Rules

Sections

• Rule 01. Preprocessor (PRE)
• Rule 02. Declarations and Initialization (DCL)
• Rule 03. Expressions (EXP)
• Rule 04. Integers (INT)
• Rule 05. Floating Point (FLP)
• Rule 06. Arrays (ARR)
• Rule 07. Characters and Strings (STR)
• Rule 08. Memory Management (MEM)
• Rule 09. Input Output (FIO)
• Rule 10. Environment (ENV)
• Rule 11. Signals (SIG)
• Rule 12. Error Handling (ERR)
• Rule 13. Application Programming Interfaces (API)
• Rule 14. Concurrency (CON)
• Rule 48. Miscellaneous (MSC)
• Rule 50. POSIX (POS)
• Rule 51. Microsoft Windows (WIN)

Rule Listing

• ARR30-C. Do not form or use out-of-bounds pointers or array subscripts
• ARR32-C. Ensure size arguments for variable length arrays are in a valid range
• ARR36-C. Do not subtract or compare two pointers that do not refer to the same array
• ARR37-C. Do not add or subtract an integer to a pointer to a non-array object
• ARR38-C. Guarantee that library functions do not form invalid pointers
• ARR39-C. Do not add or subtract a scaled integer to a pointer
• CON30-C. Clean up thread-specific storage
• CON31-C. Do not destroy a mutex while it is locked
• CON32-C. Prevent data races when accessing bit-fields from multiple threads
• CON33-C. Avoid race conditions when using library functions
• CON34-C. Declare objects shared between threads with appropriate storage durations
• CON35-C. Avoid deadlock by locking in a predefined order
• CON36-C. Wrap functions that can spuriously wake up in a loop
• CON37-C. Do not call signal() in a multithreaded program
• CON38-C. Preserve thread safety and liveness when using condition variables
• CON39-C. Do not join or detach a thread that was previously joined or detached
• CON40-C. Do not refer to an atomic variable twice in an expression
• CON41-C. Wrap functions that can fail spuriously in a loop
• CON43-C. Do not allow data races in multithreaded code
• DCL30-C. Declare objects with appropriate storage durations
• DCL31-C. Declare identifiers before using them
• DCL36-C. Do not declare an identifier with conflicting linkage classifications
• DCL37-C. Do not declare or define a reserved identifier
• DCL38-C. Use the correct syntax when declaring a flexible array member
• DCL39-C. Avoid information leakage when passing a structure across a trust boundary
• DCL40-C. Do not create incompatible declarations of the same function or object
• DCL41-C. Do not declare variables inside a switch statement before the first case label
• ENV30-C. Do not modify the object referenced by the return value of certain functions
• ENV31-C. Do not rely on an environment pointer following an operation that may invalidate it
• ENV32-C. All exit handlers must return normally
• ENV33-C. Do not call system()
• ENV34-C. Do not store pointers returned by certain functions
• ERR30-C. Take care when reading errno
• ERR32-C. Do not rely on indeterminate values of errno
• ERR33-C. Detect and handle standard library errors
• ERR34-C. Detect errors when converting a string to a number
• EXP30-C. Do not depend on the order of evaluation for side effects
• EXP32-C. Do not access a volatile object through a nonvolatile reference
• EXP33-C. Do not read uninitialized memory
• EXP34-C. Do not dereference null pointers
• EXP35-C. Do not modify objects with temporary lifetime
• EXP36-C. Do not cast pointers into more strictly aligned pointer types
• EXP37-C. Call functions with the correct number and type of arguments
• EXP39-C. Do not access a variable through a pointer of an incompatible type
• EXP40-C. Do not modify constant objects
• EXP42-C. Do not compare padding data
• EXP43-C. Avoid undefined behavior when using restrict-qualified pointers
• EXP44-C. Do not rely on side effects in operands to sizeof, _Alignof, or _Generic
• EXP45-C. Do not perform assignments in selection statements
• EXP46-C. Do not use a bitwise operator with a Boolean-like operand
• EXP47-C. Do not call va_arg with an argument of the incorrect type
• FIO30-C. Exclude user input from format strings
• FIO32-C. Do not perform operations on devices that are only appropriate for files
• FIO34-C. Distinguish between characters read from a file and EOF or WEOF
• FIO37-C. Do not assume that fgets() or fgetws() returns a nonempty string when successful
• FIO38-C. Do not copy a FILE object
• FIO39-C. Do not alternately input and output from a stream without an intervening flush or positioning call
• FIO40-C. Reset strings on fgets() or fgetws() failure
