通过fstat函数判断描述符类型

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fstat函数用于返回关于文件的信息到一个struct stat结构中，stat结构中的st_mode可以用来区分文件类型。

struct stat {               dev_t     st_dev;     /* ID of device containing file */               ino_t     st_ino;     /* inode number */               mode_t    st_mode;    /* protection */               nlink_t   st_nlink;   /* number of hard links */               uid_t     st_uid;     /* user ID of owner */               gid_t     st_gid;     /* group ID of owner */               dev_t     st_rdev;    /* device ID (if special file) */               off_t     st_size;    /* total size, in bytes */               blksize_t st_blksize; /* blocksize for file system I/O */               blkcnt_t  st_blocks;  /* number of 512B blocks allocated */               time_t    st_atime;   /* time of last access */               time_t    st_mtime;   /* time of last modification */               time_t    st_ctime;   /* time of last status change */           };

一些用来判断st_mode的宏

S_ISREG(m)  is it a regular file?S_ISDIR(m)  directory?S_ISCHR(m)  character device?S_ISBLK(m)  block device?S_ISFIFO(m) FIFO (named pipe)?S_ISLNK(m)  symbolic link? (Not in POSIX.1-1996.)S_ISSOCK(m) socket? (Not in POSIX.1-1996.)

示例:

#include <stdio.h>#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <sys/socket.h>#include <fcntl.h>#include <stdlib.h>main(){struct stat st;int sockfd, fd;sockfd = socket(AF_INET, SOCK_STREAM, 0);if (sockfd == -1){perror("socket error");exit(-1);}fd = open("/home/liyuchen/dev/net.h", O_RDWR);if (fd == -1){perror("open error");exit(-1);}fstat(sockfd, &st);if (S_ISREG(st.st_mode))printf("文件描述符\n");if (S_ISSOCK(st.st_mode))printf("套接字描述符\n");fstat(fd, &st);if (S_ISREG(st.st_mode))printf("文件描述符\n");if (S_ISSOCK(st.st_mode))printf("套接字描述符\n");}

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