json: Hook protocol 0.2 (added upgrade,downgrade,reinstall modes)

Hook protocol 0.2 makes the new fields we added mandatory, and
replaces `install` mode with `upgrade`, `downgrade`, `reinstall`
where appropriate.

Hook negotiation is hacky, but it's the best we can do for now.
Users are advised to upgrade to 0.2

1 files changed, 40 insertions, 9 deletions

diff --git a/apt-private/private-json-hooks.cc b/apt-private/private-json-hooks.cc
index a40597e0a..957140525 100644
--- a/apt-private/private-json-hooks.cc
+++ b/apt-private/private-json-hooks.cc
@@ -17,6 +17,7 @@
 #include <ostream>
 #include <sstream>
 #include <stack>
+#include <unordered_map>
 
 #include <signal.h>
 #include <sys/socket.h>
@@ -265,7 +266,7 @@ static void DpkgChrootDirectory()
 /**
  * @brief Send a notification to the hook's stream
  */
-static void NotifyHook(std::ostream &os, std::string const &method, const char **FileList, CacheFile &Cache, std::set<std::string> const &UnknownPackages)
+static void NotifyHook(std::ostream &os, std::string const &method, const char **FileList, CacheFile &Cache, std::set<std::string> const &UnknownPackages, int hookVersion)
 {
    SortedPackageUniverse Universe(Cache);
    JsonWriter jsonWriter{os};
@@ -311,7 +312,14 @@ static void NotifyHook(std::ostream &os, std::string const &method, const char *
       switch (Cache[Pkg].Mode)
       {
       case pkgDepCache::ModeInstall:
-	 jsonWriter.name("mode").value("install");
+	 if (Pkg->CurrentVer != 0 && Cache[Pkg].Upgrade() && hookVersion >= 0x020)
+	    jsonWriter.name("mode").value("upgrade");
+	 else if (Pkg->CurrentVer != 0 && Cache[Pkg].Downgrade() && hookVersion >= 0x020)
+	    jsonWriter.name("mode").value("downgrade");
+	 else if (Pkg->CurrentVer != 0 && Cache[Pkg].ReInstall() && hookVersion >= 0x020)
+	    jsonWriter.name("mode").value("reinstall");
+	 else
+	    jsonWriter.name("mode").value("install");
 	 break;
       case pkgDepCache::ModeDelete:
 	 jsonWriter.name("mode").value(Cache[Pkg].Purge() ? "purge" : "deinstall");
@@ -344,7 +352,7 @@ static void NotifyHook(std::ostream &os, std::string const &method, const char *
 static std::string BuildHelloMessage()
 {
    std::stringstream Hello;
-   JsonWriter(Hello).beginObject().name("jsonrpc").value("2.0").name("method").value("org.debian.apt.hooks.hello").name("id").value(0).name("params").beginObject().name("versions").beginArray().value("0.1").endArray().endObject().endObject();
+   JsonWriter(Hello).beginObject().name("jsonrpc").value("2.0").name("method").value("org.debian.apt.hooks.hello").name("id").value(0).name("params").beginObject().name("versions").beginArray().value("0.1").value("0.2").endArray().endObject().endObject();
 
    return Hello.str();
 }
@@ -361,11 +369,10 @@ static std::string BuildByeMessage()
 /// @brief Run the Json hook processes in the given option.
 bool RunJsonHook(std::string const &option, std::string const &method, const char **FileList, CacheFile &Cache, std::set<std::string> const &UnknownPackages)
 {
-   std::stringstream ss;
-   NotifyHook(ss, method, FileList, Cache, UnknownPackages);
-   std::string TheData = ss.str();
+   std::unordered_map<int, std::string> notifications;
    std::string HelloData = BuildHelloMessage();
    std::string ByeData = BuildByeMessage();
+   int hookVersion;
 
    bool result = true;
 
@@ -465,6 +472,20 @@ bool RunJsonHook(std::string const &option, std::string const &method, const cha
 	 goto out;
       }
 
+      if (strstr(line, "\"0.1\""))
+      {
+	 hookVersion = 0x010;
+      }
+      else if (strstr(line, "\"0.2\""))
+      {
+	 hookVersion = 0x020;
+      }
+      else
+      {
+	 _error->Error("Unknown hook version in handshake from hook %s: %s", Opts->Value.c_str(), line);
+	 goto out;
+      }
+
       size = getline(&line, &linesize, F);
       if (size < 0)
       {
@@ -476,9 +497,18 @@ bool RunJsonHook(std::string const &option, std::string const &method, const cha
 	 _error->Error("Expected empty line after handshake from %s, received %s", Opts->Value.c_str(), line);
 	 goto out;
       }
-
-      fwrite(TheData.data(), TheData.size(), 1, F);
-      fwrite("\n\n", 2, 1, F);
+      {
+	 std::string &data = notifications[hookVersion];
+	 if (data.empty())
+	 {
+	    std::stringstream ss;
+	    NotifyHook(ss, method, FileList, Cache, UnknownPackages, hookVersion);
+	    ;
+	    data = ss.str();
+	 }
+	 fwrite(data.data(), data.size(), 1, F);
+	 fwrite("\n\n", 2, 1, F);
+      }
 
       fwrite(ByeData.data(), ByeData.size(), 1, F);
       fwrite("\n\n", 2, 1, F);
@@ -490,6 +520,7 @@ bool RunJsonHook(std::string const &option, std::string const &method, const cha
 	 result = _error->Error("Failure running hook %s", Opts->Value.c_str());
 	 break;
       }
+
    }
    signal(SIGINT, old_sigint);
    signal(SIGPIPE, old_sigpipe);