• FIO41-C. Do not call getc(), putc(), getwc(), or putwc() with a stream argument that has side effects
• FIO42-C. Close files when they are no longer needed
• FIO44-C. Only use values for fsetpos() that are returned from fgetpos()
• FIO45-C. Avoid TOCTOU race conditions while accessing files
• FIO46-C. Do not access a closed file
• FIO47-C. Use valid format strings
• FLP30-C. Do not use floating-point variables as loop counters
• FLP32-C. Prevent or detect domain and range errors in math functions
• FLP34-C. Ensure that floating-point conversions are within range of the new type
• FLP36-C. Preserve precision when converting integral values to floating-point type
• FLP37-C. Do not use object representations to compare floating-point values
• INT30-C. Ensure that unsigned integer operations do not wrap
• INT31-C. Ensure that integer conversions do not result in lost or misinterpreted data
• INT32-C. Ensure that operations on signed integers do not result in overflow
• INT33-C. Ensure that division and remainder operations do not result in divide-by-zero errors
• 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
• INT35-C. Use correct integer precisions
• INT36-C. Converting a pointer to integer or integer to pointer
• MEM30-C. Do not access freed memory
• MEM31-C. Free dynamically allocated memory when no longer needed
• MEM33-C. Allocate and copy structures containing a flexible array member dynamically
• MEM34-C. Only free memory allocated dynamically
• MEM35-C. Allocate sufficient memory for an object
• MEM36-C. Do not modify the alignment of objects by calling realloc()
• MSC30-C. Do not use the rand() function for generating pseudorandom numbers
• MSC32-C. Properly seed pseudorandom number generators
• MSC33-C. Do not pass invalid data to the asctime() function
• MSC37-C. Ensure that control never reaches the end of a non-void function
• MSC38-C. Do not treat a predefined identifier as an object if it might only be implemented as a macro
• MSC39-C. Do not call va_arg() on a va_list that has an indeterminate value
• MSC40-C. Do not violate constraints
• MSC41-C. Never hard code sensitive information
• POS30-C. Use the readlink() function properly
• POS34-C. Do not call putenv() with a pointer to an automatic variable as the argument
• POS35-C. Avoid race conditions while checking for the existence of a symbolic link
• POS36-C. Observe correct revocation order while relinquishing privileges
• POS37-C. Ensure that privilege relinquishment is successful
• POS38-C. Beware of race conditions when using fork and file descriptors
• POS39-C. Use the correct byte ordering when transferring data between systems
• POS44-C. Do not use signals to terminate threads
• POS47-C. Do not use threads that can be canceled asynchronously
• POS48-C. Do not unlock or destroy another POSIX thread's mutex
• POS49-C. When data must be accessed by multiple threads, provide a mutex and guarantee no adjacent data is also accessed
• POS50-C. Declare objects shared between POSIX threads with appropriate storage durations
• POS51-C. Avoid deadlock with POSIX threads by locking in predefined order
• POS52-C. Do not perform operations that can block while holding a POSIX lock
• POS53-C. Do not use more than one mutex for concurrent waiting operations on a condition variable
• POS54-C. Detect and handle POSIX library errors
• PRE30-C. Do not create a universal character name through concatenation
• PRE31-C. Avoid side effects in arguments to unsafe macros
• PRE32-C. Do not use preprocessor directives in invocations of function-like macros
• Rules versus Recommendations
• SIG30-C. Call only asynchronous-safe functions within signal handlers
• SIG31-C. Do not access shared objects in signal handlers
• SIG34-C. Do not call signal() from within interruptible signal handlers
• SIG35-C. Do not return from a computational exception signal handler
• STR30-C. Do not attempt to modify string literals
• STR31-C. Guarantee that storage for strings has sufficient space for character data and the null terminator
• STR32-C. Do not pass a non-null-terminated character sequence to a library function that expects a string
• STR34-C. Cast characters to unsigned char before converting to larger integer sizes
• STR37-C. Arguments to character-handling functions must be representable as an unsigned char
• STR38-C. Do not confuse narrow and wide character strings and functions
• WIN30-C. Properly pair allocation and deallocation functions