Per a suggestion of JMarc's, first write the saved file to a

temporary name, then move it to its real location if we succeed.
This prevents our over-writing the existing file with a corrupt
one.
(cherry picked from commit 10364082c8351b0f4a258699742370195aadde6b)

diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index ab2164b82b7949d3f68254ea7717d4e95d212517..8fab72d82ac3aef960252e301f263989284dbbad 100644 (file)
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -1276,12 +1276,38 @@ bool Buffer::save() const
        // We don't need autosaves in the immediate future. (Asger)
        resetAutosaveTimers();
 
-       FileName backupName;
-       bool madeBackup = false;
+       // if the file does not yet exist, none of the backup activity
+       // that follows is necessary
+       if (!fileName().exists())
+               return writeFile(fileName());
+
+       // we first write the file to a new name, then move it to its
+       // proper location once that has been done successfully. that
+       // way we preserve the original file if something goes wrong.
+       string const savepath = fileName().onlyPath().absFileName();
+       string savename = "tmp-" + fileName().onlyFileName();
+       FileName savefile(addName(savepath, savename));
+       while (savefile.exists()) {
+               if (savefile.absFileName().size() > 1024) {
+                       Alert::error(_("Write failure"),
+                                    bformat(_("Cannot find temporary filename for:\n  %1$s.\n"
+                                        "Even %2$s exists!"),
+                                            from_utf8(fileName().absFileName()),
+                                from_utf8(savefile.absFileName())));
+                       return false;
+               }
+               savename = "tmp-" + savename;
+               savefile.set(addName(savepath, savename));
+       }
+
+       LYXERR(Debug::FILES, "Saving to " << savefile.absFileName());
+       if (!writeFile(savefile))
+               return false;
 
-       // make a backup if the file already exists
-       if (lyxrc.make_backup && fileName().exists()) {
-               backupName = FileName(absFileName() + '~');
+       // we will set this to false if we fail
+       bool made_backup = true;
+       if (lyxrc.make_backup) {
+               FileName backupName(absFileName() + '~');
                if (!lyxrc.backupdir_path.empty()) {
                        string const mangledName =
                                subst(subst(backupName.absFileName(), '/', '!'), ':', '!');
@@ -1291,12 +1317,11 @@ bool Buffer::save() const
 
                // Except file is symlink do not copy because of #6587.
                // Hard links have bad luck.
-               if (fileName().isSymLink())
-                       madeBackup = fileName().copyTo(backupName);
-               else
-                       madeBackup = fileName().moveTo(backupName);
+               made_backup = fileName().isSymLink() ?
+                       fileName().copyTo(backupName):
+                       fileName().moveTo(backupName);
 
-               if (!madeBackup) {
+               if (!made_backup) {
                        Alert::error(_("Backup failure"),
                                     bformat(_("Cannot create backup file %1$s.\n"
                                               "Please check whether the directory exists and is writable."),
@@ -1304,16 +1329,18 @@ bool Buffer::save() const
                        //LYXERR(Debug::DEBUG, "Fs error: " << fe.what());
                }
        }
-
-       if (writeFile(d->filename)) {
+       
+       if (made_backup && savefile.moveTo(fileName())) {
                markClean();
                return true;
-       } else {
-               // Saving failed, so backup is not backup
-               if (madeBackup)
-                       backupName.moveTo(d->filename);
-               return false;
        }
+       // else
+       Alert::error(_("Write failure"),
+                    bformat(_("Cannot move saved file to:\n  %1$s.\n"
+                              "But the file has successfully been saved as:\n  %2$s."),
+                            from_utf8(fileName().absFileName()),
+                from_utf8(savefile.absFileName())));
+       return false;
 }
 
 

diff --git a/status.21x b/status.21x
index a6a27aaa42346fae2485671c4af1aa0dbfa43cbb..74bb25afa51f0bea7564755ec508e9090c65cde1 100644 (file)
--- a/status.21x
+++ b/status.21x
@@ -28,6 +28,9 @@ What's new
 
 * DOCUMENT INPUT/OUTPUT
 
+- When saving a file, LyX now writes the saved file first to a temporary
+  filename (tmp-oldfile.lyx) and only deletes the original file once the
+  new file has successfully been written. 
 
 
 * TEX2LYX IMPROVEMENTS