prevent C++ locale number formatting in text APIs (try 3)

This time it is the formatting of floating numbers in progress
reporting with a radix charater potentially not being dot.

Followup of 7303e11ff28f920a6277c159aa46f80c007350bb. Regression of
b58e2c7c56b1416a343e81f9f80cb1f02c128e25 in so far as it exchanging
very effected with slightly less effected code.

LP: 1611010

apt-pkg/acquire.cc

@@ -1258,8 +1258,11 @@ bool pkgAcquireStatus::Pulse(pkgAcquire *Owner)
 	 snprintf(msg,sizeof(msg), _("Retrieving file %li of %li"), i, TotalItems);
 
       // build the status str
-      std::string dlstatus;
-      strprintf(dlstatus, "dlstatus:%ld:%.4f:%s\n", i, Percent, msg);
+      std::ostringstream str;
+      str.imbue(std::locale("C.UTF-8"));
+      str.precision(4);
+      str << "dlstatus" << ':' << std::fixed << i << ':' << Percent << ':' << msg << '\n';
+      auto const dlstatus = str.str();
       FileFd::Write(fd, dlstatus.data(), dlstatus.size());
    }
 

apt-pkg/install-progress.cc

@@ -78,6 +78,18 @@ void PackageManagerProgressFd::WriteToStatusFd(std::string s)
    FileFd::Write(OutStatusFd, s.c_str(), s.size());   
 }
 
+static std::string GetProgressFdString(char const * const status,
+      char const * const pkg, unsigned long long Done,
+      unsigned long long Total, char const * const msg)
+{
+   float const progress{Done / static_cast<float>(Total) * 100};
+   std::ostringstream str;
+   str.imbue(std::locale("C.UTF-8"));
+   str.precision(4);
+   str << status << ':' << pkg << ':' << std::fixed << progress << ':' << msg << '\n';
+   return str.str();
+}
+
 void PackageManagerProgressFd::StartDpkg()
 {
    if(OutStatusFd <= 0)
@@ -88,10 +100,7 @@ void PackageManagerProgressFd::StartDpkg()
    fcntl(OutStatusFd,F_SETFD,FD_CLOEXEC); 
 
    // send status information that we are about to fork dpkg
-   std::string status;
-   strprintf(status, "pmstatus:dpkg-exec:%.4f:%s\n",
-	 (StepsDone/float(StepsTotal)*100.0), _("Running dpkg"));
-   WriteToStatusFd(std::move(status));
+   WriteToStatusFd(GetProgressFdString("pmstatus", "dpkg-exec", StepsDone, StepsTotal, _("Running dpkg")));
 }
 
 APT_CONST void PackageManagerProgressFd::Stop()
@@ -103,10 +112,8 @@ void PackageManagerProgressFd::Error(std::string PackageName,
                                      unsigned int TotalSteps,
                                      std::string ErrorMessage)
 {
-   std::string status;
-   strprintf(status, "pmerror:%s:%.4f:%s\n", PackageName.c_str(),
-	 (StepsDone/float(TotalSteps)*100.0), ErrorMessage.c_str());
-   WriteToStatusFd(std::move(status));
+   WriteToStatusFd(GetProgressFdString("pmerror", PackageName.c_str(),
+	    StepsDone, TotalSteps, ErrorMessage.c_str()));
 }
 
 void PackageManagerProgressFd::ConffilePrompt(std::string PackageName,
@@ -114,10 +121,8 @@ void PackageManagerProgressFd::ConffilePrompt(std::string PackageName,
                                               unsigned int TotalSteps,
                                               std::string ConfMessage)
 {
-   std::string status;
-   strprintf(status, "pmconffile:%s:%.4f:%s\n", PackageName.c_str(),
-	 (StepsDone/float(TotalSteps)*100.0), ConfMessage.c_str());
-   WriteToStatusFd(std::move(status));
+   WriteToStatusFd(GetProgressFdString("pmconffile", PackageName.c_str(),
+	    StepsDone, TotalSteps, ConfMessage.c_str()));
 }
 
 
@@ -129,11 +134,8 @@ bool PackageManagerProgressFd::StatusChanged(std::string PackageName,
    StepsDone = xStepsDone;
    StepsTotal = xTotalSteps;
 
