Cirrus Logic CS485 Manual de usuario descargar pdf (Pagina 53)

CS485G Spring 2015 53

(a) Read: reached the end of ﬁle, or the end of a line with fgets().

(b) Network sockets or pipes: read or write can give a short count.

(d) The Rio (robust I/O) package from csapp.c handles short counts

and retries.

3. File metadata: data about the ﬁle, but not the contents.

(a) Maintained by the kernel in its data structures.

(b) A program can get some of it with stat() or fstat():

1 struct stat {

2 dev_t st_dev;

ID of device containing file

3 ino_t st_ino;

inode number

4 mode_t st_mode;

protection and file type

5 nlink_t st_nlink;

number of hard links

6 uid_t st_uid;

user ID of owner

7 gid_t st_gid;

group ID of owner

8 dev_t st_rdev;

device ID (if special file)

9 off_t st_size;

total size, in bytes

10 blksize_t st_blksize; /

blocksize for filesystem I/O

11 blkcnt_t st_blocks;

number of 512B blocks allocated

12 time_t st_atime;

time of last access

13 time_t st_mtime;

time of last modification

14 time_t st_ctime;

time of last status change

15 };

4. Directories used to be just ﬁles with a special format, but now one

reads them with different system calls: opendir(), readdir(),

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Cirrus Logic CS485 Manual de usuario Pagina 53