support '-' and no parameter for stdin in apt-helper cat-file

This way it works more similar to the compressor binaries, which we
can relief in this way from their job in the test framework avoiding the
need of adding e.g. liblz4-tool to the test dependencies.

1 files changed, 17 insertions, 3 deletions

diff --git a/cmdline/apt-helper.cc b/cmdline/apt-helper.cc
index 001b5e5f7..b92055ab7 100644
--- a/cmdline/apt-helper.cc
+++ b/cmdline/apt-helper.cc
@@ -145,14 +145,28 @@ static bool DoCatFile(CommandLine &CmdL)				/*{{{*/
    }
 
    if (CmdL.FileSize() <= 1)
-      return _error->Error("Must specify at least one file name");
+   {
+      if (fd.OpenDescriptor(STDIN_FILENO, FileFd::ReadOnly) == false)
+	 return false;
+      if (CopyFile(fd, out) == false)
+         return false;
+      return true;
+   }
 
    for(size_t i = 1; CmdL.FileList[i] != NULL; ++i)
    {
       std::string const name = CmdL.FileList[i];
 
-      if (fd.Open(name, FileFd::ReadOnly, FileFd::Extension) == false)
-         return false;
+      if (name != "-")
+      {
+	 if (fd.Open(name, FileFd::ReadOnly, FileFd::Extension) == false)
+	    return false;
+      }
+      else
+      {
+	 if (fd.OpenDescriptor(STDIN_FILENO, FileFd::ReadOnly) == false)
+	    return false;
+      }
 
       if (CopyFile(fd, out) == false)
          return false;