2 files changed, 32 insertions, 10 deletions

diff --git a/apt-pkg/install-progress.cc b/apt-pkg/install-progress.cc
index aadd28e51..8a6d87cd2 100644
--- a/apt-pkg/install-progress.cc
+++ b/apt-pkg/install-progress.cc
@@ -222,22 +222,42 @@ PackageManagerFancy::PackageManagerFancy()
    : d(NULL), child_pty(-1)
 {
    // setup terminal size
-   old_SIGWINCH = signal(SIGWINCH, PackageManagerFancy::staticSIGWINCH);
+   if (instances.empty())
+      SIGWINCH_orig = signal(SIGWINCH, PackageManagerFancy::staticSIGWINCH);
    instances.push_back(this);
 }
 std::vector<PackageManagerFancy*> PackageManagerFancy::instances;
+sighandler_t PackageManagerFancy::SIGWINCH_orig;
+volatile sig_atomic_t PackageManagerFancy::SIGWINCH_flag = 0;
 
 PackageManagerFancy::~PackageManagerFancy()
 {
    instances.erase(find(instances.begin(), instances.end(), this));
-   signal(SIGWINCH, old_SIGWINCH);
+   if (instances.empty())
+      signal(SIGWINCH, SIGWINCH_orig);
 }
 
 void PackageManagerFancy::staticSIGWINCH(int signum)
 {
-   std::vector<PackageManagerFancy *>::const_iterator I;
-   for(I = instances.begin(); I != instances.end(); ++I)
-      (*I)->HandleSIGWINCH(signum);
+   SIGWINCH_flag = 1;
+}
+
+void PackageManagerFancy::CheckSIGWINCH()
+{
+   if (SIGWINCH_flag)
+   {
+      SIGWINCH_flag = 0;
+      int errsv = errno;
+      int const nr_terminal_rows = GetTerminalSize().rows;
+      SetupTerminalScrollArea(nr_terminal_rows);
+      DrawStatusLine();
+      errno = errsv;
+   }
+}
+
+void PackageManagerFancy::Pulse()
+{
+   CheckSIGWINCH();
 }
 
 PackageManagerFancy::TermSize
@@ -296,9 +316,7 @@ void PackageManagerFancy::SetupTerminalScrollArea(int nr_rows)
 
 void PackageManagerFancy::HandleSIGWINCH(int)
 {
-   int const nr_terminal_rows = GetTerminalSize().rows;
-   SetupTerminalScrollArea(nr_terminal_rows);
-   DrawStatusLine();
+   // for abi compatibility, do not use
 }
 
 void PackageManagerFancy::Start(int a_child_pty)
diff --git a/apt-pkg/install-progress.h b/apt-pkg/install-progress.h
index 94b66ed9b..617ce2a35 100644
--- a/apt-pkg/install-progress.h
+++ b/apt-pkg/install-progress.h
@@ -126,11 +126,14 @@ namespace Progress {
  private:
     APT_HIDDEN static void staticSIGWINCH(int);
     static std::vector<PackageManagerFancy*> instances;
+    static sighandler_t SIGWINCH_orig;
+    static volatile sig_atomic_t SIGWINCH_flag;
+    APT_HIDDEN void CheckSIGWINCH();
     APT_HIDDEN bool DrawStatusLine();
 
  protected:
     void SetupTerminalScrollArea(int nr_rows);
-    void HandleSIGWINCH(int);
+    void HandleSIGWINCH(int); // for abi compatibility, do not use
 
     typedef struct {
        int rows;
@@ -138,12 +141,13 @@ namespace Progress {
     } TermSize;
     TermSize GetTerminalSize();
 
-    sighandler_t old_SIGWINCH;
+    sighandler_t old_SIGWINCH; // for abi compatibility, do not use
     int child_pty;
 
  public:
     PackageManagerFancy();
     virtual ~PackageManagerFancy();
+    virtual void Pulse() APT_OVERRIDE;
     virtual void Start(int child_pty=-1) APT_OVERRIDE;
     virtual void Stop() APT_OVERRIDE;
     virtual bool StatusChanged(std::string PackageName,