《CSAPP》（第3版）答案（第十章）

P6

fd=4

P7

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

int main(int argc, char* argv[]) {
  int n;
  char buf[MAXBUF];
  while ((n = Rio_readn(STDIN_FILENO, buf, MAXBUF)) != 0)
    Rio_writen(STDOUT_FILENO, buf, n);
    
  return 0;
}

P8

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

int main(int argc, char* argv[]) {
  struct stat stat;
  char *type, *readok;
  int fd;
  
  if (argc <= 1)
    fd = 0; // stdin
  else
    fd = atoi(argv[1]);
  Fstat(fd, &stat);
  
  if (S_ISREG(stat.st_mode))
    type = "regular";
  else if (S_ISDIR(stat.st_mode))
    type = "dir";
  else
    type = "other";
    
  if ((stat.st_mode & S_IRUSR))
    readok = "yes";
  else
    readok = "no";
    
  printf("type: %s, read: %s\n", type, readok);
  return 0;
}

P9

if (Fork() == 0) {
  Dup2(0, 3);
  Execve("fstatcheck", argv, envp);
}

P10

#include <stdio.h>
#include "csapp.h"
int main(int argc, char* argv[]) {
  int n;
  rio_t rio;
  char buf[MAXLINE];
  
  if (argc == 2) {
    int fd = Open(argv[1], O_RDONLY, 0);
    while ((n = Rio_readn(fd, buf, MAXBUF)) != 0)
      Rio_writen(STDOUT_FILENO, buf, n);
    exit(0);
  }
  
  Rio_readinitb(&rio, STDIN_FILENO);
  
  while ((n = Rio_readlineb(&rio, buf, MAXLINE)) != 0)
    Rio_writen(STDOUT_FILENO, buf, n);
  return 0;
}

第十章 完