CONTENTS IN DETAIL 1 HISTORY AND STANDARDS 1

Transcription

1 CONTENTS IN DETAIL PREFACE xxxi 1 HISTORY AND STANDARDS A Brief History of UNIX and C A Brief History of Linux The GNU Project The Linux Kernel Standardization The C Programming Language The First POSIX Standards X/Open Company and The Open Group SUSv3 and POSIX SUSv4 and POSIX UNIX Standards Timeline Implementation Standards Linux, Standards, and the Linux Standard Base Summary FUNDAMENTAL CONCEPTS The Core Operating System: The Kernel The Shell Users and Groups Single Directory Hierarchy, Directories, Links, and Files File I/O Model Programs Processes Memory Mappings Static and Shared Libraries Interprocess Communication and Synchronization Signals Threads Process Groups and Shell Job Control Sessions, Controlling Terminals, and Controlling Processes Pseudoterminals Date and Time Client-Server Architecture Realtime The /proc File System Summary SYSTEM PROGRAMMING CONCEPTS System Calls Library Functions The Standard C Library; The GNU C Library (glibc) Handling Errors from System Calls and Library Functions Notes on the Example Programs in This Book Command-Line Options and Arguments Common Functions and Header Files TLPI_FINAL_RRD.pdf 11

2 3.6 Portability Issues Feature Test Macros System Data Types Miscellaneous Portability Issues Summary Exercise FILE I/O: THE UNIVERSAL I/O MODEL Overview Universality of I/O Opening a File: open() The open() flags Argument Errors from open() The creat() System Call Reading from a File: read() Writing to a File: write() Closing a File: close() Changing the File Offset: lseek() Operations Outside the Universal I/O Model: ioctl() Summary Exercises FILE I/O: FURTHER DETAILS Atomicity and Race Conditions File Control Operations: fcntl() Open File Status Flags Relationship Between File Descriptors and Open Files Duplicating File Descriptors File I/O at a Specified Offset: pread() and pwrite() Scatter-Gather I/O: readv() and writev() Truncating a File: truncate() and ftruncate() Nonblocking I/O I/O on Large Files The /dev/fd Directory Creating Temporary Files Summary Exercises PROCESSES Processes and Programs Process ID and Parent Process ID Memory Layout of a Process Virtual Memory Management The Stack and Stack Frames Command-Line Arguments (argc, argv) Environment List Performing a Nonlocal Goto: setjmp() and longjmp() Summary Exercises xii TLPI_FINAL_RRD.pdf 12

3 7 MEMORY ALLOCATION Allocating Memory on the Heap Adjusting the Program Break: brk() and sbrk() Allocating Memory on the Heap: malloc() and free() Implementation of malloc() and free() Other Methods of Allocating Memory on the Heap Allocating Memory on the Stack: alloca() Summary Exercises USERS AND GROUPS The Password File: /etc/passwd The Shadow Password File: /etc/shadow The Group File: /etc/group Retrieving User and Group Information Password Encryption and User Authentication Summary Exercises PROCESS CREDENTIALS Real User ID and Real Group ID Effective User ID and Effective Group ID Set-User-ID and Set-Group-ID Programs Saved Set-User-ID and Saved Set-Group-ID File-System User ID and File-System Group ID Supplementary Group IDs Retrieving and Modifying Process Credentials Retrieving and Modifying Real, Effective, and Saved Set IDs Retrieving and Modifying File-System IDs Retrieving and Modifying Supplementary Group IDs Summary of Calls for Modifying Process Credentials Example: Displaying Process Credentials Summary Exercises TIME Calendar Time Time-Conversion Functions Converting time_t to Printable Form Converting Between time_t and Broken-Down Time Converting Between Broken-Down Time and Printable Form Timezones Locales Updating the System Clock The Software Clock (Jiffies) Process Time Summary Exercise xiii TLPI_FINAL_RRD.pdf 13

