ftparchive: sort discovered filenames before writing indexes

If 'apt-ftparchive packages /path/to/files/' (or sources) is used the
files to include in the generated index (on stdout) were included in the
order in which they were discovered, which isn't a very stable order
which could lead to indexes changing without actually changing content
causing needless changes in the repository changing hashsums, pdiffs,
rsyncs, downloads, ….

This does not effect apt-ftparchive calls which already have an order
defined via a filelist (like generate) which will still print in the
order given by the filelist.

Note that a similar effect can be achieved by post-processing index
files with apt-sortpkgs.

Closes: 869557
Thanks: Chris Lamb for initial patch & Stefan Lippers-Hollmann for testing

1 files changed, 4 insertions, 1 deletions

diff --git a/ftparchive/writer.h b/ftparchive/writer.h
index b2cef4f00..b7c6435bf 100644
--- a/ftparchive/writer.h
+++ b/ftparchive/writer.h
@@ -19,6 +19,7 @@
 #include <map>
 #include <set>
 #include <string>
+#include <utility>
 #include <vector>
 #include <stdio.h>
 #include <stdlib.h>
@@ -39,6 +40,7 @@ class FTWScanner
 {
    protected:
    vector<string> Patterns;
+   vector<std::pair<string, bool>> FilesToProcess;
    string Arch;
    bool IncludeArchAll;
    const char *OriginalPath;
@@ -49,7 +51,8 @@ class FTWScanner
 
    static FTWScanner *Owner;
    static int ScannerFTW(const char *File,const struct stat *sb,int Flag);
-   static int ScannerFile(const char *File, bool const &ReadLink);
+   static int ScannerFile(const char *const File, bool const ReadLink);
+   static int ProcessFile(const char *const File, bool const ReadLink);
 
    bool Delink(string &FileName,const char *OriginalPath,
 	       unsigned long long &Bytes,unsigned long long const &FileSize);