Update nfd to 1.1.0.

nfd/nfd.h

@@ -10,6 +10,23 @@
 #ifndef _NFD_H
 #define _NFD_H
 
+#if defined(_WIN32)
+#if defined(NFD_EXPORT)
+#define NFD_API __declspec(dllexport)
+#elif defined(NFD_SHARED)
+#define NFD_API __declspec(dllimport)
+#endif
+#else
+#if defined(NFD_EXPORT) || defined(NFD_SHARED)
+#if defined(__GNUC__) || defined(__clang__)
+#define NFD_API __attribute__((visibility("default")))
+#endif
+#endif
+#endif
+#ifndef NFD_API
+#define NFD_API
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif  // __cplusplus
@@ -64,21 +81,21 @@ typedef struct {
 
 /* free a file path that was returned by the dialogs */
 /* Note: use NFD_PathSet_FreePath to free path from pathset instead of this function */
-void NFD_FreePathN(nfdnchar_t* filePath);
+NFD_API void NFD_FreePathN(nfdnchar_t* filePath);
 
 /* initialize NFD - call this for every thread that might use NFD, before calling any other NFD
  * functions on that thread */
-nfdresult_t NFD_Init(void);
+NFD_API nfdresult_t NFD_Init(void);
 
 /* call this to de-initialize NFD, if NFD_Init returned NFD_OKAY */
-void NFD_Quit(void);
+NFD_API void NFD_Quit(void);
 
 /* single file open dialog */
 /* It is the caller's responsibility to free `outPath` via NFD_FreePathN() if this function returns
  * NFD_OKAY */
 /* If filterCount is zero, filterList is ignored (you can use NULL) */
 /* If defaultPath is NULL, the operating system will decide */
-nfdresult_t NFD_OpenDialogN(nfdnchar_t** outPath,
+NFD_API nfdresult_t NFD_OpenDialogN(nfdnchar_t** outPath,
                                     const nfdnfilteritem_t* filterList,
                                     nfdfiltersize_t filterCount,
                                     const nfdnchar_t* defaultPath);
@@ -88,7 +105,7 @@ nfdresult_t NFD_OpenDialogN(nfdnchar_t** outPath,
  * returns NFD_OKAY */
 /* If filterCount is zero, filterList is ignored (you can use NULL) */
 /* If defaultPath is NULL, the operating system will decide */
-nfdresult_t NFD_OpenDialogMultipleN(const nfdpathset_t** outPaths,
+NFD_API nfdresult_t NFD_OpenDialogMultipleN(const nfdpathset_t** outPaths,
                                             const nfdnfilteritem_t* filterList,
                                             nfdfiltersize_t filterCount,
                                             const nfdnchar_t* defaultPath);
@@ -98,7 +115,7 @@ nfdresult_t NFD_OpenDialogMultipleN(const nfdpathset_t** outPaths,
  * NFD_OKAY */
 /* If filterCount is zero, filterList is ignored (you can use NULL) */
 /* If defaultPath is NULL, the operating system will decide */
-nfdresult_t NFD_SaveDialogN(nfdnchar_t** outPath,
+NFD_API nfdresult_t NFD_SaveDialogN(nfdnchar_t** outPath,
                                     const nfdnfilteritem_t* filterList,
                                     nfdfiltersize_t filterCount,
                                     const nfdnchar_t* defaultPath,
@@ -108,16 +125,16 @@ nfdresult_t NFD_SaveDialogN(nfdnchar_t** outPath,
 /* It is the caller's responsibility to free `outPath` via NFD_FreePathN() if this function returns
  * NFD_OKAY */
 /* If defaultPath is NULL, the operating system will decide */
-nfdresult_t NFD_PickFolderN(nfdnchar_t** outPath, const nfdnchar_t* defaultPath);
+NFD_API nfdresult_t NFD_PickFolderN(nfdnchar_t** outPath, const nfdnchar_t* defaultPath);
 
 /* Get last error -- set when nfdresult_t returns NFD_ERROR */
 /* Returns the last error that was set, or NULL if there is no error. */
 /* The memory is owned by NFD and should not be freed by user code. */
 /* This is *always* ASCII printable characters, so it can be interpreted as UTF-8 without any
  * conversion. */
-const char* NFD_GetError(void);
+NFD_API const char* NFD_GetError(void);
 /* clear the error */
-void NFD_ClearError(void);
+NFD_API void NFD_ClearError(void);
 
 /* path set operations */
 #ifdef _WIN32
@@ -131,11 +148,11 @@ typedef unsigned int nfdpathsetsize_t;
 /* Gets the number of entries stored in pathSet */
 /* note that some paths might be invalid (NFD_ERROR will be returned by NFD_PathSet_GetPath), so we
  * might not actually have this number of usable paths */
-nfdresult_t NFD_PathSet_GetCount(const nfdpathset_t* pathSet, nfdpathsetsize_t* count);
+NFD_API nfdresult_t NFD_PathSet_GetCount(const nfdpathset_t* pathSet, nfdpathsetsize_t* count);
 /* Gets the UTF-8 path at offset index */
 /* It is the caller's responsibility to free `outPath` via NFD_PathSet_FreePathN() if this function
  * returns NFD_OKAY */
-nfdresult_t NFD_PathSet_GetPathN(const nfdpathset_t* pathSet,
+NFD_API nfdresult_t NFD_PathSet_GetPathN(const nfdpathset_t* pathSet,
                                          nfdpathsetsize_t index,
                                          nfdnchar_t** outPath);
 /* Free the path gotten by NFD_PathSet_GetPathN */
@@ -144,23 +161,24 @@ nfdresult_t NFD_PathSet_GetPathN(const nfdpathset_t* pathSet,
 #elif __APPLE__
 #define NFD_PathSet_FreePathN NFD_FreePathN
 #else
-void NFD_PathSet_FreePathN(const nfdnchar_t* filePath);
+NFD_API void NFD_PathSet_FreePathN(const nfdnchar_t* filePath);
 #endif  // _WIN32, __APPLE__
 
 /* Gets an enumerator of the path set. */
 /* It is the caller's responsibility to free `enumerator` via NFD_PathSet_FreeEnum() if this
  * function returns NFD_OKAY, and it should be freed before freeing the pathset. */
-nfdresult_t NFD_PathSet_GetEnum(const nfdpathset_t* pathSet, nfdpathsetenum_t* outEnumerator);
+NFD_API nfdresult_t NFD_PathSet_GetEnum(const nfdpathset_t* pathSet,
+                                        nfdpathsetenum_t* outEnumerator);
 /* Frees an enumerator of the path set. */
-void NFD_PathSet_FreeEnum(nfdpathsetenum_t* enumerator);
+NFD_API void NFD_PathSet_FreeEnum(nfdpathsetenum_t* enumerator);
 /* Gets the next item from the path set enumerator.
  * If there are no more items, then *outPaths will be set to NULL. */
 /* It is the caller's responsibility to free `*outPath` via NFD_PathSet_FreePath() if this
  * function returns NFD_OKAY and `*outPath` is not null */
-nfdresult_t NFD_PathSet_EnumNextN(nfdpathsetenum_t* enumerator, nfdnchar_t** outPath);
+NFD_API nfdresult_t NFD_PathSet_EnumNextN(nfdpathsetenum_t* enumerator, nfdnchar_t** outPath);
 
 /* Free the pathSet */
-void NFD_PathSet_Free(const nfdpathset_t* pathSet);
+NFD_API void NFD_PathSet_Free(const nfdpathset_t* pathSet);
 
 #ifdef _WIN32
 
@@ -177,12 +195,12 @@ typedef struct {
 /* UTF-8 compatibility functions */
 
 /* free a file path that was returned */
-void NFD_FreePathU8(nfdu8char_t* outPath);
+NFD_API void NFD_FreePathU8(nfdu8char_t* outPath);
 