-   // build the status str
-   std::string status;
-   strprintf(status, "pmstatus:%s:%.4f:%s\n", StringSplit(PackageName, ":")[0].c_str(),
-	 (StepsDone/float(StepsTotal)*100.0), pkg_action.c_str());
-   WriteToStatusFd(std::move(status));
+   WriteToStatusFd(GetProgressFdString("pmstatus", StringSplit(PackageName, ":")[0].c_str(),
+	    StepsDone, StepsTotal, pkg_action.c_str()));
 
    if(_config->FindB("Debug::APT::Progress::PackageManagerFd", false) == true)
       std::cerr << "progress: " << PackageName << " " << xStepsDone
@@ -157,17 +159,29 @@ void PackageManagerProgressDeb822Fd::WriteToStatusFd(std::string s)
    FileFd::Write(OutStatusFd, s.c_str(), s.size());   
 }
 
+static std::string GetProgressDeb822String(char const * const status,
+      char const * const pkg, unsigned long long Done,
+      unsigned long long Total, char const * const msg)
+{
+   float const progress{Done / static_cast<float>(Total) * 100};
+   std::ostringstream str;
+   str.imbue(std::locale("C.UTF-8"));
+   str.precision(4);
+   str << "Status: " << status << '\n';
+   if (pkg != nullptr)
+      str << "Package: " << pkg << '\n';
+   str << "Percent: " << std::fixed << progress << '\n'
+      << "Message: " << msg << "\n\n";
+   return str.str();
+}
+
 void PackageManagerProgressDeb822Fd::StartDpkg()
 {
    // FIXME: use SetCloseExec here once it taught about throwing
    //        exceptions instead of doing _exit(100) on failure
    fcntl(OutStatusFd,F_SETFD,FD_CLOEXEC); 
 
-   // send status information that we are about to fork dpkg
-   std::string status;
-   strprintf(status, "Status: %s\nPercent: %.4f\nMessage: %s\n\n", "progress",
-	 (StepsDone/float(StepsTotal)*100.0), _("Running dpkg"));
-   WriteToStatusFd(std::move(status));
+   WriteToStatusFd(GetProgressDeb822String("progress", nullptr, StepsDone, StepsTotal, _("Running dpkg")));
 }
 
 APT_CONST void PackageManagerProgressDeb822Fd::Stop()
@@ -179,10 +193,7 @@ void PackageManagerProgressDeb822Fd::Error(std::string PackageName,
                                      unsigned int TotalSteps,
                                      std::string ErrorMessage)
 {
-   std::string status;
-   strprintf(status, "Status: %s\nPackage: %s\nPercent: %.4f\nMessage: %s\n\n", "Error",
-	 PackageName.c_str(), (StepsDone/float(TotalSteps)*100.0), ErrorMessage.c_str());
-   WriteToStatusFd(std::move(status));
+   WriteToStatusFd(GetProgressDeb822String("Error", PackageName.c_str(), StepsDone, TotalSteps, ErrorMessage.c_str()));
 }
 
 void PackageManagerProgressDeb822Fd::ConffilePrompt(std::string PackageName,
@@ -190,10 +201,7 @@ void PackageManagerProgressDeb822Fd::ConffilePrompt(std::string PackageName,
                                               unsigned int TotalSteps,
                                               std::string ConfMessage)
 {
-   std::string status;
-   strprintf(status, "Status: %s\nPackage: %s\nPercent: %.4f\nMessage: %s\n\n", "ConfFile",
-	 PackageName.c_str(), (StepsDone/float(TotalSteps)*100.0), ConfMessage.c_str());
-   WriteToStatusFd(std::move(status));
+   WriteToStatusFd(GetProgressDeb822String("ConfFile", PackageName.c_str(), StepsDone, TotalSteps, ConfMessage.c_str()));
 }
 
 
@@ -205,10 +213,7 @@ bool PackageManagerProgressDeb822Fd::StatusChanged(std::string PackageName,
    StepsDone = xStepsDone;
    StepsTotal = xTotalSteps;
 
-   std::string status;
-   strprintf(status, "Status: %s\nPackage: %s\nPercent: %.4f\nMessage: %s\n\n", "progress",
-	 PackageName.c_str(), (StepsDone/float(StepsTotal)*100.0), message.c_str());
-   WriteToStatusFd(std::move(status));
+   WriteToStatusFd(GetProgressDeb822String("progress", PackageName.c_str(), StepsDone, StepsTotal, message.c_str()));
    return true;
 }