mirror of
https://github.com/cookiengineer/audacity
synced 2025-10-26 07:13:49 +01:00
Strong exception safety in all uses of XMLFileWriter...
... Strong, meaning that the file at the specified path is created or modified only if all write operations complete without exceptions, barring one very unlikely possibility that a final file rename fails, but even in that case the output is successfully written to some path. This commit does not add throws, but changes the type thrown to a subclass of AudacityException, so that GuardedCall will cause the user to see an error dialog in all cases. Duplicated logic for making temporary files and backups is now all in one place, the class XMLWriter. There may be more new GuardedCalls than necessary -- the catch-all for the event loop, AudacityApp::OnExceptionInMainLoop, might be trusted instead in some cases -- but they are sufficient.
This commit is contained in:
Paul Licameli
@@ -738,243 +738,207 @@ bool AutoSaveFile::Decode(const wxString & fileName)
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return true;
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}
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XMLFileWriter out;
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wxString tempName;
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len = file.Length() - len;
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using Chars = ArrayOf < char >;
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using WxChars = ArrayOf < wxChar >;
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Chars buf{ len };
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if (file.Read(buf.get(), len) != len)
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{
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using Chars = ArrayOf < char >;
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using WxChars = ArrayOf < wxChar >;
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Chars buf{ len };
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return false;
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}
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if (file.Read(buf.get(), len) != len)
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{
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return false;
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}
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wxMemoryInputStream in(buf.get(), len);
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wxMemoryInputStream in(buf.get(), len);
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file.Close();
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file.Close();
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// JKC: ANSWER-ME: Is the try catch actually doing anything?
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// If it is useful, why are we not using it everywhere?
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// If it isn't useful, why are we doing it here?
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// PRL: Yes, now we are doing GuardedCall everywhere that XMLFileWriter is
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// used.
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return GuardedCall< bool >( [&] {
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XMLFileWriter out{ fileName, _("Error Decoding File") };
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// Decode to a temporary file to preserve the original.
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tempName = fn.CreateTempFileName(fnPath);
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bool opened = false;
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// JKC: ANSWER-ME: Is the try catch actually doing anything?
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// If it is useful, why are we not using it everywhere?
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// If it isn't useful, why are we doing it here?
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try
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{
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out.Open(tempName, wxT("wb"));
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opened = out.IsOpened();
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}
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catch (const XMLFileWriterException&)
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{
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}
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if (!opened)
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{
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wxRemoveFile(tempName);
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return false;
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}
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IdMap mIds;
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IdMapArray mIdStack;
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mIds.clear();
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while (!in.Eof() && !out.Error())
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while ( !in.Eof() )
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{
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short id;
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switch (in.GetC())
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{
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case FT_Push:
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{
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mIdStack.Add(mIds);
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mIds.clear();
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}
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break;
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case FT_Push:
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{
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mIdStack.Add(mIds);
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mIds.clear();
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}
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break;
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case FT_Pop:
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{
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mIds = mIdStack[mIdStack.GetCount() - 1];
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mIdStack.RemoveAt(mIdStack.GetCount() - 1);
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}
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break;
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case FT_Pop:
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{
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mIds = mIdStack[mIdStack.GetCount() - 1];
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mIdStack.RemoveAt(mIdStack.GetCount() - 1);
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}
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break;
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case FT_Name:
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{
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short len;
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case FT_Name:
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{
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short len;
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in.Read(&id, sizeof(id));
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in.Read(&len, sizeof(len));
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WxChars name{ len / sizeof(wxChar) };
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in.Read(name.get(), len);
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in.Read(&id, sizeof(id));
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in.Read(&len, sizeof(len));
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WxChars name{ len / sizeof(wxChar) };
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in.Read(name.get(), len);
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mIds[id] = wxString(name.get(), len / sizeof(wxChar));
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}
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break;
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mIds[id] = wxString(name.get(), len / sizeof(wxChar));
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}
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break;
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case FT_StartTag:
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{
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in.Read(&id, sizeof(id));
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case FT_StartTag:
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{
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in.Read(&id, sizeof(id));
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out.StartTag(mIds[id]);
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}
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break;
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out.StartTag(mIds[id]);
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}
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break;
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case FT_EndTag:
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{
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in.Read(&id, sizeof(id));
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case FT_EndTag:
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{
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in.Read(&id, sizeof(id));
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out.EndTag(mIds[id]);
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}
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break;
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out.EndTag(mIds[id]);
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}
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break;
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case FT_String:
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{
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int len;
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case FT_String:
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{
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int len;
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in.Read(&id, sizeof(id));
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in.Read(&len, sizeof(len));
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WxChars val{ len / sizeof(wxChar) };
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in.Read(val.get(), len);
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in.Read(&id, sizeof(id));
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in.Read(&len, sizeof(len));
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WxChars val{ len / sizeof(wxChar) };
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in.Read(val.get(), len);
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out.WriteAttr(mIds[id], wxString(val.get(), len / sizeof(wxChar)));
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}