 /* single file open dialog */
 /* It is the caller's responsibility to free `outPath` via NFD_FreePathU8() if this function returns
  * NFD_OKAY */
-nfdresult_t NFD_OpenDialogU8(nfdu8char_t** outPath,
+NFD_API nfdresult_t NFD_OpenDialogU8(nfdu8char_t** outPath,
                                      const nfdu8filteritem_t* filterList,
                                      nfdfiltersize_t count,
                                      const nfdu8char_t* defaultPath);
@@ -190,7 +208,7 @@ nfdresult_t NFD_OpenDialogU8(nfdu8char_t** outPath,
 /* multiple file open dialog */
 /* It is the caller's responsibility to free `outPaths` via NFD_PathSet_Free() if this function
  * returns NFD_OKAY */
-nfdresult_t NFD_OpenDialogMultipleU8(const nfdpathset_t** outPaths,
+NFD_API nfdresult_t NFD_OpenDialogMultipleU8(const nfdpathset_t** outPaths,
                                              const nfdu8filteritem_t* filterList,
                                              nfdfiltersize_t count,
                                              const nfdu8char_t* defaultPath);
@@ -198,7 +216,7 @@ nfdresult_t NFD_OpenDialogMultipleU8(const nfdpathset_t** outPaths,
 /* save dialog */
 /* It is the caller's responsibility to free `outPath` via NFD_FreePathU8() if this function returns
  * NFD_OKAY */
-nfdresult_t NFD_SaveDialogU8(nfdu8char_t** outPath,
+NFD_API nfdresult_t NFD_SaveDialogU8(nfdu8char_t** outPath,
                                      const nfdu8filteritem_t* filterList,
                                      nfdfiltersize_t count,
                                      const nfdu8char_t* defaultPath,
@@ -207,12 +225,12 @@ nfdresult_t NFD_SaveDialogU8(nfdu8char_t** outPath,
 /* select folder dialog */
 /* It is the caller's responsibility to free `outPath` via NFD_FreePathU8() if this function returns
  * NFD_OKAY */
-nfdresult_t NFD_PickFolderU8(nfdu8char_t** outPath, const nfdu8char_t* defaultPath);
+NFD_API nfdresult_t NFD_PickFolderU8(nfdu8char_t** outPath, const nfdu8char_t* defaultPath);
 
 /* Get the UTF-8 path at offset index */
 /* It is the caller's responsibility to free `outPath` via NFD_FreePathU8() if this function returns
  * NFD_OKAY */
-nfdresult_t NFD_PathSet_GetPathU8(const nfdpathset_t* pathSet,
+NFD_API nfdresult_t NFD_PathSet_GetPathU8(const nfdpathset_t* pathSet,
                                           nfdpathsetsize_t index,
                                           nfdu8char_t** outPath);
 
@@ -220,7 +238,7 @@ nfdresult_t NFD_PathSet_GetPathU8(const nfdpathset_t* pathSet,
  * If there are no more items, then *outPaths will be set to NULL. */
 /* It is the caller's responsibility to free `*outPath` via NFD_PathSet_FreePathU8() if this
  * function returns NFD_OKAY and `*outPath` is not null */
-nfdresult_t NFD_PathSet_EnumNextU8(nfdpathsetenum_t* enumerator, nfdu8char_t** outPath);
+NFD_API nfdresult_t NFD_PathSet_EnumNextU8(nfdpathsetenum_t* enumerator, nfdu8char_t** outPath);
 
 #define NFD_PathSet_FreePathU8 NFD_FreePathU8
 

nfd/nfd_portal.cpp

@@ -77,7 +77,10 @@ struct DBusMessage_Guard {
 DBusConnection* dbus_conn;
 /* current D-Bus error */
 DBusError dbus_err;
-/* current error (may be a pointer to the D-Bus error message above, or a pointer to some string
+/* current non D-Bus error */
+constexpr size_t OWNED_ERR_LEN = 1024;
+char owned_err[OWNED_ERR_LEN]{};
+/* current error (may be a pointer to dbus_err.message, owned_err, or a pointer to some string
  * literal) */
 const char* err_ptr = nullptr;
 /* the unique name of our connection, used for the Request handle; owned by D-Bus so we don't free
@@ -88,6 +91,14 @@ void NFDi_SetError(const char* msg) {
     err_ptr = msg;
 }
 
