Fix the easy -Wformat-signedness errors.

GCC has a warning that complains about even more type mismatches in
printf. Some of these are a bit messy and will be fixed in separate CLs.
This covers the easy ones.

The .*s stuff is unfortunate, but printf has no size_t-clean string
printer. ALPN protocol lengths are bound by uint8_t, so it doesn't
really matter.

The IPv6 printing one is obnoxious and arguably a false positive. It's
really a C language flaw: all types smaller than int get converted to
int when you do arithmetic. So something like this first doesn't
overflow the shift because it computes over int, but then the result
overall is stored as an int.

  uint8_t a, b;
  (a << 8) | b

On the one hand, this fixes a "missing" cast to uint16_t before the
shift. At the same time, the incorrect final type means passing it to
%x, which expects unsigned int. The compiler has forgotten this value
actually fits in uint16_t and flags a warning. Mitigate this by storing
in a uint16_t first.

The story doesn't quite end here. Arguments passed to variadic functions
go through integer promotion[0], so the argument is still passed to
snprintf as an int! But then va_arg allows for a signedness mismatch[1],
provided the value is representable in both types. The combination means
that %x, though actually paired with unsigned, also accept uint8_t and
uint16_t, because those are guaranteed to promote to an int that meets
[1]. GCC recognizes [1] applies here.

(There's also PRI16x, but that's a bit tedious to use and, in glibc, is
defined as plain "x" anyway.)

[0] https://en.cppreference.com/w/c/language/conversion#Default_argument_promotions
[1] https://en.cppreference.com/w/c/variadic/va_arg

Bug: 450
Change-Id: Ic1d41356755a18ab922956dd2e07b560470341f4
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50765
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
10 files changed
tree: 9ee7cd87fb2dfa0e8fefb4f2b0327a511571feed
  1. .github/
  2. crypto/
  3. decrepit/
  4. fuzz/
  5. include/
  6. ssl/
  7. third_party/
  8. tool/
  9. util/
  10. .clang-format
  11. .gitignore
  12. API-CONVENTIONS.md
  13. BREAKING-CHANGES.md
  14. BUILDING.md
  15. CMakeLists.txt
  16. codereview.settings
  17. CONTRIBUTING.md
  18. FUZZING.md
  19. go.mod
  20. go.sum
  21. INCORPORATING.md
  22. LICENSE
  23. PORTING.md
  24. README.md
  25. SANDBOXING.md
  26. sources.cmake
  27. STYLE.md
README.md

BoringSSL

BoringSSL is a fork of OpenSSL that is designed to meet Google's needs.

Although BoringSSL is an open source project, it is not intended for general use, as OpenSSL is. We don't recommend that third parties depend upon it. Doing so is likely to be frustrating because there are no guarantees of API or ABI stability.

Programs ship their own copies of BoringSSL when they use it and we update everything as needed when deciding to make API changes. This allows us to mostly avoid compromises in the name of compatibility. It works for us, but it may not work for you.

BoringSSL arose because Google used OpenSSL for many years in various ways and, over time, built up a large number of patches that were maintained while tracking upstream OpenSSL. As Google's product portfolio became more complex, more copies of OpenSSL sprung up and the effort involved in maintaining all these patches in multiple places was growing steadily.

Currently BoringSSL is the SSL library in Chrome/Chromium, Android (but it's not part of the NDK) and a number of other apps/programs.

Project links:

There are other files in this directory which might be helpful: