Most C standard library functions are undefined if passed NULL, even
when the corresponding length is zero. This gives them (and, in turn,
all functions which call them) surprising behavior on empty arrays.
Some compilers will miscompile code due to this rule. See also
https://www.imperialviolet.org/2016/06/26/nonnull.html

Add OPENSSL_memcpy, etc., wrappers which avoid this problem.

BUG=23

Change-Id: I95f42b23e92945af0e681264fffaf578e7f8465e
Reviewed-on: https://boringssl-review.googlesource.com/12928
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

We may need to implement high tag number form someday. CBS_get_asn1 has
an unsigned output to allow for this, but CBB_add_asn1 takes a uint8_t
(I think this might be my fault). Fix that which also fixes a
-Wconversion warning.

Simply leaving room in tag representation will still cause troubles
because the class and constructed bits overlap with bits for tag numbers
above 31. Probably the cleanest option would be to shift them to the top
3 bits of a u32 and thus not quite match the DER representation. Then
CBS_get_asn1 and CBB_add_asn1 will internally munge that into the DER
representation and consumers may continue to write things like:

   tag_number | CBS_ASN1_CONTEXT_SPECIFIC

I haven't done that here, but in preparation for that, document that
consumers need to use the values and should refrain from assuming the
correspond to DER.

Change-Id: Ibc76e51f0bc3b843e48e89adddfe2eaba4843d12
Reviewed-on: https://boringssl-review.googlesource.com/10502
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

Last month's canary for loop did not die in the coal mine of decrepit
toolchains. Make a note of this in STYLE.md so we know to start breeding
more of them. We can indeed declare index variables like it's 1999.

I haven't bothered to convert all of our for loops because that will be
tedious, but we can do it as we touch the code. Or if someone feels
really really bored.

BUG=47

Change-Id: Ib76c0767c1b509e825eac66f8c2e3ee2134e2493
Reviewed-on: https://boringssl-review.googlesource.com/8740
Reviewed-by: Adam Langley <agl@google.com>

They match the new style not the old EAY style now. They're also not
likely to be reformatted. It's just the legacy ASN.1 stuff now and we're
intentionally not doing much with those. (The old text was written back
before the SSL stack had been reformatted.)

Change-Id: I4852761b013e8c2688ebc7eaf4970afbdc69e858
Reviewed-on: https://boringssl-review.googlesource.com/8129
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

Change-Id: I0c9d86f188cd20d256620ccbb46546678714e081
Reviewed-on: https://boringssl-review.googlesource.com/6386
Reviewed-by: Adam Langley <agl@google.com>

Since we're able to render it fancy, may as well.

Change-Id: Ia1ab4b7ad0cdd78c8ffb75342ee62365843e7d5f
Reviewed-on: https://boringssl-review.googlesource.com/5810
Reviewed-by: Adam Langley <agl@google.com>