Linux C编程——more命令的实现

#include
#include
#include
#define PAGELEN 24
#define LINELEN 512

void do_more(FILE *);
int see_more(FILE *);

int main(int argc, char *argv[])
{
FILE *fp;
if (argc == 1)
do_more(stdin);
else
{
while (--argc)
{
if ((fp = fopen(*++argv, "r")) != NULL)
{
do_more(fp);
fclose(fp);
}
else
exit(1);
}
}
return 0;
}

void do_more(FILE *fp)
{
char line[LINELEN];
int num_of_lines = 0;
int reply;
FILE *fp_tty;
fp_tty = fopen("/dev/tty", "r");
if(fp_tty == NULL)
exit(1);
while (fgets(line, LINELEN, fp))
{
if (num_of_lines == PAGELEN)
{
reply = see_more(fp_tty);
if(reply == 0)
break;
num_of_lines -= reply;
}
if (fputs(line, stdout) == EOF)
exit(1);
num_of_lines++;
}
}

int see_more(FILE *cmd)
{
int c;
printf("\033[7m more \033[m");
while ((c = getc(cmd)) != EOF)
{
if (c == 'q')
return 0;
if (c == ' ')
return PAGELEN;
if (c == '\n')
return 1;
}
return 0;
}