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authorDavid Robillard <d@drobilla.net>2023-02-07 21:15:17 -0500
committerDavid Robillard <d@drobilla.net>2023-02-12 16:11:24 -0500
commit39b2eaebb6639fcb9c291099a0681bf9ea9aac3b (patch)
tree4931c3be6c944f2d90aa85f30c2d0692b050b9a0 /src/serd_config.h
parentd6e6dfcc70212ec5cf552e446eb76caae9939426 (diff)
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Check for POSIX features with the build system
Diffstat (limited to 'src/serd_config.h')
-rw-r--r--src/serd_config.h85
1 files changed, 54 insertions, 31 deletions
diff --git a/src/serd_config.h b/src/serd_config.h
index df73522b..e54b8688 100644
--- a/src/serd_config.h
+++ b/src/serd_config.h
@@ -1,15 +1,35 @@
-// Copyright 2021-2022 David Robillard <d@drobilla.net>
+// Copyright 2021-2023 David Robillard <d@drobilla.net>
// SPDX-License-Identifier: ISC
/*
- Configuration header that defines reasonable defaults at compile time.
-
- This allows compile-time configuration from the command line (typically via
- the build system) while still allowing the source to be built without any
- configuration. The build system can define SERD_NO_DEFAULT_CONFIG to disable
- defaults, in which case it must define things like HAVE_FEATURE to enable
- features. The design here ensures that compiler warnings or
- include-what-you-use will catch any mistakes.
+ Configuration header that defines reasonable defaults at compile-time.
+
+ This allows configuration from the command-line (usually by the build system)
+ while still allowing the code to compile "as-is" with reasonable default
+ features on supported platforms.
+
+ This system is designed so that, ideally, no command-line or build-system
+ configuration is needed, but automatic feature detection can be disabled or
+ overridden for maximum control. It should never be necessary to edit the
+ source code to achieve a given configuration.
+
+ Usage:
+
+ - By default, features are enabled if they can be detected or assumed to be
+ available from the build environment, unless `SERD_NO_DEFAULT_CONFIG` is
+ defined, which disables everything by default.
+
+ - If a symbol like `HAVE_SOMETHING` is defined to non-zero, then the
+ "something" feature is assumed to be available.
+
+ Code rules:
+
+ - To check for a feature, this header must be included, and the symbol
+ `USE_SOMETHING` used as a boolean in an `#if` expression.
+
+ - None of the other configuration symbols described here may be used
+ directly. In particular, this header should be the only place in the
+ source code that touches `HAVE` symbols.
*/
#ifndef SERD_CONFIG_H
@@ -21,62 +41,65 @@
#if !defined(SERD_NO_DEFAULT_CONFIG)
// We need unistd.h to check _POSIX_VERSION
-# ifndef SERD_NO_POSIX
-# ifdef __has_include
-# if __has_include(<unistd.h>)
-# include <unistd.h>
-# endif
-# elif defined(__unix__)
+# ifdef __has_include
+# if __has_include(<unistd.h>)
# include <unistd.h>
# endif
+# elif defined(__unix__)
+# include <unistd.h>
+# endif
+
+// Define SERD_POSIX_VERSION unconditionally for convenience
+# if defined(_POSIX_VERSION)
+# define SERD_POSIX_VERSION _POSIX_VERSION
+# else
+# define SERD_POSIX_VERSION 0
# endif
// POSIX.1-2001: fileno()
# ifndef HAVE_FILENO
-# if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
-# define HAVE_FILENO
+# if SERD_POSIX_VERSION >= 200112L || defined(_WIN32)
+# define HAVE_FILENO 1
# endif
# endif
// POSIX.1-2001: posix_fadvise()
# ifndef HAVE_POSIX_FADVISE
-# ifndef __APPLE__
-# if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
-# define HAVE_POSIX_FADVISE
-# endif
+# if SERD__POSIX_VERSION >= 200112L && !defined(__APPLE__)
+# define HAVE_POSIX_FADVISE 1
# endif
# endif
// POSIX.1-2001: posix_memalign()
# ifndef HAVE_POSIX_MEMALIGN
-# if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
-# define HAVE_POSIX_MEMALIGN
+# if SERD_POSIX_VERSION >= 200112L
+# define HAVE_POSIX_MEMALIGN 1
# endif
# endif
#endif // !defined(SERD_NO_DEFAULT_CONFIG)
/*
- Make corresponding USE_FEATURE defines based on the HAVE_FEATURE defines from
- above or the command line. The code checks for these using #if (not #ifdef),
- so there will be an undefined warning if it checks for an unknown feature,
- and this header is always required by any code that checks for features, even
- if the build system defines them all.
+ Unconditionally define symbols like USE_SOMETHING based on HAVE_SOMETHING, if
+ it's defined. The code checks these using #if (not #ifdef), so there will be
+ a warning if it checks for an unknown feature or doesn't include this header.
+ This header should be the only file in the source code that touches symbols
+ like HAVE_SOMETHING.
*/
-#ifdef HAVE_FILENO
+#if defined(HAVE_FILENO) && HAVE_FILENO
# define USE_FILENO 1
#else
# define USE_FILENO 0
#endif
-#ifdef HAVE_POSIX_FADVISE
+#if defined(HAVE_POSIX_FADVISE) && HAVE_POSIX_FADVISE
# define USE_POSIX_FADVISE 1
#else
# define USE_POSIX_FADVISE 0
#endif
-#ifdef HAVE_POSIX_MEMALIGN
+#if defined(HAVE_POSIX_MEMALIGN) && HAVE_POSIX_MEMALIGN
# define USE_POSIX_MEMALIGN 1
#else
# define USE_POSIX_MEMALIGN 0