+void NFDi_SetFormattedError(const char* format, ...) {
+    va_list args;
+    va_start(args, format);
+    vsnprintf(owned_err, OWNED_ERR_LEN, format, args);
+    va_end(args);
+    err_ptr = owned_err;
+}
+
 template <typename T>
 T* copy(const T* begin, const T* end, T* out) {
     for (; begin != end; ++begin) {
@@ -119,6 +130,10 @@ constexpr const char* STR_CURRENT_FOLDER = "current_folder";
 constexpr const char* STR_CURRENT_FILE = "current_file";
 constexpr const char* STR_ALL_FILES = "All files";
 constexpr const char* STR_ASTERISK = "*";
+constexpr const char* DBUS_DESTINATION = "org.freedesktop.portal.Desktop";
+constexpr const char* DBUS_PATH = "/org/freedesktop/portal/desktop";
+constexpr const char* DBUS_FILECHOOSER_IFACE = "org.freedesktop.portal.FileChooser";
+constexpr const char* DBUS_REQUEST_IFACE = "org.freedesktop.portal.Request";
 
 template <bool Multiple, bool Directory>
 void AppendOpenFileQueryTitle(DBusMessageIter&);
@@ -469,7 +484,7 @@ void AppendSaveFileQueryDictEntryCurrentName(DBusMessageIter& sub_iter, const ch
     dbus_message_iter_close_container(&sub_iter, &sub_sub_iter);
 }
 
-void AppendSaveFileQueryDictEntryCurrentFolder(DBusMessageIter& sub_iter, const char* path) {
+void AppendOpenFileQueryDictEntryCurrentFolder(DBusMessageIter& sub_iter, const char* path) {
     if (!path) return;
     DBusMessageIter sub_sub_iter;
     DBusMessageIter variant_iter;
@@ -536,7 +551,8 @@ template <bool Multiple, bool Directory>
 void AppendOpenFileQueryParams(DBusMessage* query,
                                const char* handle_token,
                                const nfdnfilteritem_t* filterList,
-                               nfdfiltersize_t filterCount) {
+                               nfdfiltersize_t filterCount,
+                               const nfdnchar_t* defaultPath) {
     DBusMessageIter iter;
     dbus_message_iter_init_append(query, &iter);
 
@@ -550,6 +566,7 @@ void AppendOpenFileQueryParams(DBusMessage* query,
     AppendOpenFileQueryDictEntryMultiple<Multiple>(sub_iter);
     AppendOpenFileQueryDictEntryDirectory<Directory>(sub_iter);
     AppendOpenFileQueryDictEntryFilters<!Directory>(sub_iter, filterList, filterCount);
+    AppendOpenFileQueryDictEntryCurrentFolder(sub_iter, defaultPath);
     dbus_message_iter_close_container(&iter, &sub_iter);
 }
 
