Skip to content

README.md

Latest commit

 

History

History
43 lines (37 loc) · 2.5 KB

README.md

File metadata and controls

43 lines (37 loc) · 2.5 KB
Raw

Neutral libc headers for translation

These headers replace the system headers of the same name while libmpdec is translated (never when it is compiled as C). They declare only standard interfaces, so that the translation does not contain the implementation details of a particular libc, which differ between platforms:

header system header content that is avoided
assert.h __assert_rtn (macOS), __assert_fail (glibc), file/line
ctype.h inline definitions (macOS), __ctype_b_loc tables (glibc)
errno.h __error() (macOS), __errno_location() (glibc)
locale.h libc-specific struct lconv layout (a prefix is declared)
math.h vector math declarations (aarch64 glibc >= 2.39)
stdio.h FILE layout, __stderrp (macOS) / stderr (glibc)
stdint.h uint64_t as unsigned long (glibc LP64) or unsigned long long
inttypes.h format macros matching the system stdint.h
limits.h libc-specific spelling (__INT_MAX__, UCHAR_MAX chains)
stddef.h size_t via __darwin_size_t (macOS), __DARWIN_NULL
stdlib.h libc-internal typedefs and declarations
string.h same as stdlib.h
signal.h libc-specific declarations; targets without signals

Where a standard interface cannot be declared without libc details, the header redirects to an mpd_c2rust_* function of the hand-written ../shim/shim.rs:

  • stderr: the object differs between C libraries (__stderrp, stderr, __acrt_iob_func(2));
  • raise: not available on targets without signals (WASI);
  • assert: the failure handler differs between C libraries;
  • errno: libmpdec reads errno only after strtol/strtoll, so these two are implemented by the shim with a private errno, and EINVAL/ERANGE are private values.

The exact-width types are spelled the same on every platform (64-bit types as long long). size_t and ptrdiff_t are the compiler's types (__SIZE_TYPE__, __PTRDIFF_TYPE__), which c2rust translates as usize/isize. Where size_t and uint64_t are different C types (LP64), the translation converts between them; with LLP64 (Windows) they are the same type and it does not (../expected/windows-*.diff).

All platform-dependent code is therefore confined to shim.rs.