mymore.cpp

调用系统函数

/*
mymore.cpp - my version of more
read and print 24 lines then pause for a few special command
*/

#include<stdio.h>
#include<sys/stat.h>
#include<termios.h>

#define PAGELEN 17
#define LINELEN 512

int do_more(FILE *fp);
int see_more(FILE *cmd);
void set_cr_mode();
void tty_mode(int how);

int seesize;
struct stat infobuf;
struct termios original_mode;

int main(int argc, char *argv[]) {
	FILE *fp;
	if (argc == 1) do_more(stdin);
	else {
		while (--argc) {
			if ((fp = fopen(* ++argv, "r")) != NULL) {
				tty_mode(0);
				set_cr_mode();
				seesize = 0;
				stat(argv[0], &infobuf);//get size of file
				do_more(fp);
				tty_mode(1);
				fclose(fp);
			} else return(1);
		}
	}
	return(0);
}

int do_more(FILE *fp) {
	int i;
	char line[LINELEN];
	int num_of_lines = 0;
	int reply;
	FILE *fp_tty;

	fp_tty = fopen("/dev/tty", "r");
	if (fp_tty == NULL) return(1);

	while (fgets(line, LINELEN, fp)) {
		for (i = 0;i < LINELEN;i ++) {
			if (line[i] == '\0') {
				seesize += i;
				break;
			}
		}
		if (num_of_lines == PAGELEN) {
			reply = see_more(fp_tty);
			if (reply == 0) break;
			num_of_lines -= reply;
		}
		if (fputs(line, stdout) == EOF) return(1);
		num_of_lines ++;
	}
}

int see_more(FILE *cmd) {
	int c;
	printf("\033[7m--More--(%.0f%)\033[m", float(seesize)/float(infobuf.st_size) * 100);
	while ((c = getc(cmd)) != EOF) {
		if (c == 'q') return(0);
		if (c == ' ') return(PAGELEN);
		if (c == '\n') return(1);
	}
	return(0);
}

void set_cr_mode() {
/*put file descriptor into char_by_char mode*/
	struct termios ttystate;
	tcgetattr(0, &ttystate);
	ttystate.c_lflag &= ~ICANON;
	ttystate.c_cc[VMIN] = 1;
	tcsetattr(0, TCSANOW, &ttystate);
}

void tty_mode(int how) {
/*save or set the mode of tty*/
	if (how == 0) tcgetattr(0, &original_mode);
	else tcsetattr(0, TCSANOW, &original_mode);
}