Add visibility symbols (#134)

They are required to properly build DLLs on Windows, and improve the
quality of shared objects on Linux.
See https://gcc.gnu.org/wiki/Visibility for details.

This issue was first discovered here:
https://github.com/mesonbuild/wrapdb/pull/340#issuecomment-1075102565

cpp/INIReader.h

@@ -15,6 +15,27 @@
 #include <map>
 #include <string>
 
+// Visibility symbols, required for Windows DLLs
+#ifndef INI_API
+#if defined _WIN32 || defined __CYGWIN__
+#	ifdef INI_SHARED_LIB
+#		ifdef INI_SHARED_LIB_BUILDING
+#			define INI_API __declspec(dllexport)
+#		else
+#			define INI_API __declspec(dllimport)
+#		endif
+#	else
+#		define INI_API
+#	endif
+#else
+#	if defined(__GNUC__) && __GNUC__ >= 4
+#		define INI_API __attribute__ ((visibility ("default")))
+#	else
+#		define INI_API
+#	endif
+#endif
+#endif
+
 // Read an INI file into easy-to-access name/value pairs. (Note that I've gone
 // for simplicity here rather than speed, but it should be pretty decent.)
 class INIReader
@@ -22,45 +43,45 @@ class INIReader
 public:
     // Construct INIReader and parse given filename. See ini.h for more info
     // about the parsing.
-    explicit INIReader(const std::string& filename);
+    INI_API explicit INIReader(const std::string& filename);
 
     // Construct INIReader and parse given buffer. See ini.h for more info
     // about the parsing.
-    explicit INIReader(const char *buffer, size_t buffer_size);
+    INI_API explicit INIReader(const char *buffer, size_t buffer_size);
 
     // Return the result of ini_parse(), i.e., 0 on success, line number of
     // first error on parse error, or -1 on file open error.
-    int ParseError() const;
+    INI_API int ParseError() const;
 
     // Get a string value from INI file, returning default_value if not found.
-    std::string Get(const std::string& section, const std::string& name,
+    INI_API std::string Get(const std::string& section, const std::string& name,
                     const std::string& default_value) const;
 
     // Get a string value from INI file, returning default_value if not found,
     // empty, or contains only whitespace.
-    std::string GetString(const std::string& section, const std::string& name,
+    INI_API std::string GetString(const std::string& section, const std::string& name,
                     const std::string& default_value) const;
 
     // Get an integer (long) value from INI file, returning default_value if
     // not found or not a valid integer (decimal "1234", "-1234", or hex "0x4d2").
-    long GetInteger(const std::string& section, const std::string& name, long default_value) const;
+    INI_API long GetInteger(const std::string& section, const std::string& name, long default_value) const;
 
     // Get a real (floating point double) value from INI file, returning
     // default_value if not found or not a valid floating point value
     // according to strtod().
-    double GetReal(const std::string& section, const std::string& name, double default_value) const;
+    INI_API double GetReal(const std::string& section, const std::string& name, double default_value) const;
 
     // Get a boolean value from INI file, returning default_value if not found or if
     // not a valid true/false value. Valid true values are "true", "yes", "on", "1",
     // and valid false values are "false", "no", "off", "0" (not case sensitive).
-    bool GetBoolean(const std::string& section, const std::string& name, bool default_value) const;
+    INI_API bool GetBoolean(const std::string& section, const std::string& name, bool default_value) const;
 
     // Return true if the given section exists (section must contain at least
     // one name=value pair).
-    bool HasSection(const std::string& section) const;
+    INI_API bool HasSection(const std::string& section) const;
 
     // Return true if a value exists with the given section and field names.
-    bool HasValue(const std::string& section, const std::string& name) const;
+    INI_API bool HasValue(const std::string& section, const std::string& name) const;
 
 private:
     int _error;