@@ -572,7 +589,7 @@ void AppendSaveFileQueryParams(DBusMessage* query,
     AppendOpenFileQueryDictEntryHandleToken(sub_iter, handle_token);
     AppendSaveFileQueryDictEntryFilters(sub_iter, filterList, filterCount, defaultName);
     AppendSaveFileQueryDictEntryCurrentName(sub_iter, defaultName);
-    AppendSaveFileQueryDictEntryCurrentFolder(sub_iter, defaultPath);
+    AppendOpenFileQueryDictEntryCurrentFolder(sub_iter, defaultPath);
     AppendSaveFileQueryDictEntryCurrentFile(sub_iter, defaultPath, defaultName);
     dbus_message_iter_close_container(&iter, &sub_iter);
 }
@@ -656,7 +673,9 @@ nfdresult_t ReadResponseResults(DBusMessage* msg, DBusMessageIter& resultsIter)
             return NFD_CANCEL;
         } else {
             // Some error occurred
-            NFDi_SetError("D-Bus file dialog interaction was ended abruptly.");
+            NFDi_SetFormattedError(
+                "D-Bus file dialog interaction was ended abruptly with response code %u.",
+                resp_code);
             return NFD_ERROR;
         }
     }
@@ -770,47 +789,37 @@ nfdresult_t ReadResponseUrisSingleAndCurrentExtension(DBusMessage* msg,
             [&tmp_extn](DBusMessageIter& current_filter_iter) {
                 // current_filter is best_effort, so if we fail, we still return NFD_OKAY.
                 if (dbus_message_iter_get_arg_type(&current_filter_iter) != DBUS_TYPE_STRUCT) {
-                    // NFDi_SetError("D-Bus response signal current_filter iter is not a struct.");
                     return NFD_OKAY;
                 }
                 DBusMessageIter current_filter_struct_iter;
                 dbus_message_iter_recurse(&current_filter_iter, &current_filter_struct_iter);
                 if (!dbus_message_iter_next(&current_filter_struct_iter)) {
-                    // NFDi_SetError("D-Bus response signal current_filter struct iter ended
-                    // prematurely.");
                     return NFD_OKAY;
                 }
                 if (dbus_message_iter_get_arg_type(&current_filter_struct_iter) !=
                     DBUS_TYPE_ARRAY) {
-                    // NFDi_SetError("D-Bus response signal URI sub iter is not a string.");
                     return NFD_OKAY;
                 }
                 DBusMessageIter current_filter_array_iter;
                 dbus_message_iter_recurse(&current_filter_struct_iter, &current_filter_array_iter);
                 if (dbus_message_iter_get_arg_type(&current_filter_array_iter) !=
                     DBUS_TYPE_STRUCT) {
-                    // NFDi_SetError("D-Bus response signal current_filter iter is not a struct.");
                     return NFD_OKAY;
                 }
                 DBusMessageIter current_filter_extn_iter;
                 dbus_message_iter_recurse(&current_filter_array_iter, &current_filter_extn_iter);
                 if (dbus_message_iter_get_arg_type(&current_filter_extn_iter) != DBUS_TYPE_UINT32) {
-                    // NFDi_SetError("D-Bus response signal URI sub iter is not a string.");
                     return NFD_OKAY;
                 }
                 dbus_uint32_t type;
                 dbus_message_iter_get_basic(&current_filter_extn_iter, &type);
                 if (type != 0) {
-                    // NFDi_SetError("Wrong filter type.");
                     return NFD_OKAY;
                 }
                 if (!dbus_message_iter_next(&current_filter_extn_iter)) {
-                    // NFDi_SetError("D-Bus response signal current_filter struct iter ended
-                    // prematurely.");
                     return NFD_OKAY;
                 }
                 if (dbus_message_iter_get_arg_type(&current_filter_extn_iter) != DBUS_TYPE_STRING) {
-                    // NFDi_SetError("D-Bus response signal URI sub iter is not a string.");
                     return NFD_OKAY;
                 }
                 dbus_message_iter_get_basic(&current_filter_extn_iter, &tmp_extn);
@@ -1013,22 +1022,25 @@ constexpr size_t FILE_URI_PREFIX_LEN = sizeof(FILE_URI_PREFIX) - 1;
 // buffer, and make outPath point to it, and returns NFD_OKAY. Otherwise, does not modify outPath
 // and returns NFD_ERROR (with the correct error set)
 nfdresult_t AllocAndCopyFilePath(const char* fileUri, char*& outPath) {
+    const char* file_uri_iter = fileUri;
     const char* prefix_begin = FILE_URI_PREFIX;
     const char* const prefix_end = FILE_URI_PREFIX + FILE_URI_PREFIX_LEN;
-    for (; prefix_begin != prefix_end; ++prefix_begin, ++fileUri) {
+    for (; prefix_begin != prefix_end; ++prefix_begin, ++file_uri_iter) {
-        if (*prefix_begin != *fileUri) {
+        if (*prefix_begin != *file_uri_iter) {
-            NFDi_SetError("D-Bus freedesktop portal returned a URI that is not a file URI.");
+            NFDi_SetFormattedError(
+                "D-Bus freedesktop portal returned \"%s\", which is not a file URI.", fileUri);
             return NFD_ERROR;
         }
     }
     size_t decoded_len;
     const char* file_uri_end;
-    if (!TryUriDecodeLen(fileUri, decoded_len, file_uri_end)) {
+    if (!TryUriDecodeLen(file_uri_iter, decoded_len, file_uri_end)) {
-        NFDi_SetError("D-Bus freedesktop portal returned a malformed URI.");
+        NFDi_SetFormattedError("D-Bus freedesktop portal returned a malformed URI \"%s\".",
+                               fileUri);
         return NFD_ERROR;
     }
     char* const path_without_prefix = NFDi_Malloc<char>(decoded_len + 1);
-    char* const out_end = UriDecodeUnchecked(fileUri, file_uri_end, path_without_prefix);
+    char* const out_end = UriDecodeUnchecked(file_uri_iter, file_uri_end, path_without_prefix);
     *out_end = '\0';
     outPath = path_without_prefix;
     return NFD_OKAY;
@@ -1055,19 +1067,22 @@ bool TryGetValidExtension(const char* extn,
 // expected to be either in the form "*.abc" or "*", but this function will check for it, and ignore
 // the extension if it is not in the correct form.
 nfdresult_t AllocAndCopyFilePathWithExtn(const char* fileUri, const char* extn, char*& outPath) {
+    const char* file_uri_iter = fileUri;
     const char* prefix_begin = FILE_URI_PREFIX;
     const char* const prefix_end = FILE_URI_PREFIX + FILE_URI_PREFIX_LEN;
-    for (; prefix_begin != prefix_end; ++prefix_begin, ++fileUri) {
+    for (; prefix_begin != prefix_end; ++prefix_begin, ++file_uri_iter) {
-        if (*prefix_begin != *fileUri) {
+        if (*prefix_begin != *file_uri_iter) {
-            NFDi_SetError("D-Bus freedesktop portal returned a URI that is not a file URI.");
+            NFDi_SetFormattedError(
+                "D-Bus freedesktop portal returned \"%s\", which is not a file URI.", fileUri);
             return NFD_ERROR;
         }
     }
 