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break;
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out.WriteAttr(mIds[id], wxString(val.get(), len / sizeof(wxChar)));
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}
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break;
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case FT_Float:
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{
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float val;
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int dig;
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case FT_Float:
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{
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float val;
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int dig;
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&dig, sizeof(dig));
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&dig, sizeof(dig));
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out.WriteAttr(mIds[id], val, dig);
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}
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break;
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out.WriteAttr(mIds[id], val, dig);
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}
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break;
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case FT_Double:
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{
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double val;
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int dig;
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case FT_Double:
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{
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double val;
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int dig;
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&dig, sizeof(dig));
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&dig, sizeof(dig));
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out.WriteAttr(mIds[id], val, dig);
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}
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break;
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out.WriteAttr(mIds[id], val, dig);
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}
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break;
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case FT_Int:
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{
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int val;
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case FT_Int:
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{
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int val;
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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out.WriteAttr(mIds[id], val);
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}
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break;
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out.WriteAttr(mIds[id], val);
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}
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break;
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case FT_Bool:
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{
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bool val;
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case FT_Bool:
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{
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bool val;
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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out.WriteAttr(mIds[id], val);
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}
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break;
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out.WriteAttr(mIds[id], val);
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}
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break;
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case FT_Long:
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{
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long val;
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case FT_Long:
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{
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long val;
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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out.WriteAttr(mIds[id], val);
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}
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break;
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out.WriteAttr(mIds[id], val);
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}
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break;
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case FT_LongLong:
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{
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long long val;
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case FT_LongLong:
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{
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long long val;
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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out.WriteAttr(mIds[id], val);
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}
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break;
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out.WriteAttr(mIds[id], val);
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}
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break;
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case FT_SizeT:
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{
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size_t val;
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case FT_SizeT:
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{
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size_t val;
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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in.Read(&id, sizeof(id));
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in.Read(&val, sizeof(val));
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out.WriteAttr(mIds[id], val);
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}
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break;
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out.WriteAttr(mIds[id], val);
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}
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break;
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case FT_Data:
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{
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int len;
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case FT_Data:
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{
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int len;
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in.Read(&len, sizeof(len));
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WxChars val{ len / sizeof(wxChar) };
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in.Read(val.get(), len);
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in.Read(&len, sizeof(len));
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WxChars val{ len / sizeof(wxChar) };
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in.Read(val.get(), len);
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out.WriteData(wxString(val.get(), len / sizeof(wxChar)));
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}
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break;
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out.WriteData(wxString(val.get(), len / sizeof(wxChar)));
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}
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break;
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case FT_Raw:
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{
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int len;
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case FT_Raw:
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{
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int len;
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in.Read(&len, sizeof(len));
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WxChars val{ len / sizeof(wxChar) };
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in.Read(val.get(), len);
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in.Read(&len, sizeof(len));
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WxChars val{ len / sizeof(wxChar) };
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in.Read(val.get(), len);
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out.Write(wxString(val.get(), len / sizeof(wxChar)));
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}
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break;
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out.Write(wxString(val.get(), len / sizeof(wxChar)));
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}
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break;
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default:
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wxASSERT(true);
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default:
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wxASSERT(true);
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break;
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}
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}
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}
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bool error = out.Error();
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out.Close();
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out.Commit();
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// Bail if decoding failed.
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if (error)
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{
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// File successfully decoded
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wxRemoveFile(tempName);
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return false;
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}
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// Decoding was successful, so remove the original file and replace with decoded one.
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if (wxRemoveFile(fileName))
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{
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if (!wxRenameFile(tempName, fileName))
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{
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return false;
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}
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}
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return true;
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return true;
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} );
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}
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