ini.h

@@ -26,6 +26,27 @@ extern "C" {
 #define INI_HANDLER_LINENO 0
 #endif
 
+/* Visibility symbols, required for Windows DLLs */
+#ifndef INI_API
+#if defined _WIN32 || defined __CYGWIN__
+#	ifdef INI_SHARED_LIB
+#		ifdef INI_SHARED_LIB_BUILDING
+#			define INI_API __declspec(dllexport)
+#		else
+#			define INI_API __declspec(dllimport)
+#		endif
+#	else
+#		define INI_API
+#	endif
+#else
+#	if defined(__GNUC__) && __GNUC__ >= 4
+#		define INI_API __attribute__ ((visibility ("default")))
+#	else
+#		define INI_API
+#	endif
+#endif
+#endif
+
 /* Typedef for prototype of handler function. */
 #if INI_HANDLER_LINENO
 typedef int (*ini_handler)(void* user, const char* section,
@@ -52,22 +73,22 @@ typedef char* (*ini_reader)(char* str, int num, void* stream);
    stop on first error), -1 on file open error, or -2 on memory allocation
    error (only when INI_USE_STACK is zero).
 */
-int ini_parse(const char* filename, ini_handler handler, void* user);
+INI_API int ini_parse(const char* filename, ini_handler handler, void* user);
 
 /* Same as ini_parse(), but takes a FILE* instead of filename. This doesn't
    close the file when it's finished -- the caller must do that. */
-int ini_parse_file(FILE* file, ini_handler handler, void* user);
+INI_API int ini_parse_file(FILE* file, ini_handler handler, void* user);
 
 /* Same as ini_parse(), but takes an ini_reader function pointer instead of
    filename. Used for implementing custom or string-based I/O (see also
    ini_parse_string). */
-int ini_parse_stream(ini_reader reader, void* stream, ini_handler handler,
+INI_API int ini_parse_stream(ini_reader reader, void* stream, ini_handler handler,
                      void* user);
 
 /* Same as ini_parse(), but takes a zero-terminated string with the INI data
 instead of a file. Useful for parsing INI data from a network socket or
 already in memory. */
-int ini_parse_string(const char* string, ini_handler handler, void* user);
+INI_API int ini_parse_string(const char* string, ini_handler handler, void* user);
 
 /* Nonzero to allow multi-line value parsing, in the style of Python's
    configparser. If allowed, ini_parse() will call the handler with the same

meson.build

@@ -6,6 +6,7 @@ project('inih',
 #### options ####
 arg_static = []
 distro_install = get_option('distro_install')
+extra_args = []
 
 if distro_install
     pkg = import('pkgconfig')
@@ -55,15 +56,26 @@ else
     endif
 endif
 
+if host_machine.system() == 'windows'
+    lib = get_option('default_library')
+    if lib == 'both'
+        error('default_library=both is not supported on Windows')
+    elif lib == 'shared'
+        extra_args += '-DINI_SHARED_LIB'
+        add_project_arguments('-DINI_SHARED_LIB_BUILDING', language: ['c', 'cpp'])
+    endif
+endif
+
 #### inih ####
 inc_inih = include_directories('.')
 
 lib_inih = library('inih',
     ['ini.c'],
     include_directories : inc_inih,
-    c_args : arg_static,
+    c_args : [arg_static, extra_args],
     install : distro_install,
-    soversion : '0'
+    soversion : '0',
+    gnu_symbol_visibility: 'hidden'
 )
 
 if distro_install
@@ -72,12 +84,13 @@ if distro_install
     pkg.generate(lib_inih,
         name : 'inih',
         description : 'simple .INI file parser',
+        extra_cflags : extra_args,
     )
 endif
 
 inih_dep = declare_dependency(
     link_with : lib_inih,
-    compile_args : arg_static,
+    compile_args : arg_static + extra_args,
     include_directories : inc_inih
 )
 
@@ -88,10 +101,12 @@ if get_option('with_INIReader')
 
     lib_INIReader = library('INIReader',
         ['cpp/INIReader.cpp'],
+        cpp_args : extra_args,
         include_directories : inc_INIReader,
         dependencies : inih_dep,
         install : distro_install,
-        soversion : '0'
+        soversion : '0',
+        gnu_symbol_visibility: 'hidden'
     )
 
     if distro_install
@@ -100,11 +115,13 @@ if get_option('with_INIReader')
         pkg.generate(lib_INIReader,
             name : 'INIReader',
             description : 'simple .INI file parser for C++',
+            extra_cflags : extra_args,
         )
     endif
 
     INIReader_dep = declare_dependency(
         link_with : lib_INIReader,
-        include_directories : inc_INIReader
+        include_directories : inc_INIReader,
+        compile_args : extra_args
     )
 endif