Use a temporary file when saving boards/schematics to make the operation more atomic

Fixes https://gitlab.com/kicad/code/kicad/-/issues/4517

eeschema/files-io.cpp

@@ -110,7 +110,7 @@ bool SCH_EDIT_FRAME::SaveEEFile( SCH_SHEET* aSheet, bool aSaveUnderNewName,
         if( backupFileName.FileExists() )
             wxRemoveFile( backupFileName.GetFullPath() );
 
-        if( !wxRenameFile( schematicFileName.GetFullPath(), backupFileName.GetFullPath() ) )
+        if( !wxCopyFile( schematicFileName.GetFullPath(), backupFileName.GetFullPath() ) )
         {
             msg.Printf( _( "Could not save backup of file \"%s\"" ),
                         schematicFileName.GetFullPath() );
@@ -118,6 +118,10 @@ bool SCH_EDIT_FRAME::SaveEEFile( SCH_SHEET* aSheet, bool aSaveUnderNewName,
         }
     }
 
+    wxFileName tempFile( schematicFileName );
+    tempFile.SetName( wxT( "." ) + tempFile.GetName() );
+    tempFile.SetExt( tempFile.GetExt() + wxT( "$" ) );
+
     // Save
     wxLogTrace( traceAutoSave,
                 wxT( "Saving file <" ) + schematicFileName.GetFullPath() + wxT( ">" ) );
@@ -128,7 +132,7 @@ bool SCH_EDIT_FRAME::SaveEEFile( SCH_SHEET* aSheet, bool aSaveUnderNewName,
 
     try
     {
-        pi->Save( schematicFileName.GetFullPath(), aSheet, &Schematic() );
+        pi->Save( tempFile.GetFullPath(), aSheet, &Schematic() );
         success = true;
     }
     catch( const IO_ERROR& ioe )
@@ -137,12 +141,32 @@ bool SCH_EDIT_FRAME::SaveEEFile( SCH_SHEET* aSheet, bool aSaveUnderNewName,
                     schematicFileName.GetFullPath(), ioe.What() );
         DisplayError( this, msg );
 
-        msg.Printf( _( "Failed to save \"%s\"" ), schematicFileName.GetFullPath() );
+        msg.Printf( _( "Failed to create temporary file \"%s\"" ), tempFile.GetFullPath() );
         AppendMsgPanel( wxEmptyString, msg, CYAN );
 
+        // In case we started a file but didn't fully write it, clean up
+        wxRemoveFile( tempFile.GetFullPath() );
+
         success = false;
     }
 
+    if( success )
+    {
+        // Replace the original with the temporary file we just wrote
+        success = wxRenameFile( tempFile.GetFullPath(), schematicFileName.GetFullPath() );
+
+        if( !success )
+        {
+            msg.Printf( _( "Error saving schematic file \"%s\".\n"
+                           "Failed to rename temporary file %s" ),
+                        schematicFileName.GetFullPath(), tempFile.GetFullPath() );
+            DisplayError( this, msg );
+
+            msg.Printf( _( "Failed to rename temporary file \"%s\"" ), tempFile.GetFullPath() );
+            AppendMsgPanel( wxEmptyString, msg, CYAN );
+        }
+    }
+
     if( success )
     {
         // Delete auto save file.

pagelayout_editor/files.cpp

@@ -263,9 +263,27 @@ bool PL_EDITOR_FRAME::InsertPageLayoutDescrFile( const wxString& aFullFileName )
 
