Problem 2. A certain file foo contains the ASCII text string "This file contains 28 bytes.". That is, the bytes of the file, viewed as 8-bit integers, contain the values 0x54, 0x65, 0x73, 0x74, and 0x20, etc. a. Suppose a program opens foo for reading and writing (file descriptor fd is returned), and then does the following. Assume buf is a 30-byte array of char. if ((rv = read(fd,buf,10)) < 0) { ...handle error... } if ((rv = write(fd, buf,10)) < 0) {... handle error... } Assuming both calls return 10, what does the file contain after this code runs? b. Suppose the same program next calls 1seek (fd, 0, SEEK_SET) to "rewind" the file offset to the beginning, and then does the following: if ((rv = read (fd,buf,30)) < 0) { ...handle error... } strcpy (buf, "That"); if ((rv = write(fd,buf,rv)) < 0) { ... handle error... } What does the file now contain?

Problem 2. A certain file foo contains the ASCII text string "This file contains 28 bytes.". That is, the bytes of the file, viewed as 8-bit integers, contain the values 0x54, 0x65, 0x73, 0x74, and 0x20, etc. a. Suppose a program opens foo for reading and writing (file descriptor fd is returned), and then does the following. Assume buf is a 30-byte array of char. if ((rv = read(fd,buf,10)) < 0) { ...handle error... } if ((rv = write(fd, buf,10)) < 0) {... handle error... } Assuming both calls return 10, what does the file contain after this code runs? b. Suppose the same program next calls 1seek (fd, 0, SEEK_SET) to "rewind" the file offset to the beginning, and then does the following: if ((rv = read (fd,buf,30)) < 0) { ...handle error... } strcpy (buf, "That"); if ((rv = write(fd,buf,rv)) < 0) { ... handle error... } What does the file now contain?

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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No files need to be provided , the file foo is just an example.

Problem 2. A certain file foo contains the ASCII text string "This file contains 28 bytes.".
That is, the bytes of the file, viewed as 8-bit integers, contain the values 0x54, 0x65, 0x73, 0x74,
and 0x20, etc.
a. Suppose a program opens foo for reading and writing (file descriptor fd is returned), and then
does the following. Assume buf is a 30-byte array of char.
if ((rv = read(fd,buf,10)) < 0) { ...handle error... }
if ((rv = write(fd, buf,10)) < 0) {... handle error... }
Assuming both calls return 10, what does the file contain after this code runs?
b. Suppose the same program next calls 1seek (fd, 0, SEEK_SET) to "rewind" the file offset to the
beginning, and then does the following:
if ((rv = read (fd,buf,30)) < 0) { ...handle error... }
strcpy (buf, "That");
if ((rv = write(fd,buf,rv)) < 0) { ... handle error... }
What does the file now contain?

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