline is now printed
 * before querying the keyboard. */

static size_t l = 22; /* plan9 default */

static char *program_name = "p";

static int print_lines(FILE *f, size_t l){
	int c;

	while((c = getc(f)) != EOF)
		if((c = putc(c, stdout)) == EOF || (l -= (c == '\n')) == 0)
			break;

	return c;
}

int main(int argc, char *argv[]){
	unsigned char cmd[99+1];
	char *p;
	FILE *t;

	if(argc == 0)
		argv = &program_name;

	if(argc > 1){
		fprintf(stderr, "Usage: %s\n", argv[0]);
		return EX_USAGE;
	}

	if((t = fopen("/dev/tty", "rb")) == NULL){
		fprintf(stderr, "%s: Could not open /dev/tty\n", argv[0]);
		return EX_SOFTWARE;
	}

	while(print_lines(stdin, l) != EOF){
		fgets(cmd, (sizeof cmd) / (sizeof *cmd), t);
		for(p = cmd; *p != '\0' && strchr(" \t", *p) != NULL; ++p);
		if(feof(t) || (*p | 32) == 'q')
			break;
	}

exit:	fclose(t);
	return 0;
}