     size_t decoded_len;
     const char* file_uri_end;
-    if (!TryUriDecodeLen(fileUri, decoded_len, file_uri_end)) {
+    if (!TryUriDecodeLen(file_uri_iter, decoded_len, file_uri_end)) {
-        NFDi_SetError("D-Bus freedesktop portal returned a malformed URI.");
+        NFDi_SetFormattedError("D-Bus freedesktop portal returned a malformed URI \"%s\".",
+                               fileUri);
         return NFD_ERROR;
     }
 
@@ -1084,14 +1099,14 @@ nfdresult_t AllocAndCopyFilePathWithExtn(const char* fileUri, const char* extn,
     if (*file_it == '.' || !TryGetValidExtension(extn, trimmed_extn, trimmed_extn_end)) {
         // has file extension already or no valid extension in `extn`
         char* const path_without_prefix = NFDi_Malloc<char>(decoded_len + 1);
-        char* const out_end = UriDecodeUnchecked(fileUri, file_uri_end, path_without_prefix);
+        char* const out_end = UriDecodeUnchecked(file_uri_iter, file_uri_end, path_without_prefix);
         *out_end = '\0';
         outPath = path_without_prefix;
     } else {
         // no file extension and we have a valid extension
         char* const path_without_prefix =
             NFDi_Malloc<char>(decoded_len + (trimmed_extn_end - trimmed_extn));
-        char* const out_mid = UriDecodeUnchecked(fileUri, file_uri_end, path_without_prefix);
+        char* const out_mid = UriDecodeUnchecked(file_uri_iter, file_uri_end, path_without_prefix);
         char* const out_end = copy(trimmed_extn, trimmed_extn_end, out_mid);
         *out_end = '\0';
         outPath = path_without_prefix;
@@ -1107,7 +1122,8 @@ nfdresult_t AllocAndCopyFilePathWithExtn(const char* fileUri, const char* extn,
 template <bool Multiple, bool Directory>
 nfdresult_t NFD_DBus_OpenFile(DBusMessage*& outMsg,
                               const nfdnfilteritem_t* filterList,
-                              nfdfiltersize_t filterCount) {
+                              nfdfiltersize_t filterCount,
+                              const nfdnchar_t* defaultPath) {
     const char* handle_token_ptr;
     char* handle_obj_path = MakeUniqueObjectPath(&handle_token_ptr);
     Free_Guard<char> handle_obj_path_guard(handle_obj_path);
@@ -1124,13 +1140,11 @@ nfdresult_t NFD_DBus_OpenFile(DBusMessage*& outMsg,
     // TODO: use XOpenDisplay()/XGetInputFocus() to find xid of window... but what should one do on
     // Wayland?
 