4 11 SYSTEM LIMITS AND OPTIONS System Limits Retrieving System Limits (and Options) at Run Time Retrieving File-Related Limits (and Options) at Run Time Indeterminate Limits System Options Summary Exercises SYSTEM AND PROCESS INFORMATION The /proc File System Obtaining Information About a Process: /proc/pid System Information Under /proc Accessing /proc Files System Identification: uname() Summary Exercises FILE I/O BUFFERING Kernel Buffering of File I/O: The Buffer Cache Buffering in the stdio Library Controlling Kernel Buffering of File I/O Summary of I/O Buffering Advising the Kernel About I/O Patterns Bypassing the Buffer Cache: Direct I/O Mixing Library Functions and System Calls for File I/O Summary Exercises FILE SYSTEMS Device Special Files (Devices) Disks and Partitions File Systems I-nodes The Virtual File System (VFS) Journaling File Systems Single Directory Hierarchy and Mount Points Mounting and Unmounting File Systems Mounting a File System: mount() Unmounting a File System: umount() and umount2() Advanced Mount Features Mounting a File System at Multiple Mount Points Stacking Multiple Mounts on the Same Mount Point Mount Flags That Are Per-Mount Options Bind Mounts Recursive Bind Mounts A Virtual Memory File System: tmpfs Obtaining Information About a File System: statvfs() Summary Exercise xiv TLPI_FINAL_RRD.pdf 14

5 15 FILE ATTRIBUTES Retrieving File Information: stat() File Timestamps Changing File Timestamps with utime() and utimes() Changing File Timestamps with utimensat() and futimens() File Ownership Ownership of New Files Changing File Ownership: chown(), fchown(), and lchown() File Permissions Permissions on Regular Files Permissions on Directories Permission-Checking Algorithm Checking File Accessibility: access() Set-User-ID, Set-Group-ID, and Sticky Bits The Process File Mode Creation Mask: umask() Changing File Permissions: chmod() and fchmod() I-node Flags (ext2 Extended File Attributes) Summary Exercises EXTENDED ATTRIBUTES Overview Extended Attribute Implementation Details System Calls for Manipulating Extended Attributes Summary Exercise ACCESS CONTROL LISTS Overview ACL Permission-Checking Algorithm Long and Short Text Forms for ACLs The ACL_MASK Entry and the ACL Group Class The getfacl and setfacl Commands Default ACLs and File Creation ACL Implementation Limits The ACL API Summary Exercise DIRECTORIES AND LINKS Directories and (Hard) Links Symbolic (Soft) Links Creating and Removing (Hard) Links: link() and unlink() Changing the Name of a File: rename() Working with Symbolic Links: symlink() and readlink() Creating and Removing Directories: mkdir() and rmdir() Removing a File or Directory: remove() Reading Directories: opendir() and readdir() File Tree Walking: nftw() The Current Working Directory of a Process Operating Relative to a Directory File Descriptor Changing the Root Directory of a Process: chroot() Resolving a Pathname: realpath() xv TLPI_FINAL_RRD.pdf 15

6 18.14 Parsing Pathname Strings: dirname() and basename() Summary Exercises MONITORING FILE EVENTS Overview The inotify API inotify Events Reading inotify Events Queue Limits and /proc Files An Older System for Monitoring File Events: dnotify Summary Exercise SIGNALS: FUNDAMENTAL CONCEPTS Concepts and Overview Signal Types and Default Actions Changing Signal Dispositions: signal() Introduction to Signal Handlers Sending Signals: kill() Checking for the Existence of a Process Other Ways of Sending Signals: raise() and killpg() Displaying Signal Descriptions Signal Sets The Signal Mask (Blocking Signal Delivery) Pending Signals Signals Are Not Queued Changing Signal Dispositions: sigaction() Waiting for a Signal: pause() Summary Exercises SIGNALS: SIGNAL HANDLERS Designing Signal Handlers Signals Are Not Queued (Revisited) Reentrant and Async-Signal-Safe Functions Global Variables and the sig_atomic_t Data Type Other Methods of Terminating a Signal Handler Performing a Nonlocal Goto from a Signal Handler Terminating a Process Abnormally: abort() Handling a Signal on an Alternate Stack: sigaltstack() The SA_SIGINFO Flag Interruption and Restarting of System Calls Summary Exercise SIGNALS: ADVANCED FEATURES Core Dump Files Special Cases for Delivery, Disposition, and Handling Interruptible and Uninterruptible Process Sleep States Hardware-Generated Signals Synchronous and Asynchronous Signal Generation xvi TLPI_FINAL_RRD.pdf 16

