NOTE(3EXT) Extended Library Functions NOTE(3EXT)NAME
NOTE, _NOTE - annotate source code with info for tools
SYNOPSIS
#include <note.h>
NOTE(NoteInfo)
#include<sys/note.h>
_NOTE(NoteInfo)DESCRIPTION
These macros are used to embed information for tools in program source.
A use of one of these macros is called an "annotation". A tool may
define a set of such annotations which can then be used to provide the
tool with information that would otherwise be unavailable from the
source code.
Annotations should, in general, provide documentation useful to the
human reader. If information is of no use to a human trying to under‐
stand the code but is necessary for proper operation of a tool, use
another mechanism for conveying that information to the tool (one which
does not involve adding to the source code), so as not to detract from
the readability of the source. The following is an example of an anno‐
tation which provides information of use to a tool and to the human
reader (in this case, which data are protected by a particular lock, an
annotation defined by the static lock analysis tool lock_lint).
NOTE(MUTEX_PROTECTS_DATA(foo_lock, foo_list Foo))
Such annotations do not represent executable code; they are neither
statements nor declarations. They should not be followed by a semi‐
colon. If a compiler or tool that analyzes C source does not understand
this annotation scheme, then the tool will ignore the annotations. (For
such tools, NOTE(x) expands to nothing.)
Annotations may only be placed at particular places in the source.
These places are where the following C constructs would be allowed:
o a top-level declaration (that is, a declaration not within a
function or other construct)
o a declaration or statement within a block (including the
block which defines a function)
o a member of a struct or union.
Annotations are not allowed in any other place. For example, the fol‐
lowing are illegal:
x = y + NOTE(...) z ;
typedef NOTE(...) unsigned int uint ;
While NOTE and _NOTE may be used in the places described above, a par‐
ticular type of annotation may only be allowed in a subset of those
places. For example, a particular annotation may not be allowed inside
a struct or union definition.
NOTE vs _NOTE
Ordinarily, NOTE should be used rather than _NOTE, since use of _NOTE
technically makes a program non-portable. However, it may be inconve‐
nient to use NOTE for this purpose in existing code if NOTE is already
heavily used for another purpose. In this case one should use a dif‐
ferent macro and write a header file similar to /usr/include/note.h
which maps that macro to _NOTE in the same manner. For example, the
following makes FOO such a macro:
#ifndef _FOO_H
#define _FOO_H
#define FOO _NOTE
#include <sys/note.h>
#endif
Public header files which span projects should use _NOTE rather than
NOTE, since NOTE may already be used by a program which needs to
include such a header file.
NoteInfo Argument
The actual NoteInfo used in an annotation should be specified by a tool
that deals with program source (see the documentation for the tool to
determine which annotations, if any, it understands).
NoteInfo must have one of the following forms:
NoteName
NoteName(Args)
where NoteName is simply an identifier which indicates the type of
annotation, and Args is something defined by the tool that specifies
the particular NoteName. The general restrictions on Args are that it
be compatible with an ANSI C tokenizer and that unquoted parentheses be
balanced (so that the end of the annotation can be determined without
intimate knowledge of any particular annotation).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOnote(4), attributes(5)SunOS 5.10 12 Nov 2010 NOTE(3EXT)
