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.

7 files changed, 46 insertions, 24 deletions

diff --git a/include/fuse.h b/include/fuse.h
index 2888d2b..6f162dd 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -948,15 +948,15 @@ struct fuse *fuse_new_30(struct fuse_args *args, const struct fuse_operations *o
 			 size_t op_size, void *private_data);
 #define fuse_new(args, op, size, data) fuse_new_30(args, op, size, data)
 #else
-#if (defined(HAVE_LIBC_VERSIONED_SYMBOLS))
+#if (defined(LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS))
 struct fuse *fuse_new(struct fuse_args *args, const struct fuse_operations *op,
 		      size_t op_size, void *private_data);
-#else /* HAVE_LIBC_VERSIONED_SYMBOLS */
+#else /* LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS */
 struct fuse *fuse_new_31(struct fuse_args *args,
 		      const struct fuse_operations *op,
 		      size_t op_size, void *user_data);
 #define fuse_new(args, op, size, data) fuse_new_31(args, op, size, data)
-#endif /* HAVE_LIBC_VERSIONED_SYMBOLS */
+#endif /* LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS */
 #endif
 
 /**
@@ -1053,11 +1053,11 @@ int fuse_loop_mt_32(struct fuse *f, struct fuse_loop_config *config);
  *
  * See also: fuse_loop()
  */
-#if (defined(HAVE_LIBC_VERSIONED_SYMBOLS))
+#if (defined(LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS))
 int fuse_loop_mt(struct fuse *f, struct fuse_loop_config *config);
 #else
 #define fuse_loop_mt(f, config) fuse_loop_mt_312(f, config)
-#endif /* HAVE_LIBC_VERSIONED_SYMBOLS */
+#endif /* LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS */
 #endif
 
 
diff --git a/include/fuse_common.h b/include/fuse_common.h
index 1d050bb..8ee1a34 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -14,7 +14,12 @@
 #ifndef FUSE_COMMON_H_
 #define FUSE_COMMON_H_
 
+#ifdef HAVE_LIBFUSE_PRIVATE_CONFIG_H
 #include "fuse_config.h"
+#endif
+
+#include "libfuse_config.h"
+
 #include "fuse_opt.h"
 #include "fuse_log.h"
 #include <stdint.h>
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index 96088d7..9099e45 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1958,7 +1958,7 @@ struct fuse_cmdline_opts {
  * @param opts output argument for parsed options
  * @return 0 on success, -1 on failure
  */
-#if (defined(HAVE_LIBC_VERSIONED_SYMBOLS))
+#if (defined(LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS))
 int fuse_parse_cmdline(struct fuse_args *args,
 		       struct fuse_cmdline_opts *opts);
 #else
@@ -2076,7 +2076,7 @@ int fuse_session_loop(struct fuse_session *se);
 	int fuse_session_loop_mt_32(struct fuse_session *se, struct fuse_loop_config *config);
 	#define fuse_session_loop_mt(se, config) fuse_session_loop_mt_32(se, config)
 #else
-	#if (defined(HAVE_LIBC_VERSIONED_SYMBOLS))
+	#if (defined(LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS))
 		/**
 		 * Enter a multi-threaded event loop.
 		 *
diff --git a/lib/compat.c b/lib/compat.c
index cab6cbf..0bac39e 100644
--- a/lib/compat.c
+++ b/lib/compat.c
@@ -34,7 +34,7 @@
 /**
  * Compatibility ABI symbol for systems that do not support version symboling
  */
-#if (!defined(HAVE_LIBC_VERSIONED_SYMBOLS))
+#if (!defined(LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS))
 /* With current libfuse fuse_parse_cmdline is a macro pointing to the
  * versioned function. Here in this file we need to provide the ABI symbol
  * and the redirecting macro is conflicting.
diff --git a/lib/fuse_misc.h b/lib/fuse_misc.h
index 37e3635..855edc3 100644
--- a/lib/fuse_misc.h
+++ b/lib/fuse_misc.h
@@ -15,7 +15,7 @@
   Note: "@@" denotes the default symbol, "@" is binary a compat version.
 
 */
-#ifdef HAVE_LIBC_VERSIONED_SYMBOLS
+#ifdef LIBFUSE_BUILT_WITH_VERSIONED_SYMBOLS
 # if HAVE_SYMVER_ATTRIBUTE
 #  define FUSE_SYMVER(sym1, sym2) __attribute__ ((symver (sym2)))
 # else
diff --git a/lib/meson.build b/lib/meson.build
index 54d0759..9044630 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -11,7 +11,7 @@ else
 endif
 
 deps = [ thread_dep ]
-if cfg.get('HAVE_ICONV')
+if private_cfg.get('HAVE_ICONV')
    libfuse_sources += [ 'modules/iconv.c' ]
    libiconv = cc.find_library('iconv', required: false)
    if libiconv.found()
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', '.')