7 22.6 Timing and Order of Signal Delivery Implementation and Portability of signal() Realtime Signals Sending Realtime Signals Handling Realtime Signals Waiting for a Signal Using a Mask: sigsuspend() Synchronously Waiting for a Signal Fetching Signals via a File Descriptor Interprocess Communication with Signals Earlier Signal APIs (System V and BSD) Summary Exercises TIMERS AND SLEEPING Interval Timers Scheduling and Accuracy of Timers Setting Timeouts on Blocking Operations Suspending Execution for a Fixed Interval (Sleeping) Low-Resolution Sleeping: sleep() High-Resolution Sleeping: nanosleep() POSIX Clocks Retrieving the Value of a Clock: clock_gettime() Setting the Value of a Clock: clock_settime() Obtaining the Clock ID of a Specific Process or Thread Improved High-Resolution Sleeping: clock_nanosleep() POSIX Interval Timers Creating a Timer: timer_create() Arming and Disarming a Timer: timer_settime() Retrieving the Current Value of a Timer: timer_gettime() Deleting a Timer: timer_delete() Notification via a Signal Timer Overruns Notification via a Thread Timers That Notify via File Descriptors: the timerfd API Summary Exercises PROCESS CREATION Overview of fork(), exit(), wait(), and execve() Creating a New Process: fork() File Sharing Between Parent and Child Memory Semantics of fork() The vfork() System Call Race Conditions After fork() Avoiding Race Conditions by Synchronizing with Signals Summary Exercises PROCESS TERMINATION Terminating a Process: _exit() and exit() Details of Process Termination Exit Handlers Interactions Between fork(), stdio Buffers, and _exit() xvii TLPI_FINAL_RRD.pdf 17

8 25.5 Summary Exercise MONITORING CHILD PROCESSES Waiting on a Child Process The wait() System Call The waitpid() System Call The Wait Status Value Process Termination from a Signal Handler The waitid() System Call The wait3() and wait4() System Calls Orphans and Zombies The SIGCHLD Signal Establishing a Handler for SIGCHLD Delivery of SIGCHLD for Stopped Children Ignoring Dead Child Processes Summary Exercises PROGRAM EXECUTION Executing a New Program: execve() The exec() Library Functions The PATH Environment Variable Specifying Program Arguments as a List Passing the Caller s Environment to the New Program Executing a File Referred to by a Descriptor: fexecve() Interpreter Scripts File Descriptors and exec() Signals and exec() Executing a Shell Command: system() Implementing system() Summary Exercises PROCESS CREATION AND PROGRAM EXECUTION IN MORE DETAIL Process Accounting The clone() System Call The clone() flags Argument Extensions to waitpid() for Cloned Children Speed of Process Creation Effect of exec() and fork() on Process Attributes Summary Exercise THREADS: INTRODUCTION Overview Background Details of the Pthreads API Thread Creation Thread Termination Thread IDs Joining with a Terminated Thread Detaching a Thread xviii TLPI_FINAL_RRD.pdf 18

