Externals-CStdLib.Errno

Configuration of the implementation of the global ‘errno’ variable provided in the C stdlib

The number of last error of C system library calls is provided by the symbol errno. This symbol can be implemented in different ways in the header errno.h, e.g. as a global variable or as a macro dereferencing the result of a function call. E.g.:

• errno_t errno;
• #define errno (*_errno())

Please use this configuration rule to adapt the detection mechanism to the project's standard library's errno.h.

In addition, the predefined set of out-of-band and in-band errno setting functions may be adapted.

Possible Messages

This rule has no predefined messages.

Options

The following places define options that affect this rule: Analysis-GlobalOptions

function_from_macro_pattern

function_from_macro_pattern

Type: typing.Pattern[str]

Default: '\s*(?:\(|)\s*\*\s*(?:\([a-z]+\s*\*?\))?\s*([_a-zA-Z][_a-zA-Z0-9]*)\s*\(\s*\)\s*(?:\)|)\s*'

Regular expression with one group. That group's matching string is added to the set function_names. This is intended to auto-detect patterns like #define errno (*_errno()).

 

function_names

function_names : set[bauhaus.analysis.config.QualifiedName] = set()

Qualified names of functions implementing errno functionality via an indirect call. Simple cases can be auto-detected via the function_from_macro_pattern option. More complex cases can be configured here.

 

in_band_error_funcs

in_band_error_funcs

Type: dict[str, str | int]

Default:

{
   'fgetwc': 'WEOF',
   'fputwc': 'WEOF',
   'strtod': 'HUGE_VAL',
   'strtof': 'HUGE_VALF',
   'strtoimax': 'INTMAX_MAX',
   'strtol': 'LONG_MAX',
   'strtold': 'HUGE_VALL',
   'strtoll': 'LLONG_MAX',
   'strtoul': 'ULONG_MAX',
   'strtoull': 'ULLONG_MAX',
   'strtoumax': 'UINTMAX_MAX',
   'wcstod': 'HUGE_VAL',
   'wcstof': 'HUGE_VALF',
   'wcstoimax': 'INTMAX_MAX',
   'wcstol': 'LONG_MAX',
   'wcstold': 'HUGE_VALL',
   'wcstoll': 'LLONG_MAX',
   'wcstoul': 'ULONG_MAX',
   'wcstoull': 'ULLONG_MAX',
   'wcstoumax': 'UINTMAX_MAX'
}

A dictionary of errno setting functions similar to out_of_band_error_funcs. For in-band errno setting function the returned value does not uniquely determine if actually an error occurred. The returned value may also be a valid result. Therefore, if a potential error value is returned, errno should be checked additionally. And for properly checking errno, errno should have been initialized to zero before calling any of these errno setting functions. For the strings HUGE_VAL, HUGE_VALF, and HUGE_VALL also 0 and the corresponding negative values indicate an error. For the signed types the values INTMAX_MAX, LONG_MAX, and LLONG_MAX also corresponding values INTMAX_MIN, LONG_MIN, and LLONG_MIN are addressed.

 

macro_names

macro_names : set[bauhaus.analysis.config.MacroName] = {'errno'}

Names of macros implementing errno (typically just errno).

 

out_of_band_error_funcs

out_of_band_error_funcs

Type: dict[str, str | int]

Default:

{
   'c16rtomb': 'max_size',
   'c32rtomb': 'max_size',
   'fgetpos': 'nonzero',
   'fsetpos': 'nonzero',
   'ftell': -1,
   'mbrtoc16': 'max_size',
   'mbrtoc32': 'max_size',
   'mbrtowc': 'max_size',
   'mbsrtowcs': 'max_size',
   'signal': 'SIG_ERR',
   'wcrtomb': 'max_size',
   'wcsrtombs': 'max_size'
}

A dictionary of errno setting functions that return the given value in case of an error. The string max_size is the maximal value of a size_t type. The string nonzero denotes any non 0 value and testing is done in the same way as for 0, namely by testing equality or inequality with 0. For out-of-band errno setting functions there is no need to ever set or read errno as the return value is sufficient as error indication. However, errno may provide additional error information.

 

posix_error_funcs

posix_error_funcs

Type: dict[str, str | int]

Default:

{
   'chmod': -1,
   'chown': -1,
   'close': 'EOF',
   'creat': -1,
   'fchmod': -1,
   'fchmodat': -1,
   'fchown': -1,
   'fchownat': -1,
   'fclose': 'EOF',
   'fcntl': -1,
   'fdatasync': -1,
   'fdopen': 'NULL',
   'fflush': 'EOF',
   'fopen': 'NULL',
   'freopen': 'NULL',
   'fstat': -1,
   'fstatat': -1,
   'fsync': -1,
   'ioctl': -1,
   'lchown': -1,
   'lstat': -1,
   'open': -1,
   'openat': -1,
   'pread': -1,
   'read': -1,
   'stat': -1,
   'wait': -1,
   'waitid': -1,
   'waitpid': -1
}

An extra dictionary of in-band errno setting functions for posix. See in_band_error_funcs for further documentation. These functions are considered by some errno rules via the option standard_posix of the respective rule.

 

variable_names

variable_names : set[bauhaus.analysis.config.QualifiedName] = {'errno'}

Qualified names of global variables used as errno (in simple implementations errno).