The GNU C Library

Introduction Getting Started Standards and Portability ANSI C POSIX (The Portable Operating System Interface) Berkeley Unix SVID (The System V Interface Description) Using the Library Header Files Macro Definitions of Functions Reserved Names Feature Test Macros Roadmap to the Manual Error Reporting Checking for Errors Error Codes Error Messages Memory Allocation Dynamic Memory Allocation Concepts Dynamic Allocation and C Unconstrained Allocation Basic Storage Allocation Examples of malloc Freeing Memory Allocated with malloc Changing the Size of a Block Allocating Cleared Space Efficiency Considerations for malloc Allocating Aligned Memory Blocks Heap Consistency Checking Storage Allocation Hooks Statistics for Storage Allocation with malloc Summary of malloc-Related Functions Obstacks Creating Obstacks Preparing for Using Obstacks Allocation in an Obstack Freeing Objects in an Obstack Obstack Functions and Macros Growing Objects Extra Fast Growing Objects Status of an Obstack Alignment of Data in Obstacks Obstack Chunks Summary of Obstack Functions Automatic Storage with Variable Size alloca Example Advantages of alloca Disadvantages of alloca GNU C Variable-Size Arrays Relocating Allocator Concepts of Relocating Allocation Allocating and Freeing Relocatable Blocks Memory Usage Warnings Character Handling Classification of Characters Case Conversion String and Array Utilities Representation of Strings String/Array Conventions String Length Copying and Concatenation String/Array Comparison Collation Functions Search Functions Finding Tokens in a String Extended Characters Introduction to Extended Characters Locales and Extended Characters Multibyte Characters Wide Character Introduction Conversion of Extended Strings Multibyte Character Length Conversion of Extended Characters One by One Example of Character-by-Character Conversion Multibyte Codes Using Shift Sequences Locales and Internationalization What Effects a Locale Has Choosing a Locale Categories of Activities that Locales Affect How Programs Set the Locale Standard Locales Numeric Formatting Generic Numeric Formatting Parameters Printing the Currency Symbol Printing the Sign of an Amount of Money Searching and Sorting Defining the Comparison Function Array Search Function Array Sort Function Searching and Sorting Example Pattern Matching Wildcard Matching Globbing Calling glob Flags for Globbing Regular Expression Matching POSIX Regular Expression Compilation Flags for POSIX Regular Expressions Matching a Compiled POSIX Regular Expression Subexpressions Match Results Complications in Subexpression Matching POSIX Regexp Matching Cleanup Shell-Style Word Expansion The Stages of Word Expansion Calling wordexp Flags for Word Expansion wordexp Example Input/Output Overview Input/Output Concepts Streams and File Descriptors File Position File Names Directories File Name Resolution File Name Errors Portability of File Names Input/Output on Streams Streams Standard Streams Opening Streams Closing Streams Simple Output by Characters or Lines Character Input Line-Oriented Input Unreading What Unreading Means Using ungetc To Do Unreading Formatted Output Formatted Output Basics Output Conversion Syntax Table of Output Conversions Integer Conversions Floating-Point Conversions Other Output Conversions Formatted Output Functions Dynamically Allocating Formatted Output Variable Arguments Output Functions Parsing a Template String Example of Parsing a Template String Customizing printf Registering New Conversions Conversion Specifier Options Defining the Output Handler printf Extension Example Formatted Input Formatted Input Basics Input Conversion Syntax Table of Input Conversions Numeric Input Conversions String Input Conversions Dynamically Allocating String Conversions Other Input Conversions Formatted Input Functions Variable Arguments Input Functions Block Input/Output End-Of-File and Errors Text and Binary Streams File Positioning Portable File-Position Functions Stream Buffering Buffering Concepts Flushing Buffers Controlling Which Kind of Buffering Temporary Files Other Kinds of Streams String Streams Obstack Streams Programming Your Own Custom Streams Custom Streams and