9 29.8 Thread Attributes Threads Versus Processes Summary Exercises THREADS: THREAD SYNCHRONIZATION Protecting Accesses to Shared Variables: Mutexes Statically Allocated Mutexes Locking and Unlocking a Mutex Performance of Mutexes Mutex Deadlocks Dynamically Initializing a Mutex Mutex Attributes Mutex Types Signaling Changes of State: Condition Variables Statically Allocated Condition Variables Signaling and Waiting on Condition Variables Testing a Condition Variable s Predicate Example Program: Joining Any Terminated Thread Dynamically Allocated Condition Variables Summary Exercises THREADS: THREAD SAFETY AND PER-THREAD STORAGE Thread Safety (and Reentrancy Revisited) One-Time Initialization Thread-Specific Data Thread-Specific Data from the Library Function s Perspective Overview of the Thread-Specific Data API Details of the Thread-Specific Data API Employing the Thread-Specific Data API Thread-Specific Data Implementation Limits Thread-Local Storage Summary Exercises THREADS: THREAD CANCELLATION Canceling a Thread Cancellation State and Type Cancellation Points Testing for Thread Cancellation Cleanup Handlers Asynchronous Cancelability Summary THREADS: FURTHER DETAILS Thread Stacks Threads and Signals How the UNIX Signal Model Maps to Threads Manipulating the Thread Signal Mask Sending a Signal to a Thread Dealing with Asynchronous Signals Sanely xix TLPI_FINAL_RRD.pdf 19

10 33.3 Threads and Process Control Thread Implementation Models Linux Implementations of POSIX Threads LinuxThreads NPTL Which Threading Implementation? Advanced Features of the Pthreads API Summary Exercises PROCESS GROUPS, SESSIONS, AND JOB CONTROL Overview Process Groups Sessions Controlling Terminals and Controlling Processes Foreground and Background Process Groups The SIGHUP Signal Handling of SIGHUP by the Shell SIGHUP and Termination of the Controlling Process Job Control Using Job Control Within the Shell Implementing Job Control Handling Job-Control Signals Orphaned Process Groups (and SIGHUP Revisited) Summary Exercises PROCESS PRIORITIES AND SCHEDULING Process Priorities (Nice Values) Overview of Realtime Process Scheduling The SCHED_RR Policy The SCHED_FIFO Policy The SCHED_BATCH and SCHED_IDLE Policies Realtime Process Scheduling API Realtime Priority Ranges Modifying and Retrieving Policies and Priorities Relinquishing the CPU The SCHED_RR Time Slice CPU Affinity Summary Exercises PROCESS RESOURCES Process Resource Usage Process Resource Limits Details of Specific Resource Limits Summary Exercises DAEMONS Overview Creating a Daemon xx TLPI_FINAL_RRD.pdf 20

11 37.3 Guidelines for Writing Daemons Using SIGHUP to Reinitialize a Daemon Logging Messages and Errors Using syslog Overview The syslog API The /etc/syslog.conf File Summary Exercise WRITING SECURE PRIVILEGED PROGRAMS Is a Set-User-ID or Set-Group-ID Program Required? Operate with Least Privilege Be Careful When Executing a Program Avoid Exposing Sensitive Information Confine the Process Beware of Signals and Race Conditions Pitfalls When Performing File Operations and File I/O Don t Trust Inputs or the Environment Beware of Buffer Overruns Beware of Denial-of-Service Attacks Check Return Statuses and Fail Safely Summary Exercises CAPABILITIES Rationale for Capabilities The Linux Capabilities Process and File Capabilities Process Capabilities File Capabilities Purpose of the Process Permitted and Effective Capability Sets Purpose of the File Permitted and Effective Capability Sets Purpose of the Process and File Inheritable Sets Assigning and Viewing File Capabilities from the Shell The Modern Capabilities Implementation Transformation of Process Capabilities During exec() Capability Bounding Set Preserving root Semantics Effect on Process Capabilities of Changing User IDs Changing Process Capabilities Programmatically Creating Capabilities-Only Environments Discovering the Capabilities Required by a Program Older Kernels and Systems Without File Capabilities Summary Exercise LOGIN ACCOUNTING Overview of the utmp and wtmp Files The utmpx API The utmpx Structure Retrieving Information from the utmp and wtmp Files Retrieving the Login Name: getlogin() Updating the utmp and wtmp Files for a Login Session xxi TLPI_FINAL_RRD.pdf 21