-    DBusMessage* query = dbus_message_new_method_call("org.freedesktop.portal.Desktop",
+    DBusMessage* query = dbus_message_new_method_call(
-                                                      "/org/freedesktop/portal/desktop",
+        DBUS_DESTINATION, DBUS_PATH, DBUS_FILECHOOSER_IFACE, "OpenFile");
-                                                      "org.freedesktop.portal.FileChooser",
-                                                      "OpenFile");
     DBusMessage_Guard query_guard(query);
     AppendOpenFileQueryParams<Multiple, Directory>(
-        query, handle_token_ptr, filterList, filterCount);
+        query, handle_token_ptr, filterList, filterCount, defaultPath);
 
     DBusMessage* reply =
         dbus_connection_send_with_reply_and_block(dbus_conn, query, DBUS_TIMEOUT_INFINITE, &err);
@@ -1169,7 +1183,7 @@ nfdresult_t NFD_DBus_OpenFile(DBusMessage*& outMsg,
             DBusMessage* msg = dbus_connection_pop_message(dbus_conn);
             if (!msg) break;
 
-            if (dbus_message_is_signal(msg, "org.freedesktop.portal.Request", "Response")) {
+            if (dbus_message_is_signal(msg, DBUS_REQUEST_IFACE, "Response")) {
                 // this is the response we're looking for
                 outMsg = msg;
                 return NFD_OKAY;
@@ -1208,10 +1222,8 @@ nfdresult_t NFD_DBus_SaveFile(DBusMessage*& outMsg,
     // TODO: use XOpenDisplay()/XGetInputFocus() to find xid of window... but what should one do on
     // Wayland?
 
-    DBusMessage* query = dbus_message_new_method_call("org.freedesktop.portal.Desktop",
+    DBusMessage* query = dbus_message_new_method_call(
-                                                      "/org/freedesktop/portal/desktop",
+        DBUS_DESTINATION, DBUS_PATH, DBUS_FILECHOOSER_IFACE, "SaveFile");
-                                                      "org.freedesktop.portal.FileChooser",
-                                                      "SaveFile");
     DBusMessage_Guard query_guard(query);
     AppendSaveFileQueryParams(
         query, handle_token_ptr, filterList, filterCount, defaultPath, defaultName);
@@ -1253,7 +1265,7 @@ nfdresult_t NFD_DBus_SaveFile(DBusMessage*& outMsg,
             DBusMessage* msg = dbus_connection_pop_message(dbus_conn);
             if (!msg) break;
 
-            if (dbus_message_is_signal(msg, "org.freedesktop.portal.Request", "Response")) {
+            if (dbus_message_is_signal(msg, DBUS_REQUEST_IFACE, "Response")) {
                 // this is the response we're looking for
                 outMsg = msg;
                 return NFD_OKAY;
@@ -1267,6 +1279,57 @@ nfdresult_t NFD_DBus_SaveFile(DBusMessage*& outMsg,
     return NFD_ERROR;
 }
 
+nfdresult_t NFD_DBus_GetVersion(dbus_uint32_t& outVersion) {
+    DBusError err;  // need a separate error object because we don't want to mess with the old one
+                    // if it's stil set
+    dbus_error_init(&err);
+
+    DBusMessage* query = dbus_message_new_method_call("org.freedesktop.portal.Desktop",
+                                                      "/org/freedesktop/portal/desktop",
+                                                      "org.freedesktop.DBus.Properties",
+                                                      "Get");
+    DBusMessage_Guard query_guard(query);
+    {
+        DBusMessageIter iter;
+        dbus_message_iter_init_append(query, &iter);
+
+        constexpr const char* STR_INTERFACE = "org.freedesktop.portal.FileChooser";
+        dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &STR_INTERFACE);
+        constexpr const char* STR_VERSION = "version";
+        dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &STR_VERSION);
+    }
+
+    DBusMessage* reply =
+        dbus_connection_send_with_reply_and_block(dbus_conn, query, DBUS_TIMEOUT_INFINITE, &err);
+    if (!reply) {
+        dbus_error_free(&dbus_err);
+        dbus_move_error(&err, &dbus_err);
+        NFDi_SetError(dbus_err.message);
+        return NFD_ERROR;
+    }
+    DBusMessage_Guard reply_guard(reply);
+    {
+        DBusMessageIter iter;
+        if (!dbus_message_iter_init(reply, &iter)) {
+            NFDi_SetError("D-Bus reply for version query is missing an argument.");
+            return NFD_ERROR;
+        }
+        if (dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT) {
+            NFDi_SetError("D-Bus reply for version query is not a variant.");
+            return NFD_ERROR;
+        }
+        DBusMessageIter variant_iter;
+        dbus_message_iter_recurse(&iter, &variant_iter);
+        if (dbus_message_iter_get_arg_type(&variant_iter) != DBUS_TYPE_UINT32) {
+            NFDi_SetError("D-Bus reply for version query is not a uint32.");
+            return NFD_ERROR;
+        }
+        dbus_message_iter_get_basic(&variant_iter, &outVersion);
+    }
+
+    return NFD_OKAY;
+}
+
 }  // namespace
 