Cookies Custom Stream Hook Functions Low-Level Input/Output Opening and Closing Files Input and Output Primitives Setting the File Position of a Descriptor Descriptors and Streams Precautions for Mixing Streams and Descriptors Linked Channels Independent Channels Cleaning Streams Waiting for Input or Output Control Operations on Files Duplicating Descriptors File Descriptor Flags File Status Flags File Locks Interrupt-Driven Input File System Interface Working Directory Accessing Directories Format of a Directory Entry Opening a Directory Stream Reading and Closing a Directory Stream Simple Program to List a Directory Random Access in a Directory Stream Hard Links Symbolic Links Deleting Files Renaming Files Creating Directories File Attributes What the File Attribute Values Mean Reading the Attributes of a File Testing the Type of a File File Owner The Mode Bits for Access Permission How Your Access to a File is Decided Assigning File Permissions Testing Permission to Access a File File Times Making Special Files Pipes and FIFOs Creating a Pipe Pipe to a Subprocess FIFO Special Files Atomicity of Pipe I/O Sockets Socket Concepts Communication Styles Socket Addresses Address Formats Setting a Sockets Address Reading a Sockets Address The File Namespace File Namespace Concepts Details of File Namespace Example of File-Namespace Sockets The Internet Namespace Internet Socket Address Format Host Addresses Internet Host Addresses Host Address Data Type Host Address Functions Host Names Internet Ports The Services Database Byte Order Conversion Protocols Database Internet Socket Example Other Namespaces Opening and Closing Sockets Creating a Socket Closing a Socket Socket Pairs Using Sockets with Connections Making a Connection Listening for Connections Accepting Connections Who is Connected to Me? Transferring Data Sending Data Receiving Data Socket Data Options Byte Stream Socket Example Byte Stream Connection Server Example Out-of-Band Data Datagram Socket Operations Sending Datagrams Receiving Datagrams Datagram Socket Example Example of Reading Datagrams The inetd Daemon inetd Servers Configuring inetd Socket Options Socket Option Functions Socket-Level Options Networks Database Low-Level Terminal Interface Identifying Terminals I/O Queues Two Styles of Input: Canonical or Not Terminal Modes Terminal Mode Data Types Terminal Mode Functions Setting Terminal Modes Properly Input Modes Output Modes Control Modes Local Modes Line Speed Special Characters Characters for Input Editing BSD Extensions to Editing Characters Characters that Cause Signals Special Characters for Flow Control Other Special Characters Noncanonical Input Line Control Functions Noncanonical Mode Example Mathematics Domain and Range Errors Trigonometric Functions Inverse Trigonometric Functions Exponentiation and Logarithms Hyperbolic Functions Pseudo-Random Numbers ANSI C Random Number Functions BSD Random Number Functions Low-Level Arithmetic Functions "Not a Number" Values Predicates on Floats Absolute Value Normalization Functions Rounding and Remainder Functions Integer Division Parsing of Numbers Parsing of Integers Parsing of Floats Date and Time Processor Time Basic CPU Time Inquiry Detailed Elapsed CPU Time Inquiry Calendar Time Simple Calendar Time High-Resolution Calendar Broken-down Time Formatting Date and Time Specifying the Time Zone with TZ Functions and Variables for Time Zones Time Functions Example Setting an Alarm Sleeping Resource Usage Limiting Resource Usage Process Priority Non-Local Exits Introduction to Non-Local Exits Details of Non-Local Exits Non-Local Exits and Signals Signal Handling Basic Concepts of Signals Some Kinds of Signals Concepts of Signal Generation How Signals Are Delivered Standard Signals Program Error Signals Termination Signals Alarm Signals Asynchronous I/O Signals Job Control Signals Miscellaneous Signals Nonstandard Signals Signal Messages Specifying Signal Actions Basic Signal Handling Advanced Signal Handling Interaction of signal and sigaction sigaction Function Example Flags for sigaction Initial Signal Actions Defining Signal Handlers Signal Handlers That Return Handlers That Terminate the Process Nonlocal Control Transfer in