Split config.h into private and public config

This addresses https://github.com/libfuse/libfuse/issues/729

commit db35a37def14b72181f3630efeea0e0433103c41 introduced a public
config.h (rename to fuse_config.h to avoid conflicts) that
was installed with the package and included by libfuse users
through fuse_common.h. Probablem is that this file does not have
unique defines so that they are unique to libfuse - on including
the file conflicts with libfuse users came up.

In principle all defines could be prefixed, but then most of them
are internal for libfuse compilation only. So this splits out
publically required defines to a new file 'libfuse_config.h'
and changes back to include of "fuse_config.h" only when
HAVE_LIBFUSE_PRIVATE_CONFIG_H is defined.

This also renames HAVE_LIBC_VERSIONED_SYMBOLS to
LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS, as it actually
better explains for libfuse users what that variable
is for.

1 files changed, 31 insertions, 14 deletions

diff --git a/meson.build b/meson.build
index eb7b477..fb6451a 100644
--- a/meson.build
+++ b/meson.build
@@ -16,11 +16,22 @@ elif platform == 'cygwin' or platform == 'windows'
         'Take a look at http://www.secfs.net/winfsp/ instead')       
 endif
 
+cc = meson.get_compiler('c')
+
 #
-# Feature detection
+# Feature detection, only available at libfuse compilation time,
+# but not for application linking to libfuse.
 #
-cfg = configuration_data()
-cc = meson.get_compiler('c')
+private_cfg = configuration_data()
+
+#
+# Feature detection, the resulting config file is installed
+# with the package.
+# Note: Symbols need to be care fully named, to avoid conflicts
+#       with applications linking to libfuse and including
+#       this config.
+#
+public_cfg = configuration_data()
 
 # Default includes when checking for presence of functions and
 # struct members
@@ -35,27 +46,27 @@ include_default = '''
 '''
 args_default = [ '-D_GNU_SOURCE' ]
 
-cfg.set_quoted('PACKAGE_VERSION', meson.project_version())
+private_cfg.set_quoted('PACKAGE_VERSION', meson.project_version())
 
 # Test for presence of some functions
 test_funcs = [ 'fork', 'fstatat', 'openat', 'readlinkat', 'pipe2',
                'splice', 'vmsplice', 'posix_fallocate', 'fdatasync',
                'utimensat', 'copy_file_range', 'fallocate' ]
 foreach func : test_funcs
-    cfg.set('HAVE_' + func.to_upper(),
+    private_cfg.set('HAVE_' + func.to_upper(),
         cc.has_function(func, prefix: include_default, args: args_default))
 endforeach
-cfg.set('HAVE_SETXATTR', 
+private_cfg.set('HAVE_SETXATTR', 
         cc.has_function('setxattr', prefix: '#include <sys/xattr.h>'))
-cfg.set('HAVE_ICONV', 
+private_cfg.set('HAVE_ICONV', 
         cc.has_function('iconv', prefix: '#include <iconv.h>'))
 
 # Test if structs have specific member
-cfg.set('HAVE_STRUCT_STAT_ST_ATIM',
+private_cfg.set('HAVE_STRUCT_STAT_ST_ATIM',
          cc.has_member('struct stat', 'st_atim',
                        prefix: include_default,
                        args: args_default))
-cfg.set('HAVE_STRUCT_STAT_ST_ATIMESPEC',
+private_cfg.set('HAVE_STRUCT_STAT_ST_ATIMESPEC',
          cc.has_member('struct stat', 'st_atimespec',
                        prefix: include_default,
                        args: args_default))
@@ -63,7 +74,7 @@ cfg.set('HAVE_STRUCT_STAT_ST_ATIMESPEC',
 #
 # Compiler configuration
 #
-add_project_arguments('-D_REENTRANT', '-DHAVE_CONFIG_H', '-Wno-sign-compare',
+add_project_arguments('-D_REENTRANT', '-DHAVE_LIBFUSE_PRIVATE_CONFIG_H', '-Wno-sign-compare',
                       '-Wstrict-prototypes', '-Wmissing-declarations', '-Wwrite-strings',
                       '-fno-strict-aliasing', language: 'c')
 add_project_arguments('-D_REENTRANT', '-DHAVE_CONFIG_H', '-D_GNU_SOURCE',
@@ -111,7 +122,7 @@ endif
 
 if versioned_symbols == 1
      message('Enabling versioned libc symbols')
-     cfg.set('HAVE_LIBC_VERSIONED_SYMBOLS', 1)
+     public_cfg.set('LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS', 1)
 
      # gcc-10 and newer support the symver attribute which we need to use if we
      # want to support LTO
@@ -140,9 +151,15 @@ else
      message('Disabling versioned libc symbols')
 endif
 
-# Write the test results into config.h (stored in build directory)
-configure_file(output: 'fuse_config.h',
-               configuration : cfg, install: true, install_dir: 'include/fuse3')
+# Write private test results into fuse_config.h (stored in build directory)
+configure_file(output: 'fuse_config.h', configuration : private_cfg)
+
+# Write the test results, installed with the package,
+# symbols need to be properly prefixed to avoid
+# symbol (define) conflicts
+configure_file(output: 'libfuse_config.h',
+               configuration : public_cfg,
+               install: true, install_dir: 'include/fuse3')
 
 # '.' will refer to current build directory, which contains config.h
 include_dirs = include_directories('include', 'lib', '.')