libc projection

core/c/libc/setjmp.odin

@@ -0,0 +1,31 @@
+package libc
+
+// 7.13 Nonlocal jumps
+
+foreign import libc "system:c"
+
+@(default_calling_convention="c")
+foreign libc {
+	// 7.13.1 Save calling environment
+	//
+	// NOTE(dweiler): C11 requires setjmp be a macro, which means it won't
+	// necessarily export a symbol named setjmp but rather _setjmp in the case
+	// of musl, glibc, BSD libc, and msvcrt.
+	@(link_name="_setjmp")
+	setjmp  :: proc(env: ^jmp_buf) -> int ---;
+
+	// 7.13.2 Restore calling environment
+	longjmp :: proc(env: ^jmp_buf, val: int) -> ! ---;
+}
+
+// The C99 Rationale describes jmp_buf as being an array type for backward
+// compatibility. Odin does not need to honor this and couldn't as arrays in
+// Odin don't decay to pointers. It is somewhat easy for us to bind this, we
+// just need to ensure the structure contains enough storage with appropriate
+// alignment. Since there are no types in C with an alignment larger than
+// that of max_align_t, which cannot be larger than sizeof(long double) as any
+// other exposed type wouldn't be valid C, the maximum alignment possible in a
+// strictly conformant C implementation is 16 on the platforms we care about.
+// The choice of 4096 bytes for storage of this type is more than enough on all
+// relevant platforms.
+jmp_buf :: struct #align 16 { _: [4096]char, };