12 40.7 The lastlog File Summary Exercises FUNDAMENTALS OF SHARED LIBRARIES Object Libraries Static Libraries Overview of Shared Libraries Creating and Using Shared Libraries A First Pass Creating a Shared Library Position-Independent Code Using a Shared Library The Shared Library Soname Useful Tools for Working with Shared Libraries Shared Library Versions and Naming Conventions Installing Shared Libraries Compatible Versus Incompatible Libraries Upgrading Shared Libraries Specifying Library Search Directories in an Object File Finding Shared Libraries at Run Time Run-Time Symbol Resolution Using a Static Library Instead of a Shared Library Summary Exercise ADVANCED FEATURES OF SHARED LIBRARIES Dynamically Loaded Libraries Opening a Shared Library: dlopen() Diagnosing Errors: dlerror() Obtaining the Address of a Symbol: dlsym() Closing a Shared Library: dlclose() Obtaining Information About Loaded Symbols: dladdr() Accessing Symbols in the Main Program Controlling Symbol Visibility Linker Version Scripts Controlling Symbol Visibility with Version Scripts Symbol Versioning Initialization and Finalization Functions Preloading Shared Libraries Monitoring the Dynamic Linker: LD_DEBUG Summary Exercises INTERPROCESS COMMUNICATION OVERVIEW A Taxonomy of IPC Facilities Communication Facilities Synchronization Facilities Comparing IPC Facilities Summary Exercises xxii TLPI_FINAL_RRD.pdf 22

13 44 PIPES AND FIFOS Overview Creating and Using Pipes Pipes as a Method of Process Synchronization Using Pipes to Connect Filters Talking to a Shell Command via a Pipe: popen() Pipes and stdio Buffering FIFOs A Client-Server Application Using FIFOs Nonblocking I/O Semantics of read() and write() on Pipes and FIFOs Summary Exercises INTRODUCTION TO SYSTEM V IPC API Overview IPC Keys Associated Data Structure and Object Permissions IPC Identifiers and Client-Server Applications Algorithm Employed by System V IPC get Calls The ipcs and ipcrm Commands Obtaining a List of All IPC Objects IPC Limits Summary Exercises SYSTEM V MESSAGE QUEUES Creating or Opening a Message Queue Exchanging Messages Sending Messages Receiving Messages Message Queue Control Operations Message Queue Associated Data Structure Message Queue Limits Displaying All Message Queues on the System Client-Server Programming with Message Queues A File-Server Application Using Message Queues Disadvantages of System V Message Queues Summary Exercises SYSTEM V SEMAPHORES Overview Creating or Opening a Semaphore Set Semaphore Control Operations Semaphore Associated Data Structure Semaphore Initialization Semaphore Operations Handling of Multiple Blocked Semaphore Operations Semaphore Undo Values Implementing a Binary Semaphores Protocol xxiii TLPI_FINAL_RRD.pdf 23

