qapi: Tighten the regex on valid names

We already documented that qapi names should match specific
patterns (such as starting with a letter unless it was an enum
value or a downstream extension). Tighten that from a suggestion
into a hard requirement, which frees up names beginning with a
single underscore for qapi internal usage.

The tighter regex doesn't forbid everything insane that a user
could provide (for example, a user could name a type 'Foo-lookup'
to collide with the generated 'Foo_lookup[]' for an enum 'Foo'),
but does a good job at protecting the most obvious uses, and
also happens to reserve single leading underscore for later use.

The handling of enum values starting with a digit is tricky:
commit 9fb081e introduced a subtle bug by using c_name() on
a munged value, which would allow an enum to include the
member 'q-int' in spite of our reservation. Furthermore,
munging with a leading '_' would fail our tighter regex. So
fix it by only munging for leading digits (which are never
ticklish in c_name()) and by using a different prefix (I
picked 'D', although any letter should do).

Add new tests, reserved-member-underscore and reserved-enum-q,
to demonstrate the tighter checking.

Backports commit 59a92feedc6927e0e1ff87fdaccfb4dd42ad4c84 from qemu
This commit is contained in:
Eric Blake 2018-02-19 20:33:16 -05:00 committed by Lioncash
parent a5cbe099d7
commit 00e596aad2
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@ -356,9 +356,13 @@ def discriminator_find_enum_define(expr):
return find_enum(discriminator_type)
# FIXME should enforce "other than downstream extensions [...], all
# names should begin with a letter".
valid_name = re.compile('^[a-zA-Z_][a-zA-Z0-9_.-]*$')
# Names must be letters, numbers, -, and _. They must start with letter,
# except for downstream extensions which must start with __RFQDN_.
# Dots are only valid in the downstream extension prefix.
valid_name = re.compile('^(__[a-zA-Z0-9.-]+_)?'
'[a-zA-Z][a-zA-Z0-9_-]*$')
def check_name(expr_info, source, name, allow_optional=False,
enum_member=False):
global valid_name
@ -375,8 +379,8 @@ def check_name(expr_info, source, name, allow_optional=False,
% (source, name))
# Enum members can start with a digit, because the generated C
# code always prefixes it with the enum name
if enum_member:
membername = '_' + membername
if enum_member and membername[0].isdigit():
membername = 'D' + membername
# Reserve the entire 'q_' namespace for c_name()
if not valid_name.match(membername) or \
c_name(membername, False).startswith('q_'):