Preface xiii
Acknowledgments xxxvii
Contributors xxxix
About the Author xliii
Chapter 1: Preprocessor (PRE) 1
PRE30-C. Do not create a universal character name through concatenation 2
PRE31-C. Avoid side effects in arguments to unsafe macros 3
PRE32-C. Do not use preprocessor directives in invocations of function-like macros 8
Chapter 2: Declarations and Initialization (DCL) 11
DCL30-C. Declare objects with appropriate storage durations 12
DCL31-C. Declare identifiers before using them 16
DCL36-C. Do not declare an identifier with conflicting linkage classifications 20
DCL37-C. Do not declare or define a reserved identifier 23
DCL38-C. Use the correct syntax when declaring a flexible array member 29
DCL39-C. Avoid information leakage in structure padding 32
DCL40-C. Do not create incompatible declarations of the same function or object 37
DCL41-C. Do not declare variables inside a switch statement before the first case label 43
Chapter 3: Expressions (EXP) 47
EXP30-C. Do not depend on the order of evaluation for side effects 48
EXP32-C. Do not access a volatile object through a nonvolatile reference 54
EXP33-C. Do not read uninitialized memory 56
EXP34-C. Do not dereference null pointers 65
EXP35-C. Do not modify objects with temporary lifetime 70
EXP36-C. Do not cast pointers into more strictly aligned pointer types 73
EXP37-C. Call functions with the correct number and type of arguments 77
EXP39-C. Do not access a variable through a pointer of an incompatible type 83
EXP40-C. Do not modify constant objects 89
EXP42-C. Do not compare padding data 91
EXP43-C. Avoid undefined behavior when using restrict-qualified pointers 93
EXP44-C. Do not rely on side effects in operands to sizeof, _Alignof, or _Generic 102
EXP45-C. Do not perform assignments in selection statements 105
Chapter 4: Integers (INT) 111
INT30-C. Ensure that unsigned integer operations do not wrap 112
INT31-C. Ensure that integer conversions do not result in lost or misinterpreted data 118
INT32-C. Ensure that operations on signed integers do not result in overflow 126
INT33-C. Ensure that division and remainder operations do not result in divide-by-zero errors 135
INT34-C. Do not shift an expression by a negative number of bits or by greater than or equal to the number of bits that exist in the operand 138
INT35-C. Use correct integer precisions 143
INT36-C. Converting a pointer to integer or integer to pointer 145
Chapter 5: Floating Point (FLP) 151
FLP30-C. Do not use floating-point variables as loop counters 152
FLP32-C. Prevent or detect domain and range errors in math functions 154
FLP34-C. Ensure that floating-point conversions are within range of the new type 163
FLP36-C. Preserve precision when converting integral values to floating-point type 166
Chapter 6: Arrays (ARR) 169
ARR30-C. Do not form or use out-of-bounds pointers or array subscripts 170
ARR32-C. Ensure size arguments for variable length arrays are in a valid range 180
ARR36-C. Do not subtract or compare two pointers that do not refer to the same array 182
ARR37-C. Do not add or subtract an integer to a pointer to a non-array object 184
ARR38-C. Guarantee that library functions do not form invalid pointers 187
ARR39-C. Do not add or subtract a scaled integer to a pointer 196
Chapter 7: Characters and Strings (STR) 201
STR30-C. Do not attempt to modify string literals 202
STR31-C. Guarantee that storage for strings has sufficient space for character data and the null terminator 205
STR32-C. Do not pass a non-null-terminated character sequence to a library function that expects a string 218
STR34-C. Cast characters to unsigned char before converting to larger integer sizes 223
STR37-C. Arguments to character handling functions must be representable as an unsigned char 227
STR38-C. Do not confuse narrow and wide character strings and functions 229
Chapter 8: Memory Management (MEM) 233
MEM30-C. Do not access freed memory 234
MEM31-C. Free dynamically allocated memory when no longer needed 239
MEM33-C. Allocate and copy structures containing a flexible array member dynamically 241
MEM34-C. Only free memory allocated dynamically 246
MEM35-C. Allocate sufficient memory for an object 250
MEM36-C. Do not modify the alignment of objects by calling realloc() 253
Chapter 9: Input/Output (FIO) 257
FIO30-C. Exclude user input from format strings 258
FIO31-C. Do not open a file that is already open 263
FIO32-C. Do not perform operations on devices that are only appropriate for files 265
FIO34-C. Distinguish between characters read from a file and EOF or WEOF 272
FIO37-C. Do not assume that fgets() or fgetws() returns a nonempty string when successful 277
FIO38-C. Do not copy a FILE object 279
FIO39-C. Do not alternately input and output from a stream without an intervening flush or positioning call 280
FIO40-C. Reset strings on fgets() or fgetws() failure 283
FIO41-C. Do not call getc(), putc(), getwc(), or putwc() with a stream argument that has side effects 284
FIO42-C. Close files when they are no longer needed 288
FIO44-C. Only use values for fsetpos() that are returned from fgetpos() 292
FIO45-C. Avoid TOCTOU race conditions while accessing files 294
FIO46-C. Do not access a closed file 298
FIO47-C. Use valid format strings 299
Chapter 10: Environment (ENV) 305
ENV30-C. Do not modify the object referenced by the return value of certain functions 306
ENV31-C. Do not rely on an environment pointer following an operation that may invalidate it 311
ENV32-C. All exit handlers must return normally 315
ENV33-C. Do not call system() 319
ENV34-C. Do not store pointers returned by certain functions 325
Chapter 11: Signals (SIG) 333
SIG30-C. Call only asynchronous-safe functions within signal handlers 334
SIG31-C. Do not access shared objects in signal handlers 342
SIG34-C. Do not call signal() from within interruptible signal handlers 345
SIG35-C. Do not return from a computational exception signal handler 349
Chapter 12: Error Handling (ERR) 353
ERR30-C. Set errno to zero before calling a library function known to set errno, and check errno only after the function returns a value indicating failure 354
ERR32-C. Do not rely on indeterminate values of errno 361
ERR33-C. Detect and handle standard library errors 365
Chapter 13: Concurrency (CON) 383
CON30-C. Clean up thread-specific storage 384
CON31-C. Do not destroy a mutex while it is locked 388
CON32-C. Prevent data races when accessing bit-fields from multiple threads 391
CON33-C. Avoid race conditions when using library functions 394
CON34-C. Declare objects shared between threads with appropriate storage durations 398
CON35-C. Avoid deadlock by locking in a predefined order 406
CON36-C. Wrap functions that can spuriously wake up in a loop 411
CON37-C. Do not call signal() in a multithreaded program 414
CON38-C. Preserve thread-safety and liveness when using condition variables 416
CON39-C. Do not join or detach a thread that was previously joined or detached 424
CON40-C. Do not refer to an atomic variable twice in an expression 426
CON41-C. Wrap functions that can fail spuriously in a loop 430
Chapter 14: Miscellaneous (MSC) 435
MSC30-C. Do not use the rand() function for generating pseudorandom numbers 436
MSC32-C. Properly seed pseudorandom number generators 439
MSC33-C. Do not pass invalid data to the asctime() function 443
MSC37-C. Ensure that control never reaches the end of a non-void function 446
MSC38-C. Do not treat a predefined identifier as an object if it might only be implemented as a macro 449
MSC39-C. Do not call va_arg() on a va_list that has an indeterminate value 451
MSC40-C. Do not violate constraints 453
Appendix A: Glossary 459
Appendix B: Undefined Behavior 465
Appendix C: Unspecified Behavior 481
Bibliography 487
Index 495