14 47.10 Semaphore Limits Disadvantages of System V Semaphores Summary Exercises SYSTEM V SHARED MEMORY Overview Creating or Opening a Shared Memory Segment Using Shared Memory Example: Transferring Data via Shared Memory Location of Shared Memory in Virtual Memory Storing Pointers in Shared Memory Shared Memory Control Operations Shared Memory Associated Data Structure Shared Memory Limits Summary Exercises MEMORY MAPPINGS Overview Creating a Mapping: mmap() Unmapping a Mapped Region: munmap() File Mappings Private File Mappings Shared File Mappings Boundary Cases Memory Protection and File Access Mode Interactions Synchronizing a Mapped Region: msync() Additional mmap() Flags Anonymous Mappings Remapping a Mapped Region: mremap() MAP_NORESERVE and Swap Space Overcommitting The MAP_FIXED Flag Nonlinear Mappings: remap_file_pages() Summary Exercises VIRTUAL MEMORY OPERATIONS Changing Memory Protection: mprotect() Memory Locking: mlock() and mlockall() Determining Memory Residence: mincore() Advising Future Memory Usage Patterns: madvise() Summary Exercises INTRODUCTION TO POSIX IPC API Overview Comparison of System V IPC and POSIX IPC Summary xxiv TLPI_FINAL_RRD.pdf 24

15 52 POSIX MESSAGE QUEUES Overview Opening, Closing, and Unlinking a Message Queue Relationship Between Descriptors and Message Queues Message Queue Attributes Exchanging Messages Sending Messages Receiving Messages Sending and Receiving Messages with a Timeout Message Notification Receiving Notification via a Signal Receiving Notification via a Thread Linux-Specific Features Message Queue Limits Comparison of POSIX and System V Message Queues Summary Exercises POSIX SEMAPHORES Overview Named Semaphores Opening a Named Semaphore Closing a Semaphore Removing a Named Semaphore Semaphore Operations Waiting on a Semaphore Posting a Semaphore Retrieving the Current Value of a Semaphore Unnamed Semaphores Initializing an Unnamed Semaphore Destroying an Unnamed Semaphore Comparisons with Other Synchronization Techniques Semaphore Limits Summary Exercises POSIX SHARED MEMORY Overview Creating Shared Memory Objects Using Shared Memory Objects Removing Shared Memory Objects Comparisons Between Shared Memory APIs Summary Exercise FILE LOCKING Overview File Locking with flock() Semantics of Lock Inheritance and Release Limitations of flock() xxv TLPI_FINAL_RRD.pdf 25 8/5/ :46:57 AM

16 55.3 Record Locking with fcntl() Deadlock Example: An Interactive Locking Program Example: A Library of Locking Functions Lock Limits and Performance Semantics of Lock Inheritance and Release Lock Starvation and Priority of Queued Lock Requests Mandatory Locking The /proc/locks File Running Just One Instance of a Program Older Locking Techniques Summary Exercises SOCKETS: INTRODUCTION Overview Creating a Socket: socket() Binding a Socket to an Address: bind() Generic Socket Address Structures: struct sockaddr Stream Sockets Listening for Incoming Connections: listen() Accepting a Connection: accept() Connecting to a Peer Socket: connect() I/O on Stream Sockets Connection Termination: close() Datagram Sockets Exchanging Datagrams: recvfrom() and sendto() Using connect() with Datagram Sockets Summary SOCKETS: UNIX DOMAIN UNIX Domain Socket Addresses: struct sockaddr_un Stream Sockets in the UNIX Domain Datagram Sockets in the UNIX Domain UNIX Domain Socket Permissions Creating a Connected Socket Pair: socketpair() The Linux Abstract Socket Namespace Summary Exercises SOCKETS: FUNDAMENTALS OF TCP/IP NETWORKS Internets Networking Protocols and Layers The Data-Link Layer The Network Layer: IP IP Addresses The Transport Layer Port Numbers User Datagram Protocol (UDP) Transmission Control Protocol (TCP) Requests for Comments (RFCs) Summary xxvi TLPI_FINAL_RRD.pdf 26 8/5/ :46:57 AM

