The C library contains a large subset of the ISO C library. Functions are usually missing in areas, where there is no support on typical 6502 systems. Wide character sets are an example for this.
I will not go into detail about the ISO functions. If a function is not mentioned here explicitly, expect it to be available and to behave as defined in the C standard.
Functions that are not available:
ldiv function (cc65 is currently not able to return structs
with a size not equal to 1, 2 or 4 bytes by value).
SIGSEGV would be
Functions not available on all supported systems:
fopen/fread/fwrite/fclose/fputs/fgets/fscanf: The functions
are built on open/read/write/close. These latter functions are not available
on all systems.
ftell/fseek/fgetpos/fsetpos: Support depends on the
capabilities of the target machine.
rename/remove/rewind: Support depends on the capabilities of
the target machine.
time: Since many of the supported systems do not have a real
time clock, which means that the
time function is not available. Please
note that the other functions from
time.h are available.
Functions that are limited in any way:
strcspn/strpbrk/strspn: These functions have a length
limitation of 256 for the second string argument. Since this string gives a
character set, and there are only 256 distinct characters, this shouldn't be
getenv: Since there is no such thing as an environment on all
supported systems, the
getenv function will always return a
locale: There is no other locale than the "C" locale. The
native locale is identical to the "C" locale.
In addition to these limitations, some more functions are limited if inlined versions are requested by using -Os:
strlen function only works for strings with a maximum length
of 255 characters.
isxxx character classification functions from
<ctype.h> will give unpredictable results if the argument is not
in character range (0..255). This limitation may be removed by #undef'ing
the function name (when using
-Os, the functions are actually macros
that expand to inline assembler code, but the real functions are still
available if the macro definition is removed).