Merge pull request #8018 from tweag/ssh-password-prompt

SSH: don't erase password prompt if it is displayed

src/libmain/progress-bar.cc

@@ -72,6 +72,7 @@ private:
         uint64_t corruptedPaths = 0, untrustedPaths = 0;
 
         bool active = true;
+        bool paused = false;
         bool haveUpdate = true;
     };
 
@@ -120,6 +121,18 @@ public:
         updateThread.join();
     }
 
+    void pause() override {
+        state_.lock()->paused = true;
+        writeToStderr("\r\e[K");
+    }
+
+    void resume() override {
+        state_.lock()->paused = false;
+        writeToStderr("\r\e[K");
+        state_.lock()->haveUpdate = true;
+        updateCV.notify_one();
+    }
+
     bool isVerbose() override
     {
         return printBuildLogs;
@@ -339,7 +352,7 @@ public:
         auto nextWakeup = std::chrono::milliseconds::max();
 
         state.haveUpdate = false;
-        if (!state.active) return nextWakeup;
+        if (state.paused || !state.active) return nextWakeup;
 
         std::string line;
 

src/libstore/ssh.cc

@@ -1,4 +1,5 @@
 #include "ssh.hh"
+#include "finally.hh"
 
 namespace nix {
 
@@ -35,6 +36,9 @@ void SSHMaster::addCommonSSHOpts(Strings & args)
     }
     if (compress)
         args.push_back("-C");
+
+    args.push_back("-oPermitLocalCommand=yes");
+    args.push_back("-oLocalCommand=echo started");
 }
 
 std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(const std::string & command)
@@ -49,6 +53,11 @@ std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(const std::string
     ProcessOptions options;
     options.dieWithParent = false;
 
+    if (!fakeSSH && !useMaster) {
+        logger->pause();
+    }
+    Finally cleanup = [&]() { logger->resume(); };
+
     conn->sshPid = startProcess([&]() {
         restoreProcessContext();
 
@@ -86,6 +95,18 @@ std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(const std::string
     in.readSide = -1;
     out.writeSide = -1;
 
+    // Wait for the SSH connection to be established,
+    // So that we don't overwrite the password prompt with our progress bar.
+    if (!fakeSSH && !useMaster) {
+        std::string reply;
+        try {
+            reply = readLine(out.readSide.get());
+        } catch (EndOfFile & e) { }
+
+        if (reply != "started")
+            throw Error("failed to start SSH connection to '%s'", host);
+    }
+
     conn->out = std::move(out.readSide);
     conn->in = std::move(in.writeSide);
 
@@ -109,6 +130,9 @@ Path SSHMaster::startMaster()
     ProcessOptions options;
     options.dieWithParent = false;
 
+    logger->pause();
+    Finally cleanup = [&]() { logger->resume(); };
+
     state->sshMaster = startProcess([&]() {
         restoreProcessContext();
 
@@ -117,11 +141,7 @@ Path SSHMaster::startMaster()
         if (dup2(out.writeSide.get(), STDOUT_FILENO) == -1)
             throw SysError("duping over stdout");
 
-        Strings args =
-            { "ssh", host.c_str(), "-M", "-N", "-S", state->socketPath
-            , "-o", "LocalCommand=echo started"
-            , "-o", "PermitLocalCommand=yes"
-            };
+        Strings args = { "ssh", host.c_str(), "-M", "-N", "-S", state->socketPath };
         if (verbosity >= lvlChatty)
             args.push_back("-v");
         addCommonSSHOpts(args);

src/libutil/logging.hh

@@ -72,6 +72,9 @@ public:
 
     virtual void stop() { };
 
+    virtual void pause() { };
+    virtual void resume() { };
+
     // Whether the logger prints the whole build log
     virtual bool isVerbose() { return false; }