Handlers Signals Arriving While a Handler Runs Signals Close Together Merge into One Signal Handling and Nonreentrant Functions Atomic Data Access and Signal Handling Example of Problems with Non-Atomic Access Atomic Types Atomic Usage Patterns Primitives Interrupted by Signals Generating Signals Signaling Yourself Signaling Another Process Permission for using kill Using kill for Communication Blocking Signals Why Blocking Signals is Useful Signal Sets Process Signal Mask Blocking to Test for Delivery of a Signal Blocking Signals for a Handler Checking for Pending Signals Remembering a Signal to Act On Later Waiting for a Signal Using pause Problems with pause Using sigsuspend BSD Signal Handling POSIX and BSD Signal Facilities BSD Function to Establish a Handler BSD Functions for Blocking Signals Using a Separate Signal Stack Process Startup and Termination Program Arguments Program Argument Syntax Conventions Parsing Program Options Example of Parsing Arguments with getopt Parsing Long Options Example of Parsing Long Options Environment Variables Environment Access Standard Environment Variables Program Termination Normal Termination Exit Status Cleanups on Exit Aborting a Program Termination Internals Child Processes Running a Command Process Creation Concepts Process Identification Creating a Process Executing a File Process Completion Process Completion Status BSD Process Wait Functions Process Creation Example Job Control Concepts of Job Control Job Control is Optional Controlling Terminal of a Process Access to the Controlling Terminal Orphaned Process Groups Implementing a Job Control Shell Data Structures for the Shell Initializing the Shell Launching Jobs Foreground and Background Stopped and Terminated Jobs Continuing Stopped Jobs The Missing Pieces Functions for Job Control Identifying the Controlling Terminal Process Group Functions Functions for Controlling Terminal Access Users and Groups User and Group IDs The Persona of a Process Why Change the Persona of a Process? How an Application Can Change Persona Reading the Persona of a Process Setting the User ID Setting the Group IDs Enabling and Disabling Setuid Access Setuid Program Example Tips for Writing Setuid Programs Identifying Who Logged In User Database The Data Structure that Describes a User Looking Up One User Scanning the List of All Users Writing a User Entry Group Database The Data Structure for a Group Looking Up One Group Scanning the List of All Groups User and Group Database Example System Information Host Identification Hardware/Software Type Identification System Configuration Parameters General Capacity Limits Overall System Options Which Version of POSIX is Supported Using sysconf Definition of sysconf Constants for sysconf Parameters Examples of sysconf Minimum Values for General Capacity Limits Limits on File System Capacity Optional Features in File Support Minimum Values for File System Limits Using pathconf Utility Program Capacity Limits Minimum Values for Utility Limits String-Valued Parameters C Language Facilities Implemented By the Library Explicitly Checking Internal Consistency Variadic Functions Why Variadic Functions are Used How Variadic Functions are Defined and Used Syntax for Variable Arguments Receiving the Argument Values How Many Arguments Were Supplied Calling Variadic Functions Argument Access Macros Example of a Variadic Function Old-Style Variadic Functions Null Pointer Constant Important Data Types Data Type Measurements Computing the Width of an Integer Data Type Range of an Integer Type Floating Type Macros Floating Point Representation Concepts Floating Point Parameters IEEE Floating Point Structure Field Offset Measurement Summary of Library Facilities Library Maintenance How to Install the GNU C Library Reporting Bugs Adding New Functions Porting the GNU C Library The Layout of the `sysdeps Directory Hierarchy Porting the GNU C Library to Unix Systems Contributors to the GNU C Library GNU LIBRARY GENERAL PUBLIC LICENSE Preamble TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION How to Apply These Terms to Your New Libraries Concept Index Type Index Function and Macro Index Variable and Constant Macro Index Program and File Index