17 59 SOCKETS: INTERNET DOMAINS Internet Domain Sockets Network Byte Order Data Representation Internet Socket Addresses Overview of Host and Service Conversion Functions The inet_pton() and inet_ntop() Functions Client-Server Example (Datagram Sockets) Domain Name System (DNS) The /etc/services File Protocol-Independent Host and Service Conversion The getaddrinfo() Function Freeing addrinfo Lists: freeaddrinfo() Diagnosing Errors: gai_strerror() The getnameinfo() Function Client-Server Example (Stream Sockets) An Internet Domain Sockets Library Obsolete APIs for Host and Service Conversions The inet_aton() and inet_ntoa() Functions The gethostbyname() and gethostbyaddr() Functions The getservbyname() and getservbyport() Functions UNIX Versus Internet Domain Sockets Further Information Summary Exercises SOCKETS: SERVER DESIGN Iterative and Concurrent Servers An Iterative UDP echo Server A Concurrent TCP echo Server Other Concurrent Server Designs The inetd (Internet Superserver) Daemon Summary Exercises SOCKETS: ADVANCED TOPICS Partial Reads and Writes on Stream Sockets The shutdown() System Call Socket-Specific I/O System Calls: recv() and send() The sendfile() System Call Retrieving Socket Addresses A Closer Look at TCP Format of a TCP Segment TCP Sequence Numbers and Acknowledgements TCP State Machine and State Transition Diagram TCP Connection Establishment TCP Connection Termination Calling shutdown() on a TCP Socket The TIME_WAIT State Monitoring Sockets: netstat Using tcpdump to Monitor TCP Traffic Socket Options The SO_REUSEADDR Socket Option Inheritance of Flags and Options Across accept() xxvii TLPI_FINAL_RRD.pdf 27 8/5/ :46:57 AM

18 61.12 TCP Versus UDP Advanced Features Out-of-Band Data The sendmsg() and recvmsg() System Calls Passing File Descriptors Receiving Sender Credentials Sequenced-Packet Sockets SCTP and DCCP Transport-Layer Protocols Summary Exercises TERMINALS Overview Retrieving and Modifying Terminal Attributes The stty Command Terminal Special Characters Terminal Flags Terminal I/O Modes Canonical Mode Noncanonical Mode Cooked, Cbreak, and Raw Modes Terminal Line Speed (Bit Rate) Terminal Line Control Terminal Window Size Terminal Identification Summary Exercises ALTERNATIVE I/O MODELS Overview Level-Triggered and Edge-Triggered Notification Employing Nonblocking I/O with Alternative I/O Models I/O Multiplexing The select() System Call The poll() System Call When Is a File Descriptor Ready? Comparison of select() and poll() Problems with select() and poll() Signal-Driven I/O When Is I/O Possible Signaled? Refining the Use of Signal-Driven I/O The epoll API Creating an epoll Instance: epoll_create() Modifying the epoll Interest List: epoll_ctl() Waiting for Events: epoll_wait() A Closer Look at epoll Semantics Performance of epoll Versus I/O Multiplexing Edge-Triggered Notification Waiting on Signals and File Descriptors The pselect() System Call The Self-Pipe Trick Summary Exercises xxviii TLPI_FINAL_RRD.pdf 28 8/5/ :46:57 AM

19 64 PSEUDOTERMINALS Overview UNIX 98 Pseudoterminals Opening an Unused Master: posix_openpt() Changing Slave Ownership and Permissions: grantpt() Unlocking the Slave: unlockpt() Obtaining the Name of the Slave: ptsname() Opening a Master: ptymasteropen() Connecting Processes with a Pseudoterminal: ptyfork() Pseudoterminal I/O Implementing script(1) Terminal Attributes and Window Size BSD Pseudoterminals Summary Exercises A TRACING SYSTEM CALLS 1401 B PARSING COMMAND-LINE OPTIONS 1405 C CASTING THE NULL POINTER 1413 D KERNEL CONFIGURATION 1417 E FURTHER SOURCES OF INFORMATION 1419 F SOLUTIONS TO SELECTED EXERCISES 1425 BIBLIOGRAPHY 1437 INDEX 1447 xxix TLPI_FINAL_RRD.pdf 29 8/5/ :46:57 AM