nix cat/dump-path/key: stop progress bar before writeFull

These commands outputs data that may not end with a newline. This
causes problems when the progress bar redraws, as that completely
wipes the last line of output. As nix key generate-secret outputs
a single line of text with no output, it shows up entirely blank,
making it look like nothing happened.

Fixes: https://git.lix.systems/lix-project/lix/issues/320
Change-Id: I5ac706d71d839b6dfa760b60a351414cd96297cf

src/nix/cat.cc

@@ -2,6 +2,7 @@
 #include "store-api.hh"
 #include "fs-accessor.hh"
 #include "nar-accessor.hh"
+#include "progress-bar.hh"
 
 using namespace nix;
 
@@ -17,7 +18,10 @@ struct MixCat : virtual Args
         if (st.type != FSAccessor::Type::tRegular)
             throw Error("path '%1%' is not a regular file", path);
 
-        writeFull(STDOUT_FILENO, accessor->readFile(path));
+        auto file = accessor->readFile(path);
+
+        stopProgressBar();
+        writeFull(STDOUT_FILENO, file);
     }
 };
 

src/nix/dump-path.cc

@@ -1,6 +1,7 @@
 #include "command.hh"
 #include "store-api.hh"
 #include "archive.hh"
+#include "progress-bar.hh"
 
 using namespace nix;
 
@@ -20,6 +21,7 @@ struct CmdDumpPath : StorePathCommand
 
     void run(ref<Store> store, const StorePath & storePath) override
     {
+        stopProgressBar();
         FdSink sink(STDOUT_FILENO);
         store->narFromPath(storePath, sink);
         sink.flush();
@@ -55,6 +57,7 @@ struct CmdDumpPath2 : Command
 
     void run() override
     {
+        stopProgressBar();
         FdSink sink(STDOUT_FILENO);
         dumpPath(path, sink);
         sink.flush();

src/nix/sigs.cc

@@ -3,6 +3,7 @@
 #include "store-api.hh"
 #include "thread-pool.hh"
 #include "signals.hh"
+#include "progress-bar.hh"
 
 #include <atomic>
 
@@ -220,6 +221,8 @@ struct CmdKey : NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix key' requires a sub-command.");
+
+        stopProgressBar();
         command->second->run();
     }
 };