cmpsc 311 test 2 IO

Question 1

fopen() syntax

Answer 1

FILE *fopen(const char *path, const char *mode);

Question 2

IO, pointer

Answer 2

the fopen function opens a file for — and returns a —- to a FILE* structure

Question 3

stream

Answer 3

A FILE* structure is also referred to as a —-

Question 4

r

Answer 4

–: open text file for reading. The stream is positioned at the beginning of the file

Question 5

r+

Answer 5

— Open for reading and writing. The stream is positioned at the beginning of the file

Question 6

w

Answer 6

–: truncate file to zero length or create text file for writing. the stream is positioned at the beginning of the file

Question 7

w+

Answer 7

—: Open for reading and writing. The file is created if it does not exist, otherwise it is truncated

Question 8

a

Answer 8

Open for appending (writing at the end of file). The file is created if it does not exist

Question 9

a+

Answer 9

Open for reading and appending (writing at end of file). the file is created if it does not exist

Question 10

fscanf, fgets

Answer 10

there are two dominant ways to read the file: ——- and ——

Question 11

fscanf, scanf

Answer 11

— reads the data from the file just like —–, just reading and writing

Question 12

fgets

Answer 12

— reads a line of text from the file

Question 13

fprintf, fputs

Answer 13

there are two dominant ways to write the file, —- and —-

Question 14

fprintf, printf

Answer 14

— writes data to the file just like —-, just reading and writing

Question 15

fputs

Answer 15

—- writes a line of text to the file

Question 16

FILE*

Answer 16

—- based IO is buffered

Question 17

fflush

Answer 17

—- attempts to reset/the flush state

Question 18

int fflush(FILE *stream)

Answer 18

fflush syntax

Question 19

buffered, written, pushed, OS/disk

Answer 19

FILE* based writes are —–, so there may be data ——-, but not yet —– to the —/—–

Question 20

fflush()

Answer 20

—– forces a write of all buffered data

Question 21

buffered, current, current

Answer 21

FILE* based reads are —-, so the — data (in the process space) may not be —-

Question 22

fflush()

Answer 22

—– discards buffered data from the underlying file

Question 23

NULL, fflush, all

Answer 23

If the stream argument is —–, ——() flushes —- open output streams

Question 24

fclose()

Answer 24

—– closes the file and releases the memory associated with the FILE* structure

Question 25

storage

Answer 25

fclose() implicitly flushes the data to ------

Question 26

file, integer file handle

Answer 26

the open function opens a ---- for IO and returns an ------ ------ -----

Question 27

int open(const char *path, int flags, mode_tmode);

Answer 27

open() syntax

Question 28

path

Answer 28

open(): --- is a string containing the absolute or relative path to the file to be opened

Question 29

flags

Answer 29

open(): --- indicates the kind of open you are requesting

Question 30

mode

Answer 30

open(): ---- sets a security policy for the file

Question 31

file handle

Answer 31

open() returns a ---- ----

Question 32

O_RDONLY

Answer 32

open() flags: ---- read only

Question 33

O_WRONLY

Answer 33

open() flags: ---- write only

Question 34

O_RDWR

Answer 34

open() flags: ---- read and write

Question 35

O_CREAT

Answer 35

open() options: ---- if the file does not exist it will be created

Question 36

O_EXCL

Answer 36

open() options: --- ensure that this call creates the file, fail otherwise (fail if already exists)

Question 37

O_TRUNC

Answer 37

open() options: --- if the file already exists it will be truncated to length 0

Question 38

bitwise or (|)

Answer 38

You ------ ---- the mode/options you want in open()

Question 39

discretionary access control, user

Answer 39

The UNIX filesystem implements ----- ----- ---- through file permissions set by user. The permissions are set at the discretion of the ---

Question 40

bits, access

Answer 40

Every file in the file system ha has a set of ----- which determine who has ----- to the files.

Question 41

user

Answer 41

------ the owner is typically the creator of the file, and the entity in control of the access control policy

Question 42

group

Answer 42

---- a set of users on the system setup by the admin

Question 43

world

Answer 43

----- the set of everyone on the system

Question 44

root

Answer 44

Not discretionary access control can be overridden by the ---- user

Question 45

READ

Answer 45

3 rights in UNIX filesystem: ----: allows the subject(process) to read the contents of the file

Question 46

WRITE

Answer 46

3 rights in UNIX filesystem: ----: allows the subject (process) to alter the contents of the file

Question 47

EXECUTE

Answer 47

3 rights in UNIX filesystem: ---: allows the subject (process) to execute the contents of the file (eg, shell program, executable, ...)