 bool PL_EDITOR_FRAME::SavePageLayoutDescrFile( const wxString& aFullFileName )
 {
-    if( ! aFullFileName.IsEmpty() )
+    if( !aFullFileName.IsEmpty() )
     {
-        WS_DATA_MODEL::GetTheInstance().Save( aFullFileName );
+        wxFileName tempFile( aFullFileName );
+        tempFile.SetName( wxT( "." ) + tempFile.GetName() );
+        tempFile.SetExt( tempFile.GetExt() + wxT( "$" ) );
+
+        try
+        {
+            WS_DATA_MODEL::GetTheInstance().Save( tempFile.GetFullPath() );
+        }
+        catch( const IO_ERROR& ioe )
+        {
+            // In case we started a file but didn't fully write it, clean up
+            wxRemoveFile( tempFile.GetFullPath() );
+
+            return false;
+        }
+
+        if( !wxRenameFile( tempFile.GetFullPath(), aFullFileName ) )
+            return false;
+
         GetScreen()->ClrModify();
         return true;
     }

pcbnew/files.cpp

@@ -685,8 +685,8 @@ wxString PCB_EDIT_FRAME::createBackupFile( const wxString& aFileName )
         if( backupFileName.FileExists() )
             wxRemoveFile( backupFileName.GetFullPath() );
 
-        // Rename the current file from <xxx>.kicad_pcb to <xxx>.kicad_pcb-bak
+        // Copy the current file from <xxx>.kicad_pcb to <xxx>.kicad_pcb-bak
-        if( !wxRenameFile( fn.GetFullPath(), backupFileName.GetFullPath() ) )
+        if( !wxCopyFile( fn.GetFullPath(), backupFileName.GetFullPath() ) )
         {
             wxString msg = wxString::Format( _(
                     "Warning: unable to create backup file \"%s\"" ),
@@ -729,6 +729,10 @@ bool PCB_EDIT_FRAME::SavePcbFile( const wxString& aFileName, bool aCreateBackupF
         backupFileName = createBackupFile( aFileName );
     }
 
+    wxFileName tempFile( aFileName );
+    tempFile.SetName( wxT( "." ) + tempFile.GetName() );
+    tempFile.SetExt( tempFile.GetExt() + wxT( "$" ) );
+
     GetBoard()->SynchronizeNetsAndNetClasses();
 
     // Select default Netclass before writing file. Useful to save default values in headers.
@@ -747,9 +751,9 @@ bool PCB_EDIT_FRAME::SavePcbFile( const wxString& aFileName, bool aCreateBackupF
     {
         PLUGIN::RELEASER    pi( IO_MGR::PluginFind( IO_MGR::KICAD_SEXP ) );
 
-        wxASSERT( pcbFileName.IsAbsolute() );
+        wxASSERT( tempFile.IsAbsolute() );
 
-        pi->Save( pcbFileName.GetFullPath(), GetBoard(), NULL );
+        pi->Save( tempFile.GetFullPath(), GetBoard(), NULL );
     }
     catch( const IO_ERROR& ioe )
     {
@@ -759,7 +763,26 @@ bool PCB_EDIT_FRAME::SavePcbFile( const wxString& aFileName, bool aCreateBackupF
                 );
         DisplayError( this, msg );
 
-        lowerTxt.Printf( _( "Failed to create \"%s\"" ), pcbFileName.GetFullPath() );
+        lowerTxt.Printf( _( "Failed to create temporary file \"%s\"" ), tempFile.GetFullPath() );
+
+        AppendMsgPanel( upperTxt, lowerTxt, CYAN );
+
+        // In case we started a file but didn't fully write it, clean up
+        wxRemoveFile( tempFile.GetFullPath() );
+
+        return false;
+    }
+
+    // If save succeeded, replace the original with what we just wrote
+    if( !wxRenameFile( tempFile.GetFullPath(), pcbFileName.GetFullPath() ) )
+    {
+        wxString msg = wxString::Format( _(
+                "Error saving board file \"%s\".\nFailed to rename temporary file \"%s\"" ),
+                pcbFileName.GetFullPath(), tempFile.GetFullPath()
+                );
+        DisplayError( this, msg );
+
+        lowerTxt.Printf( _( "Failed to rename temporary file \"%s\"" ), tempFile.GetFullPath() );
 
         AppendMsgPanel( upperTxt, lowerTxt, CYAN );