fortify: Migrate trivial cases to dynamic check macros
|__builtin_constant_p| has become more flexible in clang. In particular,
it's no longer forcibly lowered before inlining, so we can actually use
it on function parameters (or |__bos(param)|).
This CL tweaks things so that trivially safe calls to FORTIFY'ed
functions compile into direct calls to those functions, rather than to
their _chk counterparts. This will be the most impactful with things
like |memset|, |memcpy|, etc., since clang has way more flexibility
about how to lower those than it does with |__memset_chk|,
|__memcpy_chk|, ...
As noted in the comments, the spelling of the new macros is meant to
match closely with the spelling of our |__bos_static| macros used in
|diagnose_if|.
This isn't a full cleanup of all of the cases in which we can do this.
Just a start on the super simple cases.
Bug: 131861088
Test: m checkbuild; blueline boots.
Change-Id: I696f42ce4a65231e0c4a78a4c5133a6be1cb7708
diff --git a/libc/include/bits/fortify/socket.h b/libc/include/bits/fortify/socket.h
index c9387c0..35fad3d 100644
--- a/libc/include/bits/fortify/socket.h
+++ b/libc/include/bits/fortify/socket.h
@@ -45,7 +45,7 @@
"'recvfrom' called with size bigger than buffer") {
size_t bos = __bos0(buf);
- if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+ if (__bos_trivially_not_lt(bos, len)) {
return __call_bypassing_fortify(recvfrom)(fd, buf, len, flags, src_addr, addr_len);
}
return __recvfrom_chk(fd, buf, len, bos, flags, src_addr, addr_len);
@@ -60,7 +60,7 @@
"'sendto' called with size bigger than buffer") {
size_t bos = __bos0(buf);
- if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+ if (__bos_trivially_not_lt(bos, len)) {
return __call_bypassing_fortify(sendto)(fd, buf, len, flags, dest_addr, addr_len);
}
return __sendto_chk(fd, buf, len, bos, flags, dest_addr, addr_len);