Question 48

r, w, x, -

Answer 48

UNIX Access policy: Really, this is a bit string encoding an access policy. And a policy is encoded as ---, ----, --- if enabled and --- if not

Question 49

rwxrw---x

Answer 49

encoding syntax example. says user can read, write and execute, group can read and write, and world can execute only

Question 50

S_IRWXU 00700

Answer 50

Specify a file access policy by bit-wise ORing(|): | --------: user (file owner) has read, write and execute

Question 51

S_IRUSR 00400

Answer 51

Specify a file access policy by bit-wise ORing(|): | --------: user has read permission

Question 52

S_IWUSR 00200

Answer 52

Specify a file access policy by bit-wise ORing(|): | --------: user has write permission

Question 53

S_IXUSR 0100

Answer 53

Specify a file access policy by bit-wise ORing(|): | --------: user has execute permission

Question 54

S_IRGRP 00040

Answer 54

Specify a file access policy by bit-wise ORing(|): | --------: group has read permission

Question 55

S_IWGRP 00020

Answer 55

Specify a file access policy by bit-wise ORing(|): | --------: group has write permission

Question 56

S_IXGRP 00010

Answer 56

Specify a file access policy by bit-wise ORing(|): | --------: group has execute permission

Question 57

S_IRWXO 00007

Answer 57

Specify a file access policy by bit-wise ORing(|): | --------: world has read, write, and execute permission

Question 58

S_IROTH 00004

Answer 58

Specify a file access policy by bit-wise ORing(|): | --------: world has read permission

Question 59

S_IWOTH 00002

Answer 59

Specify a file access policy by bit-wise ORing(|): | --------: world has write permission

Question 60

S_IXOTH 00001

Answer 60

Specify a file access policy by bit-wise ORing(|): | --------: world has execute permission

Question 61

S_IRWXG 00070

Answer 61

Specify a file access policy by bit-wise ORing(|): | --------: group has read, write, and execute permission

Question 62

int

Answer 62

Why is an ---- returned by open() file

Question 63

file descriptor

Answer 63

a ----- ----- is an index assigned by the kernel into a table of file information maintained in the OS.

Question 64

unique, process, open

Answer 64

The file descriptor table is ----- to each ----- and contains the details of ---- files

Question 65

calling IO system

Answer 65

File descriptors are used to reference when ----- the ----- ------ calls

Question 66

kernel, process, system call

Answer 66

The ---- accesses the file for the ----- and returns the results in ----- --- response

Question 67

primitive

Answer 67

------ reading and writing mechanisms that only process only blocks of opaque data

Question 68

ssize_twrite(int fd, const void *buf, size_tcount);

Answer 68

primitive write syntax

Question 69

ssize_tread(int fd, void *buf, size_tcount);

Answer 69

primitive read syntax

Question 70

fd, buf, count

Answer 70

primitive read/write syntax: Where --- is the file descriptor, ---- is an array of bytes to write from or read into, and ---- is the number of bytes to read or write

Question 71

number, bytes, result

Answer 71

both read() and write(0 returned the ---- of ------ read and written. Be sure to always check the ----

Question 72

buffer, output

Answer 72

On reads, you are responsible for supplying a ----- that is large enough to put the ----- into

Question 73

close(), -1

Answer 73

----- closes the file and deletes the file's entry in the file descriptor table. Always reset your file handles to ---- to avoid use after close

Question 74

fopen

Answer 74

---- provides you with buffering IO that may or may not turn out to be a faster than what you're doing with open

Question 75

fopen, binary mode

Answer 75

----- does line ending translation if the file is not opened in ----- ---, which can be very helpful if your program is ever ported to a non-UNIX environment`

Question 76

FILE*, fscanf, stdio

Answer 76

A ---- gives you the ability to use ---- and other --- functions that parse out data and support formatted output

Question 77

FILE*, file handle

Answer 77

IMO: use ----- style I/O for ASCII processing, and ---- ------ I/O for binary data processing

Question 78

include, stdio.h, sys/types.h, sys/stat.h, fcnt1.h, unistd.h

Answer 78

each of the styles of I/O requires a different set of ----- files. FILE* requires: -------- file handle I/O requires: - ------ - ------ - ------ - ------