 /* public */
@@ -1281,7 +1344,7 @@ void NFD_ClearError(void) {
 }
 
 nfdresult_t NFD_Init(void) {
-    // Initialize dbus_error
+    // Initialize dbus_err
     dbus_error_init(&dbus_err);
     // Get DBus connection
     dbus_conn = dbus_bus_get(DBUS_BUS_SESSION, &dbus_err);
@@ -1312,11 +1375,10 @@ nfdresult_t NFD_OpenDialogN(nfdnchar_t** outPath,
                             const nfdnfilteritem_t* filterList,
                             nfdfiltersize_t filterCount,
                             const nfdnchar_t* defaultPath) {
-    (void)defaultPath;  // Default path not supported for portal backend
-
     DBusMessage* msg;
     {
-        const nfdresult_t res = NFD_DBus_OpenFile<false, false>(msg, filterList, filterCount);
+        const nfdresult_t res =
+            NFD_DBus_OpenFile<false, false>(msg, filterList, filterCount, defaultPath);
         if (res != NFD_OKAY) {
             return res;
         }
@@ -1338,11 +1400,10 @@ nfdresult_t NFD_OpenDialogMultipleN(const nfdpathset_t** outPaths,
                                     const nfdnfilteritem_t* filterList,
                                     nfdfiltersize_t filterCount,
                                     const nfdnchar_t* defaultPath) {
-    (void)defaultPath;  // Default path not supported for portal backend
-
     DBusMessage* msg;
     {
-        const nfdresult_t res = NFD_DBus_OpenFile<true, false>(msg, filterList, filterCount);
+        const nfdresult_t res =
+            NFD_DBus_OpenFile<true, false>(msg, filterList, filterCount, defaultPath);
         if (res != NFD_OKAY) {
             return res;
         }
@@ -1401,9 +1462,25 @@ nfdresult_t NFD_SaveDialogN(nfdnchar_t** outPath,
 nfdresult_t NFD_PickFolderN(nfdnchar_t** outPath, const nfdnchar_t* defaultPath) {
     (void)defaultPath;  // Default path not supported for portal backend
 
+    {
+        dbus_uint32_t version;
+        const nfdresult_t res = NFD_DBus_GetVersion(version);
+        if (res != NFD_OKAY) {
+            return res;
+        }
+        if (version < 3) {
+            NFDi_SetFormattedError(
+                "The xdg-desktop-portal installed on this system does not support a folder picker; "
+                "at least version 3 of the org.freedesktop.portal.FileChooser interface is "
+                "required but the installed interface version is %u.",
+                version);
+            return NFD_ERROR;
+        }
+    }
+
     DBusMessage* msg;
     {
-        const nfdresult_t res = NFD_DBus_OpenFile<false, true>(msg, nullptr, 0);
+        const nfdresult_t res = NFD_DBus_OpenFile<false, true>(msg, nullptr, 0, defaultPath);
         if (res != NFD_OKAY) {
             return res;
         }
@@ -1435,10 +1512,15 @@ nfdresult_t NFD_PathSet_GetPathN(const nfdpathset_t* pathSet,
     DBusMessage* msg = const_cast<DBusMessage*>(static_cast<const DBusMessage*>(pathSet));
     DBusMessageIter uri_iter;
     ReadResponseUrisUnchecked(msg, uri_iter);
-    while (index > 0) {
+    nfdpathsetsize_t rem_index = index;
-        --index;
+    while (rem_index > 0) {
+        --rem_index;
         if (!dbus_message_iter_next(&uri_iter)) {
-            NFDi_SetError("Index out of bounds.");
+            NFDi_SetFormattedError(
+                "Index out of bounds; you asked for index %u but there are only %u file paths "
+                "available.",
+                index,
+                index - rem_index);
             return NFD_ERROR;
         }
     }