[libcxx-commits] [libcxx] [libc++][hardening] Classify assertions related to leaks and syscalls. (PR #77164)

[Louis Dionne via libcxx-commits]

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@@ -668,7 +668,9 @@ path __read_symlink(const path& p, error_code* ec) {
   detail::SSizeT ret;
   if ((ret = detail::readlink(p.c_str(), buff.get(), size)) == -1)
     return err.report(capture_errno());
-  _LIBCPP_ASSERT_UNCATEGORIZED(ret > 0, "TODO");
+  // `ret` indicates the number of bytes written to the buffer, `0` means that the attempt to read the symlink produced
+  // an empty string.
+  _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(ret > 0, "TODO");
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ldionne wrote:

The only case to consider here is if `ret == 0`, and I think in that case the code should "work fine". We'll return a buffer of size at least 1, and where `buf[0] == '\0'`. That's weird but valid. In that line of thought, I think this assertion is wrong (or at least it's in the wrong place).

https://github.com/llvm/llvm-project/pull/77164