Suppose the following groups are defined to shorten a system’s access control lists: – Group1: Alice, Bob, Cynthia, David, Eve – Group2: Alice, Bob, Cynthia – Group3: Bob, Cynthia Suppose the access control list for File 1 is: – File 1: Group 1, R; Group 2, READ,WRITE If Alice wants to write to File 1 giving your reasoning state whether Alice will be allowed to do so if: 2.1.1 The first relevant entry policy is applied 2.1.2 The any permission in list policy is applied

Suppose the following groups are defined to shorten a system’s access control lists: – Group1: Alice, Bob, Cynthia, David, Eve – Group2: Alice, Bob, Cynthia – Group3: Bob, Cynthia Suppose the access control list for File 1 is: – File 1: Group 1, R; Group 2, READ,WRITE If Alice wants to write to File 1 giving your reasoning state whether Alice will be allowed to do so if: 2.1.1 The first relevant entry policy is applied 2.1.2 The any permission in list policy is applied

Database Systems: Design, Implementation, & Management

12th Edition

ISBN:9781305627482

Author:Carlos Coronel, Steven Morris

Publisher:Carlos Coronel, Steven Morris

Chapter1: Database Systems

Section: Chapter Questions

Problem 10P

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Consider a computer system with three users: Alice, Bob, and Cyndy. Alice owns the file alicerc, and Bob and Cyndy can read it. Cyndy can read and write the file bobrc, which Bob owns, but Alice can only read it. Only Cyndy can read and write the file cyndyrc, which she owns. Assume that the owner of each of these files can execute it. Create the corresponding access control matrix. Cyndy gives Alice permission to read cyndyrc, and Alice removes Bob's ability to read alicerc. Show the new access control matrix
Suppose the ACL for file X is { (Alice, rx), (Bob, rw), (C, w) } where C is a groupincluding Alice and Bob. When A and B attempt to write to X, describe what the accessdecisions for A and B will be for each of the three resolving right conflicts approaches. Howwill the access decisions be if the ACL is re-organized to { (C, w), (Alice, rx), (Bob, rw) }
Consider a computer system with three users: Alice, Bob, and Cindy. Alice owns file X, and Bob and Cindy can read it. Bob owns file Y, and Cindy can read and write the file Y, but Alice can only read it. Cindy owns file Z, but neither Alice nor Bob can read or write it. If a user owns a file, he/she can also execute the file. Create the ACM (access control matrix) of the system Show the ACL and CL of the ACM Now Cindy allows Alice to read Z, Alice removes Bob's ability to read X, and Bob removes all the rights of Alice and Cindy to Y. Show the ACM after these changes.
Consider the following case: Alice, Bob, and Eve are all users on a system using the Unix File Access Control system. Alice wants to create a file (that she will own) that she and Eve can both read and edit, but Bob can't. Assign user IDs to all users and create any groups that are necessary, then use this information to specify the file's access control settings.
Suppose a file system is based on the indexed allocation strategy for managingblocks. Assume each file has a directory entry giving the file name, first index block,and the length of the file. The first index block points in turn to 128 file blocks andto the next index block. Suppose that each file block contains 4KB of data and theuser is currently reading the 441K-th byte of a file. If the user’s next operation is toread the 1201k-th byte of the same file, how many physical disk I/O operations mustbe performed in order to read that byte? Explain your answer in detail usingdiagrams as appropriate.
Suppose there are three processes, P1, P2, and P3, and three files, FileA, FileB, and FileC. P1 has FileA and wants FileC. P2 has FileB and wants FileA. P3 has FileC and wants FileB. a) Draw a resource allocation graph for this situation. b) Does the graph represent a deadlock? Why or why not? Explain.
Consider a file system on a disk that has both logical and physical block sizes of 512 bytes. Assume that the information about each file is already in memory. For each of the three allocation strategies (contiguous, linked, and indexed), answer the following question: If we are currently at logical block 10 (the last block accessed was block 10) and want to access logical block 4, how many physical blocks must be read from the disk?
Consider a file system that uses indexed file allocation. Disk block size is 1K-byte, and a file pointer is 64 bits (8-bytes). If we assume that an i-node just holds 2 direct entries and 4 single indirect entries, what is the maximum size of a file the system can allow? List the steps that lead to your conclusion.
UNIX treats file directories in the same fashion as files; that is, both are defined by the same type of data structure, called an inode. As with files, directories include a nine-bit protection strong. If care is not taken, this can create access control problems. For example, consider a file with protection mode 644(octal) contained in a directory with protection mode 730. How might the file be compromised in this case? What can we do to stop this vulnerability without changing the protection mode 730 for the directory?
Please refer to this textbook: “A. Silberschatz, P. B. Galvin and G. Gagne, “Operating System Principles,”7th Edition, John Wiley & Sons Inc., 2006.” And answer the following questions: Question:The Ricart& Argwala mutual exclusion algorithm: (a) Does not depend on time stamps in messages while Lamport's does. (b) Cannot handle the case where two or more processes request the same resource at the same time. (c) Does not require a process to send messages to the entire group while Lamport's does. (d) Requires fewer messages than Lamport's algorithm.
Write a C program that implements the parent producer and child consumer algorithms. The parent process must copy an entire source file ("input.txt") to a destination file. In addition, the parent process must produce the file contents into shared memory as read from a source file (SRC_FILE) in chunks using the read() system call. The chunk size (CHUNK_SIZE) is the same for both read() and write(). It will be accepted as input by your program as a command-line argument.
Consider a file system that uses indexed allocation with a maximum of one index node per file. Suppose the index node occupies 4096 bytes, that each block pointer occupies 4 bytes. Ignore the metadata associated with the file that is usually contained in the index node. How large should a block be (in bytes) so that this scheme is able to completely access files on a 1 GB file system?

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